Inexpensive Chinese Contax Mount to LTM- Maybe a little work required.

Just recieved the Fotofox adapter in order to use with my Sonnar 50/1.5 on my mirrorless camera, and it works fine - so thanks for the heads up! I now have an alternative way to enjoy this lens.

However, I would like to correct the infinity position, which is a bit off compared to my Contax IIIa.

52292351694_2e991b26c9_h.jpg


I thought that I could loosen the 3 set screws and turn the front part of the adapter, but when I loosen the screws (so that they are a little above flush with the surface of the adapter) the front of the adapter is still too tight to turn.
I don't have a lens which fits the outer mount to help with the torque.

I am a little paranoid to loosen the set screws too much, as I am sure I'll never find them if dropped.

How much do I need to unscrew the set-screws to turn the outer part of the adapter, and how much torque is required?

Thanks for you suggestions.
 
When I am unscrewing set screws: I use a cafeteria tray lined with small bubble-wrap and while paper towels. Undo the set screws - if one falls out, does not bounce and easy to spot.

I just looked at the adapter, I put it on the J-9 to adjust, the screws had to come out farther than just flush to turn it. With the internal mount lens- does not make a difference in use. Getting the adapter in phase is critical with an external mount lens.
 
Sonnar Brian said:
When I am unscrewing set screws: I use a cafeteria tray lined with small bubble-wrap and while paper towels. Undo the set screws - if one falls out, does not bounce and easy to spot.

I just looked at the adapter, I put it on the J-9 to adjust, the screws had to come out farther than just flush to turn it. With the internal mount lens- does not make a difference in use. Getting the adapter in phase is critical with an external mount lens.
Click to expand...

Thanks for the suggestions Brian. I will try to unscrew the setscrews a little further and see if I can turn it. If not - no big deal.
I realise it doesn't make a big difference, but it would be nice to have the aperture scale in view when the lens is at infinity.
 
Hello.
I found the 8.5cm f/2 that within my budget in C(contax) spec.
There is C on the side of barrel but without ' ' next to the letter.
It surprised me that it focus correctly on Nikon S camera but not on Contax camera nor with the adapter on LTM camera.

Removing the front optical group I found a brass shim.
***EDIT*** Removing the whole optical group from the front of the len.

Maybe the previous owner custom it to Nikon S spec.
After taking this brass shim out, the lens focus almost perfectly on Contax camera.
I replaced the brass shim with DIY paper shim (reducing thickness) and it become Contax spec.
I'm verry happy with this solution.
Thank you again for very helpful information.

Here are photos from this lens shot in front of a mirror,
using f/2, closest focusing distance, focus on the letter of the front lens.

Nikon S and the lens with original brass shim, Kentmere Pan 400.

Leotax Model F attaching adapter with diy paper shim, Kodak Ultramax400.
 

Attachments

  • photo117853.jpg
    photo117853.jpg
    162.2 KB · Views: 16
  • photo117854.jpg
    photo117854.jpg
    176.2 KB · Views: 15
  • photo117855.jpg
    photo117855.jpg
    267.6 KB · Views: 15
etarbar said:
Hello.
I found the 8.5cm f/2 that within my budget in C(contax) spec.
There is C on the side of barrel but without ' ' next to the letter.
It surprised me that it focus correctly on Nikon S camera but not on Contax camera nor with the adapter on LTM camera.
Removing the front optical group I found a brass shim.
.
Click to expand...

The brass shim was between the first ("front") group and the second group?

Note that the front group is effectively the front element, there's a single lens at the front.

Are you sure this is the best method? Because the difference between Nikon and Contax could be compensating by moving the position of the whole lens assembly; changing the position between the 1st and 2nd lens groups probably changes the focal length as well.
 
Sonnar Brian said:
The Simple Method usually works- assuming the lens works well on a Contax/Kiev to begin with. I found the Menopta and earlier 1981 and 1882 Helios-103's to have a better build quality, a Few of the later ones required some filing here and there to fit the Mount properly. I've probably gone through 20 of these lenses.
Click to expand...

I also have a 82 H-103 versus an 83 H-103 and I also prefer the earlier. I have dissasembled mine and painted the lens edges black to give better flocking against flare. As well as the shiny parts (chrome barrel) on the rear of the lens.
 
flavio81 said:
The brass shim was between the first ("front") group and the second group?

Note that the front group is effectively the front element, there's a single lens at the front.

Are you sure this is the best method? Because the difference between Nikon and Contax could be compensating by moving the position of the whole lens assembly; changing the position between the 1st and 2nd lens groups probably changes the focal length as well.
Click to expand...

Sorry for my mistaken description. The brass shim is actually the main shim.
The whole lens assembly is removed together by rotating the most front part of the lens.
Thank you for your suggestion.
 
For the 'C' Nikon, the focus must rotate a few degrees more than the S-Mount version of the lens. You can adjust the main shim for a 'C' version of the lens to work better on a Nikon camera, but I would suggest testing when used wide-open and close-up through to wide-open at infinity. Most likely- you can adjust for one or the other, preferably wide-open/close-up, and stop down for infinity. The 8.5cm F2 Nikkor is over-corrected for spherical aberration. This means the focus will shift towards infinity when stopped down.

