Alasdair Mackintosh wrote:<>
"I agree that the bit about wide-angle lenses is a bit of a red herring,
given the retro-focus nature of most SLR wide-angles. However, the fact
remains that *all* of the digital backs that you can get for
conventional
film cameras do not cover the full area of the film. The various digital
versions of 35mm SLRs do not have a 24x36mm CCD sensor, and they
typically
increase the effective focal length of a lens by 50%.
You can get CCD sensors that cover a 35mm negative, but only for medium
format backs, where the true film size is 60x45 or 60x60mm.
I can only assume that the reason why all these digital backs don't
cover
the full film area is because they cannot cope with the shallow angles
of
the incoming light at the edges of the film."
You're right it is a red herring, but the reason they don't cover the
whole area is not because of shallow angle rays. My colleagues tell me
that the CCD structure can image all of the rays that a 35mm lens can
produce, which you'll see from my table are really not that shallow.
I think the reason is cost. A digital back for medium format is aimed at
a market that can probably pay much more. My bet is that such a unit
would be many thousands of £. In the 35mm market, even high res 1/2" CCD
systems such as the Nikon are currently very much more expensive than
the equivalent film based body.
Silicon area just costs a lot.
Chris
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|