Problem mounting the Helios-40 M39, anyone?

[thienhadebetanhhung]

<p>Hi all,<br /> <br /> I have a Helios-40, the previous silver version with M39 mount. I buy a M39-M42 mount off eBay (from Roxen who is kinda reputable) then use it together with an M42-EOS adapter to mount the lens onto a Canon 350D. It may be noted that the M42-EOS adapter + 350D set has been with me for years, I'm an M42 user. But now I have few problems:<br /> <br /> 1/ When screw this adapter into the mounted M42-EOS, <strong>this adapter doesn't place the lens to the right position</strong>. In particular, the built-in tripod mount (unmovable) stays on the top where the numbers to control focusing and aperture should be, the these numbers stay on the bottom. It looks like the adapter lacks of half a step but I'm not too sure. As the result, I cannot use the tripod mount, which I do need. And I cannot focus and control the aperture properly, too. <br /> <br /> 2/ (May be just the consequence of error 1) <strong>The lens becomes short-sighted</strong>. It must allow focusing from 85cm to 25m and infinity, but using this adapter, I can only focus between about 85cm and 4.5m, infinity is lost, too.<br /> <br /> Has any of you ever had or heard about the same problems? Would it be the problem with the adapter or the problem with this copy of the lens, or the problem of all the M39 lenses? Suggestions and advice are very much appreciated.<br /> <br /> Regards,<br>

Binh</p>

[paul_wheatland]

<p>Two problems: M39 lenses don't make infinity on film or DSLR cameras (exception Micro 4/3 with adapter). Next: certain FSU M39 lenses have a slightly different pitch on the thread and they all don't go to infinity! The adapter from Roxen may only allow Leica and Canon made m39 thread lenses?</p>

[ishi_p]

<p>Agree, An m39 lens is too short, it would need to go inside the mirror box. </p>

[Dustin McAmera]

<p> I wonder if the first responders realise the Helios 40 isn't a Leica/Zorki mount lens; it's intended for the older M39 Zenit SLR, so the depth of the mirror box isn't a problem. The Zenit M39 lenses should have the same back focus as an M42 lens (this lens is sometimes sold with a factory-supplied adaptor to allow it to be used on both older and newer Zenits).<br>

I have this lens on my M39 Zenit, and I just got it out for a look. The threads 'bite' with the lens right-way up (am I making myself clear? I mean, the lens thread enters the camera thread with the depth-of-field scale in the proper place at the top). It turns exactly three full turns to finish properly mounted, with the scale again at the top. Also, that puts the tripod mount at the bottom (may be worth mentioning that the tripod mount is on a collar, which can be loosened and turned - so you can mount it with the camera in portrait format, I guess).<br>

It seems most likely to me that your suggestion is right, Binh. It seems the innner thread of the adapter may not be properly aligned with the outer one. I tried unscrewing my lens half a turn, and infinity on the scale is indeed about four or five metres away. Alternatively, it may be possible that the rear plate of the lens has been taken off and put back on 180 degrees out; I've never taken mine apart, so I don't know if this can be done.<br /><br /><br>

I don't have an M39/M42 adapter, but I know Fedka in New York sells them (that's where I got my Zenit).</p>

<p><a>http://fedka.com/catalog/index.php?cPath=49&osCsid=7d0be9cce1c07f8b6c14ddacbed5d917</a></p>

<p> </p>

[eugen_mezei]

<p>Which M39? Leica/Zorki/FED or Zenit? Zenit M39 has the same flange distance as M42 so it should work. Look at your lens if it has the moving part that would actuate the rangefinder cam on a FED or Zorki. Good chances are this isn't present, just plain screw in thread, than you have luck.</p>

[t_nu_tamm]

<p>My russian-language repair manual from 1962 says that m39 Zenit has a working distance 45,2± 0,02 mm. <a href="http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html"> This site</a> says it's 45,46, like all Practica mount lenses. I believe first source more, since I've also heard elsewhere that in order to fully adopt an old zenit's lens to a new camera one needed not only an adapter ring but also had to cut some metal away from the lens flange.<br /> But i don't think 0,26mm causes that big error with a 85 mm lens... Your lens should still go to at least to 10-20 m. Can you post a picture of your adapter?<br /> About your first problem: it is really hard to cut two threads in a single metal piece so that they are in register with each other. Much easier when one side is bayonet: you cut the threads first and decide the position of bayonet lugs only after that. I have seen a few screw mount to screw mount adapters, and they all seem to rotate lens markings to a random position.</p>

[thienhadebetanhhung]

<p>Thanks all for the responses, they are really helpful.<br>

I can confirm that my lens was made in 1960 and was a Zenith M39, so there shouldn't be any problem with the lens itself unless I'm too unlucky to get a faulty copy (hopefully not). Again, there isn't any problem with the M42-EOS adapter, I have been using it with a number of M42 lenses and can always focus to infinity. It then turns out to be most likely that the M39-M42 adapter is not quite correct. As I said, it seems to lack nearly half a turn to get the tripod clolar down and the depth-of-field scaling up. A closer examination shows that the M39-M42 adapter is a bit thinner than the M39 thread on the lens, may be this is where the early-half the turn is missed.<br>

@Pete: It sounds like you have correctly simulated my problem, that's great! I hope it's not the case with the back plate anyway. I'll try to find a good adapter as I love this lens so much.<br>

@Tõnu: I cannot unscrew the adapter by hand, it's tight and sharp, I'll need to find a tool first. And ok, the tripod collar problem is not too big but the infinity focus is. And it's likely that the latter is just a consequence of the former.</p>

[t_nu_tamm]

<p>Binh, if you can see a gap between the EOS to M42 adapter and the rear flat surface of the lens mount, only then can you blame focussing issues to the faulty threads, rotation alone doesn't change anything optically. I asked for picture because I suspected that your M39 to M42 adapter may be some special version for focusing bellows or something like that, and happens to add space between lens and sensor?</p>