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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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It's not so much the mount that's the issue, it's the 52mm of cast and machined aluminum that holds the mount and the sensor aligned. What's being suggested is that Red not screw the mount onto the body and instead onto a standoff that keeps it aligned with the plane of the senor made of invar or some other thermally stable material of their choosing.

That being said a steel mount front PL is a still good idea. I think invar may be a bit brittle for the actual mount, but I'm not sure of this.

Thanks for your care and attention!.

Matt Uhry
www.mattuhry.com
 
I only had a back-focus problem once on the RED, oddly enough it was just two days after the initial prep where the back-focus had been checked at the rental house where the lenses came from. But by Day Two, I started noticing that one of our RED's seemed off in a wide day exterior shot and it turned out that the back-focus had shifted. But after we set it again, it never was a problem -- so perhaps we had a loose screw or something.

Now this was a movie shot in summer in warm to normal temp locations, never any cold situations.

Even if you focus by eye rather than measurements, a wide-angle wide shot can be hard to get sharp if the back-focus is off. On tighter, longer-lensed shots, sure, focusing by eye usually gets around this problem, or hides it. On the other hand, a lot of eye-focusing involves zooming in tight, focusing, and then zooming back wide, which doesn't work well if the back-focus is off (in fact, that's often how you spot that it is off...)

If you're shooting for projection on a 50' or 75' screen, these little issues become big issues.

In fact, one of the advantages I've found with shooting digitally on cameras like the RED is that I spot certain lens defeats and problems more easily rather than being surprised months later.
 
Matt Uhry said:
It's not so much the mount that's the issue, it's the 52mm of cast and machined aluminum that holds the mount and the sensor aligned. What's being suggested is that Red not screw the mount onto the body and instead onto a standoff that keeps it aligned with the plane of the senor made of invar or some other thermally stable material of their choosing.

That being said a steel mount front PL is a still good idea. I think invar may be a bit brittle for the actual mount, but I'm not sure of this.

Thanks for your care and attention!.

Matt Uhry
www.mattuhry.com
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Ah, this makes more sense why you guys are suggesting invar. The reason I asked if it would be strong enough is that I thought you were referring to using it for the mount itself, which made me wonder if it would be able to take the wear. This makes sense now.
 
Any reason titanium isn't being considered as a lens mount?
 
David Mullen ASC said:
On the other hand, a lot of eye-focusing involves zooming in tight, focusing, and then zooming back wide, which doesn't work well if the back-focus is off (in fact, that's often how you spot that it is off...)

In fact, one of the advantages I've found with shooting digitally on cameras like the RED is that I spot certain lens defeats and problems more easily rather than being surprised months later.
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Definitely. Eye focusing with zoom lenses on RED does involve a lot of zooming in, hitting 1:1 image magnification (if you have time), racking focus, then pulling back to the framing. Experienced eye focusers get used to picking up nuances of the framings as they change from tight to wider - things like increased softness as you widen out, which tip you off to the possible need to reset back focus. Its obviously much better to notice that at the start of the shooting session, than later on, and have to re-shoot material. Experienced sight focusers will usually spot back focus problems quickly.

The addition of 1:1 image magnification on RED One has really enhanced sight focusing with the camera.

From f4 to more stopped down apertures I really enjoy sight focusing RED One if it works for the workflow and the needs of the shots. As you know, sight focusing obviously becomes much more of a challenge at apertures of 2.8 or wider open, which limits sight focusing to relatively static shots, and shots where subjects are not frequently moving toward or away from the lens.

I guess there is a time and place for everything. Experienced shooters develop an uncanny sense of when to do what, and when not to do what - and when to shift gears and move on to another solution.
 
I wonder when people that are really worried about this are gonna start using Invar in lenses... The expansion that happens with the metal in most lenses is just as big of an issue as thermal expansion that happens in the mounts. Specially with the bigger zooms, like the big Optimos. People forget about that part. It's why Canon makes their long zooms White.

I guess minimizing the tolerance stacking as much as possible helps though.. which is why, like Jim said, for those that really want it, we will make it :)
 
Jarred Land said:
I wonder when people that are really worried about this are gonna start using Invar in lenses... The expansion that happens with the metal in most lenses is just as big of an issue as thermal expansion that happens in the mounts. Specially with the bigger zooms, like the big Optimos. People forget about that part. It's why Canon makes their long zooms White.

