Re: Am I asking too much of a 50d plus 70-200 f/2.8
I think you misunderstand what I mean, I wasn\'t talking about \"crop factor\". DOF is not an all-or-nothing thing; it deends on print size, because there really is only one distance where things are truly sharp at any magnification. At other distances, whether or not it is sharp depends on how closely you are looking. If you print a slightly blurry image to a 2x3\" print size, or look at it on your small camera\'s LCD, you won\'t see the blur, thus everything is \"in the DOF\". But suddenly if you look at an 8x10\" print, or \"100% view\" on the monitor, the blur shows up and it\'s magically \"out of the DOF\".
DOF calculators assumes a standard *print* size, which is what I\'m talking about here. If you look at the original image (not the full size one, just the resized one) it looks reasonably sharp. It would look sharper if she were actually in true focus, but she\'s still within DOF, though just at the edge of it because you can start to pick up some softness (e.g. in her leg).
DOF doesn\'t mean *in focus*, it means *looks sharp at standard print size*. Thus DOF calculators really should include print size & viewing distance in their calculations. Instead they usually just assume 8x10 print at arms length, or something like that.
volyrat wrote:
The DOF calculator does take into account that it is a 1.6 crop camera. Still says I\'ve got 2 feet of DOF @ f/2.8.
walter23 wrote: volyrat wrote:
The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1\' in front and 1\' behind.
With 2 feet of DOF, do you think that\'s the problem?
DOF calculations assume a standard print size. If you look at the standard web-sized version (your first image), she is sharp - within the DOF, albeit at the front edge of it (so not as razor sharp as she would look if she were truly in-focus). It\'s only when you start looking at magnified crops that you see where focus falls off. If you\'re going to be scrutinizing at 100%, you need to adjust your DOF calculation to account for the increased magnification.
Re: Am I asking too much of a 50d plus 70-200 f/2.8
I think you misunderstand what I mean, I wasn\'t talking about \"crop factor\". DOF is not an all-or-nothing thing; it deends on print size, because there really is only one distance where things are truly sharp at any magnification. At other distances, whether or not it is sharp depends on how closely you are looking. If you print a slightly blurry image to a 2x3\" print size, or look at it on your small camera\'s LCD, you won\'t see the blur, thus everything is \"in the DOF\". But suddenly if you look at an 8x10\" print, or \"100% view\" on the monitor, the blur shows up and it\'s magically \"out of the DOF\".
DOF calculators assumes a standard *print* size, which is what I\'m talking about here. If you look at the original image (not the full size one, just the resized one) it looks reasonably sharp. It would look sharper if she were actually in true focus, but she\'s still within DOF, though just at the edge of it because you can start to pick up some softness (e.g. in her leg).
DOF doesn\'t mean *in focus*, it means *looks sharp at whatever print size*. Thus DOF calculators really should include print size & viewing distance in their calculations. Instead they usually just assume 8x10 print at arms length, or something like that.
volyrat wrote:
The DOF calculator does take into account that it is a 1.6 crop camera. Still says I\'ve got 2 feet of DOF @ f/2.8.
walter23 wrote: volyrat wrote:
The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1\' in front and 1\' behind.
With 2 feet of DOF, do you think that\'s the problem?
DOF calculations assume a standard print size. If you look at the standard web-sized version (your first image), she is sharp - within the DOF, albeit at the front edge of it (so not as razor sharp as she would look if she were truly in-focus). It\'s only when you start looking at magnified crops that you see where focus falls off. If you\'re going to be scrutinizing at 100%, you need to adjust your DOF calculation to account for the increased magnification.
Re: Am I asking too much of a 50d plus 70-200 f/2.8
I think you misunderstand what I mean, I wasn\'t talking about \"crop factor\". DOF is not an all-or-nothing thing; it deends on print size, because there really is only one distance where things are truly sharp at any magnification. At other distances, whether or not it is sharp depends on how closely you are looking. If you print a slightly blurry image to a 2x3\" print size, or look at it on your small camera\'s LCD, you won\'t see the blur, thus everything is \"in the DOF\". But suddenly if you look at an 8x10\" print, or \"100% view\" on the monitor, the blur shows up and it\'s magically \"out of the DOF\".
