Diffraction Limited Aperture of camera sensors

[4-TEEF]

Found some really interesting info in the 50D review from TheDigitalPicture As sensor density increases the compromise of DOF versus resolution is starting to become an issue with many of the f5.6 consumer zooms on the market... below is a partial listing of Canon cameras and their Diffraction Limited Aperture.

450D - f/8.4
400D - f/9.3
350D - f/10.4
300D - f/11.8
50D - f/7.6
40D - f/9.3
30D - f/10.3
5DII - f/10.3
5D - f/13.2
1DIII - f/11.4
1DIIN - f/12.7
1DsIII - f/10.3
1DsII - f/11.6

And there is a bunch of science type stuff at http://www.cambridgeincolour.com/tut...hotography.htm I'll read it sometime when I have a spare hour!

[Tippster]

The 5D wins! Yay!

[Hugh Conway]

shitty lenses suck

why the fuck is this news? the results scale with pixel density. this isn't fucking news, it's basic fucking science

[Microcosm]

Not so much "news" as it is something to be thought about as we cram more and more pixels onto the same sensor sizes, without regard for anything else that actually affects image quality.

[4-TEEF]

shitty lenses suck

why the fuck is this news? the results scale with pixel density. this isn't fucking news, it's basic fucking science

Who the fuck said anything about "news"?

The 5D is rated to almost twice the aperture of the 50D and I thought that would be pretty fucking interesting to people who shoot fucking landscapes. People like the fucking people on here. So I fucking posted it.

Fuck.

[Hugh Conway]

The 5D is rated to almost twice the aperture of the 50D and I thought that would be pretty fucking interesting to people who shoot fucking landscapes.

5D = 12mp full frame
50D = 15mp 1.6x crop = 38.4 mp full frame

[4-TEEF]

5D = 12mp full frame
50D = 15mp 1.6x crop = 38.4 mp full frame

And your point is?

[summit]

And your point is?

The point is that the 50D offers high MP in a small package offering the user more options than a camera with a lower sensor density.

If you want max resolving power and IQ for a higher MP on a 50D, set the aperture to f/7.1 or f/8
If your creative control of deep DoF is more important than theoretical maximum resolving power, choose a higher aperture.

The higher density sensor gives you more options. You can use the 40D max aperture and get a theoretical maximum resolving power that the 40D... or the 20D etc etc.

Back when we all shot 35mm film, we all knew that diffraction caused diminishing returns at f/10 or f/11 and above. We also knew that the few people using APS SLRs experienced the diminishing return at f/8ish.

That's why you see the 5DII @ f/10.3 because it's pretty close to 35mm and you see the 5D at f/13.2 because it doesn't have a resolution higher than 35mm could attain despite being FF (although still pretty close).

[4-TEEF]

Dammit Summit! I was trying to get Hugh to make a post with more than one sentence.

[Tippster]

Makes me wonder why the f/64 folks never talked about diffraction...?

[Rubicon]

Makes me wonder why the f/64 folks never talked about diffraction...?

Because they were using large format cameras?

[4-TEEF]

Makes me wonder why the f/64 folks never talked about diffraction...?

Ansel Adams, "The Camera," page 74 "...With diffraction causing some loss of sharpness at small apertures, and certain aberrations degrading image quality at large stops, a lens usually gives its best image quality somewhere near the middle of its aperture range."

[summit]

Because they were using large format cameras?

Exactly.

f/64 still prints a fine 20"x30" print (or larger!) from a 4x5.

In 35mm, f/16 was no biggie if you needed it. When shooting macro, I'd even do f/22, f/32, and f/45.

When shooting 4x5, I was usually shooting f/11 to f/32.

When shooting with my 1/1.8" CCD 5MP point and shoot, I know that I am essentially diffraction limited around f/4. But I don't see diminishing returns at f/5.6 or even f/8. That's why it might be useful to still stop down a lens on a 12MP crammed into a 1/2.5" CCD, however, one should not that it is essentially impossible to take full advantage of such a sensor.

Remember, going past the diffraction limited resolution aperture doesn't mean your image is crap, it just means that you cannot reach the maximum resolving power ACHIEVABLE BY YOUR SENSOR anymore. IF YOUR LENS HASN'T REACHED THE SENSOR LIMITED RESOLUTION BY THE DIFFRACTION LIMITED APERTURE, THERE IS NO NEGATIVE AFFECT ON RESOLVING POWER ANYWAY BY STOPPING DOWN PAST THAT APERTURE! So stopping down past the theoretical diffraction limit to correct for lens aberrations may be counterproductive if you have a lens that reaches the max sensor resolution before the diffraction limit aperture, and then it still may be productive to stop down if border IQ improvement is the goal. Did you memorize an MTF chart for each of your lenses? (I know I did!)

Its a totally valid choice to stop past the diffraction limit for creative control of DoF (or to a get a long exposure, though lower ISO, ND filter, and polarizers help here). And remember, many lenses may never reach that maximum resolving capability or may reach their max resolution at a smaller aperture than the sensor limit aperture, so again the diffraction limit for an individual lens may be a smaller aperture than the diffraction limit for the sensor.

Suffice to say, just pick the damned aperture you need to make a picture you want and don't worry about this stupid crap. If aperture doesn't matter creatively for DoF or shutter speed, then the old 35mm adage of f/8 and go still applies well.

[4-TEEF]

Suffice to say, just pick the damned aperture you need to make a picture you want and don't worry about this stupid crap. If aperture doesn't matter creatively for DoF or shutter speed, then the old 35mm adage of f/8 and go still applies well.

I always heard it as "f/8 and be there"... and thought of it more as a 50mm at f/8 was the closest to the way a human eye sees the world. End result is the same though.

Here's another chart with limiting aperture for a variety of formats to create a "sharp 8 x10 print". Take that with whatever grain of salt that you see fit...

8 x10 (203mm x 254mm) = f180
6 x 9 (60mm x 90mm) = f64
35mm (36mm x 24mm) = f22
APS-C (22.5mm x 15mm) = f16
1/1.8" (7.1mm x 5.3mm) = f5
1/2.5" (5.7 x 4.3mm) = f4

Above info is from http://www.bobatkins.com/photography...ffraction.html

[Tippster]

I guess it all comes down to the print size. Good discussion.