Photoshop How To Use: rec.photo.digital - 21 new messages in 5 topics

rec.photo.digital
http://groups.google.com/group/rec.photo.digital?hl=en

rec.photo.digital@googlegroups.com

Today's topics:

* Canon DSLR Live View - 7 messages, 4 authors
http://groups.google.com/group/rec.photo.digital/t/21ca0cd9457ba13c?hl=en
* Webcam vs DSLR Target Field of View - 9 messages, 4 authors
http://groups.google.com/group/rec.photo.digital/t/d0a7b8fbb27d6247?hl=en
* Corrupt Elites Plan Dispossession of American Citizens - 2 messages, 1
author
http://groups.google.com/group/rec.photo.digital/t/c79005183ee0b90d?hl=en
* Matching Pixel Size and Telephoto - 1 messages, 1 author
http://groups.google.com/group/rec.photo.digital/t/75c4b5506848d404?hl=en
* B&W photography - 2 messages, 2 authors
http://groups.google.com/group/rec.photo.digital/t/2d29e1d10678cd2d?hl=en

==============================================================================
TOPIC: Canon DSLR Live View
http://groups.google.com/group/rec.photo.digital/t/21ca0cd9457ba13c?hl=en
==============================================================================

== 1 of 7 ==
Date: Thurs, Apr 23 2009 8:05 pm
From: Chris Malcolm

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?

--
Chris Malcolm

== 2 of 7 ==
Date: Thurs, Apr 23 2009 9:13 pm
From: nospam

In article <75cojsF177nddU1@mid.individual.net>, Chris Malcolm
<cam@holyrood.ed.ac.uk> wrote:

> > 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.

== 3 of 7 ==
Date: Thurs, Apr 23 2009 9:29 pm
From: "Dudley Hanks"

"nospam" <nospam@nospam.invalid> wrote in message
news:240420090013067430%nospam@nospam.invalid...
> In article <75cojsF177nddU1@mid.individual.net>, Chris Malcolm
> <cam@holyrood.ed.ac.uk> wrote:
>
>> > 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...
Take Care,
Dudley

== 4 of 7 ==
Date: Thurs, Apr 23 2009 9:41 pm
From: nospam

In article <XebIl.23871$Db2.8683@edtnps83>, Dudley Hanks
<dhanks@blind-apertures.ca> wrote:

> >> > 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.

== 5 of 7 ==
Date: Thurs, Apr 23 2009 10:36 pm
From: "Dudley Hanks"

"nospam" <nospam@nospam.invalid> wrote in message
news:240420090041028005%nospam@nospam.invalid...
> In article <XebIl.23871$Db2.8683@edtnps83>, Dudley Hanks
> <dhanks@blind-apertures.ca> wrote:
>
>> >> > 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 XT an AT were a bit of a strange case:

" They [IBM] also decided on an open architecture , so that other
manufacturers could produce and sell peripheral components and compatible
software without purchasing licenses."

http://en.wikipedia.org/wiki/IBM_PC

Take Care,
Dudley

== 6 of 7 ==
Date: Thurs, Apr 23 2009 11:05 pm
From: Bob Larter

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.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

== 7 of 7 ==
Date: Thurs, Apr 23 2009 11:10 pm
From: Bob Larter

nospam wrote:
> In article <XebIl.23871$Db2.8683@edtnps83>, Dudley Hanks
> <dhanks@blind-apertures.ca> wrote:
>
>>>>> 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.

Well, there weren't any PC standards back then. OTOH, they did publish
the spec's for their bus, which became an industry standard.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

==============================================================================
TOPIC: Webcam vs DSLR Target Field of View
http://groups.google.com/group/rec.photo.digital/t/d0a7b8fbb27d6247?hl=en
==============================================================================

== 1 of 9 ==
Date: Thurs, Apr 23 2009 8:56 pm
From: Hughes

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? But then, can't you
consider the webcam sensor as located in the center portion
(smaller region) of the DSLR sensor chip, hence the webcam
is supposed to image only the central portion of the image
with all the sides black out? Or is it because the lens of
the webcam is able to take all field of view and converge
it to the center?

