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Throughout this project, I tested a fair number of LTM (M39) lenses. There are some fabulous lenses out there. I am in 100% agreement with the internet that there are bargains to be found with these older lenses. Moreover, if you are looking for lenses with soul, the old stuff is where it’s at. If, however, you are planning on adapting these lenses to an M-mount camera* there is an issue with the adapter that nobody talks about.

The problem arises if you plan to have an LTM lens + mounted adapter + rear cap in your camera bag. If you are like me and you might take two or three lenses out with you on a day of shooting or on vacation you will encounter this issue. 

The problem is that when you go to remove the rear cap, oftentimes, the adapter unwinds from the lens (it is a screw mount remember?) rather than releasing from the rear cap and you are left holding 1) your snappy vintage LTM lens in one hand and 2) an adapter stuck inside the rear cap in the other hand. In the following image, the adapter is the little silver sliver sticking up from the rear lens cap.

Look closely, the LTM-M adapter is extremely thin. There is nothing to hold on to when you are trying to get it unstuck from the rear cap. In my experience, the only way to get that adapter unstuck from the rear cap is with a tool like a car key or pen cap.

If you were just sitting around your house, it wouldn’t be a huge deal to get the adapter unstuck from the rear cap. This whole situation, however, becomes a bigger deal if you are in the middle of shooting anything other than garden gnomes or parked cars. If you have, for example, a human being in front of your camera, you will look like a complete dope with your fancy rangefinder camera while you stick a key in the back of the rear lens cap and fiddle around prying the adapter loose. I am pretty sure that Cartier-Bresson once said, “the decisive moment won’t happen if you are fiddling around with an adapter stuck in a rear lens cap.”

I am sure someone will comment that there are loose end caps and tight end caps and I am a complete imbecile for not knowing that there is some dude in Japan who makes specialty loose end caps so this doesn’t happen. But, if you a normal person (like me), you are busy, you are trying to keep your kid from contracting coronavirus, the dog just ate a tampon, and dealing with loose vs tight end caps is nonsense you would prefer not to deal with. 

I know what you are thinking. “Why don’t you just leave the adapter off and put it on when you need the lens?” That certainly works but then you will be lugging around threaded rear caps, bayonet rear caps, multiple adapters, and you will soon have a whole mess on your hands that I am not willing to deal with.

There is a lot of talk about “form over function” on this site when it comes to lenses because I believe that most lens reviews focus on minute differences in image quality but miss the fact that that you have to actually interact with manual focus lenses to make pictures and this can be difficult if you are photographing things other than garden gnomes. In this case, it is the opposite. Function is paramount. It seems that one function of an adapter shoot be that is won’t get stuck in the rear lens cap. In my hands, LTM-M adapters fail this test.

*Technical note: this is a non-issue for LTM to Sony (L39 to NEX adapter), LTM to Leica SL (L39-Sl adapter) or other mirrorless cameras. The adapter for cameras other than M mount cameras is much thicker so you can just pull it off with your hand. Check out the header image on this post. The black adapters on the right and left of the image are examples of how thick those adapters are. The one on the right is actually a LM-A7III but it is almost exactly the same size as the L39-NEX adapter.