Andrew Dacey wrote:
> There's been a lot of discussion on the list lately regarding
> telecentric lenses and the debate over the performance of wide angles
> on a full frame sensor vs. a smaller sensor.
>
> I understand the principles of telecentric design, a digital sensor is
> not as sensitive to light hiting it at an oblique angle (compared to
> film) so you want your lens to be designed so that the light strikes
> the sensor as close to perpindicular as possible across the entire
> frame.
>
> What I'm wondering is why isn't this possible with a full frame (35mm)
> sensor? Is it simply a size concern? I know that Tamron (and likely
> others) has their Di series of lenses and I believe that part of that
> design is to make the light rays hit the sensor at more of a
> perpendicular.
>
> In other words, is it the case that telecentric lenses covering the
> 35mm frame can't be made for a 35mm sized body/mount or is it just
> that there haven't been any (many?) released to date?
>
> If it's just a matter of them not being released yet then I'd say we
> should expect to see C*n*n release more telecentric designs now that
> they've introduced a full frame sensor in something other than their
> flagship body.
Several factors meet (clash?) at that challenge:
Wide angle lenses for film are 'allowed' to be
non-telecentric, since film does not care so much.
There is 'only' the problem of a longer light path
to the edges of the frame. These lenses will be
problematic until sensors get more tolerant.
Could they? Should they? Must they? If the wides
have to be redesigned, a fully new concept can
be choosen all well.
Being fully telecentric makes neccessary a lens
mount wide enough to handle all gear involved. As
I understand, not all lens mounts from film cameras
meet that criteria.
The reason to go for full frame sensor, and with
'old' lens mounts, would be to enable users of older
film camera gear to use their stuff the same way
they used it with film. ALL their stuff, at least
all the lenses.
Now the market research folks start screaming. Is
there really a market for that approach? Is there?
Just selling new digital bodies to folks like us
with cabinets full of 'old' excellent lenses? That
applies for other brands too. I think tha market
potential is simply (considered) not large enough.
They are new generations of camera buyer not
'plagued' by inheriting 'good old' glass. I strongly
guess they outnumber us by far.
Andreas
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