Tanar 5cm Question

haempe

haempe

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Brian,
I read in another thread, that you also own a tanar 5cm.
I want to modify it for coupling to 0.7 m as some has done this with the Nikkor.
Can you take a look at it, whether I have difficulties to expect?
Any other hints?
I'm not experienced when it comes to mods like this.
Thanks,
 
The mod would be identical to the Nikkor. Place the LTM adapter on the lens, trace where the cut-out for the cam is. You need to file those threads down.
You must be VERY CAREFUL about keeping the filings out of the helical.

When i do this on a J-3 or J-8, I remove the Mount to do the filing.
 
Done.

Done.

Could not wait. Tried it. Works well. Coupling is now down till 2.25 feet.

attachment.php


Thanks again,
 
So, here are some pictures with the modified Tanar 50/2.
It looks like the lens have a serious backfocusing problem.
But it gives a nice creamy bokeh, so I hope for some guidance to resolve this... :angel:
All at F2; first 2 PolypanF in Rodinal 1+25, last PX in Rodinal 1+25.
 
Not much backfocus it seems. I suggest to add a very thin shim, or tape between adapter and lens. Start with teflon tape, for instance. And redo the test with a tripod.

Good filing job.
 
ferider said:
Not much backfocus it seems. I suggest to add a very thin shim, or tape between adapter and lens. Start with teflon tape, for instance. And redo the test with a tripod.

Good filing job.
Click to expand...

Thanks for the hint, ferider.
But damned, I should have done this before filing. Now is the notch no longer in the right place ... :bang:
 
haempe said:
Thanks for the hint, ferider.
But damned, I should have done this before filing. Now is the notch no longer in the right place ... :bang:
Click to expand...

If you have a spanner, take the optics out and put a shim inside. You can start with very thin paper to try.

Roland.
 
The notch will be in the proper place. The Tanar has a guide pin for the optics.

My Tanar 5cm f2 also has a back-focus issue. I am adding a 0.2mm braded wire shim for a stand-off. The Tanar uses a very thin ring shim, much like the Nikkor 5cm f2- but slightly larger in diameter. I'll report back on how the braded wire goes.
 
Brian Sweeney said:
The notch will be in the proper place. The Tanar has a guide pin for the optics.

My Tanar 5cm f2 also has a back-focus issue. I am adding a 0.2mm braded wire shim for a stand-off. The Tanar uses a very thin ring shim, much like the Nikkor 5cm f2- but slightly larger in diameter. I'll report back on how the braded wire goes.
Click to expand...

I added a paper shim between adapter and lens and then the filed notch wasn´t more in the proper place.
Now I removed the front part (with the optical elements) but I´m unsure, where the shim is to be placed.
 
Looking into the front of the focus mount with the optics module removed: The shim should be added on the rim that is just behind the guide pin for the optics module. It is deep into the focus mount. The optics module has a cutout that lines up with the guide pin. Put the shim on the ridge, line up the optics module with the guide pin, carefully push into place. Use the retaining ring to tighten it all up.

I use the aluminum seal from a plastic coffee can. It is about 0.1mm thick. I cut a thin strip, and twisted it so it formed two layers- like an aluminum string. Pushed it into place on the rim and carefully guided the optics module past it. Tightened it up, checking the focus as I went. The "braids" gave some spring action, so it essentially made a variable shim as I collasped it with the retaining ring. It is perfect at F2 on my M8. Sonnar focus shift, F4 back-focus.
 
Thanks for the explanation, Brian.
After some dumb looking and turning right, turning left, I found the place...🙄
I tried a 0,2mm copper rod, bend a ring and put it in place, I will report, what came out...
 
I can report some success.
The focus is now under 1cm off.
Many thanks for your help, very interesting mini-project for a beginner like me.
 
Looks good to me. Maybe very slight front-focus at F2 from the ruler picture. With Sonnar formula lenses, the focus shifts toward infinity as you stop down. Having it slightly front-focus wide-open improves things at F2.8 and F4.
 
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