Help! Olympus mount to M42 or Canon EF: I recently bought a Samyang 100-500mm lens on ebay. I could not get any info regarding the mount from the seller. I figured it would be a...

graybeard

I recently bought a Samyang 100-500mm lens on ebay. I could not get any info regarding the mount from the seller. I figured it would be a T-mount lens anyway, and I could put put my own T-mount on it. It seems however, that it is not a T-mount. It is labeled with an OM (Olympus) on it, and seems to be screwed on to the back of the lens. What I am doing is getting old manual lenses, then converting them via an adapter to an M42 mount, which I use on my Canon T3. I would appreciate any information from people who are familiar with Samyang lenses and/or Olympus mounts and adapters. Thank you.

Dngallagher Loc: Wilmington De.

graybeard wrote:

I recently bought a Samyang 100-500mm lens on ebay... (show quote)

Aren't the M42 mounts actually the screw mounts that are built into the lenses onto which a T-Mount adapter screws onto to mount to your brand of camera?

I have had several old manual lenses that had screw threads instead of a mounting flange onto which a T-Mount adapter for my camera mounted.

Perhaps if you posted a picture of the lens mount it would be clearer.

Cdouthitt Loc: Traverse City, MI

M42 is a screw mount. If you look at my signature, that's what my asahi and super tak lenses are.

johnmowry Loc: Northern Indiana, USA

I have a Fotodiox adapter for my old OM lenses to Canon EF, and it works well (tho totally manual) with the Olympus brand lenses. I have one off-brand that is a bit of a sloppy fit. It sounds like you have a M42 to Canon adapter, and I would not want to do a two step adaptation (OM > M42 > Canon).

graybeard

johnmowry wrote:

I have a Fotodiox adapter for my old OM lenses to Canon EF, and it works well (tho totally manual) with the Olympus brand lenses. I have one off-brand that is a bit of a sloppy fit. It sounds like you have a M42 to Canon adapter, and I would not want to do a two step adaptation (OM > M42 > Canon).

Yes, I have a Canon T3 and a few EF-S lenses. But quite a few more Pentax/Mamiya/Praktica etc screw mount lenses, and Vivitar tele extenders, that I wanted to use on it. So I bought some M42-EOS adapters, which work quite well. Now I have a non-screw mount lens, and I thought I could either A. get an adapter to convert it to screw mount, or B. get an adapter to mount it directly on the Canon. (or C. get 2 adapters). I am just fishing now to see how feasible this is, and if there is a better alternative. Do you think an OM-M42-Canon approach is unworkable, or just clumsy?

graybeard

johnmowry wrote:

I have a Fotodiox adapter for my old OM lenses to Canon EF, and it works well (tho totally manual) with the Olympus brand lenses. I have one off-brand that is a bit of a sloppy fit. It sounds like you have a M42 to Canon adapter, and I would not want to do a two step adaptation (OM > M42 > Canon).

Yes, I have a Canon T3 and a few EF-S lenses. But quite a few more Pentax/Mamiya/Praktica etc screw mount lenses, and Vivitar tele extenders, that I wanted to use on it. So I bought some M42-EOS adapters, which work quite well. Now I have a non-screw mount lens, and I thought I could either A. get an adapter to convert it to screw mount, or B. get an adapter to mount it directly on the Canon. (or C. get 2 adapters). I am just fishing now to see how feasible this is, and if there is a better alternative. Do you think an OM-M42-Canon approach is unworkable, or just clumsy?

macquesta Loc: North Carolina

If you use 2 adapters, you will move the lens further away from the sensor. It will likely not focus at all or will not focus to infinity, depending on the lens focal length. It would be best to use only one adapter: OM to EF. I am not sure if that would focus properly, but if things have worked well with other lenses, then it may be okay with the OM to EF adapter. Do your adapters have built-in glass?

johnmowry Loc: Northern Indiana, USA

graybeard wrote:

... Now I have a non-screw mount lens, and I thought I could either A. get an adapter to convert it to screw mount, or B. get an adapter to mount it directly on the Canon. (or C. get 2 adapters). I am just fishing now to see how feasible this is, and if there is a better alternative. Do you think an OM-M42-Canon approach is unworkable, or just clumsy?

I think you could convert the lens to an M42 and use your existing adapters. It may be a YS or similar type adapter used to convert the generic lens mount to the camera. My reason to avoid two adapters is clumsiness, and twice the chance for a poor fit. The OM to EF adapter does not have glass, as the flange to sensor distance for the EOS is shorter than most other systems.
BTW, have you had your camera focusing screen converted to the SLR style prism, or do you use the standard Canon screen (which is hard for me to focus)?

graybeard

macquesta wrote:

If you use 2 adapters, you will move the lens further away from the sensor. It will likely not focus at all or will not focus to infinity, depending on the lens focal length. It would be best to use only one adapter: OM to EF. I am not sure if that would focus properly, but if things have worked well with other lenses, then it may be okay with the OM to EF adapter. Do your adapters have built-in glass?

No they do not have glass, but they do have chips.

graybeard

johnmowry wrote:

I think you could convert the lens to an M42 and u... (show quote)

No, I have the standard Canon screen it came with. What is a YS type adapter?

johnmowry Loc: Northern Indiana, USA

graybeard wrote:

No, I have the standard Canon screen it came with. What is a YS type adapter?

A YS adapter is similar to a T adapter, but it provides auto aperture operation (a big deal in the 70's). I have a
Sigma and 2 Spiratone (remember them?) lenses. I don't think the auto aperture function will work on the adapters for the old lenses with any of the newer electronic cameras. Of course, someone will find an exception!

graybeard

johnmowry wrote:

A YS adapter is similar to a T adapter, but it provides auto aperture operation (a big deal in the 70's). I have a
Sigma and 2 Spiratone (remember them?) lenses. I don't think the auto aperture function will work on the adapters for the old lenses with any of the newer electronic cameras. Of course, someone will find an exception!

This thing doesn't come off easily, like a T-mount or TX mount would. I may have to unscrew it, but I want to be sure of what I am doing first. So I hoped some Oly users could help.

johnmowry Loc: Northern Indiana, USA

graybeard wrote:

This thing doesn't come off easily, like a T-mount or TX mount would. I may have to unscrew it, but I want to be sure of what I am doing first. So I hoped some Oly users could help.

I will post or send a photo of a YS mount later today. Mine are clearly (but small) labelled with a "YS" on the adapter. It sounds like an OM to EF adapter is the easier way to go.

johnmowry Loc: Northern Indiana, USA

Here's a photo of a YS mount lens.

graybeard

johnmowry wrote:

Here's a photo of a YS mount lens.

Not the same. Mine has 2 silver buttons to squeeze in, it says OM in it if I remember correctly. I will look at again later. In any case it mounts to an Olympus camera. I agree it sounds problematical if I got an adapter from Oly to M42 which goes to an adapter from M42 to EOS. It is just that I wanted all my lenses that weren't Canon EOS to be M42 so that 1. they could all then fit into my M42-EOS adapter and 2. so I could use any M42 lens with my 2X and 3X teleconverters. This is all part of my project to test cheap telephoto lenses to see how well they work. I have this Samsung 100-500mm ($18) with an OM mount, I have a Vivitar 400mm (free) that had a Nikon TX mount, which I converted to a M42 TX mount, and I have a Spiratone 500mm ($20) lens which I converted with a M42 T-mount. I also have a Hannimex 80-200mm and Vivitar 2X and 3X teleconverters (all M42). I want to test all of these and see which gives me 1. the most bang for the buck 2. overall practicality re length, weight, handiness etc. The winner will be a keeper. The losers go on sale on ebay.