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[OM] Re: Figuring out depth of field with 4/3 adaptor

Subject: [OM] Re: Figuring out depth of field with 4/3 adaptor
From: "Piers Hemy" <piers@xxxxxxxx>
Date: Sun, 27 Mar 2005 22:37:21 +0100
Yes, true - but that isn't what I said! 

I described enlarging an entire 35mm shot vs an entire half-frame shot.

--
Piers 
 
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Walt Wayman
Sent: 27 March 2005 22:33
To: olympus@xxxxxxxxxx
Subject: [OM] Re: Figuring out depth of field with 4/3 adaptor

No, I think not.  Blowing up equal-size areas of an image shot with the same
lens, no matter what format the image fell upon, should produce the same
results.  It's the same degree of magnification, whether you're talking
about a 12x18mm portion of a 35mm frame or the same size section of an 8x10
in. piece of sheet film.  Just because the lens is projecting the image onto
a smaller format doesn't cause an increase in resolution or contrast, nor
does it reduce the COC.  Same lens=same image, same size, same resolution,
same DOF, same COC, same good or bad exposure, no matter what it's projected
on.

Walt

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

 -------------- Original message ----------------------
From: "Piers Hemy" <piers@xxxxxxxx>
> 
> That's true of the negatives, Walt, but don't forget that a half frame 
> negative is enlarged twice as much as a full frame negar=tive ti get 
> an 8x10.  That extra enlargement "magnifies" the out-of-fcous areas on 
> the final print.
> 
> Thus the convention that DOF is related to format, specificaaly the 
> size of the circle of confusion is related to the diagonal of the 
> format.  Smaller CoC gives smaller DoF, other things being equal.
> 
> Don't imagine that I am a stickler for the conventional view of DoF - 
> as it happens, I am not at all - but I do believe that the usable DoF 
> from a given lens will be different if a smaaler portion of the frame 
> ends up on a print of a given size.
> 
> --
> Piers
> 
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