What a shambles!
dmo580 wrote in post #10212082
Well remember that 50mm in a 7D is like an 85mm FF equivalent, so if you want the same perspective on the 5D as 7D with a 50/1.8 you will stand at different distances.
To achieve the same perspective, you MUST stand at the same distance. The same result would be attained by cropping the FF accordingly, and when this is done, the DoF will be identical.
If you shoot from the same distance, yeah you'll get a slightly more than 1-stop difference (1.6x crop factor) in terms of bokeh.
Yes, there is a difference in DoF in this case, but there is also a difference in the resulting image. There is no difference in bokeh.
diabolus wrote in post #10212126
Yes, you should see a difference. With the 5D2, you will need to get closer to your subject to get the same shot you would see on your 7D. This difference in distance is what will give you the shallower DOF on a 5D2.
Again - if you change distance, you change perspective, so the results will not be the same. If you do change distance though, yes, there will be a difference in DoF, but that is true irrespective of what body is used.
sportsshooter50 wrote in post #10212168
For a valid depth of field comparison between cameras (crop and full-frame sensors) you have to use the same focal length and set at it the same f-stop.
The only variable would be the camera to subject distance.
Not so good. For that comparison, distance must also be held constant. The only variable should be sensor size.
You'll have to step back farther with the crop camera to get the same size image.
Bad. Perspective changes.
Therefore doing so increases the depth of field for the crop camera.
Or any camera.
Using a 50mm lens on one camera and a 35mm lens on the other camera doesn't seem like a good way to compare depth of field.
Why not? That's the only way to achieve compositionally identical images other than cropping the FF to the size of APS-C.
aboss3 wrote in post #10212020
I'm considering selling my 7D for 5D MK II, and wanted to know if there's a huge difference in the shallow depth of field when going full-frame? Let's say if we take 50mm f/1.8 lens on the 7D vs 5D MKII, will there be a noticeable difference when shooting portraits?
You are changing formats. The appropriate focal length to use to frame each shot will be different. What point is there in comparing the results of using the correct focal length for one format (e.g. 50 mm on APS-C), with the incorrect focal length for another (e.g. 50 mm on FF).
Establish where you need to be to achieve the perspective you want. Then, select the correct focal length for framing the scene given the format in use*. This will of necessity be different for different formats. Then, select the aperture you need for the DoF you want based on focal length, subject distance, and format. Then arrange shutter speed, ISO, or lighting to obtain correct exposure.
* If you don't have a lens of the correct focal length, you have the option of choosing one shorter and cropping, with some loss of resolution.