[Leica] new Puts article

[hlritter at mindspring.com (Howard L Ritter, Jr)]

I still believe that what I posted before is correct: If you take two photos
at the same f/ ratio, from the same distance, with different focal length
lenses and different size sensors (or not, it doesn't matter), and then
print both pictures scaled and cropped to show the same area and the same
subject size, the pictures will look identical including the DOF.

The photo taken with the shorter FL lens will have a smaller CoC on the
sensor, but will have to be enlarged proportionally more to make the subject
the same size, offsetting the smaller CoC. The DoF with a smaller sensor and
shorter FL lens will be deeper only if the print is enlarged to the same
_degree_ (e.g., 15 x the sensor size) not the same image scale (e.g.,
subject's head 2" high), because the viewer will be looking at detail that
appears smaller and not see unsharp focus as well.

Same distance + same f/ ratio + same subject size on print = same DoF.

--howard

----- Original Message ----- 
From: "Adam Bridge" <abridge@gmail.com>
To: "Leica Users Group" <lug@leica-users.org>
Sent: Tuesday, June 28, 2005 4:16 PM
Subject: Re: [Leica] new Puts article


>I don't understand this, Henning.
>
> It seems to me that the depth of field is solely a fuction of the
> geometry of the lens/film system. That the print and enlargement has
> nothing to do with it.
>
> If I took an R8 with a 50 shot wide open at f1.4 I'd get some depth of
> field. I replace the back with the DMR. Same shot. Same depth of field
> but cropped.
>
> So then I open the images on photoshop and look at them. How does the
> depth of field change?
>
> So I'm confused but I could certainly be enlightened! :)
>
> Adam
>