Or another way to look at it. Supposed you use a 640x480
webcam and put it in the image plane of the Canon 300 F/2.8
EF. Would the image you see the tiny portion of the center
of the target only or would you see the whole image???

== 2 of 9 ==
Date: Thurs, Apr 23 2009 9:19 pm
From: Me

Hughes 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? But then, can't you
> consider the webcam sensor as located in the center portion
> (smaller region) of the DSLR sensor chip, hence the webcam
> is supposed to image only the central portion of the image
> with all the sides black out? Or is it because the lens of
> the webcam is able to take all field of view and converge
> it to the center?
>
> Or another way to look at it. Supposed you use a 640x480
> webcam and put it in the image plane of the Canon 300 F/2.8
> EF. Would the image you see the tiny portion of the center
> of the target only or would you see the whole image???
>
> Hu
Hughes.
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.

== 3 of 9 ==
Date: Thurs, Apr 23 2009 9:33 pm
From: Hughes

On Apr 24, 12:19 pm, Me <u...@domain.invalid> wrote:
> Hughes 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? But then, can't you
> > consider the webcam sensor as located in the center portion
> > (smaller region) of the DSLR sensor chip, hence the webcam
> > is supposed to image only the central portion of the image
> > with all the sides black out? Or is it because the lens of
> > the webcam is able to take all field of view and converge
> > it to the center?
>
> > Or another way to look at it. Supposed you use a 640x480
> > webcam and put it in the image plane of the Canon 300 F/2.8
> > EF. Would the image you see the tiny portion of the center
> > of the target only or would you see the whole image???
>
> > Hu
>
> Hughes.
> 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.- Hide quoted text -
>
> - Show quoted text -

No troll dude. I'm installing this old webcam and it can't
run.. thinking of buying a new one.. but I remember before when used
it years ago the resolution seemd to be quite low. But when they used
webcam in astrophotography, it can image the planets. So maybe it has
to do with the lens? Just want to be sure because I'm going out to buy
a webcam in the store and if there are choices, I'd like to select one
compatible with astrophotography. Well. Rather than getting a Canon
1000D. I may just get a webcam to image my target which is bees and
flowers and want to
see it to the resolving limit allowed.. I'm not interested in
the sides or don't need larger field of view.. so I'm thinking if
640x480 webcam is sufficient for me as it has both the
same 5 micron pixel as the Canon 1000D.

Hughes

== 4 of 9 ==
Date: Thurs, Apr 23 2009 9:49 pm
From: Hughes

On Apr 24, 12:33 pm, Hughes <eugenhug...@gmail.com> wrote:
> On Apr 24, 12:19 pm, Me <u...@domain.invalid> wrote:
>
>
>
>
>
> > Hughes 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? But then, can't you
> > > consider the webcam sensor as located in the center portion
> > > (smaller region) of the DSLR sensor chip, hence the webcam
> > > is supposed to image only the central portion of the image
> > > with all the sides black out? Or is it because the lens of
> > > the webcam is able to take all field of view and converge
> > > it to the center?
>
> > > Or another way to look at it. Supposed you use a 640x480
> > > webcam and put it in the image plane of the Canon 300 F/2.8
> > > EF. Would the image you see the tiny portion of the center
> > > of the target only or would you see the whole image???
>
> > > Hu
>
> > Hughes.
> > 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.- Hide quoted text -
>
> > - Show quoted text -
>
> No troll dude. I'm installing this old webcam and it can't
> run.. thinking of buying a new one.. but I remember before when used
> it years ago the resolution seemd to be quite low. But when they used
> webcam in astrophotography, it can image the planets. So maybe it has
> to do with the lens? Just want to be sure because I'm going out to buy
> a webcam in the store and if there are choices, I'd like to select one
> compatible with astrophotography. Well. Rather than getting a Canon
> 1000D. I may just get a webcam to image my target which is bees and
> flowers and want to
> see it to the resolving limit allowed.. I'm not interested in
> the sides or don't need larger field of view.. so I'm thinking if
> 640x480 webcam is sufficient for me as it has both the
> same 5 micron pixel as the Canon 1000D.
>
> Hughes- Hide quoted text -
>
> - Show quoted text -

