Well, Skip, you've lost me now. I thought we were talking about DOF and
perspective with lenses of the same focal length, no matter the film format,
not equivalent FOV for different formats. :-]
Walt
--
"Anything more than 500 yards from
the car just isn't photogenic." --
Edward Weston
-------------- Original message ----------------------
From: Skip Williams <om2@xxxxxxxxxxxxxxxx>
>
> The answer is NO.
>
> Photo 1: 180mm lens, 6x9 film.
> Photo 2: 50mm lens 35mm film
> Photo 3: 25mm lens 4/3 sensor
>
> All three will have about the same FOV from the same camera position.
>
> All three will show the same perspective compression.
>
> At the same apertures, the shorter lenses will show much more depth of field.
>
> Skip
>
>
> ----- Original Message ---------------
>
> 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
> To: <olympus@xxxxxxxxxx>
>
> >
> >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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