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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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I've run into the issue on cameras from all different generations/batches. Primes, zooms... Even the 12:1. Chalk me down as another... But with dozens of cameras instead of one.

Thanks for re-investigating the issue. Invar is your friend. :)
 
The lens mounts on Scarlet and EPIC are quite a bit shorter than the RED ONE... and quite a bit less complicated. Any "expansion" issues should be quite a bit less than a RED ONE. But. Doing mounts in Invar is no big deal. They will certainly cost significantly more, but that is not a problem for you guys. :-) We aim to please...

Jim
 
Jannard said:
The lens mounts on Scarlet and EPIC are quite a bit shorter than the RED ONE... and quite a bit less complicated. Any "expansion" issues should be quite a bit less than a RED ONE. But. Doing mounts in Invar is no big deal. They will certainly cost significantly more, but that is not a problem for you guys. :-) We aim to please...

Jim
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Reasonable additional cost is not a problem. Invar is cool, but even stainless steel has about half the thermal expansion of aluminum and seems to work well enough on other professional digital cinema cameras which don't use invar standoffs to hold the stainless steel PV or PL mounts in place.

I'm not sure why the expansion / contraction of the FFD would be more or less if the materials ( aluminum ) were the same. The mechanical design should not matter. There's formula's out there, but I suck at math. But in concept a 52mm block or a 52mm tube of aluminum will elongate the same amount with the same amount of heat. My Brother in law is a material science PhD and I'll get him to show me how to calculate it correctly and get back with the actual #'s

Matt Uhry
www.mattuhry.com


Matt Uhry
www.mattuhry.com
 
Jannard said:
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
Click to expand...

I've had backfocus shifts too. By making sure the mount isn't loose, you mean all the tiny screws that are swapped out whenever switching from nikon to pl, right? How tight should they be?
 
Matt Uhry said:
Reasonable additional cost is not a problem. Invar is cool, but even stainless steel has about half the thermal expansion of aluminum and seems to work well enough on other professional digital cinema cameras which don't use invar standoffs to hold the stainless steel PV or PL mounts in place.

I'm not sure why the expansion / contraction of the FFD would be more or less if the materials ( aluminum ) were the same. The mechanical design should not matter. There's formula's out there, but I suck at math. But in concept a 52mm block or a 52mm tube of aluminum will elongate the same amount with the same amount of heat. My Brother in law is a material science PhD and I'll get him to show me how to calculate it correctly and get back with the actual #'s

Matt Uhry
www.mattuhry.com


Matt Uhry
www.mattuhry.com
Click to expand...

At what point are you OK with thermal expansion? Is stainless OK with you even though it is less stable than invar? There comes a point of practical vs. theoretical. We certainly don't have a problem making anything you guys want, assuming you guys know what that is. There is a price to pay. If you want Zero movement ever (any condition and any lens), we need to make an invar mount that weighs quite a bit and is pretty expensive. No problem with us. If you want a stainless mount that is reasonable in weight, how much expansion can you tolerate and under what conditions. One thing we can't do is make 22 versions of mount materials. Well, I guess we can, actually. Cost is the only factor.

Jim
 
After considering our customers wishes, we will make the PL mounts in 3 versions. Aluminum, stainless and Invar. There will be 3 price points. Take your pick. Just consider that stainless and Invar will weigh more and cost more.

Happy Holidays.

Jim
 
as i understand epic and scarlet (like red one) will not have a hardfront. so even if the plate (with the 4 screws) plus the PL mount is made of invar, the body (made from aluminum) will still expand.

image of a hardfront (invar) where the PL or nikon mount is seated - not connected to the front housing made of aluminum

hardfrontxs2.jpg
 
What Nell has pictured is the design change I was getting at not the twisting part of the mount itself. Does Aaton actually use Invar in the hard front ?

Matt Uhry
www.mattuhry.com
 
no..aaton does not use an invar hard front. in film cameras the use of a hard front has less to do with thermal expansion but with reducing noise from the pull down claw and gears and with keeping tolerances. like in an arri 35BL or an arri 16BL or the new 416 the PL mount, hard front, pulldown mechanism and filmgate are precisely machined and rigidly interconnected..but only connect to the outside body (which is less precise (sand cast or die cast)) through rubber mounted connectors..it's actually more complex than that but that's the general idea.
 