To add to the above.. i was kinda thikning that the 5 micron
may be the sensel and the separation between pixels
could be greater than it resulting in poor resolution when
getting the same field of view than the DSLR CCD. But
then it could be the lens itself solely and whenever a
sensel is 5 micron, all CCDs from webcam and dslr would
have the same support chip dimension around it.

Now if it's all 100% got to do with the lens. This means a
webcam is sufficient for my application in my 1000mm
russian telephoto f/10 with 1.25" visual back adapter.. Now the next
obvious question is.. what webcam has the closest
quality as a Canon 1000D?? I think it's reasonable because
the webcam can be 640x480 only but it's sensor could be
using some modern implementation that could not be far
from the Canon 1000D. Is there such??

Hughes

== 5 of 9 ==
Date: Thurs, Apr 23 2009 10:28 pm
From: Jürgen Exner

Hughes <eugenhughes@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?

jue

== 6 of 9 ==
Date: Thurs, Apr 23 2009 10:41 pm
From: Hughes

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?
>
> jue

Here's what I want.

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
get a webcam 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?
Would a Canon 300D produce other field of view?
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'm not
interested in the whole image because I'm using
doing this to understand certain optical physics).

Hughus

== 7 of 9 ==
Date: Thurs, Apr 23 2009 10:57 pm
From: Jürgen Exner

Hughes <eugenhughes@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?

>get a webcam

What is the focal length and the sensor size on that webcam?

>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.

jue

== 8 of 9 ==
Date: Thurs, Apr 23 2009 11:13 pm
From: Bob Larter

Hughes wrote:
> To add to the above.. i was kinda thikning that the 5 micron
> may be the sensel and the separation between pixels
> could be greater than it resulting in poor resolution when
> getting the same field of view than the DSLR CCD. But
> then it could be the lens itself solely and whenever a
> sensel is 5 micron, all CCDs from webcam and dslr would
> have the same support chip dimension around it.

No.

> Now if it's all 100% got to do with the lens. This means a
> webcam is sufficient for my application in my 1000mm
> russian telephoto f/10 with 1.25" visual back adapter.. Now the next
> obvious question is.. what webcam has the closest
> quality as a Canon 1000D?? I think it's reasonable because
> the webcam can be 640x480 only but it's sensor could be
> using some modern implementation that could not be far
> from the Canon 1000D. Is there such??

You're not going to be able to find a webcam with quality anything like
that of a DSLR.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

== 9 of 9 ==
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?

>
> jue- Hide quoted text -
>
> - Show quoted text -

==============================================================================
TOPIC: Corrupt Elites Plan Dispossession of American Citizens
http://groups.google.com/group/rec.photo.digital/t/c79005183ee0b90d?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Apr 23 2009 9:29 pm
From: John McWilliams

Twibil wrote:
> On Apr 23, 12:38 pm, Omega <Omega....@gmail.com> wrote:
>> On Apr 23, 3:09 pm, Twibil <nowayjo...@gmail.com> wrote:
>>
>>> On Apr 23, 12:04 pm, wis...@yahoo.com wrote:
>>>> A fine evaluation of a problem that will be terminal for America
>>>> unless corrected.
>>> Er, but it's circa 8 1/3 years out of date.
>>> Bush is no longer in office.
>> But then Obama is basically Bush III
>
> On closer examination I think you'll find several thousand distinct
> differences. Some of those may be improvements, and some probably
> aren't; but "basically Bush III? Hardly.
>
> (Unless, of course, you're comparing them both to either Christ or
> Satan; in which case your need for intensive therapy outweighs any
> other factor in the equation.)

