Tim Hughes wrote:
> Modern photography tested some simple negative adapters and found they worked
> pretty well, mainly
> because the lens power required is very low so dispersion etc is limited.
> That giant MF website with cult lens info and lots of tech info, used to have
> exerpts from the
> modern tests.
>
Yeah, I'm aware of that. I thought it was on the Cult Classics page,
which I have saved, but it must be elsewhere.
In any case, while there is only modest degradation with the linmited
focal lengths tested, there is some, and the focal length is changed.
But more important are two factors that change with a digital sensor.
First, the better DSLRs seem to provide a greater test of lens quality
than film did. So the weakness of the adapters may appear worse.
Remember, the small sensors magnify the image circle designed for FF and
the FF sensors appear to resolve more problems than film did.
Second, the front surfaces of sensors, AA filters, etc. are very flat,
unlike film, and quite reflective. One of the major issues in making
lenses for digital turns out to be special care with the multi-coating,
to avoid problems from these reflections. And the old adapters had
lenses that I believe were single coated. At least the one I tried was.
Put such a lens way back close to the sensor, and you are asking for
trouble, I suspect.
I just don't see any point in encouraging someone new to this area to go
in this obscure and questionable direction.
Moose
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