Welcome to our community

Be a part of something great, join today!

Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

backfocus from EOS to PL

They are pretty close from my limited experience. As stills lens markings are approximate at best, just set backfocus with your PL mount lenses and let the EOS lenses fall where they may (assuming none of your lenses are waaay out, and can't focus at infinity. Note most stills lenses will focus beyond infinity by design to take account of mass manufacturing tolerances).
 
I have had issues changing mounts. And have been burned with back focus being out on the PL mount. Reluctantly, I ended up spending 4,500.00 on a Denz collimator to check BF on a regular basis. Maybe unnecessary, but great peace of mind, worth the money.
 
our red focus is dead on. setting it for pl and then swaping back and forth with no issues.
 
Resurrecting this thread because my issue matches the subject...

After adjusting backfocus for a PL Cine Zoom (Funinon Premier 24-180 T2.6) I get really great performance from the lens and the witness marks across the zoom range. So far so good. But when I switch to the Canon mount, my Canon lenses won't even focus to infinity. It takes about 6 turns (to the right) of the backfocus adjustment screw to get the Canon lenses to really agree with their (admittedly limited) witness marks. However, once I do this, several Canon lenses all seem to agree pretty well with each other and the camera.

What on earth could explain such a huge discrepancy between the RED Canon Ti mount and the RED PL Ti mount that six turns of the screw are needed?
 
Three Canon lenses (24 f1.4L, 24-105 f4L, 200 f2.8L) all agreed that they cannot tolerate the PL backfocus that makes my zoom work. And all three agreed that when the backfocus made the witness marks work for the 24 f1.4L, all three had good agreement with both witness marks and, of course, infinity focus. So it really seems that either my Canon mount, my PL mount, or both, are way out of spec.
 
Inevitable follow up question. Are both mounts RED or do you have a 'dumb' PL mount from a third party? I have one of the ebay PL mounts and it works great but I'm not convinced it's matched with the RED Canon mount.
 
Michael Tiemann said:
What on earth could explain such a huge discrepancy between the RED Canon Ti mount and the RED PL Ti mount that six turns of the screw are needed?
Click to expand...

Gavin Greenwalt said:
Inevitable follow up question. Are both mounts RED or do you have a 'dumb' PL mount from a third party?
Click to expand...

As I specified above, both are RED mounts (and both are titanium, in case that matters).
 
I assume the Canon lenses work fine on a Canon DSLR?


Note most stills lenses will focus beyond infinity by design to take account of mass manufacturing tolerances), so make sure when you are checking infinity on the Canons that you aren't turning the focus ring beyond infinity. If you're hitting the end point where the focus ring slips, you have focussed beyond infinity. This caught me out before I knew lenses could do that!


Otherwise contact Red support.
 
The Canon lenses work great on Canon cameras. And remember that my problem is that when the backfocus is set so that (1) the witness marks on the PL zoom match reality, and (2) the zoom stays in sharp focus across the focal length range (i.e., 16' is 16' at both the wide and long ends), then the Canon lenses cannot reach infinity, even when the Canon lenses are asked to focus "past" infinity. It really seems as if one mount or the other is missing a shim.
 
Something likely out of whack with with one of those parts. Those tolerances sound like they are out beyond what I and others have experienced. Maybe go to a rental house or a friend who has multiple mounts / reds and try to identify which part is out of spec.

Matt Uhry
www.mattuhry.com
 
Michael Tiemann said:
Resurrecting this thread because my issue matches the subject...

After adjusting backfocus for a PL Cine Zoom (Funinon Premier 24-180 T2.6) I get really great performance from the lens and the witness marks across the zoom range. So far so good. But when I switch to the Canon mount, my Canon lenses won't even focus to infinity. It takes about 6 turns (to the right) of the backfocus adjustment screw to get the Canon lenses to really agree with their (admittedly limited) witness marks. However, once I do this, several Canon lenses all seem to agree pretty well with each other and the camera.

What on earth could explain such a huge discrepancy between the RED Canon Ti mount and the RED PL Ti mount that six turns of the screw are needed?
Click to expand...

It is also quite possible that the PL zoom was not correct. I recently had a set of Zeiss primes from one rental house ans a couple of PL zooms from another. The lenses were not set up the same, so we had to choose which one to adjust back focus for.
 
Michael Tiemann said:
Resurrecting this thread because my issue matches the subject...

After adjusting backfocus for a PL Cine Zoom (Funinon Premier 24-180 T2.6) I get really great performance from the lens and the witness marks across the zoom range. So far so good. But when I switch to the Canon mount, my Canon lenses won't even focus to infinity. It takes about 6 turns (to the right) of the backfocus adjustment screw to get the Canon lenses to really agree with their (admittedly limited) witness marks. However, once I do this, several Canon lenses all seem to agree pretty well with each other and the camera.




What on earth could explain such a huge discrepancy between the RED Canon Ti mount and the RED PL Ti mount that six turns of the screw are needed?
Click to expand...


Michael,
If you're located in LA I'd be happy to check your PL mount back focus with my Denz. I also have a Canon Ti mount we can check on your Epic. Six turns of the adjustment screw is a massive correction…..
Best,
Steve

stevegreen123@gmail.com
 
Unfortunately I'm in North Carolina. I may have to head up to NYC to have things looked at.
 
I discovered the source of my backfocus problems: a previously unknown (to me) backfocus adjustment ring that was dialed in to one extreme of its range. Once I discovered this, I moved the sensor back to its happy place (with respect to Canon EF glass), then adjusted the backfocus of the lens (using the ring) to true up backfocus for the PL zoom. Now everything is in agreement and I'm happy. The moral of the story? RTFM, both Camera and Lens!
 
You must log in or register to reply here.
Back
Top