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rec.photo.digital
http://groups.google.com/group/rec.photo.digital?hl=en
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Today's topics:
* Webcam vs DSLR Target Field of View - 10 messages, 4 authors
http://groups.google.com/group/rec.photo.digital/t/d0a7b8fbb27d6247?hl=en
* Canon DSLR Live View - 8 messages, 4 authors
http://groups.google.com/group/rec.photo.digital/t/21ca0cd9457ba13c?hl=en
* Matching Pixel Size and Telephoto - 4 messages, 4 authors
http://groups.google.com/group/rec.photo.digital/t/75c4b5506848d404?hl=en
* DLSR and Pixels - 1 messages, 1 author
http://groups.google.com/group/rec.photo.digital/t/4e110bd229839ce7?hl=en
* Are todays LCD screen any good in bright weather - 1 messages, 1 author
http://groups.google.com/group/rec.photo.digital/t/d70e4ce3863b627f?hl=en
* New Portugese convertible !!!! - 1 messages, 1 author
http://groups.google.com/group/rec.photo.digital/t/82d9d8b041ec3d8c?hl=en
* Great forum! - 1 messages, 1 author
http://groups.google.com/group/rec.photo.digital/t/ac2220a39a1c052b?hl=en
==============================================================================
TOPIC: Webcam vs DSLR Target Field of View
http://groups.google.com/group/rec.photo.digital/t/d0a7b8fbb27d6247?hl=en
==============================================================================
== 1 of 10 ==
Date: Thurs, Apr 23 2009 11:34 pm
From: Hughes
On Apr 24, 1:57 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
> Hughes <eugenhug...@gmail.com> wrote:
> >On Apr 24, 1:28 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
> >> Hughes <eugenhug...@gmail.com> wrote:
> >> >Supposed both of them has pixel pitch of 5 micron. The
> >> >webcam has resolution of 640x480. The DSLR has resolution
> >> >of 10 Megapixel. When taking pictures of target, would both
> >> >cover the same image field of view?
>
> >> Guess what, even with just the DSLR with 10MP you are getting a
> >> different field of view depending upon what lens or what focal length on
> >> a zoom lens you are using.
> >> Now, which of those infinite number of fields of view would you like to
> >> compare to the web cam?
>
> >I have a russian Rubinar 4" Telephoto F/10 with M42
> >screw. But because there is an M42-Canon EOS
> >adaptor. I can use any Canon EOS. I initially planned to get
> >a Canon 1000D. But just found out that one could
>
> What is the focal length of that lens?
>
1,000mm.
> >get a webcam
>
> What is the focal length and the sensor size on that >webcam?
I still haven't bought a webcam that's why I wrote
this thread. I'm thinking whether if I buy a webcam
with 5.7 micron pixel size the same size as the
Canon 1000D pixel, I'd be able to get the central
image of the target with same pixel scale (see
last paragraph of this thread to explain).
>
> >and it can produce the same detail
> >(that is, the central portion of the canon target
> >image). So I was wondering what the rule of thumb
> >in this scenerio. So with my Telephoto above,
> >what field of view can it produce in a Canon 1000D?
>
> What is the focal length of that lens? A 18mm lens obviusly has a very
> different field of view than a 1000mm lens.
>
> >Would a Canon 300D produce other field of view?
>
> The sensor size on both cameras is virtually identical, therefore the
> same lens will have the identical field of view on both cameras.
>
> >What webcam can I use such that it can produce
> >the same image scale like the Canon but only
> >taking the central portion of the image
>
> I have no idea what you mean by this.
Well.. Using the 1000mm telephoto, Imagine the
Canon 1000D taking a shot of your entire house
at a distance and whole house taken. Using a webcam at the same
distance and same 1000mm telephoto, the image taken would be only the
tiny central portion of your
house or only say the door. But with same detail or
pixel scale. Agree?
Hu
>
> jue- Hide quoted text -
>
> - Show quoted text -
== 2 of 10 ==
Date: Fri, Apr 24 2009 12:42 am
From: Hughes
On Apr 24, 2:34 pm, Hughes <eugenhug...@gmail.com> wrote:
> On Apr 24, 1:57 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
>
>
>
>
>
> > Hughes <eugenhug...@gmail.com> wrote:
> > >On Apr 24, 1:28 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
> > >> Hughes <eugenhug...@gmail.com> wrote:
> > >> >Supposed both of them has pixel pitch of 5 micron. The
> > >> >webcam has resolution of 640x480. The DSLR has resolution
> > >> >of 10 Megapixel. When taking pictures of target, would both
> > >> >cover the same image field of view?
>
> > >> Guess what, even with just the DSLR with 10MP you are getting a
> > >> different field of view depending upon what lens or what focal length on
> > >> a zoom lens you are using.
> > >> Now, which of those infinite number of fields of view would you like to
> > >> compare to the web cam?
>
> > >I have a russian Rubinar 4" Telephoto F/10 with M42
> > >screw. But because there is an M42-Canon EOS
> > >adaptor. I can use any Canon EOS. I initially planned to get
> > >a Canon 1000D. But just found out that one could
>
> > What is the focal length of that lens?
>
> 1,000mm.
>
> > >get a webcam
>
> > What is the focal length and the sensor size on that >webcam?
>
> I still haven't bought a webcam that's why I wrote
> this thread. I'm thinking whether if I buy a webcam
> with 5.7 micron pixel size the same size as the
> Canon 1000D pixel, I'd be able to get the central
> image of the target with same pixel scale (see
> last paragraph of this thread to explain).
>
>
>
>
>
>
>
> > >and it can produce the same detail
> > >(that is, the central portion of the canon target
> > >image). So I was wondering what the rule of thumb
> > >in this scenerio. So with my Telephoto above,
> > >what field of view can it produce in a Canon 1000D?
>
> > What is the focal length of that lens? A 18mm lens obviusly has a very
> > different field of view than a 1000mm lens.
>
> > >Would a Canon 300D produce other field of view?
>
> > The sensor size on both cameras is virtually identical, therefore the
> > same lens will have the identical field of view on both cameras.
>
> > >What webcam can I use such that it can produce
> > >the same image scale like the Canon but only
> > >taking the central portion of the image
>
> > I have no idea what you mean by this.
>
> Well.. Using the 1000mm telephoto, Imagine the
> Canon 1000D taking a shot of your entire house
> at a distance and whole house taken. Using a webcam at the same
> distance and same 1000mm telephoto, the image taken would be only the
> tiny central portion of your
> house or only say the door. But with same detail or
> pixel scale. Agree?
>
> Hu
>
>
>
>
>
> > jue- Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
I finally got my old webcam to work, but upon removing
the lens, I can't make it get any images in the
1000mm 4" telephoto. I put it in the 44.5mm flange
distance where the CCD of the Canon 300D/1000D is
supposed to be located. Anyone know why?
The webcam is 640x480 1/4 progressive scan.
Compare it to the Canon 1000D with 3888 x 2592
resolution.
