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Inexpensive Chinese m42 extension tube quality.
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PostPosted: Sun Oct 20, 2019 8:36 pm    Post subject: Inexpensive Chinese m42 extension tube quality. Reply with quote
I have been rescuing folder lenses and converting to m42. I buy aluminum m42 body caps drill a proper size hole for the base and use the original flange nut where possible. I have a couple of sets of vintage m42 extension tubes, and 3 different m42 helicals. I also have a nex m42 helical. But it has become a time consuming chore swapping out the extension tubes on each lens when I want a different look or FL. I was thinking of picking up a few more sets of low cost new extension tubes to just leave attached to the folder lenses (also enlarger lenses) but I had a helical adapter that ghosts badly with some lenses. Anybody have experience with the new extension tubes.?


PostPosted: Sun Oct 20, 2019 9:22 pm    Post subject: Re: Inexpensive Chinese m42 extension tube quality. Reply with quote
jamaeolus wrote:
I have been rescuing folder lenses and converting to m42. I buy aluminum m42 body caps drill a proper size hole for the base and use the original flange nut where possible. I have a couple of sets of vintage m42 extension tubes, and 3 different m42 helicals. I also have a nex m42 helical. But it has become a time consuming chore swapping out the extension tubes on each lens when I want a different look or FL. I was thinking of picking up a few more sets of low cost new extension tubes to just leave attached to the folder lenses (also enlarger lenses) but I had a helical adapter that ghosts badly with some lenses. Anybody have experience with the new extension tubes.?


Ideally, could you provide a link to the tubes you have in mind? I bought a set of (extremely) cheap PK bayonet tubes and they're so bad they even seize onto each other, I have reservations about using them on a camera! As for m42 tubes, second-hand tubes from recognised makers are so cheap on eBay I wonder if it's worth considering anything else! I use plastic m42 body-caps, much cheaper and easier to work than aluminium. can even cut the hole slightly undersize and screw the lens assembly straight into the plastic Wink

I'd guess your "ghosting" helical may have some bright spots inside. Black card tubes or discs with a hole in, strategically placed within the assembly, can often help resolve these problems. They can also help with low-level reflections from non-matt surfaces causing a loss in contrast. These older lenses project a much wider image circle than is necessary for modern digital sensors, all that extra light has got to go somewhere if it's not absorbed by a good matt surface Wink

Good luck Smile


PostPosted: Sun Oct 20, 2019 9:25 pm    Post subject: Reply with quote
I've been using all the old filters that turn up on lenses, which I don't want for use. After removing the filter glass I epoxy the first filter on to the lens body, then use as many more as I need to space the lens away, before using an Xmm to M42 male adapter which goes nicely into a 1mm M42 to CameraX adapter. The lens can then stay that way and is ready to mount at any stage. (Obviously only useful for lenses that have their own helicoid)

I haven't done any folder cameras yet, mostly rangefinders, but have a Retina IIIC ready for conversion.


PostPosted: Sun Oct 20, 2019 10:09 pm    Post subject: Reply with quote
If you are buying 1 set a 12-15 dollar is OK vs 3 dollar isn't much but for me the differential cost for 10 to 15 sets adds up. Just seeing what people's experience has been.


PostPosted: Sun Oct 20, 2019 10:14 pm    Post subject: Reply with quote
I purchased two of these sets. Just hollow, no automatic aperture mechanisms.
You can't get better for what you want to use them for!


PostPosted: Sun Oct 20, 2019 10:26 pm    Post subject: Reply with quote
Alun Thomas wrote:
I've been using all the old filters that turn up on lenses, which I don't want for use. After removing the filter glass ....


I've made a lens hood from a stack of de-glassed unwanted filters! I wanted a 46mm hood and had a stack of old filters I was never going to use ... works for me Wink

Alun Thomas wrote:
I haven't done any folder cameras yet, mostly rangefinders, but have a Retina IIIC ready for conversion.


Examine the Retina lens carefully before starting work, there's some awkward aperture coupling in that DKL mount. The Schneider lenses are really very good, I've got a complete set from my film days and use them on my Pentax DSLRs with an appropriate adaptor. However, if your camera has a Rodenstock lens, it may have a little more collector value and might be worth while selling on and replacing it with a rather more common camera with a Schneider fitted Wink

Good luck Smile


PostPosted: Mon Oct 21, 2019 12:02 am    Post subject: Reply with quote
kypfer wrote:


Examine the Retina lens carefully before starting work, there's some awkward aperture coupling in that DKL mount. The Schneider lenses are really very good, I've got a complete set from my film days and use them on my Pentax DSLRs with an appropriate adaptor. However, if your camera has a Rodenstock lens, it may have a little more collector value and might be worth while selling on and replacing it with a rather more common camera with a Schneider fitted Wink

Good luck Smile


Mine has an Xenon 50/2, it's the one where you can take the lens front off and fit either 35/4, 35/5.6 or 80/4 front section. Sitting in a box with a few other potential donor cameras just at the minute...


