11-20-2011, 11:40 PM
(This post was last modified: 11-20-2011, 11:47 PM by Brightcolours.)
[quote name='wim' timestamp='1321826635' post='13077']
Quoted again, but now with highlight in blue and bolded.
Well, maybe I read to much into it: you didn't mention it is equivalent to... etc. That is, IMO, quite a difference.
Well, the CoC stays important, because DoF is calculated based on a certain size CoC. IOW, if it is non-existent, then neither is DoF. CoC is part of the definition of perceived sharpness at a certain magnification and viewing distance, based on the (average) acuity of the human eye. And DoF is delimited by the area which is perceived as sharp according to this definition.
Whether you choose a quick and dirty method to calculate apparent aperture doesn't matter, but please do indicate that it is an equivalent aperture, compared to FF. That's what I meant by saying that the aperture stays the same. Same with FL. The aperture doesn't suddenly change because one is using a crop camera, neither does the FL. The effect is different, that's all.
Regards, Wim
[/quote]
Ian was SPECIFICALLY asking about FF equivalence. Why would I have to specifically repeat that, if it is him I was replying to? Should be obvious to anyone, really. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='
' />
DOF calculations are not based on CoC, the non-existent CoC is used to cover many variables which may or may not be of importance depending on what one is comparing.
In case of DOF equivalences, the only thing that matters is the crop factor, nothing else. Not the print size (if we print at the same size), not the pixel pitch, not the viewing distance.
BTW, it helps to differ between aperture (size in mm) and f-value. The aperture I did not change in finding out what was equivalent. The (equivalent) f-value was what changed. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' />
Quoted again, but now with highlight in blue and bolded.
Well, maybe I read to much into it: you didn't mention it is equivalent to... etc. That is, IMO, quite a difference.
Well, the CoC stays important, because DoF is calculated based on a certain size CoC. IOW, if it is non-existent, then neither is DoF. CoC is part of the definition of perceived sharpness at a certain magnification and viewing distance, based on the (average) acuity of the human eye. And DoF is delimited by the area which is perceived as sharp according to this definition.
Whether you choose a quick and dirty method to calculate apparent aperture doesn't matter, but please do indicate that it is an equivalent aperture, compared to FF. That's what I meant by saying that the aperture stays the same. Same with FL. The aperture doesn't suddenly change because one is using a crop camera, neither does the FL. The effect is different, that's all.
Regards, Wim
[/quote]
Ian was SPECIFICALLY asking about FF equivalence. Why would I have to specifically repeat that, if it is him I was replying to? Should be obvious to anyone, really. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='
' /> DOF calculations are not based on CoC, the non-existent CoC is used to cover many variables which may or may not be of importance depending on what one is comparing.
In case of DOF equivalences, the only thing that matters is the crop factor, nothing else. Not the print size (if we print at the same size), not the pixel pitch, not the viewing distance.
BTW, it helps to differ between aperture (size in mm) and f-value. The aperture I did not change in finding out what was equivalent. The (equivalent) f-value was what changed. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' />