Please don't xpost to these lovely groups:

alt.pro-wrestling.wwf
rec.equestrian
rec.boats
soc.culture.jewish

It just keeps on going much longer when you do.

--
lsmft

== 2 of 2 ==
Date: Thurs, Apr 23 2009 9:30 pm
From: John McWilliams

Omega wrote:
> On Apr 23, 3:04 pm, wis...@yahoo.com wrote:
>> On Thu, 23 Apr 2009 10:18:22 -0700, Felix <fe...@nada.net> wrote:
>>
>>> Stop Immigration, Start Deportation
>>> Commentary by Mitchell Brooks
>>> When someone, say myself, obsessively scans the news every single day
>>> they will probably develop an overwhelming fear of the current
>>> situation within the United States. This is especially true if one
>>> reads real news; the kind that is now found almost exclusively on the
>>> Internet. The contrast between mainstream news sources and Internet
>>> news sites is astounding, especially as it pertains to the topic of
>>> immigration.
>>> I am convinced that immigration, legal and illegal, is the most deadly
>>> threat to the United States. The facts are in and the facts are
>>> powerful and disturbing. These facts will rarely be presented by the
>>> mainstream press. The third-world immigrant invasion will be
>>> portrayed, if it is portrayed at all, as a wonderful development
>>> bringing lively, diverse and joyous gifts to the drab old U.S. of A.
>>> At the very least, immigrants will be portrayed as morally superior
>>> victims.
>>> If you think overpopulation, ignorance, crime, disease, dependence on
>>> government handouts, grist for the racist affirmative-action mill,
>>> depressed wages, and cultural balkanization are wonderful new
>>> developments then you are no doubt brimming with enthusiasm for the
>>> destruction of your own country. You might also be a member of the
>>> ACLU, the Southern Poverty Law Center, the Democratic Party, the Bush
>>> wing of the Republican Party or some other organization. Or perhaps
>>> you are just a victim of politically-correct social engineering.
>>> Whatever the case, I predict many of you will be shocked when all the
>>> group hugs you have planned prove to resemble Maoist self-criticism
>>> sessions.
>>> But if you are looking for the facts and are prepared to act on them
>>> you might have to put out a little effort. Once that's done the bad
>>> news is that there is precious little good news.
>>> Every time citizens' groups manage to thwart legislation that would
>>> give amnesty to illegal aliens or increase legal immigration it is
>>> ultimately a meaningless victory. As long as our current leadership is
>>> in place they will continue to refuse to enforce the inadequate
>>> immigration laws we have and they will continue to plot with
>>> American's enemies, foreign and domestic, to increase the immigrant
>>> invasion.
>>> The only hope is for a massive defection from the two major parties
>>> that are plotting the dispossession of American citizens.
>> A fine evaluation of a problem that will be terminal for America
>> unless corrected.
>>
>> ted
>>
>>
>>
> I have had several rabbis comment that we are heading towards being a
> third world country. Since 1910 each generation has been a bit worst
> than the previous generation. We seem to have become too comfortable,
> too wealthy, as people (total US population that is). But this may be
> the natural cycle of things.
>
fu set

==============================================================================
TOPIC: Matching Pixel Size and Telephoto
http://groups.google.com/group/rec.photo.digital/t/75c4b5506848d404?hl=en
==============================================================================