I guess minimizing the tolerance stacking as much as possible helps though.. which is why, like Jim said, for those that really want it, we will make it :)
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Absolutely but RED is infamous by now and one of the points for naysayers so why not go for stainless? It's proven itself to work for years and years.

I would also appreciate if we don't have a self adjustable mount. It has proven itself to be nothing but trouble.
 
weirdcrew said:
I would also appreciate if we don't have a self adjustable mount. It has proven itself to be nothing but trouble.
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I completely disagree with that. I own several RED One cameras and I've had no problems whatsoever with the new adjustable mounts. The ability for us to adjust back focus ourselves was a major advancement

What has proven itself to be nothing but trouble is the "never satisfied" attitude of some posters here. No matter how many improvement RED has made to RED One, and the excellent proposals for the new cameras, there are some nitpickers who are never satisfied no matter what advancements RED makes.

If you want to go back to mounts that can only be adjusted by a technician and not by the owner or operator, then IMO you should seriously consider buying your cameras from another company.
 
I'm with Gibby on this one...

The attitude is frustrating. Specially after Jim bends and offers up a solution in this very thread.. people still bitch bitch bitch...
 
Steve Gibby said:
What has proven itself to be nothing but trouble is the "never satisfied" attitude of some posters here. No matter how many improvement RED has made to RED One, and the excellent proposals for the new cameras, there are some nitpickers who are never satisfied no matter what advancements RED makes.

If you want to go back to mounts that can only be adjusted by a technician and not by the owner or operator, then IMO you should seriously consider buying your cameras from another company.
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Fair go Gibby.... I'm with Fredrik on this one.

I've seen top notch camera technicians and focus pullers really struggle to set back focus properly - mainly because of the way the focus changes as you tighten the mount.

We all are fans of the camera and want to see that future models are as good as they possibly can be. If we just accepted everything as being as good as it can be, then there would be no progress at all.
 
INVAR??? Stainless will do just fine...

INVAR??? Stainless will do just fine...

I think some of you guys here need some perspective. RED does NOT , in a practical sense, need to make an Invar lens mount. Stainless steel, grade 303 or 416 will do just fine.

If RED can use a material that will control the thermal expansion of the lens mount to within +/- 0.01 mm for a +/- 17º C temperature change, I think that would be a very practical solution, and anything beyond that will be diminishing returns.

So if you calibrate the mount at 52.00 mm @ 20º C and it measures: 51.99 mm at 3º C and 52.01 mm at 37º C, you've got a very big temperature range to work with with no more than +/- 0.01 mm dimensional change.

The steel my gage blocks are made of has a thermal expansion of .0000115 mm per ºC per mm. A 52 mm gage block will expand 0.0006 mm (0.6 µm) per ºC. It takes a 17º C temperature change to for the block to expand 0.01 mm. Most steels are in a similar range.

Chromium Carbide gage blocks would reduce that expansion to 0.00045 mm at a huge increase in cost that I would never be able to recover since everyone will want their focus calibration for the lowest possible cost (or not be willing to pay at all).

Those steel blocks are the standards that my gages are calibrated to, which then calibrate the autocollimator, which then calibrates the test lens, then the test lens and the autocollimator calibrate the FFD of the camera (your RED ONE).

There is no point to making the lens mount on the camera more thermally stable than the tools that are being to used to calibrate the focus of that lens mount.

Especially since every lens that is used on the mount is going to be predominantly made out of aluminum and brass, and will expand way more than the lens mount...

A 52 mm Invar 36 gage block or PL mount expands 0.0000014 in/ºF = 0.000035 mm/ºF. Nice... but Invar is costly, not available from most metal suppliers, and very difficult to machine (wears out cutting tools rapidly).

I'm sure you get the idea... Aluminum mount for the weight conscious and Stainless for production work. Invar? Maybe for the lens projector.

I need to get back to work and actually make some money. Happy Holidays everyone... I'm outta here!
 
Thanks Jim for considering to offer options.
For me, I'm with Jorge. Stainless has proven itself over time and would be a great option to have. Is it a done deal Jim/Jarred? Will we see that as an option in the store? Or simply contact our reps about getting a new mount?
I also agree with Gibby. The adjustability is a fantastic option over shims. I have actually been pretty lucky and have only had to do it once. It IS a bit tricky when tightening the set screws but way better than shims.
Really great to be a customer of a company that listens!
Anyway, happy holidays all...
Cheers,
Harry
 
If you think professional people can't be just as nitpicky when talking about other companies' products, you'd be wrong. I've been to trade presentations and seen Sony or Kodak reps get grilled for not adding this or that feature, etc.