PostPosted: Mon Oct 21, 2019 9:53 pm    Post subject: Reply with quote
It looks like you may have to be your own test pilot here, jamaeolus. But I'd be very interested in how you find them if you take the plunge.

I hit the same problem as you, but have opted for lightweight bellows, one single and one double extension, as a solution in the first instance. If that doesn't work out for me, I'll be looking for a load of tubes too, probably.


PostPosted: Tue Oct 22, 2019 8:46 am    Post subject: Reply with quote
The cheapest sets can be a bit prone to galling, but if you are just using them the standardise the registration of home adapted lenses this shouldn't be an issue.
Perhaps a tiny amount of graphite/lubricant on the threads that you will want to undo might be worthwhile. Just be careful not to get it into the camera.

My sets have not been M42 tubes but bayonet types, which each seem to be in different threads. The MFT ones have M52 threads just the same as filter rings which has proved very convenient, as one of my helicoids is M52 & I can easily add threads to lenses from old UV filters or stepping rings...


PostPosted: Fri Oct 25, 2019 1:50 pm    Post subject: Reply with quote
Use helicals rather than extension tubes I have set similar to this. Search ebay for M42 helicals. You can get a direct mount adaptor Mine is M42-NEX flat adaptor so you dont have the extension a normal M42 one does. I can use just about any lens with these.

This is a normal selection



PostPosted: Fri Oct 25, 2019 3:25 pm    Post subject: Reply with quote
DConvert wrote:
Perhaps a tiny amount of graphite/lubricant on the threads that you will want to undo might be worthwhile.

This.

I have a couple of cheap M42 tube sets, and the threads are so coarse that they are very unpleasant to use.
A tiny dabs of teflon grease here and there had solved the problem.

philslizzy wrote:
Use helicals rather than extension tubes

But be careful, these helicoids often come with the ridiculous amount of lube that is just plain dangerous for the camera.


PostPosted: Fri Oct 25, 2019 5:08 pm    Post subject: Reply with quote
I have several helicals as well. I was just trying to set the lenses up "in the ballpark" so I didn't have to dig through my bins of adapters each time I wanted to switch to a different lens. I did pull the trigger and bought 5 of the cheapest sets. Big spender, set me back just over 15 bucks. I figure the ones nearest the lens would be unlikely to cause issues even if the coating was crap. I let yo know what I find out when they come in.


PostPosted: Fri Oct 25, 2019 7:00 pm    Post subject: Reply with quote
What about the cheap Mexican, cheap Korean, cheap US, cheap Pakistani, cheap German, cheap *. lol. And the cheap used... And by cheap we mean inexpensive.

Materials count. Mating surfaces too.

Yes, there are plastics.

Brass are probably best, however mating dissimilar metals can generate electricity leading to corrosion; mating aluminum with aluminum might be best practice.

Some of the aluminum alloys and anodizes are quite sturdy; some are quite soft not so long wearing.

Tools and workmanship count.


PostPosted: Sat Oct 26, 2019 3:15 am    Post subject: Reply with quote
I don't own an M42 set, but I do own a set of 52mm tubes that are Chinese and that I bought for cheap off eBay. They work just fine for what they are. The only cheap regular extension tube set I've bought so far has been a Nikon mount set. Honestly I don't have any complaints with it. The tubes do what they're supposed to do. No meter coupling mechanisms. Just tubes.

One problem I've come across with threaded tubes, like my 52mm set, is when one wants to unscrew them, one must be careful not to squeeze them when unscrewing them because this can cause a tube to get squeezed out of round, in which case it will bind against the tube it's mated to. As long as I keep this in mind, my 52mm tubes will unscrew with no difficulties.


PostPosted: Sat Oct 26, 2019 10:43 am    Post subject: Reply with quote
jamaeolus wrote:
I did pull the trigger and bought 5 of the cheapest sets. Big spender, set me back just over 15 bucks.


Wow. If they work out okay, that's quite a deal. Fingers crossed for you.
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