GS1200 focus uniformity

[Paul Adsett]

The Elmo GS1200 has provision for adjusting the focus uniformity, or flatness of field, in both vertical and horizontal axes. For vertical (top to bottom) uniformity adjustment you have to loosen the two screws which mount the hinged lens holder to the chassis. You then have to try making very minor tilt adjustments up and down, within the range permitted by the oversize holes on the hinge of the lens barrel, to try and hit on the best position so that the focus is uniform from top to bottom on the screen. For side-to -side focus uniformity you make minor adjustments to the little set screw on the bottom right corner of the lens holder. You have to do all this while projecting film, and have the patience of a saint to do both these adjustments, as to a large extent they are hit and miss, and you can spend hours getting it just right. But the results can literally be the difference between night and day on the sharpness of your screened films. This is particularly true if you are using a fast f1.0 lens where the depth of field is only a few thousandths of an inch. Despite the hassle and frustration though, this adjustment of focus flatness is well worth doing. I did this on one of my GS's yesterday and the sharpness improvement was really noticeable,

But it's too bad that Elmo did not incorporate a precision micrometer adjustment for at least the side=to=side adjustment, as Beaulieu did on their projectors. And, as critical as focusing is with f1.0 lenses , the use of a threaded lens barrel design ,with sprung ball , would have been far superior to the sloppy cam design they went with.

[Shane C. Collins]

Paul, I've come to the conclusion the threaded lens barrel design is the best ever made! It's why I love those early Eumig's, and the very first Bolex 18-5. The Eumig Mark S Super 8 projector is fitted with the Eumig Suprovar 1.0 from the mid 60's. It's critical to get precise focusing with this lens. The twist-to-focus action allows me to dial in for perfect sharp images corner to corner. There's no way I would go back to those sloppy cam designs...

[Graham Ritchie]

True Paul

I have spent time in the past doing those adjustments you mention, its even more critical to have it right for Scope I spliced a test loop for getting the Scope lens focused, that was fun but having a test loop going round and round gave me the time to do adjustments .

Its still not perfect but close enough

PS just read Shane reply and totally agree that the manufactures should have stayed with the threaded barrel design, those cams were a disaster

[Alan Rik]

I didn't know about the focusing adjustments on the GS1200 until much later. So I sold my really nice print of "Alien" because I thought that it was a Derann White box special since it was soft on one side of the screen. About a year later I found out how to adjust the gate for side to side sharpness.
Then I used a SMPTE film to check focus and found that out of all the fast zoom lenses I had, including the 1.1 Schneider made specifically for the Elmo, the 1.0 lens reigned supreme. Incredibly tack sharp bested only by the 1.2 long throw. But the best/easiest focusing I've ever used is the Micrometric focusing on the Beaulieu 708. That one the lens locks into a holder and the holder moves forward or backwards and doesn't move once set. I think the Fumeo might have the same.

[Thomas Knappstein]

I have changed the little M2 Screw to a new longer one with a nut to lock the Screw after found the right Position.
I also use the Elmo 1:1,0 Zoom Lens and for get the right Focus I have a focus Remute Stepper Motor in use. Now I can pull the Focus near the Screen and I can see if it is perfect. On my Photo you can see this Motor with a Worm Gear attached on my Machine. The other Motor is for adjusting the Frame from my Seat in the Cinema.

[Joerg Polzfusz]

I didn’t know that Kaiser also produced (or distributed) such test film. I always thought that the SMPTE was the only one (with Wittner taking over SMPTE‘s remaining stock and now producing a version with the SMPTE-logo being replaced by its own logo):
https://www.wittnercinetec.com/epage.../Products/1054

(I wish that my wages would have increased like Wittner‘s prices - I’m pretty sure that the test film was something like 35€ approximately 10 years ago!)

[Alan Rik]

I appreciate the fact that a company like Wittner exists but since they know they are one of the few remaining players left in a niche market their prices are insane. The small capstan roller on the Beaulieu cost me 34€ initially. Last I checked a few years ago the price was 269€ !! I never knew the price of rubber increased so much! Highway robbery at its finest!

[Joerg Polzfusz]

In 2020, the Testfilm was still „only“ 232€ (current price: 275€):
https://web.archive.org/web/20200929.../Products/1054

In 2013, it was 29,90€:
https://web.archive.org/web/20131206...ik.de/home.php (you will have to scroll down to get to the Testfilm)

[Ricky Daniels]

Available…

Kaiser FOCUS TEST FILM



NEW!
UNOPENED!
UNUSED!

The Kaiser TEST FILM for Adjusting and Focusing alignment, as shown in action earlier in this thread!

£ 69

Get it while you can!

Please private message me if you want to buy this Rare FOCUS ALIGNMENT TEST FILM

Best,
Rick

[Chip Gelmini]

$300.00 for a test loop?

Youve got to be kidding

why not opening text from a faded digest? That's what I have been using for the last 30 years.

I did order the Derann test loop many years ago, but even that seemed like it was printed off center and for me that was not right either

[Kevin Faulkner]

Ive got some of the Wittners supplied SMPTE test film from many years a go. The chart was printed on colour stock and guess what? Yes its now red 😡
Fortunately its still useable and I've set up many an Elmo's focus with it.