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Thread: Is the good ol fashion Hyperfocal distance formula accurate for LF? I think not!

  1. #21

    Is the good ol fashion Hyperfocal distance formula accurate for LF? I think not!

    Tuan, thank you for the response...I fully understand, however, when one goes through all the lens tests on C Perez page you will notice that up to f32, 1/R still is accurate... so what's remaining that you are questioning, f45?

    I understand that these "super lenses" can not yield better than diffraction limited resolutions...I don't have a good answer why these few lenses seem to out perform difraction limited lpmm on film?? But as I mentioned, they represented less than 5% of the total bunch tested, so their is still an overwhelming amount of evidence that 1/R is accurate. right?

  2. #22

    Is the good ol fashion Hyperfocal distance formula accurate for LF? I think not!

    OK, I want to close this thread out...sorry for belaboring this point... it was quite confusing getting detailed informaiton on this, and sometimes the responses and the test data did not coincide. Glen, you wrote..

    Thus the formula is pretty good for 35mm work where lenses and films are operating near their limits. In LF work, we are usually interested in frequencies (lp/mm) where the film is not near its limit. This is particularly true with 8x10 where 20 lp/mm is way short of the films limits. This is where Q is correct, that you can essentially neglect the film, and consider only the lens limits.

    Glen, I think this is by far the best explanation of 1/R purpose in photography. From studying this and the test results, there is a compromise between the dif. limited lens resolving power and 1/R for fstops f22 and f32. This compromise at f22 leans more towards 1/R and at f32 leans more towards the lenses resolving power. My guess is, at f45 and above, the difraction limited reloving power goes straight to film and is no longer compromised by 1/R. (I never saw any tests at f45 or >)

    So in summary, I would say 1/R is ceiling to be used and respected up to and including f16, then at f22 and f32 it's a mix, and at f45 and above, forget 1/R ever existed! Thank you all for your input... What a battle to get to this conclusion!

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