8mm Forum: Elmo's Poor Design

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Posted by Paul Adsett (Member # 25) on September 18, 2008, 09:27 AM:

Do you find that you are constantly fiddling with the focus when running films on your GS1200, especially when using an f1.0 lens?
I find this to be the case on both my GS's and have concluded that it has nothing to do with the film or the lens itself. The problem lies in Elmo's poor design of the lens holder, which permits small misalignments of the lens to occur even after you have initially focused the picture. Bear in mind with a fast f1.1 or f1.2 lens the positional accuracy of the lens probably has to be within .001 or .002 ins to get really sharp focus. As I see it, the GS lens holder design is a failure on that criteria because:

1. The length of the cyclindrical lens holder is much to short in relation to the lens itself. Basically you have a long heavy glass lens cantilevered out from a short lens snout.

2. The lens does not ride on a precise location. Yes, there are 3 flat areas on the inside of the snout, but I would not call these precision. They are rough and have sharp edges.

3. The little spring loaded ball is insufficient force to remove all the 'slop' from the lens holder.

4. The two oversize holes on the lens holder and the little adjusting screw on the side provide capability for vertical and horizontal plane alignment of the lens, but make it virtually impossible to do so accurately, because you are constantly juggling the "cross talk' between these two adjustments.

So overall, I give Elmo a poor grade for this very crucial part of the GS design.

In contrast, I find that I never have to adjust the focus on my Eumig 938 when fitted with the f1.0 Kodak Ektar lens. Adjust it once, and it stays dead nuts through the whole reel. Set it and forget it. And the reason is obvious. Unlike the Elmo, the Eumig lens is heavily spring loaded into a massive V-GROOVE precision machined directly into the chassis. This groove engages most of the length of the lens, and the lens 'overhang' is nowhere near that of the Elmo. So the lens stays put, and 10 out of 10 for the Eumig designers in this critical area.
Bottom line is, film projection on the 938 is a very relaxing experience whereas the GS projection needs constant monitoring for focus and is therefore less enjoyable.

Posted by David Pannell (Member # 300) on September 18, 2008, 09:48 AM:

Paul,

I have the same experience with my ST 1200 HD and the 1.1 lens.

Do I feel a project coming on???

Are you going to tackle this one, or shall I have a go at it?

The only thing is, is that I won't be able to get down to it for some time.........maybe you would like to start it off.

Cheers,

Posted by Claus Harding (Member # 702) on September 18, 2008, 10:15 AM:

David,

I was about to post the exact same thing (ST1200HD/1.1 lens), but I didn't know if the lens mount was the same as on the GS.
Well, count me in among the ones who feel that particular design could have been better.
(I still wouldn't trade the ST for anything but a GS, a Fumeo or a Beaulieu, but this focus issue is a valid point.)

Claus.

Posted by Osi Osgood (Member # 424) on September 18, 2008, 10:23 AM:

Hoo Hoo!

What is this I hear? Problems with the almighty ELMO?

"snicker snicker", goes the proud owner of the EUMIGS!!

Posted by Gary Crawford (Member # 67) on September 18, 2008, 01:34 PM:

The problem on the Elmo's seems to be inconsistent from machine to machine. I have a half dozen st1200Hd's...two 800's and a 180....I don't have a 1.0 lens, but I do have two 1.1's and I have focus stablility issues with only two of the 1200's....in both the lens sits in there fairly loosely. The others are very very good on maintaining focus. When I have had to use the other two machines....I've either used the 1.3 lens that came with it ....or taken a small piece of duct tape and taped the lens down carefully after focusing. Seemed to work ok.

Posted by Joerg Niggemann (Member # 611) on September 18, 2008, 02:01 PM:

This thread takes us back to Paul's beloved masterpiece "Elmig GS 938" once again [Smile]

Posted by Alan Rik (Member # 73) on September 18, 2008, 02:09 PM:

I use to have the problem with the GS and the 1.0 lens. But when I switched it out for the Schneider 1.1 all is perfect.
The lens holder assembly on the Beaulieu is MUCH better as well. The lens gets locked onto a holder and then the holder goes forward or back depending using a very fine adjustment. Its very precise and stays put!
With the Eumigs the manner in which you are supposed to focus the lens is not very precise. You turn this knob but it seems to have a little play. You never feel its truly dialed in like with the Beaulieu.

Posted by Kevin Faulkner (Member # 6) on September 18, 2008, 03:17 PM:

Yes I have to agree with all that has been said. Focus or should I say maintaining focus cane be a real chore sometimes.

Now I have suggestion for you all with focus problems. Check to see if it always goes out in the same direction. Do you always have to move the lens back again towards the gate to get it in focus?

