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06-21-2013, 09:53 PM   #2041
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QuoteOriginally posted by VoiceOfReason Quote
How bad would diffration hurt an APS-C sensor in 24mp size?
Why are you concerned with pixel sharpness?

What matters is the image sharpness. For a given sensor size, a particular f-stop will always produce the same image-level diffraction, independently of the MP.

Worrying about the effect of diffraction at the pixel level is like worrying about noise at the pixel level.

Yes, higher MP sensors have higher per-pixel noise (everything else being the same). But the image-level noise is the same.

As a matter of fact, the higher MP sensors have a finer grain pattern (once images are scaled to the same size). Likewise, increasing resolution with more MPs is possible even when the diffraction limit has been passed. An image chain does not work according the "weakest link defines the maximum"-principle. All individual link performances multiply so every improvement helps (to a degree that is naturally also determined by other links).

06-21-2013, 10:10 PM   #2042
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QuoteOriginally posted by Digitalis Quote
yes diffraction is gradual, however there are few lenses that perform optimally at f/9.1 - f/7.1 is closer to f/8 which is where most 50mm lenses perform identically.



The trick is to stop the lens down so the DOF is "just so" and fits the needs of the subject.
Thanks for reminding me of home with those images. On tarmac in LA waiting to come home.
06-21-2013, 11:35 PM   #2043
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QuoteOriginally posted by thibs Quote
Digitalis, these are part of bigger image I guess. Could you please post the uncropped image? Just to put things in perspective..
sadly I no longer have the original images. I didn't see the point in keeping them because I know all about diffraction as things stand.But with each image resized to 3Mp you can still spot differences in micro-contrast between the images, because the micro-contrast in the image at f/29 has been diminished by the scattering of diffraction, the image taken at f/5.6 is clearly superior.

QuoteOriginally posted by Class A Quote
Worrying about the effect of diffraction at the pixel level is like worrying about noise at the pixel level.
Camera shake is a bigger problem than diffraction is for a majority of users, even with the Built in SR pentax offers.... I really don't worry my self all that much about diffraction, because I can stack images if I choose to.

QuoteOriginally posted by southlander Quote
Thanks for reminding me of home with those images. On tarmac in LA waiting to come home.
Adelaide airport will be a welcome sight. As I recall I didn't really enjoy being in the LA airport, it was a rather uninspiring place to me.
06-22-2013, 12:42 AM   #2044
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QuoteOriginally posted by Digitalis Quote
sadly I no longer have the original images. I didn't see the point in keeping them because I know all about diffraction as things stand.But with each image resized to 3Mp you can still spot differences in micro-contrast between the images, because the micro-contrast in the image at f/29 has been diminished by the scattering of diffraction, the image taken at f/5.6 is clearly superior.
Too bad. Yes the differences between those two are huge.
I just wanted to see the effect on the complete image. But those differences are...
Fortunately, it is easy to spot on digital.
I should test my 4x5 lenses sometimes but I really don't want to throw so many sheets at this

Thanks again.

06-22-2013, 01:42 AM   #2045
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QuoteOriginally posted by thibs Quote
I should test my 4x5 lenses sometimes but I really don't want to throw so many sheets at this
Tell me which lenses you have, I work with 4X5 and 8X10 on a regular basis - I might be familiar with the lenses you use. on 4X5 you can frequently get away with using f/11~16 with 150mm lenses, many 4X5 lenses perform at their best in that aperture range. Most 8X10 lenses work best around f/22~f/32 range.
06-22-2013, 03:50 AM   #2046
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QuoteOriginally posted by Digitalis Quote
Tell me which lenses you have, I work with 4X5 and 8X10 on a regular basis - I might be familiar with the lenses you use. on 4X5 you can frequently get away with using f/11~16 with 150mm lenses, many 4X5 lenses perform at their best in that aperture range. Most 8X10 lenses work best around f/22~f/32 range.
I often end with f/22 which is a bit too small, probably.

1/ Schneider Super Angulon 75mm/5.6
2/ Schneider Symmar-S 150/5.6

Thank you.
06-22-2013, 06:32 AM   #2047
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QuoteOriginally posted by Class A Quote
Why are you concerned with pixel sharpness?

What matters is the image sharpness. For a given sensor size, a particular f-stop will always produce the same image-level diffraction, independently of the MP.

Worrying about the effect of diffraction at the pixel level is like worrying about noise at the pixel level.

Yes, higher MP sensors have higher per-pixel noise (everything else being the same). But the image-level noise is the same.

