03-26-2011, 10:45 AM
[quote name='miro' timestamp='1301098141' post='7098']
Hello Wim,
How do you come to this numbers 1,5 and 1 2/3 stops?
According to my cacluations.
1,5 crop must have 2,25 times higher DOF - in terms of stops it is 1,17 Stops
1,6 crop must have 2,56 times higher DOF - 1,35 Stops.
With Kind Regards,
Miro
PS Finally I fond Wim to say something wrong. :-)
[/quote]
Hold on, the DOF difference between FF and 1.5x crop is exactly 1.5x, or at least online DOF calculators show that. One aperture stop is 1.4, which affects DOF exactly in the same way - 1.4x. So 1.5 crop is slower by 1.5/1.4 = 1.07 stop, not a huge difference.
For nitpickers - I know that Nikon's crop is nearly 1.52x, however one aperture stop (sqrt 2) is not exactly 1.4 either <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/cool.gif' class='bbc_emoticon' alt='B)' />
Hello Wim,
How do you come to this numbers 1,5 and 1 2/3 stops?
According to my cacluations.
1,5 crop must have 2,25 times higher DOF - in terms of stops it is 1,17 Stops
1,6 crop must have 2,56 times higher DOF - 1,35 Stops.
With Kind Regards,
Miro
PS Finally I fond Wim to say something wrong. :-)
[/quote]
Hold on, the DOF difference between FF and 1.5x crop is exactly 1.5x, or at least online DOF calculators show that. One aperture stop is 1.4, which affects DOF exactly in the same way - 1.4x. So 1.5 crop is slower by 1.5/1.4 = 1.07 stop, not a huge difference.
For nitpickers - I know that Nikon's crop is nearly 1.52x, however one aperture stop (sqrt 2) is not exactly 1.4 either <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/cool.gif' class='bbc_emoticon' alt='B)' />