I'm assuming that if the Canon can take picture
of a house (all contained in the picture) with the 1000mm Telephoto,
the webcam with smaller chip can only
take picture of the door.. both having the same pixel
scale (or the pixel containing same detail since
it is lets say both 5 micron).
But before delving into that. How come I can't even let the webcam see
any images in the telephoto? It's just white image, not even any
structure of the house can be seen nor
colors. Any genius know why??
Hughes
== 3 of 10 ==
Date: Fri, Apr 24 2009 12:48 am
From: Hughes
On Apr 24, 3:42 pm, Hughes <eugenhug...@gmail.com> wrote:
> On Apr 24, 2:34 pm, Hughes <eugenhug...@gmail.com> wrote:
>
>
>
>
>
> > On Apr 24, 1:57 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
>
> > > Hughes <eugenhug...@gmail.com> wrote:
> > > >On Apr 24, 1:28 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
> > > >> Hughes <eugenhug...@gmail.com> wrote:
> > > >> >Supposed both of them has pixel pitch of 5 micron. The
> > > >> >webcam has resolution of 640x480. The DSLR has resolution
> > > >> >of 10 Megapixel. When taking pictures of target, would both
> > > >> >cover the same image field of view?
>
> > > >> Guess what, even with just the DSLR with 10MP you are getting a
> > > >> different field of view depending upon what lens or what focal length on
> > > >> a zoom lens you are using.
> > > >> Now, which of those infinite number of fields of view would you like to
> > > >> compare to the web cam?
>
> > > >I have a russian Rubinar 4" Telephoto F/10 with M42
> > > >screw. But because there is an M42-Canon EOS
> > > >adaptor. I can use any Canon EOS. I initially planned to get
> > > >a Canon 1000D. But just found out that one could
>
> > > What is the focal length of that lens?
>
> > 1,000mm.
>
> > > >get a webcam
>
> > > What is the focal length and the sensor size on that >webcam?
>
> > I still haven't bought a webcam that's why I wrote
> > this thread. I'm thinking whether if I buy a webcam
> > with 5.7 micron pixel size the same size as the
> > Canon 1000D pixel, I'd be able to get the central
> > image of the target with same pixel scale (see
> > last paragraph of this thread to explain).
>
> > > >and it can produce the same detail
> > > >(that is, the central portion of the canon target
> > > >image). So I was wondering what the rule of thumb
> > > >in this scenerio. So with my Telephoto above,
> > > >what field of view can it produce in a Canon 1000D?
>
> > > What is the focal length of that lens? A 18mm lens obviusly has a very
> > > different field of view than a 1000mm lens.
>
> > > >Would a Canon 300D produce other field of view?
>
> > > The sensor size on both cameras is virtually identical, therefore the
> > > same lens will have the identical field of view on both cameras.
>
> > > >What webcam can I use such that it can produce
> > > >the same image scale like the Canon but only
> > > >taking the central portion of the image
>
> > > I have no idea what you mean by this.
>
> > Well.. Using the 1000mm telephoto, Imagine the
> > Canon 1000D taking a shot of your entire house
> > at a distance and whole house taken. Using a webcam at the same
> > distance and same 1000mm telephoto, the image taken would be only the
> > tiny central portion of your
> > house or only say the door. But with same detail or
> > pixel scale. Agree?
>
> > Hu
>
> > > jue- Hide quoted text -
>
> > > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -
>
> I finally got my old webcam to work, but upon removing
> the lens, I can't make it get any images in the
> 1000mm 4" telephoto. I put it in the 44.5mm flange
> distance where the CCD of the Canon 300D/1000D is
> supposed to be located. Anyone know why?
>
> The webcam is 640x480 1/4 progressive scan.
Details:
1/4" color progressive CMOS
640×480pixels
Lens Specification
F=2.4,f=4.9mm,View Angle 54
See:
http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
> Compare it to the Canon 1000D with 3888 x 2592
> resolution.
> I'm assuming that if the Canon can take picture
> of a house (all contained in the picture) with the 1000mm Telephoto,
> the webcam with smaller chip can only
> take picture of the door.. both having the same pixel
> scale (or the pixel containing same detail since
> it is lets say both 5 micron).
>
> But before delving into that. How come I can't even let the webcam see
> any images in the telephoto? It's just white image, not even any
> structure of the house can be seen nor
> colors. Any genius know why??
>
> Hughes- Hide quoted text -
>
> - Show quoted text -
== 4 of 10 ==
Date: Fri, Apr 24 2009 1:50 am
From: "David J Taylor"
Hughes wrote:
[]
> Details:
> 1/4" color progressive CMOS
> 640×480pixels
>
> Lens Specification
> F=2.4,f=4.9mm,View Angle 54
>
> See:
> http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
So the lens has an entrance pupil of 2mm when wide open. Are you matching
your telescope to that?
David
== 5 of 10 ==
Date: Fri, Apr 24 2009 2:12 am
From: Hughes
On Apr 24, 4:50 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
part.nor-this.co.uk.invalid> wrote:
> Hughes wrote:
>
> []
>
> > Details:
> > 1/4" color progressive CMOS
> > 640×480pixels
>
> > Lens Specification
> > F=2.4,f=4.9mm,View Angle 54
>
> > See:
> >http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
>
> So the lens has an entrance pupil of 2mm when wide open. Are you matching
> your telescope to that?
>
> David
My 1000mm f/10 telephoto has aperture of 4 inches, so
entrance pupil is 4 inches.
I finally got to focus with my Webcam. I wasn't able
to focus earlier because it was out of focus :)
Now after checking. It is correct that the webcam
can only image a very tiny portion of the target
when using the 1000mm telephoto. Therefore
it is really true that the lens of the webcam is
able to take in the whole scene into the sensor,
while that of telephoto can spread it to larger
sensor.
Now what's left to do is to look for the best webcam
in the world. But first something I noticed. Digicam
has pixel pitch the size of 2 micron while Webcam
has pixel pitch the size of 5 micron. Why is the pixel
pitch of Webcam larger? It's large enough to match
the pixel pitch of DSLR, is this one reason why
astrophotography uses webcam a lot besides the
ease of downloading images.
Now having mentioned that the pixel pitch of webcam
and DSRL is similar in roughly 5 micron. What is
the best webcam in the world in terms of noise
suppression and color saturation that it can be
at least 3/4 to that of DSLR in quality (or 1/2 if
3/4 is not possible??) Anyone?
Hu
== 6 of 10 ==
Date: Fri, Apr 24 2009 2:25 am
From: "David J Taylor"
Hughes wrote:
[]
> Now having mentioned that the pixel pitch of webcam
> and DSRL is similar in roughly 5 micron. What is
> the best webcam in the world in terms of noise
> suppression and color saturation that it can be
> at least 3/4 to that of DSLR in quality (or 1/2 if
> 3/4 is not possible??) Anyone?
>
> Hu
I think you will find that many Webcams are designed simply for
surveillance purposes, and that cost, not quality, is the driving factor.