== 1 of 1 ==
Date: Thurs, Apr 23 2009 9:55 pm
From: Hughes

On Apr 24, 8:44 am, Me <u...@domain.invalid> wrote:
> Hughes wrote:
> > On Apr 23, 11:41 pm, Martin Brown <|||newspam...@nezumi.demon.co.uk>
> > wrote:
> >> Me wrote:
> >>> Hughes wrote:
> >>>> On Apr 23, 7:27 pm, Me <u...@domain.invalid> wrote:
> >>>>> Hughes wrote:
> >>>>>> On Apr 23, 5:56 pm, Me <u...@domain.invalid> wrote:
> >>>>>>> Hughes wrote:
> >>>>>>>> Hi,
> >>>>>>>> My experience is mostly on astronomical telescopes
> >>>>>>>> and I now want to view terrestrial daytime subject
> >>>>>>>> like sceneries or trees/nature.
> >>>>>>>> I have a 4" 1000mm F/10 Telephoto. I want to get
> >>>>>>>> a digicam that can produce the optimum image
> >>>>>>>> quality. In Astrophography, what we do is get
> >>>>>>>> the resolving power of the scope and get a CCD
> >>>>>>>> with pixel scale that is at least 1/2 of it.
> >>>>>>>> Calculating:
> >>>>>>>> Resolving power of 4" telephoto is 1.16 arcsec
> >>>>>>>> Airy disc linear size of F/10 is 13 micron
> >>>>>>>> that subtends 2.68 arcseconds of the target
> >>>>>>>> Questions.
> >>>>>>>> What do you do in terrestrial photography? Do you
> >>>>>>>> also get pixel scale that is 1/2 the resolving
> >>>>>>>> power of the telephoto? Or do you just match
> >>>>>>>> the pixel size to the airy disc size (in my
> >>>>>>>> case, 13 micron which is the linear diameter
> >>>>>>>> of the airy disc)??
> >>>>>>> We have variable apertures, and we tend to buy cameras with the pixel
> >>>>>>> pitch that the manufacturers happen to churn out. I never heard of
> >>>>>>> anyone checking available lens resolution figures before buying more
> >>>>>>> megapixels in the latest camera body - but you do hear the occasional
> >>>>>>> whine that existing lenses can't match sensor resolution, which is
> >>>>>>> probably true in some cases.
> >>>>>> I plan to buy a Canon 1000D. Calculating the pixel
> >>>>>> scale of the 1000mm telephoto f/10:
> >>>>>> pixel scale = 206265 x 5.7 micron/1000
> >>>>>> pixel scale = 1.175 arcsec/pixel
> >>>>>> resolving power of telephoto is 1.16 arcsec
> >>>>>> airy disc subtended is 2.68 arcsec
> >>>>>> In terrestrial photography, do you admit that we
> >>>>>> shouldn't aim to match the resolving power of
> >>>>>> the telephoto but the airy disc size itself or
> >>>>>> its average diffraction rings. If so, then the 1000D
> >>>>>> is oversampling already?
> >>>>>> If I get a used Canon 300D, the pixel scale is
> >>>>>> 206265 x 0.0074/1000= 1.5 arcsec/pixel, which is
> >>>>>> about optimally sampled?
> >>>>>> But here's a complication. My telephoto is a mirror
> >>>>>> or mak, central light of airy disc is pumped to the
> >>>>>> diffraction rings. Add to it is possible wavefront
> >>>>>> error of 1/3 wave, then my airy disc is twice the
> >>>>>> size so it's about 26 micron or subtending 5.3
> >>>>>> arcsecond. So I think I must get a camera
> >>>>>> with pixel size of at least 11 micron? Resolution
> >>>>>> there can be lower than 5 megapixel (this
> >>>>>> means if my telephoto, increasing the megapixel
> >>>>>> wouldn't produce better image, but just magnifying
> >>>>>> all the defects).
> >>>>>> I'm calculating what is the theoretical pixel pitch
> >>>>>> I should get for my 1000mm f/10 fixed aperture telephoto where
> >>>>>> decreasing its size wouldn't
> >>>>>> produce improvement in quality. Note this is for
> >>>>>> theoretical exploration and to better understand
> >>>>>> the optical concept of telephoto and sensor sizes
> >>>>>> and their optimum matching depending on target
> >>>>>> structures.
> >>>>>> Hughes
> >>>>> I'd say forget the "waste" of oversampling.
> >> A small amount of oversampling upto about 1.5x makes the image look more
> >> natural. Hard sampling below the lens resolution limit will produce the
> >> photographic equivalent of jaggies in artificially rendered images.
>
> >>>>> I'd expect a newer Canon dslr sensor to have lower read noise and higher
> >>>>> quantum efficiency than an older Canon DSLR. I'd also expect a higher
> >>>>> end Canon dslr (ie 40d or 50d) to have lower read noise than a digital
> >>>>> rebel model with the same pixel count and density, as that's the way it
> >>>>> seems to have worked in the past when raw data has been analysed. Canon
> >>>>> seem to cheapen out the sensors and support electronics on the lower
> >>>>> models - for normal photography there's actually not a lot of
> >>>>> difference, but there might be for you.
> >>>>> It might be ideal if Canon made a new 6 megapixel APS-c sensor dslr, but
> >>>>> they haven't done so for years now, and sensor technology has moved on
> >>>>> quite a lot over that time - since the 300d. Some terrestrial
> >>>>> photographers would be happy if they did make some lower pixel count
> >>>>> models, but that opens up an argument that's a can of worms.
> >>>>> But I suggest you ask further questions on specific astrophotography
> >>>>> sites. Sorry I can't offer links, but I've seen sites where dslr
> >>>>> performance for astrophotography is tested very thoroughly by
> >>>>> enthusiasts who are very quick to check out new models as soon as they
> >>>>> can get their hands on them.- Hide quoted text -
> >>>>> - Show quoted text -
> >>>> I won't be using it on astrophotography. I'd use it only
> >>>> terrestrially to image flowers, bees, trees, etc.
> >>>> So astrophotographers can't answer my questions
> >>>> because their only concern are the stars and
> >>>> nothing more. My main question is simply this.
> >>>> 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???
>
> No - you should "oversample" and use as many pixels as possible, but
> balance overall sensor efficiency against pixel density. As I've said