I conducted some tests a few years a go and I found I got much better stability by removing the spring strip from the lens holder which pushes against the back of the lens.

My theory is that with the spring pushing on the rear of the lens and the natural vibration from the machine that the lens moves forward on its own.
I ran a machine without the spring which I think is there to keep the lens focusing pin forward in the focus worm. Without the spring the lens is slightly more floppy when adjusting the foduc. I didn't go much further than this with my tests but I'm sure this is what is happening and I'm sure the focus held better.

Anyone fancy following this theory up....DAVID?

Kev.

Posted by Patrick Walsh (Member # 637) on September 18, 2008, 08:53 PM:

MY GS HAS FOCUS PROBLEMS AS WELL, ALSO MINE HAS THE TENDENCY TO BE OUT OF FOCUS ON ONE SIDE OF THE SCREEN FROM TOP TO BOTTOM..... ANY IDEAS WHAT THAT IS?????? [Confused]

PAT

Posted by David Kilderry (Member # 549) on September 18, 2008, 09:51 PM:

Yep, spot on Paul. My two ST 1200 projectors have always suffered from the focus problem.

I can tell you it is even more of a pain when your projectors are in a separate projection room!

David

Posted by John W. Black (Member # 1082) on September 18, 2008, 09:56 PM:

I finally get to rant an opinion I've had for years.Elmo is the most overrated projector out there.I've had a gs-1200,which was a fussy diva of a machine for the money.The person who got me stared in film collecting when I was a child was a projector repairman.He purchased one and hated it.The framer is always a pain,film jumps if everything isn't perfect.He did like the GS800.I also had a couple ST1200s M/O.Same jumping problems and truth be told,The Chinon 9500 reproduced optical tracks much better.
I'm glad to see others don't worship at the alter of Elmo,I never understood it and never will.

Posted by Alan Rik (Member # 73) on September 18, 2008, 10:33 PM:

It could be that you got a "bad" Elmo GS1200! I know that there are a lot of them around. With all the electronics that you have in there...if the previous owner didn't take care of it you can bet somewhere down the line you will have problems. It isn't perfect but I have to say I have owned many hi end Super 8 Projectors. After trying them all I have come full circle and realized for me...the GS1200 is the best one. It may not have the sharpest focus all the time like the Beaulieu, or the huge reel capacity of the Fumeos, or the cool mixing console of the Eumigs...but it seems to be the best of all the projectors around. Great bright picture, very good sound, Pulse sync, 1200ft reels, optical reproduction...just a great machine. And now I'm looking to get another Xenon machine. I had a total of 3 in the past and I let them all go. What was I thinking? [Smile]

Posted by Graham Ritchie (Member # 559) on September 19, 2008, 12:10 AM:

Hi Pat
In this picture there is a small adjusting screw on the bottom of the lens barrel you can just see this and is for adjusting the focus, even it up "left or right" , not for top or bottom.

Excuse the reflection in this photo this is due to my "ultra clean gate" [Smile]

kidding aside...once the lens holder is aligned top/bottom, left/right the projector should run fine. I have my GS1200 adjusted for the least film resistance through the gate and it runs really smooth. The Elmo design might not be the best but I would not to change it for any other make of projector, one must also remember that films do shrink and dry out over time so focus problems can occur and its not always the projectors fault. I do have films that need constant watching when running, in saying that I also have films I can leave alone and the focus stays fine throughout, Super8 film is more critical focus wise than 16mm simply due to its small frame size, well thats my tuppence worth [Wink]

Graham.

Posted by Paul Adsett (Member # 25) on September 19, 2008, 09:41 AM:

I tried something last night which seemed to help quite a bit with the focus retention issue, at least on my particular projector. I removed the flat spring which is on top of the lens barrel (the one which pushes down on the ball) and bent it into a downward curve by about 30 degrees. Then I reinstalled it over the ball. When you do this the spring force on the ball is increased significantly and it seems to hold the lens in place much better, with a lot less wobble. After doing this I ran a whole reel of one of my sharpest prints and the projector stayed in focus all the way. Something you might want to try, and it is only a 5 minute job.

Posted by Maurice Leakey (Member # 916) on September 19, 2008, 09:48 AM:

With my luck the spring would break.

Posted by Osi Osgood (Member # 424) on September 19, 2008, 09:49 AM:

Trying to be a help for once (at least with the GS 1200), could it vary with the film? If the film is aged and perhaps even warped, it may slide through the film gate with more difficulty, therefore causing a slight vibration, causing the focus to go a-wry?