David
== 7 of 10 ==
Date: Fri, Apr 24 2009 4:04 am
From: ASAAR
On Fri, 24 Apr 2009 16:19:53 +1200, Me wrote:
> That's a really dumb question with an obvious answer. Either you've
> been reading far too much for your mind to digest (but are capable of
> regurgitating parts of it in a semi-coherent manner), or you're a troll.
> I'll give you the benefit of the doubt and suspect that it's just the
> latter, because I really wouldn't want to call you an idiot, as I'm
> usually too polite.
Because he simultaneously demonstrates knowledge, extreme
ignorance and a screwy lack of logic, Hughes can only be out for a
lark, a troll's walk in the park. I mean, instead of talking
pixels, he refers to sensels, yet hasn't a clue about cheap webcam
sensors. It wouldn't surprise me if this wasn't our pathetic
anti-DSLR sock puppet troll, tired of his old persona and trying a
new one on for size.
== 8 of 10 ==
Date: Fri, Apr 24 2009 4:08 am
From: "whisky-dave"
"Hughes" <eugenhughes@gmail.com> wrote in message
news:69e0d238-c260-46b7-ab63-2b88c4675193@l16g2000pra.googlegroups.com...
On Apr 24, 4:50 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
part.nor-this.co.uk.invalid> wrote:
> Hughes wrote:
>
> []
>
> > Details:
> > 1/4" color progressive CMOS
> > 640×480pixels
>
> > Lens Specification
> > F=2.4,f=4.9mm,View Angle 54
>
> > See:
> >http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
>
> So the lens has an entrance pupil of 2mm when wide open. Are you matching
> your telescope to that?
>
> David
}My 1000mm f/10 telephoto has aperture of 4 inches, so
}entrance pupil is 4 inches.
}I finally got to focus with my Webcam. I wasn't able
}to focus earlier because it was out of focus :)
What makes you think a webcam is suitable for this remember that the webcam
has both the sensor and the lens in a single unit they are fixed, they go
together.
}Now after checking. It is correct that the webcam
}can only image a very tiny portion of the target
}when using the 1000mm telephoto. Therefore
}it is really true that the lens of the webcam is
}able to take in the whole scene into the sensor,
}while that of telephoto can spread it to larger
}sensor.
Don;t think so.
What relevance is it that the telephoto spreads over a wider sensor. ?
A cameras lens is designed so that the image produced covers the sensor
of any camera that the lens has been designed for, while the webcam
lens is only designed to cover the sensor in ONE camera the webcam and
nothing else.
}Now what's left to do is to look for the best webcam
}in the world.
I could look for the most expensive motorbike in the wolrd and expect it
to perform the same as a push bike because both have 2 wheels.
Not really a webcam is mostly used for moving images.
You could use a camcorder in the same way.
Why don;t people forget about DLSRs and just get a camcorder......
The optical quality is one reason.
If you want a large optical magnification then why not buy a camcorder
rathern than a DLSR or a webcam.
}But first something I noticed. Digicam
}has pixel pitch the size of 2 micron while Webcam
}has pixel pitch the size of 5 micron. Why is the pixel
}pitch of Webcam larger?
Could it be the webcam has lower resolution.
Most webcams are for 72DPI viewing,
I don;t think any photographic lenses would sell with that spec,
they are expected to resolve at DPI is the 1000s
} It's large enough to match
}the pixel pitch of DSLR, is this one reason why
}astrophotography uses webcam a lot besides the
}ease of downloading images.
where have you got that idea from ?
Webcams might be use as spotting scopes.
I doubt the Hubble space telescope is using a webcam.
Most Astrophotography uses specialist equipment of relatively large focal
lengths
unless they are mapping the sky.
webcams generally have wider fields of view in comparison.
}Now having mentioned that the pixel pitch of webcam
}and DSRL is similar in roughly 5 micron. What is
}the best webcam in the world in terms of noise
}suppression and color saturation that it can be
}at least 3/4 to that of DSLR in quality (or 1/2 if
}3/4 is not possible??) Anyone?
The thing about proper astrophotography regarding noise is the temperature
of the sensor,
they like to keep it to as close to absolute zero as possible which usually
requires
liquid nitrogen or better still liquid helium at around -270C.
== 9 of 10 ==
Date: Fri, Apr 24 2009 4:45 am
From: Hughes
On Apr 24, 7:04 pm, ASAAR <cau...@22.com> wrote:
> On Fri, 24 Apr 2009 16:19:53 +1200, Me wrote:
> > That's a really dumb question with an obvious answer. Either you've
> > been reading far too much for your mind to digest (but are capable of
> > regurgitating parts of it in a semi-coherent manner), or you're a troll.
> > I'll give you the benefit of the doubt and suspect that it's just the
> > latter, because I really wouldn't want to call you an idiot, as I'm
> > usually too polite.
>
> Because he simultaneously demonstrates knowledge, extreme
> ignorance and a screwy lack of logic, Hughes can only be out for a
> lark, a troll's walk in the park. I mean, instead of talking
> pixels, he refers to sensels, yet hasn't a clue about cheap webcam
> sensors. It wouldn't surprise me if this wasn't our pathetic
> anti-DSLR sock puppet troll, tired of his old persona and trying a
> new one on for size.
My experience is mostly analog telescopy or
traditional amateur astronomy where one looks
at saturn, cassini, galaxies, nebulae, planets,
etc. I haven't tried astrophotography as the
actual visual experience is better. Then I learnt
that using digicams, one can image the airy
disc diameter itself or even image the resolving
limit of the scope. This is great because one
can know from the images itself how big
exactly is the range of the airy disc, etc. Now
viewing extended objects, I wonder how it
performs. Then to understand it better, I
want to try terrestrial photography to see
effects of extended object and resolution.
Slowly I go into the world of digital photography
and learning about it each day. No, not a troll.
After gaining crucial knowledge, I'd just leave
the group anytime soon.
Hu
== 10 of 10 ==
Date: Fri, Apr 24 2009 4:49 am
From: Hughes
On Apr 24, 7:08 pm, "whisky-dave" <whisky-d...@final.front.ear> wrote:
> "Hughes" <eugenhug...@gmail.com> wrote in message
>
> news:69e0d238-c260-46b7-ab63-2b88c4675193@l16g2000pra.googlegroups.com...
> On Apr 24, 4:50 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
>
>
>
>
>
> part.nor-this.co.uk.invalid> wrote:
> > Hughes wrote:
>
> > []
>
> > > Details:
> > > 1/4" color progressive CMOS
> > > 640×480pixels
>
> > > Lens Specification
> > > F=2.4,f=4.9mm,View Angle 54
>
> > > See:
> > >http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
>
> > So the lens has an entrance pupil of 2mm when wide open. Are you matching
> > your telescope to that?
>
> > David
> }My 1000mm f/10 telephoto has aperture of 4 inches, so
> }entrance pupil is 4 inches.
> }I finally got to focus with my Webcam. I wasn't able
> }to focus earlier because it was out of focus :)
>
> What makes you think a webcam is suitable for this remember that the webcam
> has both the sensor and the lens in a single unit they are fixed, they go
> together.
