Red 18-50 Question

[Steve Gal]

It sounds like it could be a simple back focus adjustment.
Although, I have yet to see a RED 18-50mm and I am not certain as to how the focus mechanics work.

Matthew, the rear shims are exactly the same as the Cooke S4's so I tried to use the Cooke shim in the Red 18-50 but although they look the exact same, the inner diameter of the Cooke shim is just a hair smaller and would not fit. I guess I should order some shims from Red to have for these 18-50 adjustments. I usually just make my own shims but these are not so simple design. I have not played with the front focus and I hope that is an easy adjustment like most other zooms.

 

[Finner]

I usually just make my own shims but these are not so simple design.

What if you were to use some dubble bubble, after 3 chews it becomes one of the hardest elements in the world. I suggest 2 chews, form it as needed and wolla, instant shim. Added bonus is all the flavour is gone after 1 chew so you also get in on that.

 

[chuck colburn]

Aha. I was under the impression that the Arris in particular did not, in exchange for better optical qualities than they otherwise would have if they were true zooms.

They are true zooms and probally the best.

http://www.cinematography.net/Pages GB/ARRIVP.HTM

 

[chuck colburn]

RDG I can not recomend the Duclos team highly enough. Paul was accommodating, extremely precise, very favorably priced and a pleasure to deal with. Matt recomended them to me and when I was in LA for LART I had them do some work on my cooke. I hope you take down the lens and your camera to them and would be really interested to hear the results. You may even be able to have them engrave focus witness marks on the barrel as this would be a big benifit that the lens currently does not have and may be part of the reason why it is so much cheaper then other current similar cine versions. I would also be interested to hear about how the T-stops hold up and you could get them to test that there as well. Please note that every cine zoom lens is not 100% truely accurate with its T-stop marks as all are slightly off, most being off by very miniscule amounts. There are actual tollerances that are acceptable for these differences. I would be very interested in hearing how your lens fairs with that testing also.

Hey Finner,

Do they have an intergrating sphere there for reading "T" stops?

cheers,

 

[Steve Gal]

What if you were to use some dubble bubble, after 3 chews it becomes one of the hardest elements in the world. I suggest 2 chews, form it as needed and wolla, instant shim. Added bonus is all the flavour is gone after 1 chew so you also get in on that.

After working on so many lenses, I think there are a few techs out there that do use the Double Bubble technique. I personally like Bazooka

 

[JD Holloway]

Whatever happened to Big League Chew......?

 

[Matthew Duclos]

Matthew, the rear shims are exactly the same as the Cooke S4's so I tried to use the Cooke shim in the Red 18-50 but although they look the exact same, the inner diameter of the Cooke shim is just a hair smaller and would not fit. I guess I should order some shims from Red to have for these 18-50 adjustments. I usually just make my own shims but these are not so simple design. I have not played with the front focus and I hope that is an easy adjustment like most other zooms.

Like I said, I have yet to see a RED zoom in our shop and am quite curious as to it's assembly and quality.
If the shims are similar to the Cooke S4 type, I'm sure we wouldn't have a problem adjusting back focus. We used to use the "bubble gum" method but have recently upgraded to Tootsie Rools that are at least 4 years of age... (I hope people don't take this running joke serious. I would hate to get a lens in the shop from someone who tried it..)

 

[Evin Grant]

I'll chime in on my appreciation of the Ducloses. They are top drawer, honest and very professional. Speaking of which...

Matthew,
My 50mm Zeiss standard was rolled out of it's pelican a few weeks ago (The AC was a tool:ranting2 and the focus gear is ever so slightly loose now. The elements seem to be fine and it tapes out OK but I'm curious if I should nip this in the bud before it causes problems down the line?

Suggestions?

I'll PM you this as well.

 

[Matthew Duclos]

I'll chime in on my appreciation of the Ducloses. They are top drawer, honest and very professional. Speaking of which...
Matthew,
My 50mm Zeiss standard was rolled out of it's pelican a few weeks ago (The AC was a tool:ranting2 and the focus gear is ever so slightly loose now. The elements seem to be fine and it tapes out OK but I'm curious if I should nip this in the bud before it causes problems down the line?
I'll PM you this as well.

Evin,
On a Zeiss standard prime, not much harm can come from a loose focus scale other than slightly inaccurate focus marks. It's possible that the screws could eventually loosen enough to the point where the scale would just fall off to the rear, but that is highly unlikely. I've always believed that proper, regular maintenance prevents costly repairs. That said, we would be glad to tighten that down and make sure nothing else was disturbed during the fall. Let me know if you want to send it in.

 

[Nova Invicta]

18-50mm

18-50mm

This Sigma lens is good for what it was designed for STILLS it was not designed for cinematography and the re-focusing after zooming is a common trait of stills lenses. That said the mechanical changes used to make it a Red Zoom must be very basic as mechanical image shift can be corrected.
The Zeiss/Arri variable primes differed some exhibited image shift whilst zooming while others didnt. Overall though this was not a successful product for Arri. If it really matter to you then the only real options are Angenieux and Cooke ahh but then theirs the cost! Welcome to professional cinematography.

 

[Jeff Kilgroe]

We used to use the "bubble gum" method but have recently upgraded to Tootsie Rools that are at least 4 years of age... (I hope people don't take this running joke serious.

How could we possibly take you serious with a comment like that? Anyone who's familiar with Tootsie Rolls knows that they must be fresh and pliable. 4 year old ones would require heating in order to be pliable. But that damages the sugar matrix, resulting in a sub-standard material.

 

[Matthew Duclos]

How could we possibly take you serious with a comment like that? Anyone who's familiar with Tootsie Rolls knows that they must be fresh and pliable. 4 year old ones would require heating in order to be pliable. But that damages the sugar matrix, resulting in a sub-standard material.

Ah, we have overcome the heating/sugar matrix dilemma. We use a precise mixture of Sprite and Pop-Rocks to boil the Tootsie Rools. This returns the rolls to a flexible state, while retaining the proper sugar ratio. After the cooling process, the tootsie rolls become hard and are rated a 10 on the Mohs scale. Please don't share this secret with anyone.