Isn't Invar susceptible to wearing down over time. Are other materials added to strengthen it?

I'm all for a solution that is stable but doesn't send the cost sky high. Once the price/performance ratio gets too out of whack, it might not make sense. Having the option as Jim mentioned might be a good way to compromise. Although, having several mounts could make it confusing out in the field, so they would have to be distinguishable from each other I would think.
 
Jannard said:
After considering our customers wishes, we will make the PL mounts in 3 versions. Aluminum, stainless and Invar. There will be 3 price points. Take your pick. Just consider that stainless and Invar will weigh more and cost more.

Happy Holidays.

Jim
Click to expand...

That's pretty cool.

What of the sensor moving mechanism? I already wrote a bit about my concerns on that subject a few weeks ago. Will that mechanism be of similar thermal stability? The same question applies to the rest of the body as Nell mentioned.

Invar is the key word because it was mentioned once upon a time with the RED ONE and - for better or for worse - it has been elevated to "best mount ever" theoretical status in our collective minds. While it does have some awesome thermal characteristics, your point about bang:buck is a good one.

So what of a machined hard front design? Is that outside the realm of engineering based on the aforementioned adjustable sensor plan?
 
brook..what's the point of machining a hard front if it's not in invar or stainless steel? if it's in aluminum it will expand like the body..so you can leave PL mount attached to the body like we see in the renderings..no difference.

anyway..i think the scarlet and epics will run alot less hot so it might not be necessary.
 
Nell said:
brook..what's the point of machining a hard front if it's not in invar or stainless steel? if it's in aluminum it will expand like the body..so you can leave PL mount attached to the body like we see in the renderings..no difference.
Click to expand...

Trust me, I'm probably the most anti-aluminum mount guy here.
 
New product idea?

New product idea?

Re: the present problem and avoiding what happened to Finner.
Heater with controlling circuitry pulling power from the battery plate D connector. Camera is collimated at X degrees. Heater prevents lens mount assembly from dropping below X degrees. Batteries are cheaper than a reshoot. While I'm thinking about it, Anton Bauer has a hot swappable dual battery plate. Are there any other versions/options of a hot swappable dual battery plate?
 
Albert Malvaez said:
Re: the present problem and avoiding what happened to Finner.
Heater with controlling circuitry pulling power from the battery plate D connector. Camera is collimated at X degrees. Heater prevents lens mount assembly from dropping below X degrees. Batteries are cheaper than a reshoot. While I'm thinking about it, Anton Bauer has a hot swappable dual battery plate. Are there any other versions/options?
Click to expand...

Yep: build a more stable lens mount. :):wink:
 
Nell said:
anyway..i think the scarlet and epics will run alot less hot so it might not be necessary.
Click to expand...

I have found the heat of the camera has far less effect on the mount as compared to external temperature swings.
 
Jannard said:
After considering our customers wishes, we will make the PL mounts in 3 versions. Aluminum, stainless and Invar. There will be 3 price points. Take your pick. Just consider that stainless and Invar will weigh more and cost more.

Happy Holidays.

Jim
Click to expand...

That's an excellent solution if these guys need/want it. One observation: Everyone on this thread who has complained about thermal expansion of the PL mount is working in crew situations using traditional focusing. Thermal expansion of the mounts has been a non-issue for those of us who mostly sight focus RED One. Even when my crews have used traditional focusing on my RED cameras, with the new mount installed, we haven't experienced any noticeable degree of thermal expansion problems. Our mount screws are torked correctly.

Since you've mentioned three options for PL mount materials, for my PL mounts on the new cameras I'll probably go with stainless, because I use a lot of long heavy lenses (obviously with bottom lens support) but a little extra added weight of stainless won't be a problem. I also use a lot of mid-weight lenses unsupported in hand held configurations, and run a lot with them, so a bit stronger mount in stainless may be a good idea. That said, I've had no problems whatsoever with the new mounts on my cameras, so if I ended up with aluminum, that would probably be fine too. The back focus on the new mounts on my cameras has been rock solid.

-----------------------

Happy Holidays Jim!
 
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