Overturning a Lens

[costa43]

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Hi all

 

I’ve just picked up a 28mm Minolta and it brings up the 35mm framelines on my m9p. If I overturn it a touch the 28mm frame lines come up. Has anyone used a lens in this manner for a prolonged period of time without repercussion?

Thanks

 

[a.noctilux]

Of course you can use like that, just a couple of drawbacks not harmful

- the RF coupling can be out, to verify take the lens to infinity then check if it's right at long range

- the lens is not locked in place, so it can fall out, not likely in normal use

 

I use that sometimes only with M lacking field/frame preview lever.

If the M has the lever like your M9P, I just put under the lever something to lock it at the field in use, metro ticket, a piece of rubber cut to right thickness, etc.

[costa43]

Thanks Arnaud. In your experience does it actually affect the accuracy of the rangefinder permanently, or is it specific to the lens mounted?

[a.noctilux]

This will not affect the accuracy but the adjustment of whole distance range RF.

 

To understand this, we can consider the M's roller position which can be at different a bit from 12:00 (by construction and final adjust from factory).

The coupling ramp of the lens is adjusted for let's admit 12:00 of CLE ( = on the M roller), if you push further the lens, the 12:00 can be 11:50 at the point of contact.

Have a critical look at these three Leica M rollers position, comparing to 12:00 of black screw.

In real life the left M4's is the most adjusted to right (12:10 ?)

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[costa43]

6 hours ago, a.noctilux said:

This will not affect the accuracy but the adjustment of whole distance range RF.

 

To understand this, we can consider the M's roller position which can be at different a bit from 12:00 (by construction and final adjust from factory).

The coupling ramp of the lens is adjusted for let's admit 12:00 of CLE ( = on the M roller), if you push further the lens, the 12:00 can be 11:50 at the point of contact.

Have a critical look at these three Leica M rollers position, comparing to 12:00 of black screw.

In real life the left M4's is the most adjusted to right (12:10 ?)

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!

Thank you. When I focus at infinity with the Minolta it is slightly out when not overturned. When I overturn it the infinity focus is accurate. This is just on the rangefinder patch. The pictures are sharp in both circumstances. Depth of field compensates I guess. My only concern is lasting inaccuracy with other lenses on the RF. 

[a.noctilux]

👍

Don't your M-Rokkor 28mm have some white spots ?

Don't worry then, if the results are fine.

Just use the combo as you like.

 

Suggest another thing:

why don't you try 28mm aux. finder.

[costa43]

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Just now, a.noctilux said:

👍

Don't your M-Rokkor 28mm have some white spots ?

Don't worry then, if the results are fine.

Just use the combo as you like.

 

Suggest another thing:

why don't you try 28mm aux. finder.

 No I managed to find a clean copy. The glass is mint. I considered an external finder but having to critically focus via one viewfinder and compose via another is a bit of a faff for a walk around lens. Thanks for your help and input. I appreciate it.

[a.noctilux]

I use 28mm lenses ( like Winogrand even by then I didn't know who he was),

with aux, VF and not needing to RF focus, fine from f/5.6 or even f/2.8 at a couple of meters.

Even without looking in the VF (aux or M's), with some practices, good rate came quickly.

Just try it (...if you want to of course) without RF focus, adjust the distance at 'about' where the subject will be.

[costa43]

37 minutes ago, a.noctilux said:

I use 28mm lenses ( like Winogrand even by then I didn't know who he was),

with aux, VF and not needing to RF focus, fine from f/5.6 or even f/2.8 at a couple of meters.

Even without looking in the VF (aux or M's), with some practices, good rate came quickly.

Just try it (...if you want to of course) without RF focus, adjust the distance at 'about' where the subject will be.

Yes the 28mm is a dream in that respect. I might just do that and pick up an external finder. 

[84bravo]

The only negative thing with doing this is that you will lose the RF coupling at the closest distance.

[costa43]

5 hours ago, 84bravo said:

The only negative thing with doing this is that you will lose the RF coupling at the closest distance.

Hi. Just when I use the Minolta or with any lens?

[84bravo]

3 hours ago, costa43 said:

Hi. Just when I use the Minolta or with any lens?

Any time that you "overturn" a lens. There is no damage caused, only that the cam on the lens does not connect through the whole focusing range. Your lenses that bring up the proper frame lines won't be affected.

I did this with a Minolta 28mm when I had the lens and it worked well. I just lost the RF coupling at close focus.

[costa43]

On 12/1/2021 at 12:40 PM, 84bravo said:

Any time that you "overturn" a lens. There is no damage caused, only that the cam on the lens does not connect through the whole focusing range. Your lenses that bring up the proper frame lines won't be affected.

I did this with a Minolta 28mm when I had the lens and it worked well. I just lost the RF coupling at close focus.

Thank you.