>
> }Now after checking. It is correct that the webcam
> }can only image a very tiny portion of the target
> }when using the 1000mm telephoto. Therefore
> }it is really true that the lens of the webcam is
> }able to take in the whole scene into the sensor,
> }while that of telephoto can spread it to larger
> }sensor.
>
> Don;t think so.
> What relevance is it that the telephoto spreads over a wider sensor. ?
> A cameras lens is designed so that the image produced covers the sensor
> of any camera that the lens has been designed for, while the webcam
> lens is only designed to cover the sensor in ONE camera the webcam and
> nothing else.
>
> }Now what's left to do is to look for the best webcam
> }in the world.
>
> I could look for the most expensive motorbike in the wolrd and expect it
> to perform the same as a push bike because both have 2 wheels.
>
> Not really a webcam is mostly used for moving images.
> You could use a camcorder in the same way.
> Why don;t people forget about DLSRs and just get a camcorder......
> The optical quality is one reason.
> If you want a large optical magnification then why not buy a camcorder
> rathern than a DLSR or a webcam.
>
> }But first something I noticed. Digicam
>
> }has pixel pitch the size of 2 micron while Webcam
> }has pixel pitch the size of 5 micron. Why is the pixel
> }pitch of Webcam larger?
>
> Could it be the webcam has lower resolution.
> Most webcams are for 72DPI viewing,
> I don;t think any photographic lenses would sell with that spec,
> they are expected to resolve at DPI is the 1000s
>
> } It's large enough to match
> }the pixel pitch of DSLR, is this one reason why
> }astrophotography uses webcam a lot besides the
> }ease of downloading images.
>
> where have you got that idea from ?
> Webcams might be use as spotting scopes.
> I doubt the Hubble space telescope is using a webcam.
What you haven't consider (and which I just realised
today) is that when you take off the lens of a webcam,
and put the ccd in a big telephoto or even Hubble, the
resolution of it is equal to expensive dedicated CCDs or even DSLR
because the determining factor in getting
the pixel scale in arcsecond is the pixel size. So
if the webcam say has 4 micron and the Hubble
CCD has 4 micron, they would have similar resolution.
Surprise? Well, I was surprised to just learnt it today.
Hu
> Most Astrophotography uses specialist equipment of relatively large focal
> lengths
> unless they are mapping the sky.
> webcams generally have wider fields of view in comparison.
>
> }Now having mentioned that the pixel pitch of webcam
> }and DSRL is similar in roughly 5 micron. What is
> }the best webcam in the world in terms of noise
> }suppression and color saturation that it can be
> }at least 3/4 to that of DSLR in quality (or 1/2 if
> }3/4 is not possible??) Anyone?
>
> The thing about proper astrophotography regarding noise is the temperature
> of the sensor,
> they like to keep it to as close to absolute zero as possible which usually
> requires
> liquid nitrogen or better still liquid helium at around -270C.- Hide quoted text -
>
> - Show quoted text -
==============================================================================
TOPIC: Canon DSLR Live View
http://groups.google.com/group/rec.photo.digital/t/21ca0cd9457ba13c?hl=en
==============================================================================
== 1 of 8 ==
Date: Fri, Apr 24 2009 12:33 am
From: rfischer@sonic.net (Ray Fischer)
nospam <nospam@nospam.invalid> wrote:
> Dudley Hanks
>> >> > Has Sony ever made a product that wasn't proprietary and worked well?
>> >>
>> >> How could a company make anything which wasn't proprietary?
>> >
>> > by using existing standards, not inventing their own like memory stick.
>>
>> The original IBM PC...
>
>that was definitely proprietary.
The manual that came with it included a diagram of the electronics and
a listing of the BIOS. Hardly proprietary since anyone could develop
software/hardware for the machine.
Of course, they were just copying what Apple had done with the Apple II.
--
Ray Fischer
rfischer@sonic.net
== 2 of 8 ==
Date: Fri, Apr 24 2009 3:22 am
From: Chris Malcolm
nospam <nospam@nospam.invalid> wrote:
> In article <75b7baF17oin3U2@mid.individual.net>, Chris Malcolm
> <cam@holyrood.ed.ac.uk> wrote:
>> The slow focussing and lag are a feature of Canon's specific current
>> implementation of live view. There are other way of doing it without
>> those problems, one of which is used in the Sony Alpha live view
>> models which use fast phase detection AF in live view, no difference
>> in speed when using live view.
> except that sony uses an entirely separate sensor for live view which
> means it lacks the advantage of focusing using the imaging sensor
> itself.
As does every DSLR which uses phase detection focussing, which as far
as I know is all of them, although a few also use image sensor
contrast detection in live view. Generally speaking the phase
detection focussing method using dedicated AF sensors is considered to
be a superior method of focussing, which is why Sony went to the
trouble and expense of making it possible to use it in live view.
--
Chris Malcolm
== 3 of 8 ==
Date: Fri, Apr 24 2009 3:28 am
From: Chris Malcolm
Bob Larter <bobbylarter@gmail.com> wrote:
> Chris Malcolm wrote:
>> Mr. Strat <rag@nospam.techline.com> wrote:
>>> In article <230420091126589333%nospam@nospam.invalid>, nospam
>>> <nospam@nospam.invalid> wrote:
>>
>>>> except that sony uses an entirely separate sensor for live view which
>>>> means it lacks the advantage of focusing using the imaging sensor
>>>> itself.
>>
>>> Has Sony ever made a product that wasn't proprietary and worked well?
>>
>> How could a company make anything which wasn't proprietary?
> He's using "proprietary" in the sense it's used within the electronics
> industry, meaning that (for example) it uses special connectors, or is
> gratuitously incompatible with other manufacturers devices.
In which case I can't see the relevance to camera auto focussing
methods, since there's probably more ways that has been implemented
than there are camera manufacturers, no proprietary standards, and no
need for them.
--
Chris Malcolm
== 4 of 8 ==
Date: Fri, Apr 24 2009 4:05 am
From: Shawn Hirn
In article
<49f0277e$0$12577$5a62ac22@per-qv1-newsreader-01.iinet.net.au>,
Doug Jewell <ask@and.maybe.ill.tell.you> wrote:
> Shawn Hirn wrote:
> > In article
> > <49ef8c0a$0$12595$5a62ac22@per-qv1-newsreader-01.iinet.net.au>,
> > Doug Jewell <ask@and.maybe.ill.tell.you> wrote:
> >
> >> Yes. Slightly more useful than a gimmick, but only slightly.
> >> Out of about 10,000 shots I've made with my 450D, I'd say
> >> I've used liveview for no more than 20. A couple of "over
> >> the crowd" shots at a local parade, and a few macro shots.
> >
> > To each his own. I use my 450D in liveview mode a lot. I am very happy
> > with it.
> The slow focussing, lag, and extra battery drain don't
> exactly thrill me. If I wanted those features I use my P&S.
> For what I do most (candid portraits), live-view is
> completely hopeless.
