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.
Tim Hughes
--- Moose <olymoose@xxxxxxxxx> wrote:
> Matthew Granger wrote:
> > Hi guys, does anyone know of an adapter that lets you use OM lenses on a
> > nikon digital body?
> Nope. Such a thing probably exists somewhere, smiply because people will
> make anything. However, it's not a good idea.
>
> The problem is what's called register distance, the distance from the
> lens mount on the body to the image plane. Lenses made for each mount
> take this into consideration.
>
> Nikon register distance in 46.5 mm and OM is 46 mm. so even with an
> adapter of zero thickness, an OM lens on a Nikon body would not focus to
> infinity. The only solution is an adapter with a negative lens built
> into it. This makes the effective combined focal length of lens plus
> adapter long enough for infinity focus.
>
> I really acts like a weak teleconverter. Not a terrible idea, but is
> does introduce an additional lens into the system. So in the old days of
> manual focus (MF) there were some such adapters. I don't know about OM
> to Nikon, but I once tried an M42 to OM. The cheap ones use a single
> element lens that was clearly not multi-coated. The whole business is
> bound to introduce some image degradation.
>
> So the answer is:
>
> 1. If you want to use your OM lenses on a DSLR, go Oly(4/3) or Canon.
> Both have shorter register distances than the OM mount, so there is room
> for an adapter with no optical elements. That is one significant reason
> for several of the Canon DSLRs owned by list members. Although I now
> mostly use AF lenses, I started out with a Canon 300D, mount converter
> and OM lenses.
>
> 2. If you decide that Nikon DSLRs are what meet your needs, just get
> Nikon mount lenses for them, current AF or old MF. Forget the OM lenses
> for that mount.
>
> Moose
>
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