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02-16-2013, 04:42 AM - 1 Like   #16
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QuoteOriginally posted by Ponosby Britt Quote
A K20 example at F22 with "massively degraded" image quality.
I have a better example than that.


Example of lens diffraction on the Pentax K5IIs with the Sigma 180mm f/3.5 APO EX MACRO - these are unsharpened 100% crops, note the loss of fine detail at f/22

In a nutshell diffraction is only really obvious at 100% level, if you are shooting a 16Mp camera and composing properly (not cropping too much) producing 8X12" prints - no one is really going to notice it at normal viewing distances. However, if you make larger prints 16X24" and larger, the choice to stop down more or maintain greater sharpness is a delicate balance. I know landscape photographers who will stop their lenses down to f/8 take a series of images at different focus settings and composite the images together so they can create richly detailed landscapes with deep DOF - and avoid the issue of diffraction.


Last edited by Digitalis; 02-16-2013 at 05:00 AM.
02-16-2013, 02:37 PM   #17
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QuoteOriginally posted by Digitalis Quote
yes, using f/22 would have a massively negative impact on image quality. An image taken at f/22 on the Pentax K5IIs will still be slightly sharper than an image taken at the f/22 on the regular K5II because of the missing bayer AA filter - however to really reap the benefits of the K5IIs keep the aperture around f/5.6 which is where most lenses perform their best. No 35mm lens ever performs well at f/22 - for landscape photography I suggest using f/11 besides most high performance prime lenses start to lose image quality a few stops after f/5.6. At f/11 you still have enough DOF to cover large subjects, at f/13 fine details start to lose acutance at f/16 diffraction is visibly detectable. It is important to note that sharpening an image doesn't recover detail lost to diffraction, it only makes the details that have been captured clearer.
I perked up when I noticed "landscape photography" in your note, Digitalis. I absolutely love the late Galen Rowell's advice re: landscape photography: "f/8 and be there." I'm pretty sure he didn't use just f/8 but, it was a great one liner. If you've never seen his stuff, click on one of the galleries on this site. He did most of his stuff on film and, tragically, was killed before digital really took off: Mountain Light Photography: Fine Art Prints
02-19-2013, 02:33 AM   #18
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Here is a better image for demonstrating the effects of diffraction on the Pentax K5IIs:
02-19-2013, 03:58 AM   #19
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QuoteOriginally posted by Digitalis Quote
Here is a better image for demonstrating the effects of diffraction on the Pentax K5IIs:
Yep that's a good example

What's been you experience with sharpening images from the IIs? (RAW files). Is it a case of if the lens itself is of good enough quality, you don't have to sharpen at all? (besides from the 25 or so that lightroom/ACR are doing on the import). Or are you capture sharpening all images to some degree?

I've finally decided between the two- the IIs will be arriving in a few days

02-19-2013, 04:34 AM   #20
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QuoteOriginally posted by linds Quote
Is it a case of if the lens itself is of good enough quality, you don't have to sharpen at all? (besides from the 25 or so that lightroom/ACR are doing on the import). Or are you capture sharpening all images to some degree?

I use lenses that all offer a level of sharpness where post capture sharpening is kept to a minimum - with my lenses apertures around f/2.8 ~ f/8 typically offer the best image quality. However, sometimes having enough DOF to cover the subject is more of a priority and the use of apertures of f/11 ~ f/16 are necessary - so post sharpening is essential under those circumstances . I personally make it a priority that the lenses I have perform their best around the f/2.8~f/8 aperture range.

Last edited by Digitalis; 02-19-2013 at 04:41 AM.
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