For portraits, who needs Live View anyway? I think its better for things
such as landscape photography, macro, and that sort of thing where you
are shooting inanimate objects and you don't mind the disadvantages that
Live View has. For example, if I shoot a bed of flowers in the ground,
Live View comes in really handy. Ditto for when I put my camera on a
tripod to shoot some scenes at night. In fact, I recently had a photo
published in my employer's newspaper that was shot at night on a tripod
with Live View and I have received numerous compliments on it, including
kudos from my employer's senior staff photographer.
== 5 of 8 ==
Date: Fri, Apr 24 2009 4:09 am
From: Shawn Hirn
In article
<49ef063a$0$12596$5a62ac22@per-qv1-newsreader-01.iinet.net.au>,
"N" <N@onyx.com> wrote:
> "Eugene" <eugenhughes@gmail.com> wrote in message
> news:a61171bc-8d5f-43e5-aae1-8d54f913ad9a@v35g2000pro.googlegroups.com...
> On Apr 22, 7:28 pm, "N" <N...@onyx.com> wrote:
> > "Eugene" <eugenhug...@gmail.com> wrote in message
> >
> > news:6c6c28aa-a852-4739-a050-2b5d2daa24c7@z16g2000prd.googlegroups.com...
> >
> > > Hi,
> >
> > > Canon Live View in the 1000D/XS for example
> > > can give live view in the LCD rather than
> > > optical viewfinder. How come previous Digital
> > > SLR didn't make this feature available?
> >
> > For the same reason that climate control wasn't available on a Model-T
> > Ford.
>
> All predecessors and point&shoot use Live View.
> If what the XS did is simply hold the mirror upward
> while the view is being seen live. Earlier model
> could have use such simple principle like in
> Canon 300D.
That makes no sense. I had a 300D and if you held the shutter open, it
would create an image and lock the shutter and aperture settings while
doing it.
== 6 of 8 ==
Date: Fri, Apr 24 2009 6:20 am
From: nospam
In article <49f16b2c$0$1629$742ec2ed@news.sonic.net>, Ray Fischer
<rfischer@sonic.net> wrote:
> >> The original IBM PC...
> >
> >that was definitely proprietary.
>
> The manual that came with it included a diagram of the electronics and
> a listing of the BIOS. Hardly proprietary since anyone could develop
> software/hardware for the machine.
those who tried got sued. the publishing of the bios listing (which
wasn't included with every machine) was to make cloning legally harder
since ibm could (and did) claim people were illegally copying it.
several were sued, and not until cloners did a clean room reproduction
did the flood of clones begin. plus pc-dos was not exactly the same as
ms-dos.
== 7 of 8 ==
Date: Fri, Apr 24 2009 6:24 am
From: nospam
In article <75di7hF17hj8jU3@mid.individual.net>, Chris Malcolm
<cam@holyrood.ed.ac.uk> wrote:
> >> The slow focussing and lag are a feature of Canon's specific current
> >> implementation of live view. There are other way of doing it without
> >> those problems, one of which is used in the Sony Alpha live view
> >> models which use fast phase detection AF in live view, no difference
> >> in speed when using live view.
>
> > except that sony uses an entirely separate sensor for live view which
> > means it lacks the advantage of focusing using the imaging sensor
> > itself.
>
> As does every DSLR which uses phase detection focussing, which as far
> as I know is all of them, although a few also use image sensor
> contrast detection in live view. Generally speaking the phase
> detection focussing method using dedicated AF sensors is considered to
> be a superior method of focussing, which is why Sony went to the
> trouble and expense of making it possible to use it in live view.
phase detection is faster but not always perfect. contrast detection
is slower but guaranteed 100% accurate if it uses the imaging sensor,
which sony *doesn't* do. there is no way to guarantee focus with
sony's live view, whereas on sony/canon there is.
== 8 of 8 ==
Date: Fri, Apr 24 2009 6:38 am
From: nospam
In article <240420090924519350%nospam@nospam.invalid>, nospam
<nospam@nospam.invalid> wrote:
> In article <75di7hF17hj8jU3@mid.individual.net>, Chris Malcolm
> <cam@holyrood.ed.ac.uk> wrote:
>
> > >> The slow focussing and lag are a feature of Canon's specific current
> > >> implementation of live view. There are other way of doing it without
> > >> those problems, one of which is used in the Sony Alpha live view
> > >> models which use fast phase detection AF in live view, no difference
> > >> in speed when using live view.
> >
> > > except that sony uses an entirely separate sensor for live view which
> > > means it lacks the advantage of focusing using the imaging sensor
> > > itself.
> >
> > As does every DSLR which uses phase detection focussing, which as far
> > as I know is all of them, although a few also use image sensor
> > contrast detection in live view. Generally speaking the phase
> > detection focussing method using dedicated AF sensors is considered to
> > be a superior method of focussing, which is why Sony went to the
> > trouble and expense of making it possible to use it in live view.
>
> phase detection is faster but not always perfect. contrast detection
> is slower but guaranteed 100% accurate if it uses the imaging sensor,
> which sony *doesn't* do. there is no way to guarantee focus with
> sony's live view, whereas on sony/canon there is.
eh, nikon/canon, that is. olympus 4/3rds too for that matter. the
panasonic g1's contrast detect focus is fairly fast too.
==============================================================================
TOPIC: Matching Pixel Size and Telephoto
http://groups.google.com/group/rec.photo.digital/t/75c4b5506848d404?hl=en
==============================================================================
== 1 of 4 ==
Date: Fri, Apr 24 2009 1:02 am
From: Chris H
In message <b966847a-ba11-4f38-80ce-7425bdc2e827@y34g2000prb.googlegroup
s.com>, Hughes <eugenhughes@gmail.com> writes
>
>I won't be using it on astrophotography. I'd use it only
>terrestrially to image flowers, bees, trees, etc.
Then you are very much over complicating things I think.
--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
== 2 of 4 ==
Date: Fri, Apr 24 2009 1:22 am
From: Martin Brown <|||newspam|||@nezumi.demon.co.uk>
Me wrote:
> Hughes wrote:
>> On Apr 23, 11:41 pm, Martin Brown <|||newspam...@nezumi.demon.co.uk>
>> wrote:
>>> Me wrote:
>>>> Hughes wrote:
>>>>> First resolving power is not the same as airy
>>>>> disc size. Resolving power is smaller. For example,
>>>>> in my 4" aperture f/10 telephoto. Resolving power
>>>>> is 1.16 arcsecond while the airy disc is 2.68
>>>>> arcsecond. Now should my pixel be based
>>>>> on resolving power or airy disc size?
>>> If you expect to be routinely trying to photograph and separate equal
>>> brightness double stars at the diffraction limit then you would need 3
>>> pixels in the 1.16" arc to match the ultimate resolution and see the dip
>>
>> How about if I want to see the most details in
>> the flowers or bees. Should I also use 3 pixels in
>> the 1.16" arc???
You probably do not want to be using a 1000mm mirror lens for this.
Something between 100-200mm with a dedicated macro mode would be more
appropriate.
