Remembering Christopher original question:
Say I take a Leica S2 with a 70mm f2.5 and compare shots with a Nikon d3x with a 50mm f 1.4, how will the dof compare:
At what f stop will the Nikon dof be approx equal to the Leica @ f 2,5?
Will this change if Nikon comes with a D4x at say 30 mp?
Is there som kind of multiplyer I can use across focalranges to get som idea of the dof similarities/differences?
Christopher
I've had the same question in mind, specially "how will the dof compare?" between 35mm and MF. I've been using a H4D-40 for several months, and I had the D3x (now only the D700) and I still have doubts regarding the DOF.
I have and example for Christopher, please correct me if I'm wrong.
Imagine that you are taking a picture of a family with a 100mm lens, f/4 at 8 meters of distance with a Nikon D3x, Leica S2 and Hasselblad H4D-40. Lens, f-stop, and distance doesn't change, you only change the cameras.
First you have to take notice that Leica, NIkon, and the H4d-40 have almost the same pixel density (6µm, 5.94µm and 6µm respectively) and therefore the same pixel per determinated area, or density.
The only thing that changes is the sensor size, that look something like this:
If you took the image with the H4D-40 (remembering 100mm lens, f/4 and distance of 8 meters), you could crop the image and get the "same" image of the Nikon D3x (with the same 100mm lens, f/4 and distance of 8 meters). You will get same image size, same angle of view, same perspective view and same DoF. That's only if you don't change any variable.
Leica S2 has more pixels horizontally. Here's an example:
Here's an example of the angles of view:
Here's an example if you downsample the Leica S2 and H4D-40 to get the same height of the Nikon D3x.
To me the catch is in the
framing and in the
distance from the subject. If you would like to frame the image the same way the nikon D3x looks (tighter), with the hasselblad h4d-40 and S2 (because the bigger sensor) you will need to get closer and as we know the closer you get to the subject at any fstop, the shallower DoF we get.
I would say that with the Hasselblad H4d-40,
framing the same way (closer distance to the subject) at f/4 the DOF will look like f/2.8 in the nikon D3x or about 2 stops, that's just my opinion, nothing scientific
, of course the perspective view would be different between the 2 images.