I did a calculation for the Leica Mount J-9, which is a nominal 84.5mm focal length. The focal length must be reduced to 83.2mm for perfect focus across range on a Leica. Focus error for a 'C' contax mount lens is about the same when used on a Nikon. For this particular J-9, after all the calculations were done: I polished down an LTM to M-Mount adapter to about 0.8mm to get better agreement. Trial and Error, worked better than before. But does not work as well as using the Chinese Adapter on a Contax/Kiev J-9 on the Leica.

Click image for larger version Name: FOCUSERR.jpg Views: 0 Size: 88.0 KB ID: 4798827
 
I received my Fotofox adapter today. I'm not familiar with this kind of adapters, so it was a bit of a puzzle. I replaced the bayonet clip with a nickel one from a scrap Contax I. Fits exactly and keeps the lens inside. The original part was too flimsy and didn't hold the lens properly.

The adapter displays infinity neatly and runs fairly smooth. I expect it to get smoother in time. I've put a few drops of oil in the screw thread.

I couldn't get the adapter on a Barnack, but I could get it on a screw to bayonet adapter. From the above I understand that the pre-war Sonnars fit well. I'm going to try the thing this afternoon with my uncoated nickel Sonnar f1.5 - 5cm (1628901) on the Leica MP.

I am surprised by the precision and the quality of the device. It's not a toy - and that for EUR 60. An instruction manual would however have been helpful.

The rangefinder of the MP is a bit off with the adapter mounted, but with my slanted screwdriver I can get it with ease on infinity. I am very curious. I've never shot with a Sonnar or a Nikkor on a Leica.

Erik.
 
I also just got one of these adapters and it mounts onto my ltm-m adapter but strangely not onto my iiia or iiic. I’m curious if you resolved this, Erik, or if anyone else ran into this problem and figured it out.
 
drangus said:
I also just got one of these adapters and it mounts onto my ltm-m adapter but strangely not onto my iiia or iiic. I'm curious if you resolved this, Erik, or if anyone else ran into this problem and figured it out.
Click to expand...

Like you I can't get my adapter on a Barnack - too bad - but I can put it on an LTM to M bayonet adapter. I can use Nikon S lenses on an M with it, which is already very nice. I also have a pre-war Sonnar 50mm f1.5. I'll try that one too. I've heard that prewar Sonnars have a slightly different fit than the later ones.

Erik.
 
Thank you, Erik. I’ve tried a post war 1.5 Sonnar and also a Nikkor 50/1.4. They both fit well. It’s nice to be able to use them on an M but I was really hoping to use them on my screw mounts.
 
The seller either switched suppliers to save a few pennies, or the manufacturer cheapened the design. I checked the most recent one bought- screwed into a Nicca III but not a Leica IIIf. The taper of the threads is off. I've found the same to be true on a couple of J-3's and J-8's, solved those by using a fine file on the threads. The last adapter I bought- could not align the external threads as could be done on the first two. The design has been changed, some minor cost-savings that limits the adapter to internal mount lenses. Too bad, the first two worked well enough. I contacted the Ebay seller, no reply.

The earlier adapters, now on my J-9 and Zeiss Triotar: both fit the Leica IIIf, same camera that the most recent adapter jams up on when screwing in. I just tested this.
 
  • Like
Reactions: JMF
Thank you for checking, Brian. It’s too bad they changed it. I was hoping to have some cheap(er) Sonnar fun on my old screw mounts but it looks like I’ll have to keep looking.
 
First shots with my 1934 Sonnar 50mm f1.5. I like the lens very much.

A shot with my Sonnar on the adapter. The focusing is stiff.

I think that when making this shot the adapter was not for 100% correctly mounted. The maximum sharpness is not on the head but on the leaves behind her. This shot is at full aperture.

More in this theatre soon.


gelatin silver print (sonnar 50mm f1.5 No.1628901) leica m3

Erik.

657-C-Carla-2e-Oosterparkst.jpg
 
Last edited:
  • Like
Reactions: JMF
I noted this over on another thread, but the info may be of interest to folks attempting to use the Fotofox adapter to mount Contax RF lenses on LTM cameras: The Head Bartender now has in stock Amedeo adapters for Contax RF to LTM and Nikon RF to LTM. Both the internal only mount and the internal/external mount adapters are advertised. I just ordered a Nikon RF to LTM adapter. Pricey, yes, but if past experience w/ Amedeo adapters is any guide, it should work much better than the cheap adapters from China.
 
I´ve seen the advertisements of the Head Bartender, but I understood he will send out only to the US and some other places, but not to Europe. I´ve been looking out on the internet, but there is no good information where and how to order the Amadeo adapter for the internal early Contax mount, in other words, for the 1934 Sonnar. Is there anybody with some good information about this.

Erik.
 
You must log in or register to reply here.
Back
Top Bottom