Chances are your lens and photographic technique are nowhere near good
enough to get close to even the 2.6" arc criterion with an f10 mirror
lens. Depth of field issues will drive you nuts.
>>
> No - you should "oversample" and use as many pixels as possible, but
> balance overall sensor efficiency against pixel density. As I've said
Oversampling by more than a factor of 2 has no benefits at all, and
could be deleterious in the event that signal to noise is compromised by
the smaller sensor areas with more silicon lost to the gaps between
cells. Astronomers tend to think about this a lot more and there are
plenty of FAQs the OP could read. The thing he needs to remember about
camera lenses is that they are only close to diffraction limited at
around f8 or slower.
The trend towards ever more insane pixel numbers has run its course.
There are already P&S cameras with 12Mpixel sensors and lenses that
cannot provide the required detail to use them.
At least with DSLRs you can buy top grade lenses that can use all the
available pixels to store real image data.
> elsewhere, the dslr manufacturers have consistently increased overall
> sensor performance despite increasing pixel density. Buy something that
> they currently make - they know what they're doing, even if there's a
> lot of "puffery" involved in marketing dslrs with ever increasing
> megapixel counts.
That is still good advice.
Although I would look very carefully at the astroimaging reviews if use
for deep sky astrophotography is also intended. Not all digital cameras
have long exposure friendly electronics. The ones with warm corners
suffer extra dark current there and in some cases weak IR emission from
the readout electronics.
> The final objective for a terrestrial photograph is for a print of a
> certain size, or an image file to be displayed at a certain size on
> screen. Even if "pixel level" sharpness is reduced at higher pixel
> densities, after resampling to final display size, the result should be
> better. At low pixel densities, there will be a limit to the maximum
> size that the image (or a crop from it) can be displayed without
> pixelisation (and stair stepping/ aliasing) being visible to the naked
> eye. There's no point where increasing pixel size (thus reducing pixel
> count) fails to deliver better signal to noise ratio based on "shot
> noise", so that fact leads to an inevitable but totally absurd
> conclusion that a "one pixel" sensor must be best.
No it doesn't lead to that conclusion at all. It leads to the conclusion
that one pixel for each idependently sampled point across the image is
the optimum in terms of minimum file size against maximum information
content. And you can derive this specification from the theory of
optics. Once you go beyond that sampling theorem limit you are not
gaining any new knowledge by increasing the number of pixels.
But as I said before a practical sweet spot is about 1.5x the
theoretical limit which allows some linear dependence in adjacent
pixels. Some cameras have internal anti-alias screens on the CCD.
A circular aperture cannot measure frequency content in the image finer
than the diffraction limit of 1.22 lambda/D. Anything at higher
frequency will be lost and/or aliased into the measured band.
Some oversampling upto about 1.5x is good because it helps make the
adjacent pixels linearly related and so smooths the edges of sharp
transitions rather than a jagged staircase effect if undersampled.
Thus the counter
> argument, that there's something to be gained by increasing pixel
> density (so long as overall quantum efficiency is maintained) appears to
> be the correct one. (the only other possibility is that we're currently
> at the perfect pixel pitch, and because pixel pitch has decreased over
> time, you can happily eliminate that unlikely argument from consideration).
The only reason there is an advantage to increasing the pixel density is
that marketting men can say "Hey buy our new N+1 *mega* pixel camera".
Regards,
Martin Brown
== 3 of 4 ==
Date: Fri, Apr 24 2009 2:23 am
From: Hughes
On Apr 24, 4:22 pm, Martin Brown <|||newspam...@nezumi.demon.co.uk>
wrote:
> Me wrote:
> > Hughes wrote:
> >> On Apr 23, 11:41 pm, Martin Brown <|||newspam...@nezumi.demon.co.uk>
> >> wrote:
> >>> Me wrote:
> >>>> Hughes wrote:
> >>>>> First resolving power is not the same as airy
> >>>>> disc size. Resolving power is smaller. For example,
> >>>>> in my 4" aperture f/10 telephoto. Resolving power
> >>>>> is 1.16 arcsecond while the airy disc is 2.68
> >>>>> arcsecond. Now should my pixel be based
> >>>>> on resolving power or airy disc size?
> >>> If you expect to be routinely trying to photograph and separate equal
> >>> brightness double stars at the diffraction limit then you would need 3
> >>> pixels in the 1.16" arc to match the ultimate resolution and see the dip
>
> >> How about if I want to see the most details in
> >> the flowers or bees. Should I also use 3 pixels in
> >> the 1.16" arc???
>
> You probably do not want to be using a 1000mm mirror lens for this.
> Something between 100-200mm with a dedicated macro mode would be more
> appropriate.
Well. I'm just studying the theoretical principles involved
and want to know what is the case. Also you can assume
a situation where macro is not good like imaging the
face of a cobra in a zoo. So you think that in terrestrial
imaging using telescopes and CCDs, it is still correct
to use 2 pixels for the resolving power or resolution
in arcsecond of the scope (even if we are not imaging double stars)? I
just want to hear a Yes to confirm my
understanding that the 2 pixels per resolving arcsecond
is a rule for both the sky and terrestrial targets.
>
> Chances are your lens and photographic technique are nowhere near good
> enough to get close to even the 2.6" arc criterion with an f10 mirror
> lens. Depth of field issues will drive you nuts.
I know. It's just to understand optics. What do you mean
depth of field issues can drive one nuts. At f/10,
depth of field is big so you don't have to worry about
focusing.
>
>
> > No - you should "oversample" and use as many pixels as possible, but
> > balance overall sensor efficiency against pixel density. As I've said
>
> Oversampling by more than a factor of 2 has no benefits at all, and
> could be deleterious in the event that signal to noise is compromised by
He meant by more than 2 pixels is the airy disc which
can even have 5 pixels while only 2 pixels is optimum
for the resolving power or resolution in arcsecond.
> the smaller sensor areas with more silicon lost to the gaps between
> cells. Astronomers tend to think about this a lot more and there are
> plenty of FAQs the OP could read. The thing he needs to remember about
> camera lenses is that they are only close to diffraction limited at
> around f8 or slower.
>
> The trend towards ever more insane pixel numbers has run its course.
> There are already P&S cameras with 12Mpixel sensors and lenses that
> cannot provide the required detail to use them.
>
> At least with DSLRs you can buy top grade lenses that can use all the
> available pixels to store real image data.
>
> > elsewhere, the dslr manufacturers have consistently increased overall
> > sensor performance despite increasing pixel density. Buy something that
> > they currently make - they know what they're doing, even if there's a
> > lot of "puffery" involved in marketing dslrs with ever increasing
> > megapixel counts.
>
> That is still good advice.
>
> Although I would look very carefully at the astroimaging reviews if use
> for deep sky astrophotography is also intended. Not all digital cameras
> have long exposure friendly electronics. The ones with warm corners
> suffer extra dark current there and in some cases weak IR emission from
> the readout electronics.
