VIP question- m42/m39

[kubakaznowski]

Hello to everyone!
A new Voigtlander Bessa L user from Poland, Europe here.

I have a v.i.p. question as I look forward to buy a nice wide angle
lense, but as far as people told me better (newer) lenses within
russian and german shelf are availible for m42 screw.

so as i have on my Bessa L body an m39 screw I bought
an adapter, reduction wich has an m39 screw (looking from down)
then it has about 1mm space and spreads to m42 screw.

Do you have any checked practically information on how
my focus distances will change whan using m42 lens via adapter on
m39 body (non reflex, non range finder, V Bessa L), and does
it all have sense since -maybe- someone can sugest buying smth
cheap for m39.


THX in advance...

 

[ClaremontPhoto]

There would be no rangefinder coupling, and the distance scale would be way out of whack because SLR's are thicker than rangefinder cameras (to allow space for the mirror) so the lens is further from the film. I can't see how you'd ever focus this set up.

 

[ampguy]

Jon is right, you'll have to do some calibration tests to work at all, and most likely lose infinity focus.

M42's do work well on m42 cameras, as well as K-mount slr/dslrs, and Canon cameras with simple adapters.

Nikon's are more difficult, as the adapters need some optics in them, at least for infinity focus support.

I've seen the adapters being sold, but I don't know that M42 fitted lenses are a good match for RFs.

 

[ClaremontPhoto]

As for good cheap lenses in Leica thread mount head for the FSU forum here and they'll soon tell you what the winners are.

 

[Jocko]

Hallo kubakaznowski!

Unfortunately the two commonest Soviet wide-angle M39 lenses are not really suitable. The J-12 35mm lens does not fit in Bessas due to the protruding rear element, whilst the Orion-15 28mm is seriously over-priced. The same is true of the rather rare Russar 20mm

The current Voigtlander lenses are excellent, and the obvious choice for a "cheap" wideangle would be the discontinued (but still available from Cameraquest) uncoupled 25mm Snapshot Scopar - but "cheap" is a relative term.

I believe that your M42 adaptor will give correct focussing - good quality ones most certainly do ( http://cameraquest.com/adaptnew.htm ) - but you will of course need accessory finders...
There is no easy answer, unfortunately,

Cheers, Ian

 

[rxmd]

Rangefinder coupling is completely irrelevant in the context of a Bessa L, which doesn't have a rangefinder to begin with.

If you don't want to buy Canon or Voigtländer M39 wideangles (which should start at about 150 EUR, that's I think about 600 złoty IIRC, unfortunately you can't use the cheaper Russian Jupiter-12 lens very well), then I would suggest getting a M39-M42 adapter tube (not a ring but a regular tube, in order to compensate for the different lens register of M42 and M39 lenses). One has to be a bit careful because there are a lot of adapter rings with improper thickness that are designed for use on bellows. Lens register on M39 is 28.8 mm, on M42 it's 45.46 mm. Proper adapter tubes shouldn't be hard to find, but you could have a machine shop make a brass adapter tube for you with a M39x26tpi male thread on one end and a M42x1 female thread on the other and a length of 16.66mm from the female end to the foot of the male thread. This should take a technician about ten minutes on a lathe. Then you can paint it black and use the cheap East German 28 and 35mm M42 lenses that eBay and other places are overflowing with. You'll have to get external viewfinders, though.

Philipp

 

[lubitel]

some of the J-12 lenses fit the bessa, I have a black one which does not interfere with the shutter on bessa-R, but the lightmeter does not work of course. you have to check it with the open shutter before you use it.

 

[kubakaznowski]

----Lens register on M39 is 28.8 mm, on M42 it's 45.46 mm.----

So please explain one more thing, is that LENS REGISTER is measured from film
surface to the last lens part, so why do I measure distances between screws,
If ofcourse I got it right?

 

[rxmd]

Basically lens register is the depth of the camera, from the mount to the film plane. With M39 and M42 lenses, lens register is measured from the film plane to the flat part of the lens mount where camera body and lens mounting flange are pressed flat together. The threaded part of the lens that goes into the body thread when screwing in the lens, doesn't count.

That's why when measuring the thickness of an adapter the threaded part doesn't get measured. Basically, the thickness of everything that has an internal thread gets counted, while the thickness of everything with an external thread doesn't get counted (see this link for English screw terminology).

Philipp

 

[kubakaznowski]

Thank you for your sophisticated reply. Just to ensure I wonder if the adapter I have which has about 5 mm space between the end of m39 screw and the beginning of
m42 screw will do?
Basicly is there any difference between M39 and M42 lenses apart of the screw.
Suppose they both have hypotheticly the same thread are there any other differences that affect the possiblity to focus on minimun and infinity...
Asking about last lens part construction on both m39 and m42

 

[Mazurka]

There would be no rangefinder coupling, and the distance scale would be way out of whack because SLR's are thicker than rangefinder cameras (to allow space for the mirror) so the lens is further from the film. I can't see how you'd ever focus this set up.

Why isn't that possible? The distance scale is perfectly useable with a proper adapter that retains infinity focus.

 

[rxmd]

Thank you for your sophisticated reply. Just to ensure I wonder if the adapter I have which has about 5 mm space between the end of m39 screw and the beginning of
m42 screw will do?

No, it won't. You will be able to take pictures, but they will be way out of focus if you focus by the distance scale on the lens. Basically all your pictures will be out of focus, and there will be no way of saying what is in focus and what isn't.

Lens register is important if you want the distance scale to be right and if you want to be able to focus at infinity. If your adapter is too short (or too long), focusing will be wrong.

Basicly is there any difference between M39 and M42 lenses apart of the screw. Suppose they both have hypotheticly the same thread are there any other differences that affect the possiblity to focus on minimun and infinity... Asking about last lens part construction on both m39 and m42

Mechanically there is little difference, but the whole optical construction is different. Any lens is built for a certain working distance from the film plane in order to focus correctly. This working distance is called lens register, and it's specific to the mount system (see this list). This is why mounting the lens at the correct working distance is important. An adapter with the correct length that mounts the lens at the correct working distance is called an adapter that retains infinity focus; with such an adapter it is possible to focus at infinity and the distance scale on the lens is correct. With the Bessa L this is important because there is no other way to guarantee focusing. So basically you need an adapter that has the right length.

Philipp

 

[rxmd]

Why isn't that possible? The distance scale is perfectly useable with a proper adapter that retains infinity focus.

But his adapter doesn't, it's just a plain ring for mounting lenses on bellows with no consideration for length or infinity focus whatsoever.

Philipp

 

[kubakaznowski]

Thank you...

 

[Mazurka]

But his adapter doesn't, it's just a plain ring for mounting lenses on bellows with no consideration for length or infinity focus whatsoever.Philipp

Oddly enough, I seem to recall someone saying "Proper adapter tubes shouldn't be hard to find." 🙄

 

[Dougg]

Hard to find, or easy; either way he will need to find a way to move that lens more than one cm farther from the camera body to achieve infinity focus. Rex is right, this adaptor won't do the job. If I were dedicated to this solution, then I'd seek out an adaptor with the correct register distance. But it may be one of those instances where the "cheap solution" turns more expensive than anticipated... and a nice used 25mm or 35mm Skopar would start to look attractively economical. 🙂