DOF calculators assumes a standard *print* size, which is what I\'m talking about here. If you look at the original image (not the full size one, just the resized one) it looks reasonably sharp. It would look sharper if she were actually in true focus, but she\'s still within DOF.
DOF doesn\'t mean *in focus*, it means *looks sharp at whatever print size*. Thus DOF calculators really should include print size & viewing distance in their calculations. Instead they usually just assume 8x10 print at arms length, or something like that.
volyrat wrote:
The DOF calculator does take into account that it is a 1.6 crop camera. Still says I\'ve got 2 feet of DOF @ f/2.8.
walter23 wrote: volyrat wrote:
The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1\' in front and 1\' behind.
With 2 feet of DOF, do you think that\'s the problem?
DOF calculations assume a standard print size. If you look at the standard web-sized version (your first image), she is sharp - within the DOF, albeit at the front edge of it (so not as razor sharp as she would look if she were truly in-focus). It\'s only when you start looking at magnified crops that you see where focus falls off. If you\'re going to be scrutinizing at 100%, you need to adjust your DOF calculation to account for the increased magnification.
Re: Am I asking too much of a 50d plus 70-200 f/2.8
Yes, but it think you misunderstand what I mean. DOF is not an all-or-nothing thing; it deends on print size, because there really is only one distance where things are truly sharp at any magnification. At other distances, whether or not it is sharp depends on how closely you are looking. If you print a slightly blurry image to a 2x3\" print size, or look at it on your small camera\'s LCD, you won\'t see the blur, thus everything is \"in the DOF\". But suddenly if you look at an 8x10\" print, or \"100% view\" on the monitor, the blur shows up and it\'s magically \"out of the DOF\".
DOF calculators assumes a standard *print* size, which is what I\'m talking about here. If you look at the original image (not the full size one, just the resized one) it looks reasonably sharp. It would look sharper if she were actually in true focus, but she\'s still within DOF.
DOF doesn\'t mean *in focus*, it means *looks sharp at whatever print size*. Thus DOF calculators really should include print size & viewing distance in their calculations. Instead they usually just assume 8x10 print at arms length, or something like that.
volyrat wrote:
The DOF calculator does take into account that it is a 1.6 crop camera. Still says I\'ve got 2 feet of DOF @ f/2.8.
walter23 wrote: volyrat wrote:
The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1\' in front and 1\' behind.
With 2 feet of DOF, do you think that\'s the problem?
DOF calculations assume a standard print size. If you look at the standard web-sized version (your first image), she is sharp - within the DOF, albeit at the front edge of it (so not as razor sharp as she would look if she were truly in-focus). It\'s only when you start looking at magnified crops that you see where focus falls off. If you\'re going to be scrutinizing at 100%, you need to adjust your DOF calculation to account for the increased magnification.
Re: Am I asking too much of a 50d plus 70-200 f/2.8
Yes, but it still assumes a standard *print* size, which is what I\'m talking about here. If you look at the original image (not the full size one, just the resized one) it looks reasonably sharp. It would look sharper if she were actually in true focus, but she\'s still within DOF.
DOF doesn\'t mean *in focus*, it means *looks sharp at whatever print size*. Thus DOF calculators really should include print size & viewing distance in their calculations. Instead they usually just assume 8x10 print at arms length, or something like that.
volyrat wrote:
The DOF calculator does take into account that it is a 1.6 crop camera. Still says I\'ve got 2 feet of DOF @ f/2.8.
walter23 wrote: volyrat wrote:
The DOF calculator that I use says at 50 ft, 200mm, 1.6 crop and f/2.8, I should have about 2 feet of DOF- 1\' in front and 1\' behind.
With 2 feet of DOF, do you think that\'s the problem?
DOF calculations assume a standard print size. If you look at the standard web-sized version (your first image), she is sharp - within the DOF, albeit at the front edge of it (so not as razor sharp as she would look if she were truly in-focus). It\'s only when you start looking at magnified crops that you see where focus falls off. If you\'re going to be scrutinizing at 100%, you need to adjust your DOF calculation to account for the increased magnification.
Nov 08, 2009 at 01:36 PM
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