Telyt 280 f4.8 Adjustment

[spydrxx]

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I need some advice from experienced tinkerers in Leica land. I have an old Telyt 280 f4.8 which I use on a variety of cameras with two different focussing mounts...the regular one (shown in the attachment) and a second one, which is a Televit mount. My problem is shown in the second attached photo...both pictures were shot from a tripod with the lens at f8 focussed at infinity on some trees about 1800 feet away within one minute of each other. Taking into account any variation in ambient temperature or vapor in the distance between the camera and the subject, the picture using the televit mount appears slightly more in focus, to me at least, than the picture taken with the regular mount. Neither is perfect, as I had to shoot thru a window. Is there a simple way to adjust the regular mount to slightly retract the lens into it, at infinity, so that the focus is a little crisper. I know I'm splitting hairs, but in my mind the detail should be exactly the same. Thanks for your comments in advance.

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[telewatt]

Hello Steve,

 

I use the Telyt with the "Focorapid" (like the Televit but older!)...and the contrast is better! the original mount has more flare-problems.....

 

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regards,

Jan

[telyt]

the original mount has more flare-problems.....

 

That was my experience as well. The 280 f/4.8 with the helical focussing mount flared badly any time sunlight was near the front element but with the lens head on the Televit the flare control was much better.

[doubice]

Doug,

 

The Telyt pictured above is the first version of the lens. In your experience, did the second version which coupled directly to Viso II/III have the same problem? Could it be that the OUBIO adapter which had to be used with the first Telyt 280 version contributed to the flare?

 

All the best,

 

Jan

[jo_ernst]

SPYDRXX,

 

Perhaps a rotating movement of ca. 1 to 2 mm more than the actual infinity stop will help.

To achieve this, you should have a pencil, some good screw drivers and a tool to loose ring nut screws with a diameter of about 54 mm, further a dremel or a suitable cross-hair file. The work is not complicated at all and needs not more than about 30 min.

 

1) Dismount the tripod mount of your Telyt (2 screws)

2) Find a little securing screw beneath this mount, loose it completely and store it in a secure place (caution, rather tiny screw!).

3) Re-mount the tripod mount (see 4)).

4) Loose the back ring nut screw 54mm diameter with a suitable tool, using the tripod mount as a grip. Mark the now visible hole for the securing screw at the plane back side of the ring with a pencil.

5) Mount an OUBIO and dismount the back insert from your Telyt. Caution: Pull GENTLY.

6) Find at the bottom (=tripod) side of the insert two plates of brass, one thicker (the inner one) and the outer one, which is a little bit thinner.

7) From the LEFT or upper (look from the end of the lens twoards the front-lens) side of the thinner plate take away at first 1 mm using a Dremel with corund tool or a sharp little cross-hair file.

8) Remount the back insert. Push GENTLY.

9) Remount the ring nut screw temporary (pencil-mark and hole for securing screw should

correspond, however) and test your focus. The sign of infinity schould be now ca. 1 mm

at left of the center mark.

10) If focus is good now, dismount the tripod mount, align pencil-mark and hole again and srew in the little securing screw. Remount the tripod mount finally.

11) Else, do points 7) to 9) [and then 10)] again.

Good luck!

Regards, Joachim

[jo_ernst]

That was my experience as well. The 280 f/4.8 with the helical focussing mount flared badly any time sunlight was near the front element but with the lens head on the Televit the flare control was much better.

 

Telyt,

Glare: this is a well-known problem.

The reason is a rather glossy surface in the inner wall of the original focusing part

(Telyt 240 4.8, Telyt 400 5.0 as well). It can be seen if you look through the helicoil end with the lens part dismounted towards a bright lamp.

To solve this problem, I finally performed a hint from an astro-freak and took thin black velvet and some scotch of that type both sides are adhesive (I do not know the exact english word, sorry).

The inner wall is 'dressed' with back velvet now, and problems dedicated to flare caused by glossy surfaces are solved.

Besides, most ot the old fashioned analogue tele-lenses made by Leitz-Minolta are 'dressed' at the inner sides as well, but this is done already in the factory, not by me. So, that should be have had a reason .

If you do not want to 'dress' with velvet (some people are afraid because of dust or fluff): You can take Palpas - if you know where to get it from. Palpas is a dark gray *very* matte coating used by Hasselblad for their inner surfaces, but hard to find .

Regards,

Joachim