As a matter of fact, the higher MP sensors have a finer grain pattern (once images are scaled to the same size). Likewise, increasing resolution with more MPs is possible even when the diffraction limit has been passed. An image chain does not work according the "weakest link defines the maximum"-principle. All individual link performances multiply so every improvement helps (to a degree that is naturally also determined by other links).
Not true. Megapixels matter. Please see the article below:
http://www.cambridgeincolour.com/tut...ensor-size.htm
06-22-2013, 07:34 AM   #2048
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QuoteOriginally posted by Ferdinand Quote
Not true. Megapixels matter. Please see the article below:
http://www.cambridgeincolour.com/tut...ensor-size.htm
Your link doesn't work.


Class A is still correct.

06-22-2013, 07:40 AM   #2049
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The reason I like maximum sharpness is because I do pixel peep. I wanted to know with a larger MP sensor at what point could I start noticing a difference if I were to do a full resolution print. I do have a reason I am asking, and that is because some friends with a gallery want me to do some prints for it. I don't think my stuff is anywhere near good enough for a gallery, but it would be cool to get it in one. I want to push myself to get the best photos I can, and to do the best I can on them, but I wouldn't want to buy my next camera later on with more MP just to find I was shooting myself in the foot.
06-22-2013, 07:59 AM   #2050
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QuoteOriginally posted by ElJamoquio Quote
Your link doesn't work.


Class A is still correct.
I am sorry that the link does not work. Nevertheless please try to look up the article on
Cambridge in Colour - Photography Tutorials & Learning Community
about why sensor size matters, and make a better informed judgement about whether Class A is correct.

Other parts of the article are very good too, not just the part on diffraction.
06-22-2013, 09:06 AM   #2051
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QuoteOriginally posted by VoiceOfReason Quote
The reason I like maximum sharpness is because I do pixel peep.
I did not question your need for sharpness.

I questioned why you care about individual pixels.

Your question was about the impact of the number of MP with respect to diffraction. The answer is that if you print two images (one from a 16MP and another from a 24MP sensor) to the same size with the same f-ratio then they will look the same. Even though at a 100% view the 24MP image will look softer (due to the higher magnification).

If you are printing the two images to two different sizes -- e.g., by maintaining 300dpi for both -- then obviously diffraction will be more visible in the larger image. That is, if you view them from the same distance. But in this case the DOF will be shallower in the larger print as well.
06-22-2013, 09:10 AM   #2052
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QuoteOriginally posted by Ferdinand Quote
Not true. Megapixels matter. ...
QuoteOriginally posted by Ferdinand Quote
Nevertheless please try to look up the article on
Cambridge in Colour - Photography Tutorials & Learning Community
about why sensor size matters, and make a better informed judgement about whether Class A is correct.
Please note that "Megapixels" and "sensor size" are two different things.

I only wrote about "Megapixels".

Of course "sensor size" matters, but "megapixels" don't (for the subject at hand).
06-22-2013, 09:12 AM   #2053
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QuoteOriginally posted by VoiceOfReason Quote
The reason I like maximum sharpness is because I do pixel peep. I wanted to know with a larger MP sensor at what point could I start noticing a difference if I were to do a full resolution print. I do have a reason I am asking, and that is because some friends with a gallery want me to do some prints for it. I don't think my stuff is anywhere near good enough for a gallery, but it would be cool to get it in one. I want to push myself to get the best photos I can, and to do the best I can on them, but I wouldn't want to buy my next camera later on with more MP just to find I was shooting myself in the foot.
On a full rex print of what size? To notice the difference your image would have to be printed in metres.

Diffraction is by far the least of your worries.
06-22-2013, 09:18 AM   #2054
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Maybe I better need to explain my premise which is to assume that one wants to know whether two images taken with different sensors that have a different pixel-pitch will look different for a given f-ratio. They won't.

There is another legitimate question which is to ask: "Beyond which f-ratio will I reduce the maximum sharpness that I can achieve with a given sensor?" The answer to the latter question of course depends on the number of megapixels. Sensors with less MP just resolve less, so they can tolerate more diffraction until the latter starts compromising pixel-level sharpness.
06-22-2013, 09:21 AM   #2055
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QuoteOriginally posted by Aristophanes Quote
Diffraction is by far the least of your worries.
Depends on the f-ratio.

At f/22 on APS-C, you are not producing more then 2MP worth of resolution. This significantly limits your print size.
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