11-19-2011, 09:27 PM
[quote name='Brightcolours' timestamp='1321732917' post='13043']
I agree with Studor13, DOF "scales" and calculation tools are a bit nonsensical.
You use a certain aperture size for either the look of the photo, or the light conditions. Not to get a "measured" depth in focus (which is nonsense anyway).
If you do not want a blurry background, no need for a 85mm f1.8 lens. If you need a whole person somewhat in focus, no need to fiddle with DOF blah either, just set the lens to f5.6 and you will be fine.
85mm on your Nikon gives approximately the field of view of a 85 x 1.5 = 127mm lens.
The aperture of the lens is 85mm / 1.8 = 47.2mm. For that 127mm lens that means: 127mm focal length, 47.2mm aperture: 127 / 47.2 = f2.69
Now that did not make your head hurt, I am sure.. Very simple really <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />
[/quote]
Sorry, but your last statement is wrong. On crop the FL doesn't change, neither does the actual aperture.
However, what changes, due to the smaller format, is the CoC, and that is what causes DoF to change. This because DoF and sharpness is all about definitions, involving sharpness at a certain image size and viewing distance, from such a format.
Kind regards, Wim
I agree with Studor13, DOF "scales" and calculation tools are a bit nonsensical.
You use a certain aperture size for either the look of the photo, or the light conditions. Not to get a "measured" depth in focus (which is nonsense anyway).
If you do not want a blurry background, no need for a 85mm f1.8 lens. If you need a whole person somewhat in focus, no need to fiddle with DOF blah either, just set the lens to f5.6 and you will be fine.
85mm on your Nikon gives approximately the field of view of a 85 x 1.5 = 127mm lens.
The aperture of the lens is 85mm / 1.8 = 47.2mm. For that 127mm lens that means: 127mm focal length, 47.2mm aperture: 127 / 47.2 = f2.69
Now that did not make your head hurt, I am sure.. Very simple really <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />[/quote]
Sorry, but your last statement is wrong. On crop the FL doesn't change, neither does the actual aperture.
However, what changes, due to the smaller format, is the CoC, and that is what causes DoF to change. This because DoF and sharpness is all about definitions, involving sharpness at a certain image size and viewing distance, from such a format.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....