Buy cheap buy twice - M39 lens mount adapter

[Thury]

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1 hour ago, Ecar said:

Not quite. The focus range varies (whilst all lenses - hopefully - reach infinity, the minimum focus distance is not the same).

If you look at the schematics of the rangefinder, there is a direct fixed mechanical link between the cam roller and the rotating prism/mirror which moves the rangefinder patch image in the viewfinder. The position of the rangefinder cam is linked only to the distance. All lenses push the cam roller in the same position at infinity focus whatever their focal length or age M mount or LTM. When a lens has a 1m minimum focus distance, the cam simply is not allowed to move forward as far as with a lens that has a 0.7m minimum focusing distance but at 1m focus, the cam roller is in the same position whether you use a 21 or a 90mm lens.

Excluding the 6 bit coding system which can be deactivated and apart from the rangefinder cam roller position the only information transmitted from the lens to the body is the type of frames to display in the viewfinder (mechanically and by pairs so that the camera itself cannot know for sure which focal length it is working with). So it is not possible for the rangefinder to adapt its way of working to different lenses.

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[Ecar]

1 hour ago, Thury said:

If you look at the schematics of the rangefinder, there is a direct fixed mechanical link between the cam roller and the rotating prism/mirror which moves the rangefinder patch image in the viewfinder. The position of the rangefinder cam is linked only to the distance. All lenses push the cam roller in the same position at infinity focus whatever their focal length or age M mount or LTM. When a lens has a 1m minimum focus distance, the cam simply is not allowed to move forward as far as with a lens that has a 0.7m minimum focusing distance but at 1m focus, the cam roller is in the same position whether you use a 21 or a 90mm lens.

Excluding the 6 bit coding system which can be deactivated and apart from the rangefinder cam roller position the only information transmitted from the lens to the body is the type of frames to display in the viewfinder (mechanically and by pairs so that the camera itself cannot know for sure which focal length it is working with). So it is not possible for the rangefinder to adapt its way of working to different lenses.

Thanks for the RF 101 course, but my point was just that some lenses (old and new) go below the minimum Leica RF distance.

Also, while I'm no technology expert, wouldn't you need to recalibrate the whole sensor-to-processing chain every time you adjust the RF to make sure that the distance information is correct?

[Thury]

10 minutes ago, Ecar said:

Thanks for the RF 101 course, but my point was just that some lenses (old and new) go below the minimum Leica RF distance.

Also, while I'm no technology expert, wouldn't you need to recalibrate the whole sensor-to-processing chain every time you adjust the RF to make sure that the distance information is correct?

Sorry that I misunderstood your point. I was just not confident that my first post was clear enough.

You are quite right that if the lens goes below the minimum focusing distance, the information would be the minimum focusing distance and that would be wrong. You are also right that - theoretically at least - one would have to recalibrate the distance sensor when recalibrating the rangefinder but this being digital you probably only need to set the lens on infinity and tell the processor that this is infinity and set the lens to 1.5m and tell the chip that it is so, the rest it can compute.

Now, I'm not sure that you need an enormous degree of precision on this distance information as long as the point is only to adjust the in camera software corrections and store a distance information in the exif.

Waving the flag, one could even say that Leica introduced the lens focus distance information transfer to the camera body before any other brand. The thing being that it is mechanical and yet to be digitized.

[01maciel]

vor 19 Stunden schrieb UliWer:

Better and easier option than a dremel and other manipulative devices is just to switch lens detection off. Liveview will work without complaining, that it "feels" no lens. 

I tried it today and turned the lens detection on my M10 off.  Liveview works with my cheap M39 adapter and J3 lens. Thanks for that.

[UliWer]

12 hours ago, Ecar said:

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

Yes, I tried the Summaron and the Hektor with an adapter without the cutout. Other than I had assumed, the focus button is not hindered by the adapter in the region on the 6-bit-code, but only at the infinity lock. So if the Rayqual adapter has the cutout at this position and leaves the 6-bit-sensor covered, it will work.

I think I‘ll try to order it from US, as it seems not to be available here. 

[UliWer]

10 hours ago, jaapv said:

Assuming that one has only one old lens  

Well, though if one has more than one old 5cm lens, the EXIF won‘t help. Automatic lens detection is just the Leica  way to become unhappy.

I admit that I make a provisional exception for the 28 Summaron. I cannot rule out that there is some automatic correction which is helpful. The menu for the M 10 even has a manual entry for this lens - which is unusuable as long as you don’t have an adapter which covers the 6-bit sensor. 

