notBert Loc: Ft. Collins, Colorado

Is the OM to Canon EF this one from Fotodiox? -- LINK2>

https://fotodioxpro.com/collections/lens-mount-adapters/products/om35-eos

I am looking for an adapter to fit Zuiko rectilinear fisheye, 40mm, 85mm 75-150 lenses and a 300mm Tokina all of which were used on OM 2 &4 cameras to Canon 6T body. TIA

JimH123 Loc: Morgan Hill, CA

If you unscrew this OM mount from the lens, what is the size of the screw mount behind it? Do you have an m42 rear lens cap that you could try to screw onto it (without forcing it)? In googling Samyang 100-500, I find little information. And no information about the mount. One user did mention that if someone were to attack you, that this lens would make a very lethal club.

FYI:

m42 is 42mm x 1mm where the 1mm is the thread pitch. T-Mount is 42mm x 0.75 where the thread pitch is 0.75mm. Also be aware that there is a 48mm variation of the T-mount also which provides a wider opening to prevent vignetting with a FF camera.

User ID

`



Can't happen. Other than a very few very
special purpose [usually macro] adapters,
you cannot physically stack adapters in a
manner that would prevent infinity focus.

IOW you can't stack 2 "camera brand to
camera brand" adapters between a lens
and a body. Brand-to-brand adapters do
not fit together like that.

=========================

FWIW, an example of a special exception
is Nikon body to Leica screw lens [M39].
It will put a Leica lens on a Nikon body,
which will be focused on the dust on the
front element ... no infinity focus. Its real
purpose is to fit enlarger lenses to Nikon
bellows or tubes.

.

User ID

T2 and M42 are verrry similar threads.
In most cases off user error, one can
screw a T2 mount onto an M42 lens to
a depth of less than 2 threads ... and
then realize the error.

BUT ! Tolerances can be sloppy and
aluminum is soft. Someone may have
lubed the threads and got a good grip
and force-fit a T2 mount onto a set of
M42 threads ... which would be verrry
hard to unscrew years later :-(

The text description sugggests either
a permanent OM-mount version or an
M42 version equipt with an added-on
M42 to OM adapter. In either case an
OM to EOS adapter will put the lens
onto an EOS body.

If it's an M42 version wearing an M42
to EOS adapter, don't worry about the
use of two adapters at once. The M42
to OM adapter is secure cuz threaded
adapters are foolproof compared to
bayonet-to-bayonet adapters. IOW it
is OK to treat an M42-to-OM adapter
as if it's an original part of the lens it
is screwed onto.

If the 100-500 Samyang is the one
pictured below, it is DEFINITELY NOT
a T2 mount. It's a more modern SLR
lens with auto-iris and meter coupling
for a film era camera.

(Download)

User ID

`

The OM flange depth is 0.54mm deeper
than for M42. If both mounts were the
same diameter, this means one cannot
build an adapter for M42 lens onto OM
body. HOWEVER, if the OM body flange
diameter is much wider than the M42
lens mount, one can machine an inset
"step down" adapter that is also milled
down on its face to bring the M42 lens
mount 0.54mm closer to the film plane
and provide normal infinity focus.

The OM throat is 46mm and M42 just
happens to be 42mm, barely enuf to
possibly allow that 0.54mm set back
to get infinity focus. Chances are that
any adapter machined to such close
dimensions would be chromed brass,
not the typical black aluminum ... but
who knows.

.

blackest Loc: Ireland

just as an aside.
filter threads
Metric threads are always specified per thread turn. Today, retail filter diameters between about 30 mm and 86 mm have a 0.75 mm thread pitch. Below 30 mm filter diameter, the thread pitch is 0.5 mm; above 86 mm diameter, the thread pitch is 1 mm. Note that these upper and lower bounds of filter diameters are not hard; there are some filter threads with a diameter larger than 30 mm that have a 0.5 mm thread pitch, and some filter threads smaller than 30 mm that have a 0.75 mm thread pitch. But generally speaking, most lenses readily available in this range will have 0.75 mm thread pitch.

I've never found an adapter ring that converts 48 or 42mm, filter ring sizes seem to be available in 3mm increments e.g 58-55-52-49 - 46 i have also seen 39-49 and 37-49,52,55,58 and 37 to 30.5 mm (30.5mm is the same size as a 35mm film container cap) auxillary lens often use 12.5 , 37mm and 46mm. Extension rings can be something else ...

graybeard

This was quite some time back that I bought this lens. I said it could be a lethal club. I also said it was so awkward and heavy you needed a crane to use it. In truth, once secured on target, it gives decent enough exposures. It came with an OL mount, and I bought an OL/EOS adapter, which works the same way an M42/EOS adapter does, in that it allows a physical coupling. Using Manual mode on the camera, you can use it just as if you were back in manual/film days, which to me is "normal" while apparently to many today it is primitive and indecipherable. You are right tho about little info available on it. I got it from a Goodwill shop for $20.

User ID

`

I checked all the respected makers.
You cannot adapt M42 lenses to the
OM body flange for normal use.

.

User ID

`

Any time you encounter a T2 mount lens with
what might be a camera adapter on it, if the
adapter is for a typical SLR, the adapter itself
will be about 9mm from flat face to flat face.
A few will be a bit deeper, like the T2 adapter
for EOS which will be about 11mm deep, flat
face to flat face.

The flat face on the rear of a T2 lens, without
any adapter in place, needs to be 55mm from
the film plane/sensor.

This should help you to recognize T2 lenses
as being T2 lenses.

Flange distance for most SLRs ranges from
about 43mm to 46mm.

Thaz pretty much all you need to know ;-)

.

JimH123 Loc: Morgan Hill, CA

There are even step up/down rings on eBay. I have 42 to 48, 48 to 49, and several more sizes in both step up and step down. Also have a T2 to m42 adapter too.