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  • 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 :)

Thermally Stable Lens Mount ( this time around )

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Matt Uhry

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The lens mounts on all the Red 1's I've used shifts as the camera warms up. It's a pretty significant problem on many lenses. On my Cooke 18-100 from warm to cold it shifts a significant amount - 2 or 3 feet at a 10ft distance. On a MP 14mm it's quite nasty, 20ft cold is 30ft warm. Not acceptable guys !

Could you look into not using aluminum on the Epic and instead use Invar or at least Stainless ? It's not so much the mount itself but the standoffs that align the mount and the sensor plane. At least offer it as an upgrade for the cine lens - focus by scale crowd.

Aluminum is pretty much the worst metal ever as far as thermal stability goes.

Matt Uhry
www.mattuhry.com
 
That is so strange since i believe my mount is really solid. I work a lot on the set as a technician for my camera and tend to check every shot for focus and never find there to be a shift when the camera warms up.

In fact, because of your post I just did a check with a cool camera; I focussed it with the 1:1 pixel zoom with a 28mm lens wide open and let it warm up. After the camera got warm to the touch, the fan spinning full and the lens mount hand warm it was still spot on.
 
All the reports we have from the field... guys using them everyday for months... have been telling us the mount is rock solid. They check them every day out of precaution, but never need to adjust them.

I'm all ears. If there are real problems we haven't heard about, please let us know. We have been very sensitive to this issue since we changed to the adjustable (and much better) mount.

Jim
 
I thought the mount was stainless steel?
 
I've been hearing about problems with the mount. Problems with the big Optimo. Not many but some. Also I hear Clairmont is designing their own stainless mount for their red cameras, perhaps this is a rumor.
 
Matt, I had backfocus shifts with may RedOne and my Cooke. That was in Fabruary/March. The backfocus shifts were sever and a major problem. It happened with all lenses I used.

When the camera was cold all was fine, after half an hour or so the backfocus started to drift. 80 cm were 1m on an 18mm SuperSpeed.

I contacted Red and after some difficulties regarding e-mail/spamfolder etc... we solved the problem by tightening the screws on the mount. Apparently my camera was shipped with a lose mount. The backfocus shift never came back.

Hans
 
Jannard said:
All the reports we have from the field... guys using them everyday for months... have been telling us the mount is rock solid. They check them every day out of precaution, but never need to adjust them.

I'm all ears. If there are real problems we haven't heard about, please let us know. We have been very sensitive to this issue since we changed to the adjustable (and much better) mount.

Jim
Click to expand...

Sorry, but it's really not stable over the cameras warm up. I've tested it carefully several times, while shooting on stage and during a long lighting setups. On my cooke 18-100 @ 18mm A Putora chart set and sharp at 10ft will be focusing at 8.8 to 9ft once the camera warms up. Same thing with wide Ultraprimes and Master Primes.

One has to choose to set the mount to "warm" or "cold". Warm is probably the smart choice here but it's not one I want to have to make.

I think the current camera for the most part is great and like much about the new Epic designs, just pointing out an area that should be improved on the next camera. It's not that strange - aluminum has a poor thermal expansion coefficient and the red heats up quite a bit.

Have a look here for a list of various materials: http://en.wikipedia.org/wiki/Coefficient_of_thermal_expansion

Matt Uhry
www.mattuhry.com
 
Hans von Sonntag said:
Matt, I had backfocus shifts with may RedOne and my Cooke. That was in Fabruary/March. The backfocus shifts were sever and a major problem. It happened with all lenses I used.

When the camera was cold all was fine, after half an hour or so the backfocus started to drift. 80 cm were 1m on an 18mm SuperSpeed.

I contacted Red and after some difficulties regarding e-mail/spamfolder etc... we solved the problem by tightening the screws on the mount. Apparently my camera was shipped with a lose mount. The backfocus shift never came back.

Hans
Click to expand...

I'll check for proper torque on the mount screws.

Matt Uhry
www.mattuhry.com
 
I have not had this problem with my cameras. Perhaps that 18-100 has done some warping to the mount due. Sometimes I see AC's using the low bridge support wrong and they actually are pulling the lens downward and that puts alot of stress on the mount.
 
s816mm35mm said:
I have not had this problem with my cameras. Perhaps that 18-100 has done some warping to the mount due. Sometimes I see AC's using the low bridge support wrong and they actually are pulling the lens downward and that puts alot of stress on the mount.
Click to expand...

I've observed the same problem with master and ultra primes. Support situation on 18-100 seems OK.

Matt Uhry
www.mattuhry.com
 
macgregor said:
I´ve seen this problem with different sets of Superspeeds and different red ones. After some hours, the marks do not match.
Click to expand...

Hi,

I have seen it too on a few later cameras, but not on early cameras, did anything change in the production about sn 750?

Best

Stephen
 
I have definately had this problem. Especially outdoor nights if there is a 10degree or more celsius change the back focus will be way off. I had a night car explosion shot ruined because of this.
 
We'll look at this issue again internally if those of you that are having problems double check to make sure the mount is properly tight.

We did have some issues here awhile back with loose mounts. Tightening them solved the problem.

Jim

Jim
 
I have seen this problem with the 16mm Ultra Prime, All other lenses in the set seem to be fine, except the 16
 
Alex Carr said:
I have seen this problem with the 16mm Ultra Prime, All other lenses in the set seem to be fine, except the 16
Click to expand...

Hi,

Was 16mm your widest lens? Wide fast lenses are the most critical for FFD.

Stephen
 
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