>
> > The final objective for a terrestrial photograph is for a print of a
> > certain size, or an image file to be displayed at a certain size on
> > screen. Even if "pixel level" sharpness is reduced at higher pixel
> > densities, after resampling to final display size, the result should be
> > better. At low pixel densities, there will be a limit to the maximum
> > size that the image (or a crop from it) can be displayed without
> > pixelisation (and stair stepping/ aliasing) being visible to the naked
> > eye. There's no point where increasing pixel size (thus reducing pixel
> > count) fails to deliver better signal to noise ratio based on "shot
> > noise", so that fact leads to an inevitable but totally absurd
> > conclusion that a "one pixel" sensor must be best.
>
> No it doesn't lead to that conclusion at all. It leads to the conclusion
> that one pixel for each idependently sampled point across the image is
> the optimum in terms of minimum file size against maximum information
> content. And you can derive this specification from the theory of
> optics. Once you go beyond that sampling theorem limit you are not
> gaining any new knowledge by increasing the number of pixels.
>
> But as I said before a practical sweet spot is about 1.5x the
> theoretical limit which allows some linear dependence in adjacent
> pixels. Some cameras have internal anti-alias screens on the CCD.
>
> A circular aperture cannot measure frequency content in the image finer
> than the diffraction limit of 1.22 lambda/D. Anything at higher
> frequency will be lost and/or aliased into the measured band.
>
> Some oversampling upto about 1.5x is good because it helps make the
> adjacent pixels linearly related and so smooths the edges of sharp
> transitions rather than a jagged staircase effect if undersampled.
>
> Thus the counter
>
> > argument, that there's something to be gained by increasing pixel
> > density (so long as overall quantum efficiency is maintained) appears to
> > be the correct one. (the only other possibility is that we're currently
> > at the perfect pixel pitch, and because pixel pitch has decreased over
> > time, you can happily eliminate that unlikely argument from consideration).
>
> The only reason there is an advantage to increasing the pixel density is
> that marketting men can say "Hey buy our new N+1 *mega* pixel camera".
>
> Regards,
> Martin Brown- Hide quoted text -
>
> - Show quoted text -
What do you think is the best Webcam in the world
about 5 micron pixel that can be at least 1/2, 3/4
as good as a DSLR like a canon 1000d?? I'm only
after the pixel scale and not field of view (noting
that a webcam and dlsr with similar 5 micron
pixel would have the same pixel scale or resolution
in the target).
Also I saw many astrophotographers using Webcam
when they can use just a cheap dslr like 1000d.
Maybe there is some situation that webcam can
even produce better colors than the dslr??
Hu
== 4 of 4 ==
Date: Fri, Apr 24 2009 3:20 am
From: Me
Martin Brown wrote:
> Me wrote:
>> Hughes wrote:
>>> On Apr 23, 11:41 pm, Martin Brown <|||newspam...@nezumi.demon.co.uk>
>>> wrote:
>>>> Me wrote:
>>>>> Hughes wrote:
>>>>>> First resolving power is not the same as airy
>>>>>> disc size. Resolving power is smaller. For example,
>>>>>> in my 4" aperture f/10 telephoto. Resolving power
>>>>>> is 1.16 arcsecond while the airy disc is 2.68
>>>>>> arcsecond. Now should my pixel be based
>>>>>> on resolving power or airy disc size?
>
>>>> If you expect to be routinely trying to photograph and separate equal
>>>> brightness double stars at the diffraction limit then you would need 3
>>>> pixels in the 1.16" arc to match the ultimate resolution and see the
>>>> dip
>>>
>>> How about if I want to see the most details in
>>> the flowers or bees. Should I also use 3 pixels in
>>> the 1.16" arc???
>
> You probably do not want to be using a 1000mm mirror lens for this.
> Something between 100-200mm with a dedicated macro mode would be more
> appropriate.
>
> Chances are your lens and photographic technique are nowhere near good
> enough to get close to even the 2.6" arc criterion with an f10 mirror
> lens. Depth of field issues will drive you nuts.
>>>
>> No - you should "oversample" and use as many pixels as possible, but
>> balance overall sensor efficiency against pixel density. As I've said
>
> Oversampling by more than a factor of 2 has no benefits at all, and
> could be deleterious in the event that signal to noise is compromised by
> the smaller sensor areas with more silicon lost to the gaps between
> cells. Astronomers tend to think about this a lot more and there are
> plenty of FAQs the OP could read. The thing he needs to remember about
> camera lenses is that they are only close to diffraction limited at
> around f8 or slower.
>
At dslr pixel density, the gap between photosites isn't so significant,
as microlenses re-focus light back to the photodiode. At very high
pixel densities (P&S cameras etc) backlit sensors are coming.
> The trend towards ever more insane pixel numbers has run its course.
> There are already P&S cameras with 12Mpixel sensors and lenses that
> cannot provide the required detail to use them.
>
> At least with DSLRs you can buy top grade lenses that can use all the
> available pixels to store real image data.
>
>> elsewhere, the dslr manufacturers have consistently increased overall
>> sensor performance despite increasing pixel density. Buy something
>> that they currently make - they know what they're doing, even if
>> there's a lot of "puffery" involved in marketing dslrs with ever
>> increasing megapixel counts.
>
> That is still good advice.
>
> Although I would look very carefully at the astroimaging reviews if use
> for deep sky astrophotography is also intended. Not all digital cameras
> have long exposure friendly electronics. The ones with warm corners
> suffer extra dark current there and in some cases weak IR emission from
> the readout electronics.
>
>> The final objective for a terrestrial photograph is for a print of a
>> certain size, or an image file to be displayed at a certain size on
>> screen. Even if "pixel level" sharpness is reduced at higher pixel
>> densities, after resampling to final display size, the result should
>> be better. At low pixel densities, there will be a limit to the
>> maximum size that the image (or a crop from it) can be displayed
>> without pixelisation (and stair stepping/ aliasing) being visible to
>> the naked eye. There's no point where increasing pixel size (thus
>> reducing pixel count) fails to deliver better signal to noise ratio
>> based on "shot noise", so that fact leads to an inevitable but totally
>> absurd conclusion that a "one pixel" sensor must be best.
>
> No it doesn't lead to that conclusion at all. It leads to the conclusion
> that one pixel for each idependently sampled point across the image is
> the optimum in terms of minimum file size against maximum information
> content. And you can derive this specification from the theory of
> optics. Once you go beyond that sampling theorem limit you are not
> gaining any new knowledge by increasing the number of pixels.
>
Conversely "each individually sampled point" doesn't really exist in
terrestrial photography, as (within limits), the closer you look at a
scene, the more you'll see. That might be different for
astrophotography, where sample points are effectively finite (because I
guess that even though faint stars exist between the stars you intend to
image, the signal is below the threshold where you can detect them over
noise, so then they're effectively ignored?). So (forgetting optical
capabilities, diffraction etc) you're limited by availability of
sufficient signal, which may not be the case for terrestrial photography
back on planet earth.
Sorry if that sounds dumb - but astrophotography is foreign to me.
