On Mon, 29 Oct 2012, Chris Tofu wrote:
I have a perfectly nice Nikon 12mpix, so its not on
account of being
cheap, though I am, and proud, and cheap people are the SOTE. But if I
were interested in salvaging a smallish zoom lense and fitting it to
this godawful Vivitar, just for fun, it came with with what I think is
called a barrel lense, which is threaded, what specs can I presume to be
1) what distance does the lens need to physically be from the "film"?
2) What distance is the lense mount on the camera from the "film"?
If #2 is greater than #1, it will be quite difficult. If the lens is
fairly small diameter, perhaps it can sit back into the camera, with a
recessed mount - watch out for needed clearance for mirror in the camera!
Or additional optics can be placed between the camera and lens - carefully
compare the difference between an adapter for using Canon EOS lenses on
Canon FD, verus the adapters for using FD lenses on EOS. One of them needs
extra glass in it to compensate for the unwanted "extension", and to
degrade the quality of the image.
If #1 is greater than #2, then you need to find/buy or MAKE an adapter
that fits the camera lens mount and the back of the lens, with the exact
correct thickness (any chage in the thickness affects the distance that it
In general such adapters will permit "manual" mode, but in most cases,
they do NOT successfully couple auto-focus, camera control of the
diaphragm in the lens, or camera knowledge of the current setting of the
There is an entire category on eBay for lens mount adapters, and the
COMMON ones get enough price competition that the cheap ones from China
cost almost nothing (I can get adapters to use C-mount (16mm/video) lenses
on Sony Nex for less than $5)
Most digital SLRs are too thick. (#2 is way too large). There is very
little interchange possible, other than maybe using T-Mount lenses (which
MIGHT be what you've got!).
The "mirrorless" interchangeable lens digital cameras are thin enough!
Micro4/3s and Sony-Nex are thin enough that they can easily use Leica
lenses (in manual modes, of course), and even C-mount.
The Pentax-Q is the only one thin enough to use D-mount (8mm movie).
(Leica screw-mount is especially useful, since that is what more than half
of enlarger lenses use, and those are "flat-field" lenses)
3) Is the focal length of use to you?
Micro4/3's and Sony-Nex (APS-C) have a CCD that is amller than a 35mm
frame, so you get less vignetting and a narrower angle. A 50mm lens on
one of them is like a 90mm lens on 35mm. Unfortunately, that leads to
ASSSHOLES wanting to use "35mm equivalent" as a unit of measure, sometimes
not even wanting to tell you what the actual focal length is! Damn it!
I KNOW what a 90mm lens is - it is an extreme wide angle for my Linhof,
bordering on a fisheye for my big cammera, a telephoto for my Bolex, etc.
For a "normal" lens on my Lumix, I want about 25mm and about 35mm on my
Grumpy Ol' Fred cisin at xenosoft.com