D-O-F. cropped or full frame
Nov 9, 2011 08:18:05 #
If I take a picture with full frame sensor (Mark 1). then use the same lens same settings ( EF 24-105mm f/4.0) on a cropped sensor( 7D) from the same position. Next Cropping the full frame image to the same as the cropped frame image size. Isn't the depth of field the same on both images? if not, How did it change.? I hear depth of field is different between 'cropped ' and 'full frame'. Doesn't the Cropped frame just use less of the image projected by the lens? 5/8 of it hence the 1.6 factor.
Nov 9, 2011 08:36:16 #
Interesting question. DOF should depend on the lense, not the sensor BUT with the smaller sensor you have an effectively longer lense which will shorten the DOF.
I think. :)
I think. :)
Nov 9, 2011 08:50:46 #
The fundamental differences between full-frame sensors and 'cropped' sensors are price and field of view. (There are other technical differences, hence the price difference.) Depth of field may be different between the two systems when taking the same shot, but that's not to say there's advantages/disadvantages to either. With any camera system, if the DOF is not what you wanted, stop down, recompose, re-focus and take the shot again, regardless of which system you are using.
Nov 9, 2011 10:28:05 #
Maybe I answered my own question. using a 50mm f-1.8 at 10 feet the DOF is about one foot(more or less) full frame. Cropped sensor, the lens is close to an 80mm equivalent. but the DOF is still the 50mm lens making it appear that it has a deeper DOF. And yes I just sit around just thinking of stuff.
Nov 10, 2011 07:02:57 #
Do a mind experiment with this one. Take a photograph with full frame, print it, then with sharp scissors cut a portion of the photo out of the full print. Did the DOF magically change? :idea: Nope! Amazing it remained the same. Stephe certain aromatic inhalants aid in mind experiments, I note in your picture your eyes are dilated suggesting a smaller f stop and did that expand your thinking and reduce your DOF!:lol::twisted:
The lens is the lens, the f stop set to a particular f stop the only change is that the sensor gets smaller at the exact same distance from the lens mount (in focus point) so the smaller sensor did not get as much (width & height) of the image as the full sensor. :arrow: Area of image differed, but the amount of distance, near/far, that is in focus did not. :thumbup:
The lens is the lens, the f stop set to a particular f stop the only change is that the sensor gets smaller at the exact same distance from the lens mount (in focus point) so the smaller sensor did not get as much (width & height) of the image as the full sensor. :arrow: Area of image differed, but the amount of distance, near/far, that is in focus did not. :thumbup:
Nov 10, 2011 09:42:48 #
Stephe wrote:
Maybe I answered my own question. using a 50mm f-1.8 at 10 feet the DOF is about one foot(more or less) full frame. Cropped sensor, the lens is close to an 80mm equivalent. but the DOF is still the 50mm lens making it appear that it has a deeper DOF. And yes I just sit around just thinking of stuff.
Comment withdrawn - not applicable. Sorry! :-)
Nov 10, 2011 09:45:20 #
The DOF will be different on a full frame sensor vs. a cropped sensor, even when using the same lens with the same settings. This is because of the Circle of Confusion (CoC) factor, which is different for the two types of sensors. (.02501 on full frame and .019948 on cropped sensors) This does not seem like much, but makes a differance. Probably more so in close up and macro shots. The CoC changes the Hyperfocal Distance, thus changes the DOF. Although I knew what DOF was, I did not understand how it changed. So, I did some research. One site that was really helpful was posted recently, camersdojo/2011/07/08/how-to-calculate-depth-of field. Helped me a lot in understanding DOF. Now to take this knowledge to the field and take better photos!!
Nov 10, 2011 14:06:17 #
My reputation has a contusion, from that foul circle of confusion. Personally, I prefer to keep my error in hyperfocal local. Here is a site for free for calculations so critical.
www.dofmaster.com/
www.dofmaster.com/
Nov 10, 2011 17:43:58 #
It is questions like this one that Stephe posed that force us to learn more than we knew. So Stephe we should all thank you. Altho it may not change the way we shoot, certainly it will change the way we think. Live, Listen, Learn. d/p
Nov 10, 2011 19:44:37 #
Bridgeman wrote:
The DOF will be different on a full frame sensor v... (show quote)
Absolute hogwash!
DOF is determined strictly by relationship of aperture to lens length, in any given lens. This is a mathematical principle, regardless of film grain or sensor pixel density. DOF will be the same for all lenses of same length at same f/stop, regardless of lens manufacturer. Neither ISO nor CoC have any bearing on DOF.
Any given lens used on an 8x10, 4x4, 6x7, 6x6, 135, 126, etc. film cameras, or DX, FX, 4/3, or any DSLR camera, will result in exactly the same DOF.
Nov 10, 2011 20:28:48 #
Nikonian72 wrote:
quote=Bridgeman The DOF will be different on a fu... (show quote)
So could we put that down as being close to your last word on that then? :) Let me try you on another issue. Our friend JimH keeps telling us that when you put a 400mm lens on a crop sensor the focal length remains at 400mm and does not become a 640mm lens but merely a 400mm lens with a more narrow field of vision. Where do you stand on that question? And thanks.
Nov 10, 2011 21:32:55 #
gessman wrote:
Let me try you on another issue. Our friend JimH keeps telling us that when you put a 400mm lens on a crop sensor the focal length remains at 400mm and does not become a 640mm lens but merely a 400mm lens with a more narrow field of vision. Where do you stand on that question? And thanks.
The actual circular image projected by any lens is called field of view. If your sensor is big enough to capture that image, corner to corner, it is full field of view. If you substitute a smaller sensor in its place, the projected image has not changed, but that smaller sensor will capture only 75%, or so, of the projected image.
The narrower image captured by the smaller sensor is equivalent to placing a longer lens on the larger sensor. The difference factor (from FX full sensor to DX smaller sensor) for Nikon & Olympus is 1.5, and for Canon is 1.6.
A 400-mm lens on a smaller (DX) sensor (x 1.6) is equivalent to a 640-mm on a full (FX) sensor.
Nov 10, 2011 21:49:52 #
Nikonian72 wrote:
quote=gessman Let me try you on another issue. O... (show quote)
Thank you and I really admire and enjoy your images.
Nov 10, 2011 23:28:07 #
Nikonian72 wrote:
quote=Bridgeman The DOF will be different on a fu... (show quote)
You are right, it is just math. So lets take a 50mm lens with the f/stop set at f8 and a subject at 10'. On the 5D the DOF is 6.28 feet. For the 7D the DOF is 3.77 feet. That's a pretty big difference the math produces.
Nov 10, 2011 23:34:00 #
imagesintime wrote:
You are right, it is just math. So lets take a 50mm lens with the f/stop set at f8 and a subject at 10'. On the 5D the DOF is 6.28 feet. For the 7D the DOF is 3.77 feet. That's a pretty big difference the math produces.
As with any mathematical conclusion, please provide your mathematical proof.
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