Epson R-D1 and DOF?

[jaapv]

Except and just to make it worse the human FOV is more than 130° equivalent to a 10mm on 135 not 40 or 50mm that its perceived to be

Correct. That is why at 30 cm viewing distance a 6x9 print looks like the FOV of a 90 mm lens. In the 40-ies and 50-ies when such prints were normal, 90 mm was regarded as the "ideal" focal length. Nowadays standard prints are larger, so 35 to 50 has the most natural look at normal reading distance.

 

[edodo]

I must say that the crop of modern CCD i.e 1.5 factor gives every photog a portrait lens equivalent with the most common prime on every bag the 50mm (75mm crop)/
But the major drawback is that you have still the depth of field of a 50mm lens. You need maybe a 1.2 or a f1 lens to counter act the crop factor.
I think that the crop sensor won't last because photogs still love the 80mm lens for portraiture because of the distance to subject plus creamy backgrounds advantages

 

[LCT]

As far as DoF is concerned, the 1.5x crop factor makes just loose one full stop in practice.
So those using their 75/2 at full aperture on a 135 RF should feel at home with a 50/1.4 on the R-D1

 

[edodo]

LCT it might be something like 1 full stop and a half
exemple:
full frame: 80mm lens f2 focus at 1 meter equal 0.019 meter or 1.9 centimeter DOF

crop sensor:50mm lens f1.4 focus at 1 meter equal 0.027m or 2.7 centimeter DOF

The difference is 0.8 centimeter, thats more than 40% more DOF, so its not equivalent even with a "full" stop

 

[LCT]

Does your calculation take the CoC reduction into account?
If i do the maths or use a DoF calculator i find that the difference is roughly one full stop.
For instance:
- LeicaM - 75/2 at f/2 - 0.03 mm CoC - 93.8 meter hyperfocal distance
- R-D1 - 50/1.4 at f/1.4 - 0.03/1.53 = 0.01961mm CoC - 91.1 meter hyperfocal distance
.... If i'm not wrong of course!

 

[Toby]

Right, I'm going to add my 2 cents worth. As I have always understood it a lens does not become different just because you shove it on another different format body. What does change is is the distance from the subject to fill the frame at any given format. In other words, if you want to take a head shot with a 50mm lens you will have to be that much closer with 35mm sensor than with a APS sensor and as any fool knows, as you get closer to the subject the DOF goes down, anyone who can read the distance scale on a lens knows that. So to produce an identical image in different formats with the same focal length the camera to subject distance changes and that is what changes the DOF

 

[jaapv]

You are correct, in theory. A lot of lenses do have some kind of distortion though (barrel or pincushion), visible at the edges. This is minimal on prime lenses, but not non-existant.

We've just read that the Elmarit-M 2.8/28 (the new one) has a distortion of less than 0.5 % (!!)