[Ecar]

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1 hour ago, UliWer said:

Yes, I tried the Summaron and the Hektor with an adapter without the cutout. Other than I had assumed, the focus button is not hindered by the adapter in the region on the 6-bit-code, but only at the infinity lock. So if the Rayqual adapter has the cutout at this position and leaves the 6-bit-sensor covered, it will work.

I think I‘ll try to order it from US, as it seems not to be available here. 

No, unfortunately they are not easily available in Europe. I buy these from a Japanese vendor and have them shipped over. You can find them on eBay as well.

Edited August 11, 2021 by Ecar

[Ecar]

1 hour ago, 01maciel said:

I tried it today and turned the lens detection on my M10 off.  Liveview works with my cheap M39 adapter and J3 lens. Thanks for that.

Unless your adapter covers the 6-bit sensor (or your M10 is different from the others) chances are it won't work anymore as soon as you take it out of the house in the sunlight.

[Alberti]

Thanks for showing the problem with the Urth LTM>M adapter. They “wisely” nowhere - not on their home site, not amazon - show a picture of the camera side of the adapter, so one can see and check.

Note there are adapters with a short cutout that still have 6-bit. For my Elmar 50mm LTM I have used the Kipon 6-bit (great quality but maybe a bit stiff which I don’t mind); not readily available in the EU anymore; Amazon-CA not Amazon in EU.

• the alternative is the Fotodiox adapter at various shops. I will take that next.

Edited February 19 by Alberti

[Ecar]

15 hours ago, Alberti said:

the alternative is the Fotodiox adapter at various shops. I will take that next.

This thread started in 2021. We are now in 2025 and LLL is also making LTM->M adapters. All-brass and with the cutout. Dimensions are accurate. Better than Fotodiox IMO and not quite as good as Rayqual, but substantially less expensive. The main drawback is that they are not easy to code, if that's important to you.

[TomB_tx]

5 hours ago, Ecar said:

This thread started in 2021. We are now in 2025 and LLL is also making LTM->M adapters. All-brass and with the cutout. Dimensions are accurate. Better than Fotodiox IMO and not quite as good as Rayqual, but substantially less expensive. The main drawback is that they are not easy to code, if that's important to you.

I bought a set of the 3 LLL adapters, and the good points you mention are correct. However, the alignment of the "thread start" of the ltm thread to the M bayonet isn't as exact as with the original Leitz adapters, so the lens may align differently than intended. This is mostly a problem with the 35 f3.5 Summaron which has a narrow cutout for the camera cam follower to enter, and if the ltm is off on the adapter the RF can't focus the entire close range. Most lenses will work "OK" but it shows they don't fully duplicate the Leitz tolerances.

[RexGig0]

I have seen Japanese vendors, such as Japan Hobby Tool, listing Rayqual adapters on e-bay, shipping world-wide. I have not been afraid to order lenses, flashes, and accessories from Japan, for USA delivery. I have not yet, personally, ordered from Japan Hobby Tool, but see that they have a listing, at this moment, for one LTM-to-M adapter. 

DO keep in mind that Japanese sellers do tend  use the letter “L” to mean Leica Threaded Mount! L mount, in Japan, is not the same thing as SL mount.

For North American customers, Camera Quest sells Rayqual adapters. 

[Ecar]

5 hours ago, TomB_tx said:

I bought a set of the 3 LLL adapters, and the good points you mention are correct. However, the alignment of the "thread start" of the ltm thread to the M bayonet isn't as exact as with the original Leitz adapters, so the lens may align differently than intended. This is mostly a problem with the 35 f3.5 Summaron which has a narrow cutout for the camera cam follower to enter, and if the ltm is off on the adapter the RF can't focus the entire close range. Most lenses will work "OK" but it shows they don't fully duplicate the Leitz tolerances.

Thanks. It may very well be. I can't remember which adapter I have on my Summaron 35/3.5 LTM. I'm currently away from home, but will have a look next week.

[Ecar]

4 hours ago, RexGig0 said:

I have seen Japanese vendors, such as Japan Hobby Tool, listing Rayqual adapters on e-bay, shipping world-wide. I have not been afraid to order lenses, flashes, and accessories from Japan, for USA delivery. I have not yet, personally, ordered from Japan Hobby Tool, but see that they have a listing, at this moment, for one LTM-to-M adapter. 

JHT are a well-established and very reliable supplier. I have bought bits from them many times (incl. Rayqual adapters) and never had an issue. Shipping is also very fast.