Is the a difference in Depth of field between a DX & FX lens at the same equivalent focal length?
Just curious, thanks in advance for any responses.
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Difference in DOF between DX & FX
(13 posts) (11 voices)-
Posted 1 year ago #
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Yes, there is a difference. See http://www.dofmaster.com/dofjs.html A good DOF calculator.
Posted 1 year ago # -
Wow thanks, it appears that to achieve the DOF a 52mm 1.8 on fx would have you would need a 35mm 1.2 on dx!? That's a much greater difference than I expected.
Are there any other differences, maybe in distortion?
Posted 1 year ago # -
Between DX and FX one usually loses the equivalent of 1 stop in DOF, all the rest unchanged. But there's more to it: because to get the same composition (fill the frame with a head, for instance), with FX you have to stand closer, and that also affects DOF and changes perspective (flatness and subject relation to background)!
Would it be correct to say DOF is a function of magnification, aperture and sensor size, instead of putting it in terms of focal length, distance to subject, aperture and sensor size?
Might as well give up. Go out and shoot. I would, if I could.
Have a nice weekend :)
Posted 1 year ago # -
JSP said:
Are there any other differences, maybe in distortion?No - in that regards it reacts the same as cropping an image. FX lenses appear to have less distortion due to only the center of the lens being used.
JSP said:
Wow thanks, it appears that to achieve the DOF a 52mm 1.8 on fx would have you would need a 35mm 1.2 on dx!? That's a much greater difference than I expected.Crocodilo hit the nail on the head. It is easier to go longer (say 85mm 1.8) for better bokeh. Look for some comparison shoots of the 85 1.4 vs 70-200vr. Even if the aperture is 2.8 on the latter, it throws backgrounds out similarly as the 85.
Posted 1 year ago # -
crocodilo said:
Would it be correct to say DOF is a function of magnification, aperture and sensor size, instead of putting it in terms of focal length, distance to subject, aperture and sensor size?no. DOF is a function of focal length, aperture and distance to subject. nothing else.
why does sensor size affect this?
Because you are 1.5 the distance to your subject when framing the same shot on an FX vs a DX camera.To the OP. It makes a HUGE difference.
The 35 at 1.8 on a DX at 4ft to subject (i'd say a typical shot for me) has a DOF of 0.28'
The 50 at 2.5 on a FX at 4ft to subject (i'd say a typical shot for me) has a DOF of 0.28'
If I take a shot on with my 35 1.4 at 1.4 on my d700 at four feet from subject the DOF is 0.33'
If I take the same shot on with my 35 1.4 at 1.4 on my d300s at six feet from subject (same framing) the DOF is 0.5'
Posted 1 year ago # -
Depth of Field (DOF) rules of thumb:
1. As the aperture gets larger the DOF get shorter. The inverse is true as the aperture gets smaller the DOF gets larger.2. As focal length gets longer the DOF get shorter. The inverse is true as the focal length gets get shorter the DOF gets larger.
3. As the sensor/film format gets larger the DOF get shorter. The inverse is true as the sensor/film format gets smaller the DOF gets larger.
4. As the distance to the object gets shorter the DOF get shorter. The inverse is true as the distance to the object gets farther the DOF gets larger.
These hold true as long as all other variable stay the same. As was all ready posted check out the DOF calculator at: http://www.dofmaster.com/dofjs.html
Other good reading can be found at:
http://en.wikipedia.org/wiki/Depth_of_field
http://en.wikipedia.org/wiki/Circle_of_confusionThe very first post asked if there was a “difference in depth of field between a DX and FX lens”. There is no difference between lenses; there is a difference in depth of field with DX and FX sensors. I assume JSP really meant DX and FX Sensors anyway. The difference between DX and FX lens is just the size of the circle of light projected on the sensor. The FX projects a larger circle to cover the larger FX sensor. (caveat: Yes there are other differences in these lens, quality etc. but nothing to effect DOF) Remember focal length is focal length and it doesn’t change between sensors.
A mistake new photographer often make is to confuse DOF with sharpness and will use the smallest aperture in hopes of getting the sharpest image. The smallest aperture will get you the most area in focus but will often lose sharpness to diffraction. Often a couple of stops down from the smallest aperture will be the sharpest, depends on the lens of course.
Ken Rockwell has a good explanation of diffraction and some good example of boken.Posted 1 year ago # -
andrewz said:
3. As the sensor/film format gets larger the DOF get shorter. The inverse is true as the sensor/film format gets smaller the DOF gets larger.Backwards. As the sensor gets larger, so does the DOF. Go look at the DOF master site and keep fixed variables for a D300s and a D700....
BTW, it's a really good exercise to do this yourself with an excel spreadsheet and look at how the DOF changes as you move away from your subject.... Good graphing too.
Posted 1 year ago # -
At the same equivalent focal length and same entrance pupil size (usually results in similar lens size), both DX and FX have the same DOF. Read this for more info - http://www.josephjamesphotography.com/equivalence/
Posted 1 year ago # -
The above is not true. DX and FX have different Depth of Fiend. This is well documented everywhere. Even Wiki has that calculation and examples correct.
Posted 1 year ago # -
Posted 1 year ago #
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Let's continue this conversation over here:
http://nikonrumors.com/forum/topic.php?id=2165
I'm closing this thread because we already have one so similar. No offense intended, JSP.Posted 1 year ago #
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