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Sensor resolution, any sites with actual measurements?

 
 
Rich
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      03-05-2006
I'm not talking about sites like dpreview.com that might be testing
sensors with less
than perfect lenses that happen to be used with some cameras. What I
mean are sites that have done tests with lenses that resolve (clearly)
beyond the sensor's capability.
No Canon 5D shots with wide open WA lenses, or related horrors.
I'm curious about how (for e.g.) the resolution of a FF camera compares
to cameras with smaller sensors, to see what effect pixel size (as
opposed to pixel count) has on absolute resolution, if any. I know its
not possible to avoid in camera processing which varies from brand to
brand,
but you have to start somewhere.
My preconception (correct by Mr. Roger Clark) was that pixel counts
determine absolute
resolution. The more pixels you can use to image something, the more
detail you will see.
But this seems to vary due to a lot of other factors.
-Pixel count
-Pixel size
-lens quality
-in-camera conversion and processing
-in-camera sharpening
-post camera processing
Even the image (it's characteristics) will effect different sensors
differently.

 
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David J. Littleboy
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      03-05-2006

"Rich" <(E-Mail Removed)> wrote:
> I'm not talking about sites like dpreview.com that might be testing
> sensors with less
> than perfect lenses that happen to be used with some cameras. What I
> mean are sites that have done tests with lenses that resolve (clearly)
> beyond the sensor's capability.


The dpreview test chart images are all taken with decent lenses at sensible
f stops.

David J. Littleboy
Tokyo, Japan


 
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Alfred Molon
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      03-05-2006
In article <(E-Mail Removed) .com>,
http://www.velocityreviews.com/forums/(E-Mail Removed) says...

> No Canon 5D shots with wide open WA lenses, or related horrors.


Speaking about this, are there lenses for full-frame DSLRs with corner-
to-corner sharpness even wide open (and also at wide angle, why not)?
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E300, E330 and E500 forum at
http://groups.yahoo.com/group/MyOlympus/
Olympus E500 resource - http://myolympus.org/E500/
 
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Helen
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      03-05-2006

"Rich" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> Even the image (it's characteristics) will effect different sensors


Still spelling its with an apostrophe I see.

And it's 'affect', not 'effect'.


 
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Philip Homburg
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Posts: n/a
 
      03-05-2006
In article <(E-Mail Removed)>,
Alfred Molon <(E-Mail Removed)> wrote:
>In article <(E-Mail Removed) .com>,
>(E-Mail Removed) says...
>
>> No Canon 5D shots with wide open WA lenses, or related horrors.

>
>Speaking about this, are there lenses for full-frame DSLRs with corner-
>to-corner sharpness even wide open (and also at wide angle, why not)?


'Wide open' is a rather useless requirement. It is quite possible that an
f/1.4 lens set to f/4 is sharper than an f/4 lens wide open. But the f/4
lens is likely to be sharper wide open than the f/1.4 lens.

If you look at MTF graphs, wide angle lenses simply don't have great
corner sharpness. You want high-end telephoto lenses for that (or stop
down far enough).


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Alfred Molon
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Posts: n/a
 
      03-05-2006
In article <(E-Mail Removed)>, (E-Mail Removed)
says...
>
> "Rich" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) oups.com...
> > Even the image (it's characteristics) will effect different sensors

>
> Still spelling its with an apostrophe I see.
>
> And it's 'affect', not 'effect'.


Maybe Rich is not a native English speaker.
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E300, E330 and E500 forum at
http://groups.yahoo.com/group/MyOlympus/
Olympus E500 resource - http://myolympus.org/E500/
 
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Alfred Molon
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Posts: n/a
 
      03-05-2006
In article <snq7dt1v8fhbggo9if3rmj9ks3@inews_id.stereo.hq.phi coh.net>,
(E-Mail Removed) says...

> 'Wide open' is a rather useless requirement.


Well no, you might have to use the lens at the widest aperture because
there is not sufficient light.

> If you look at MTF graphs, wide angle lenses simply don't have great
> corner sharpness. You want high-end telephoto lenses for that (or stop
> down far enough).


Why can't they design WA lenses with corner to corner sharpness (even
wide open)?
--

Alfred Molon
------------------------------
Olympus 50X0, 7070, 8080, E300, E330 and E500 forum at
http://groups.yahoo.com/group/MyOlympus/
Olympus E500 resource - http://myolympus.org/E500/
 
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Kennedy McEwen
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Posts: n/a
 
      03-05-2006
In article <(E-Mail Removed)>, Alfred Molon
<(E-Mail Removed)> writes
>In article <(E-Mail Removed)>, (E-Mail Removed)
>says...
>>
>> "Rich" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed) oups.com...
>> > Even the image (it's characteristics) will effect different sensors

>>
>> Still spelling its with an apostrophe I see.
>>
>> And it's 'affect', not 'effect'.

>
>Maybe Rich is not a native English speaker.


Unlikely, his English isn't that good!
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)
 
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Philip Homburg
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Posts: n/a
 
      03-05-2006
In article <(E-Mail Removed)>,
Alfred Molon <(E-Mail Removed)> wrote:
>In article <snq7dt1v8fhbggo9if3rmj9ks3@inews_id.stereo.hq.phi coh.net>,
>(E-Mail Removed) says...
>
>> 'Wide open' is a rather useless requirement.

>
>Well no, you might have to use the lens at the widest aperture because
>there is not sufficient light.


If you have enough light to use a f/2.8 lens wide open, then you have
enough light to use an f/1.4 at f/2.8 as well. Or you have to compare
the f/1.4 wide open with the f/2.8 at a two stops higher ISO or a two stops
slower shutter speed.

>> If you look at MTF graphs, wide angle lenses simply don't have great
>> corner sharpness. You want high-end telephoto lenses for that (or stop
>> down far enough).

>
>Why can't they design WA lenses with corner to corner sharpness (even
>wide open)?


It is probably physics that gets in the way. But you have to define 'corner
to corner sharpness'. Does that refer to an MTF curve that approaches a
straight horizontal line (ignoring the actual MTF value) or does it mean a
specific minimum MTF in the corners for a given resolution?


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Don Stauffer
Guest
Posts: n/a
 
      03-05-2006
Unless there is an uncommon amount of crosstalk, most CCD chips come
close to their theoretical capability, which is about 0.7 of the line
frequency of the detectors. That is, if there are 100 detectors per mm,
then the chip will usually test out at about 70 lines (35 lp) per mm.
While the mtf curve for a discrete sensor is shaped a bit different than
for a scanning sensor (Kell factor), the curves are close near the
cutoff frequency or the 2% contrast point.

Rich wrote:
> I'm not talking about sites like dpreview.com that might be testing
> sensors with less
> than perfect lenses that happen to be used with some cameras. What I
> mean are sites that have done tests with lenses that resolve (clearly)
> beyond the sensor's capability.
> No Canon 5D shots with wide open WA lenses, or related horrors.
> I'm curious about how (for e.g.) the resolution of a FF camera compares
> to cameras with smaller sensors, to see what effect pixel size (as
> opposed to pixel count) has on absolute resolution, if any. I know its
> not possible to avoid in camera processing which varies from brand to
> brand,
> but you have to start somewhere.
> My preconception (correct by Mr. Roger Clark) was that pixel counts
> determine absolute
> resolution. The more pixels you can use to image something, the more
> detail you will see.
> But this seems to vary due to a lot of other factors.
> -Pixel count
> -Pixel size
> -lens quality
> -in-camera conversion and processing
> -in-camera sharpening
> -post camera processing
> Even the image (it's characteristics) will effect different sensors
> differently.
>

 
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