>
> But as I said before a practical sweet spot is about 1.5x the
> theoretical limit which allows some linear dependence in adjacent
> pixels. Some cameras have internal anti-alias screens on the CCD.
>
> A circular aperture cannot measure frequency content in the image finer
> than the diffraction limit of 1.22 lambda/D. Anything at higher
> frequency will be lost and/or aliased into the measured band.
>
> Some oversampling upto about 1.5x is good because it helps make the
> adjacent pixels linearly related and so smooths the edges of sharp
> transitions rather than a jagged staircase effect if undersampled.
>
> Thus the counter
>> argument, that there's something to be gained by increasing pixel
>> density (so long as overall quantum efficiency is maintained) appears
>> to be the correct one. (the only other possibility is that we're
>> currently at the perfect pixel pitch, and because pixel pitch has
>> decreased over time, you can happily eliminate that unlikely argument
>> from consideration).
>
> The only reason there is an advantage to increasing the pixel density is
> that marketting men can say "Hey buy our new N+1 *mega* pixel camera".
>
Many people expect way too much in increased "resolution" than they will
ever get from a few more pixels. Here's a reasonable comparison between
12mp on APS-c format, and 24mp on 35mp format:
http://www.astroweb.no/a900/a700-vs-a900.html
With the conclusion that there's really not very much difference, even
between about a theoretical ~40% increase in linear resolution (OTOH I
understand that about 25% increase is about the minimum of what can be
seen clearly by the naked eye as a difference, unless you're looking at
images taken of converging lines etc designed to highlight resolution
differences. So just a little bit above the minimum that can be seen
seems to correlate nicely with what the writer of the article above
observed.) It also correlates exactly with tests I did with a 6mp and a
12mp dslr.
Now proponents for the extra pixels and larger format would say that
it's worth it because of the small incremental gain. But another way of
looking at it (yes - perhaps a cheapskates viewpoint - because larger
formats cost much more as a system) is to say that if 12mp truly isn't
enough, then it's fairly unlikely that 24mp will be enough either.
> Regards,
> Martin Brown
==============================================================================
TOPIC: DLSR and Pixels
http://groups.google.com/group/rec.photo.digital/t/4e110bd229839ce7?hl=en
==============================================================================
== 1 of 1 ==
Date: Fri, Apr 24 2009 3:12 am
From: Chris Malcolm
Don Stauffer <stauffer@usfamily.net> wrote:
> Eugene wrote:
>>
>> DLSR is supposed to be good because the pixel
>> is bigger. In the Canon 300D. The pixel size is
>> 7.4 micron, 6+ megapixels. Now with the Canon 1000D,
>> pixel size is 5.7 micron, 10+megapixel. Both has
>> the same CCD size of 22.5 x 15mm. Notice the pixel
>> size has gone smaller. Wouldn't this defeat the purpose
>> of DSLR (Bigger Pixel Rocks)? Has anyone compared
>> the quality of the 300D vs 1000D? Which is cleaner?
>> Using the same 22.5 x 15mm grid, how small can
>> the pixel get (or how large can the megapixels be,
>> as they are inversely proportional) before noise would become bad
>> enough that it won't be far from
>> point&shoot CCDs?
> The DSLR has a number of advantages over other types of cameras. I have
> never considered pixel size one of them. One can use ANY focal plane in
> a DSLR, in a compact, a rangefinder, or any other type of camera.
> To me the big advantages of an SLR are easily interchangable lenses, and
> the ability to see the actual optical focus when using manual focus.
> Also, for macro work there is no parallax error.
> I do not consider electronic viewfinders acceptable until the display
> has as many pixels as the primary sensor.
Why do you want it be so much better than an optical viewfinder, and
so much better than you can see?
--
Chris Malcolm
==============================================================================
TOPIC: Are todays LCD screen any good in bright weather
http://groups.google.com/group/rec.photo.digital/t/d70e4ce3863b627f?hl=en
==============================================================================
== 1 of 1 ==
Date: Fri, Apr 24 2009 3:34 am
From: Chris Malcolm
Mike S. <retsuhcs@xinap.moc> wrote:
> In article <8XUHl.18007$OO7.943@text.news.virginmedia.com>,
> David J Taylor <david-taylor@blueyonder.not-this-part.nor-this.co.uk.invalid> wrote:
>>Charles wrote:
>>[]
>>> LCDs are terrible in outside bright light.
>>
>>You haven't seen a transreflective LCD, have you?
> I'm not the OP, but your point is a good one.
> I have seen a transflective screen. I see it every day on my Nokia cell
> phone, and every time I drive, on my Garmin GPS unit. Both of them are
> equally readable (but not necessarily true to color) in the dark as well
> as bright, direct sunlight.
> Why the hell can't camera makers get with the program?
I suspect it's the current impossibility of getting reasonably good
colours and contrasts over the transmissive/reflective transition
which bothers them. The LCD would stop being a reasonably accurate
impression of the final image and could mislead people.
--
Chris Malcolm
==============================================================================
TOPIC: New Portugese convertible !!!!
http://groups.google.com/group/rec.photo.digital/t/82d9d8b041ec3d8c?hl=en
==============================================================================
== 1 of 1 ==
Date: Fri, Apr 24 2009 3:42 am
From: Bruce
ASAAR <caught@22.com> wrote:
>On Thu, 23 Apr 2009 11:53:45 +0100, Bruce wrote:
>
>>>> I couldn't find "dono" in the dictionary so I gave up reading after
>>>> that. ;-)
>>>
>>> A freaking lie on the face of it.
>>>
>>> Buh bye.
>>
>>
>> I couldn't find "Buh" in the dictionary so I gave up reading
>> after that. ;-)
>
> Did you just try
>
> For an r.p.d. lie?
>
> The court's sympathetic.
>
> Its verdict - a bye.
Just a bye? Without a Buh?
==============================================================================
TOPIC: Great forum!
http://groups.google.com/group/rec.photo.digital/t/ac2220a39a1c052b?hl=en
==============================================================================
== 1 of 1 ==
Date: Fri, Apr 24 2009 4:33 am
From: "Focus"
"Paul Bartram" <paul.bartram AT OR NEAR lizzy.com.au> wrote in message
news:49effb50$0$14218$c30e37c6@pit-reader.telstra.net...
>
>> "^Tems^" <stevebrooks13@live.com> wrote:
>
>> A great forum with 7 posts with all but one of these made by Paul Bertram
>
> Wow, nearly had a seizure there. Had to go look to make sure I hadn't had
> my identity stolen, but the surname is spelt differently!
>
> Paul
Funny: he counts the posts, but reverses my name. And you too.
---
Bertram Paul
http://atlantic-diesel.com
Digital Photography Forum
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| ||||||
| Kind of a wild one from me today. I used a couple of MuRa's Seamless effects on that pattern. I think they were Shift at Random and Shift at Wave. Used a feathery tube to create some other layers of pattern and played with blend mode Used the colorized pattern for the frame and background. And now I'm out of here to get ready to head out of town for the afternoon. Hugs from Roni | ||||||
|
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