Well. 3 pixels for the resolving power of 1.16" arcsecond for the 4"
telephoto is already optimally sampling because to
get 5 pixels or more inside the 1.16" arcsecond is literally
wasting pixels. This is true for astrophotography.

Now when imaging terrestrially where I'm only interested
in the optical principles, does one still need to get 3 pixels
in a 1.16 arcsecond resolving power, or can it be 1 pixel
for 1.16 arcsecond?

Well. You may be confusing the Airy Disc size and resolving
power which is not the same, the resolving power is 2X or even 4X
smaller than the Airy Disc, therefore in Martin
message... he is like saying there are 6-8 pixels in the
airy disc because the 1.16 arcsecond being the resolving
power is 2-3X smaller than the airy disc.

Ultimately. My sole purpose of imaging bees and flowers is
not to print it or display it but just solely to have experimental and
conceptual demonstration of optical
principles. It's like i'm studying optics and just want to
understand the imaging of extended object terrestrially
rather than the moon, planets or the stars.

Hughes

> 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.
> 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. 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).- Hide quoted text -
>
> - Show quoted text -

==============================================================================
TOPIC: B&W photography
http://groups.google.com/group/rec.photo.digital/t/2d29e1d10678cd2d?hl=en
==============================================================================

== 1 of 2 ==
Date: Thurs, Apr 23 2009 9:58 pm
From: "Willem Wernsen"

Updated my photoweblog

B&W photography

www.fotowillem.com/weblog

Comments and critiques are welcom

Gr.

Willem

== 2 of 2 ==
Date: Thurs, Apr 23 2009 10:19 pm
From: Bob Williams

Willem Wernsen wrote:
> Updated my photoweblog
>
>
> B&W photography
>
>
> www.fotowillem.com/weblog
>
> Comments and critiques are welcom
>
> Gr.
>
> Willem
>
>
> --
You do very good work.
You have a good eye for composition
Congratulations .......Keep it up.
Bob Williams