I can recall a Sony presentation on the in-development F23 over at the ASC clubhouse and boy did those engineers get a grilling. Some comments were useful, some were way offbase. Some were implemented and some were ignored, and some were saved for the F35 years later.

On the other hand, that's the sort of feedback that causes progress to be made. Imagine how useless it would be if all we ever did was thank or praise manufacturers with never one suggestion on what could be better? RED wouldn't even exist if there wasn't some dissatisfaction with other companies' products that they could capitalize on by doing better. And they won't survive if they don't in turn provide better and better products, and the only way that's going to happen is with customer feedback.

Yes, some of the feedback is contradictory because we all have different opinions and different needs, different tastes, which is why it is ultimately up to RED to figure what to implement and what to ignore.

The need or lack of need to be able to set back-focus oneself is a prime example -- one can make excellent arguments either way, so there is no right or wrong answer here. It has its strengths and weaknesses.

Filmmaking, for better or worse, is a job that attracts very focused individuals who are incredibly nitpicky, anal-retentive-types. It's even worse among camera assistants, DIT's, and engineers. Not all are like that, but a high percentage are.

So if you are open to customer feedback, as RED is, it's a bit of Pandora's Box being opened, or a floodgate -- it's hard to control. But don't think that cinematographers aren't as critical of the products of other companies; they are, and given half a chance, they will tell the company... just that the company doesn't give as much of an opportunity for that feedback as RED does. So either RED can embrace the chaos of this relentless feedback as positive, or they can shut the door to it, it's up to them... but the one thing that is hard to do is control the nature of people.
 
I'm with Jorge. Stainless Steel or Titanium all the way. Forget about Invar. I don't know anyone who uses it in this industry.
 
David Groundwater said:
Fair go Gibby.... I'm with Fredrik on this one.

I've seen top notch camera technicians and focus pullers really struggle to set back focus properly - mainly because of the way the focus changes as you tighten the mount.

We all are fans of the camera and want to see that future models are as good as they possibly can be. If we just accepted everything as being as good as it can be, then there would be no progress at all.
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I can just comment on our own experience with the multiple RED One cameras I own - and that is that the new adjustable mount has been rock solid on my cameras, and that the ability to adjust and re-set back focus if needed on location is a major plus in our workflow. For an affirmation of that from another highly experienced shooter, you need go no farther than David Mullen's post #42 on this thread, where only once in his experience with RED One cameras using the new mount did he experience a back focus problem. And what did he/they do to solve it? They went to the self adjusting back focus setup on the new mount, re-adjusted it, and had no further problems.

I use highly experienced camera technicians when I need them, but in doing so I know that there are progressive ones who want to acclimate themselves to emerging technology and procedures - and there are also a lot of them who have a "but we've always done it this other way" attitude.

So I know your background with RED camera, I'd like to ask you a few questions, with added insight into my experience with RED One:

How many RED One cameras do you own? (I own several)

How long have you been using them? (I've owned and extensively used my RED One cameras for over 16 months now)

How many different camera technicians have you used on the RED cameras you own or have used? (I rarely have to use camera technicians for simple things like setting back focus.)

Have you personally ever attempted to adjust the back focus on a RED camera equipped with the new RED mount? (Once set properly with the new mount, I check back focus regularly, and watch for any signs of drift in it, and I haven't had any problems whatsoever)

I'm leaving to go mobile right now and won't have internet access until late tonight at the earliest, but when I get a chance I'll re-visit this thread and review your added input.

Yes, input to RED is and has been critical to the development of the camera. I'm the wrong one to preach to about that. I've been giving extensive field experience input to RED since 2005 when the camera was announced. My style of doing that is different though. I generally send my input directly to RED via email or PM - the most direct and rapid way to have it analyzed, rather than feeling the need to parade my suggestions by the whole RED User board. Once I give RED my input I don't worry much if it is adopted or not. They have a company to run, and I'm sure there is a multitude of factors they have to weigh out in order to get a "yah" or "nah" to a suggestion.
 
