F stop focus test
Mar 21, 2024 13:11:59 #
imagemeister wrote:
Ever heard of DIFFRACTION ??
Thanks but see my most recent post ...addressed to TriX.
Mar 21, 2024 13:35:12 #
EJMcD wrote:
Thanks but I don't spend time "testing" lenses. If it looks good to the naked eye, it's good enough for me. I don't view my images (prints/enlargements) with a microscope but thanks again for the suggestion.
Completely understand - just answering your question as to whether f9 is sharper than f16. Given that the DOF at f9 is appropriate for the subject and all else being the same, the answer is yes. f16 in this case hurts you in 2 ways - diffraction and the need for higher ISO to compensate.
Mar 22, 2024 07:32:15 #
TriX wrote:
Completely understand - just answering your question as to whether f9 is sharper than f16. Given that the DOF at f9 is appropriate for the subject and all else being the same, the answer is yes. f16 in this case hurts you in 2 ways - diffraction and the need for higher ISO to compensate.
and the higher ISO would contribute to poorer IQ.
Mar 22, 2024 09:39:44 #
TriX wrote:
Completely understand - just answering your question as to whether f9 is sharper than f16. Given that the DOF at f9 is appropriate for the subject and all else being the same, the answer is yes. f16 in this case hurts you in 2 ways - diffraction and the need for higher ISO to compensate.
EJMcD wrote:
and the higher ISO would contribute to poorer IQ.
The OP did not mention changing ISO in the example he posted. My take on that example was that the apparent sharpness difference was due to excessive noise in the f/16 shot. While ISO can be a source of noise increase, we don't know what ISO was used in the shots presented. The f/ number change could have been compensated for by changing the shutter speed. As far as diffraction is concerned my diffraction study only showed a change in edge width from 0.9 pixel to 1.28 pixel from f/9 to f/16 (https://static.uglyhedgehog.com/upload/2024/3/20/t1-316451-hot_2024_03_20_at_08.46.48.jpg). I don't believe that small change would be really significant as far as apparent sharpness is concerned.
In short, I think we can't infer anything from the example presented.
Mar 22, 2024 10:10:26 #
DirtFarmer wrote:
The OP did not mention changing ISO in the example... (show quote)
The more input I get, the more I believe the observations noted in my posts are valid.
Mar 22, 2024 12:18:52 #
Mar 25, 2024 10:07:55 #
buckscop wrote:
Do I keep them RAW unedited and just look for sharpness, or edit them in some fashion to compare them (I have LR)?
I find that performing test shots on targets is the best way to learn how to use my gear. If you want to know the limits of your gear, then unmolested RAW images is the way to go. If you normally shoot JPG, than you should do those tests to so you can find the sweet spots for your lenses and camera settings.
I personally shoot JPG+Raw so I learn to get to know both.
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