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[OM] Re: Great E-1 150/2.0 pix on dpreview.com

Subject: [OM] Re: Great E-1 150/2.0 pix on dpreview.com
From: "Piers Hemy" <piers@xxxxxxxx>
Date: Thu, 2 Dec 2004 17:34:21 -0000
Yes, I see that clearly.

But typically we look at 10x8 prints.  So produce a 10x8 from each.  Would
they each appear to be as 'in focus' as each other? 

I would try it myself, but the batteries on my Graflex are flat.  Or
something. 

--
Piers 
 
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Walt Wayman
Sent: 02 December 2004 16:33
To: olympus@xxxxxxxxxx
Subject: [OM] Re: Great E-1 150/2.0 pix on dpreview.com

Exactly.  Skip explains it quite correctly, but allow me an example:

I have a 180mm Rodenstock lens I use fairly often with my 6x9cm Graflex
XLRF.  If I were to take a photograph of an object from a fixed point with
it on the Graflex and the 180/2.8 Zuiko on an OM, assuming the same aperture
is set on each lens, if I cropped a 24x36mm section from the center of the
6x9cm negative, it and the 35mm frame shot with the Zuiko would be, for all
intents and purposes, identical.

Walt

--
"Anything more than 500 yards from
the car just isn't photogenic." --
Edward Weston

 -------------- Original message ----------------------
From: Skip Williams <om2@xxxxxxxxxxxxxxxx>
> 
> > On a film camera, for a given focal length, as the format gets 
> > smaller, so the
> DoF gets narrower.
> 
> (I'm no optical engineer, just a hack.)
> 
> Calculation of DOF is independent of the film/sensor size.  This 
> assumes that DOF is really a measure of apparant sharpness based on 
> some minimum circle-of-confusion.
> 
> A 300mm lens that has an image circle large enough to cover a 5x7 
> piece of film produces the exact same image size as a 300mm lens on a 
> 4/3 camera.  The 4/3 camera only uses a small crop of the 5x7 lens' 
> image.  The DOF characteristics are the same.  That's why you 
> typically see LF photographers using f/45-128 to get enough depth of 
> field to cover reasonable subjects.  You could stop a 4/3 300mm lens 
> down to f/22 or so, but the long exposure times wouldn't make is usable,
whereas the LF lens is used for fixed subjects.
> 
> Your statement above should really say:  As image magnification 
> on-the-film/sensor stays constant, the DOF increases as the 
> film/sensor format gets smaller.
> 
> Skip
> 
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