Focusing Leica L-mount lenses on non Leica bodies

[LocalHero1953]

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I have a Blackmagic Cinema Camera 6k, which is L-mount. I use it exclusively for video with Leica L-mount lenses.
I have focusing trouble with a couple of the lenses, and want to find out if others have similar problems with Panasonic or Sigma cameras.

The BMCC6K is set up for manual focus, but there is a back button for one-off autofocus. There is a separate focus magnification button, and a focus peaking function.
This works fine with my 24-90 zoom, and with the Apo-Summicron-SL 35 and 75, and the Summilux-SL 50.

With the 16-35 zoom, pressing the back button causes the focus to move to out of focus and stop, even if it was in focus beforehand. I can manually focus if needed.
With the 90-280 zoom, it is unresponsive to the back button, and manual focusing appears to be inactive: I turn the ring and nothing happens.

All lenses are just fine on the SL2-S. They appear to be properly mounted and locked on the BMCC6k.
The BMCC6K has the latest firmware, as does the SL2-S (which has had the problematic lenses attached, so they should be up to date as well).

Has anyone else come across similar issues with their non-Leica bodies?
If there's no obvious reason, I'll contact BM and Leica and hope they don't blame each other.

 

Edit.
TL/DR The 90-280 seems to be working correctly now, but still not the 16-35.

There is no way to edit the lens settings on the BMCC6K. For video I would like to use linear focusing. So I set manual focus on the SL2-S to 180deg, then mounted both 16-35 and 90-280 to it, checked they were working and transferred them to the BMCC6K. The 90-280 now focuses properly. The 16-35 behaves as before. NB I have had the 90-280 on and off the BMCC6K several times today, so I don't think it was something as simple as a mounting error.

I checked what the 16-35 actually focuses to when I press the back button: it is the close focus point every time.

Edited February 18, 2024 by LocalHero1953

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[Babylonia]

 

Not having another camera than Panasonic.

 

vor 17 Stunden schrieb LocalHero1953:

If there's no obvious reason, I'll contact BM and Leica and hope they don't blame each other.

I would also contact Panasonic for the 16-35mm lens behaviour. (But from various sources it seems that their support is not that good??)
With the right attitude of them, they should be grateful that you are contacting them about these issues. So it can be solved by a firmware update.
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Edited February 19, 2024 by Babylonia

[LocalHero1953]

41 minutes ago, Babylonia said:

 

Not having another camera than Panasonic.

 

I would also contact Panasonic for the 16-35mm lens behaviour. (But from various sources it seems that their support is not that good??)
With the right attitude of them, they should be grateful that you are contacting them about these issues. So it can be solved by a firmware update.
-

To be clear, I have no Panasonic equipment!
My 16-35 is the Leica zoom.

[mkxndrs]

just one question, new user here. according to your edit, does that mean we can use linear focusing with stills lenses on the blackmagic cinema camera fullframe 6k? Is that a workaround?

Edited April 13, 2024 by mkxndrs
punctuation

[LocalHero1953]

2 hours ago, mkxndrs said:

just one question, new user here. according to your edit, does that mean we can use linear focusing with stills lenses on the blackmagic cinema camera fullframe 6k? Is that a workaround?

I found it works as long as you have another camera (in my case the SL2-S) where you can set the lens to linear focus. That setting seems to carry over when I mount the same lens on the BM. I have only tried it with a couple of lenses.

I have sold the Leica 16-35, so back button focus with that lens is no longer an immediate problem for me.

[mkxndrs]

wow, that's amazing to hear. appreciate the quick response. I have been looking for an answer for weeks about it.