This is quite a dance we have going on here. We try to listen to everyone's opinion, take the ones we feel are valid and implement them if possible. That has lead to more and more "opinions" from our customers. Some opinions are completely valid and some are completely unreasonable. Some are great suggestions that just can't be done given current technology. Some are easy to do but completely counter-productive.

Sifting through all this stuff is exciting, frustrating, energizing and time-consuming. That is RED.

If we look back at where we were and compare to where we are, I think it is pretty unbelievable. The new modular program is our best solution to giving as many options, updates and upgrades as possible, along with flexibility to expand the system as we go along.

Thanks to all for the contributions. We are all learning here...

Jim
 
weirdcrew said:
...
I would also appreciate if we don't have a self adjustable mount. It has proven itself to be nothing but trouble.
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Hi Freddy

Got to disagree... I believe there is only 2 problems (post 1 to 1 zoom) with self adjusting.

1) adjust to what? Not everyone has a 21mm MP (very telecentric) sitting in a box waiting to set mounts. If Red (or third party) can give us a PL device that we set to for less than £1000 there is every reason to keep self adjustment. This should be a piece of cake for somebody to make when you have guaranteed sales of over a 1000.

2) The actually locking of the backfocus is a little tricky. It tend to push it out a tad. You end up guessing the needed compensation. If this is improved I would be doubly delighted!

ADVANTAGES

Back focus can be used creatively.. I shot a whole programme with the backfoucus out. A number of shots couldn't have been achieved in any other way.

Not everyone is geographically and for business reasons connected to hire houses that can shim their mount. These people benefit from being able to do this themselves.

Emergency problems on a shoot where adjusting backfocus gets you a technical workaround.

For me the loss would simply be the loss of a creative option.. I hope this is not what Red needs to do!!

kind regards

Michael L
 
Mitch Gross said:
Forget about Invar. I don't know anyone who uses it in this industry.
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Panavision...

Anyway, I also agree that Invar should probably be left alone. I am with Jorge and everything he has said. I can attest to his point about lens behavior with temperature changes. I shot quite a bit in -15F/-26C cold last sunday. All of the marks on my Cooke zoom were way off, we couldn't measure focus, a total lost cause. In spite of that, the Cooke actually performed admirably. After a brief use of a 14mm Zeiss standard prime, all the Zeiss glass went back in the case. The cold had those lenses so tightened-up that I did not feel comfortable using them and risking damage. I'm sure the mount was off, due to the temperature, the last time back focus was check was the friday before at about 70F room temperature. But I know that the lens was the bigger culprit as it had become much tighter to operate and by how far some of the marks appeared to be off. We did not attempt to adjust the backfocus in the cold. Didn't see much point, if the lens marks were going to be off anyway. All the marks on the lens are spot-on again after returning the lens and the mount to indoor temps and checking them again yesterday.

What Hans said a few posts back about making sure the mount screws are all properly tightened is good advice. I had some focus shifting with my mount last summer in high temps. Or at least I think I did because it was real hot and I had backfocus issues. After re-collimating and making sure that not only the screws on the adjustment collar were tight, but the other mount screws as well, seems to have made all the difference. After the adjustment and screw check, I didn't have any further fluctuations and have not had any until my recent severe cold testing.

Not so sure about a titanium mount either, titanium can probably be left alone. Yes, it's strong and light weight compared to steel, but offers no thermal advantages over stainless and it would be more expensive. Titanium also does not hold up as well as stainless or 707x aluminum when it comes to scraping or galling or other effects that will wear a mount down over time. A stainless mount would be my first choice as it does have better thermal characteristics than aluminum and should theoretically be tougher over continuous wear and tear.

I can't comment about EPIC or Scarlet and their construction, having only seen renders and last year's NAB mock-ups. But with the current RED One, I don't see an invar mount offering any significant advantage. The entire body, front plate and mounting structures that hold the mount and sensor block, are all aluminum and vulnerable to thermal variations.
 
We don't see any advantage to Invar in a lens mount as well... but we are kind of tired hearing that we need to do it. So, if our customers think they need it, we'll make them. It is easy to do, just expensive. My bet is that as soon as we make two of them, one will sit on the shelf and ultimately end up in the RED Museum. People ask for stuff here because "they have heard"... if we don't offer it, they continue to NEED it. As soon as it is available, they go silent. That is just human nature.

Jim
 
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