Is it on all films going through your GS1200 Paul?

Posted by Gary Crawford (Member # 67) on September 19, 2008, 11:59 AM:

I don't own a GS1200 ...yet...but I do have half a dozen st1200hd's and a D model and an older plain green 1200 as well...and two 800's and one 180...and I can say for sure, I have never had a problem wit film jumping or losing loops with any of them. I do have one I've had since it was new back in 75 or 76...and it's beginning to get a little unsteadiness to it, but that's it. All my 1200's take splices like they aren't there. I run film that goes from brand new today to films I bought in the early 70's...and still no real problems. I have had sometimes some clatter or jitter with a few films...and a little film cleaner /lubricant took care of it. I am not mechanically endowed, so the most I've ever done to these machines is change belts, clean heads and paths...and clean and regrease gears. I do know people with GS1200's that have the machines spend more time on the bench being worked on than on the projector stand showing movies. I have heard , even from the earliest days of the GS that it was a little more finicky with film....not as forgiving of any little defect or flaw with the film. Not so with any of the ST1200's I have.

And, as I said earlier in the thread, only two of them seem to have problems holding focus.

Posted by Bill Brandenstein (Member # 892) on September 19, 2008, 03:34 PM:

Lest you choose to worship at the Eumig shrine too quickly, let me add that the 938 might be a crackerjack machine, but that the 800 series units must certainly be sloppy in focus by comparison. At least that's been my experience.

Posted by Kevin Faulkner (Member # 6) on September 19, 2008, 04:45 PM:

Paul, Your suggestion with the top spring on the ball bearing may also be a counter measure to what I was saying in my earlier thread.

As for the Elmo's being finicky with film problems etc that has not been something I have encountered either unless the machines have been badly maintained or fiddled with.
What I will say is that green film and old film runs better if lubricated other than that they are as reliable transporting film as any other projector.

Top to bottom focus is achieved by slackening the two screws which hold the lens holder to the machine and then moving the whole assembly forward or back to achieve optimum focus in that plane. Do not move the lens assembly up or down as this will move the pressure plate position with regards to the gate.

Kev.

Posted by John Clancy (Member # 49) on September 20, 2008, 03:39 AM:

I have three GS1200's and don't have this problem on any of them. And that's with the F1.0 lens installed in each of them.

Posted by Adrian Winchester (Member # 248) on September 20, 2008, 09:02 AM:

I've never had the pleasure of using a Eumig 938, or any Eumig beyond the 826, but I must say that the focussing knob/mechanism on all of the 800 series projectors I've owned has been so poor that Eumig should certainly have learned how NOT to keep a film in focus by the 900 series!

Posted by Maurice Leakey (Member # 916) on September 20, 2008, 12:18 PM:

A problem with the later Eumigs is the small plastic pin on the lens which mates with the focus knob. This pin wears down with use and then becomes "sloppy" in the helical groove.

Posted by David Pannell (Member # 300) on September 20, 2008, 01:20 PM:

Kevin, Paul et al,

Maybe I'm getting a bit too technical here, particularly in view of the 2 simple remedies already described, but I'm thinking in terms of a locking thumb screw arrangement with a tapped hole somewhere on the lens holder, so that the threaded portion of the thumb screw just bears onto the lens barrel when screwed in 'finger tight'.

I don't know how feasible this would be, as I'm just thinking aloud at the moment, so to speak. I'll have to investigate further.

Any thoughts?

Posted by Martin Jones (Member # 1163) on September 20, 2008, 02:12 PM:

Maurice,
I succesfully repaired a broken off focus pin on my Eumig 926 by filing it flush to the lens barrel, carefully drilling a 3mm (?) hole just through the barrel, tapping with a steel screw bolt and then fitting a nylon screw. Finished off by cutting the head off the screw. Snug fit in the snail cam and rock steady focussing.

Martin

Posted by Maurice Leakey (Member # 916) on September 20, 2008, 03:01 PM:

David

My early Bell & Howells in both 16mm and Standard 8 have the feature you describe.

Loosen the thumb screw, rotate lens for focus, tighten thumb screw.

Martin

Sounds wonderful, although the tapped hole is no doubt quite short so as not to contact the inside zooming part of the lens.

Posted by Kevin Faulkner (Member # 6) on September 20, 2008, 04:14 PM:

This maybe is the way to go. Maybe this is why some other manufacturers put locking systems on their lens assembly's.

Kev.

Posted by Paul Adsett (Member # 25) on September 20, 2008, 07:28 PM:

The best focusing system that I have on any of my projectors is on my Bolex 18-5. The outside of the metal lens barrel has a deep helical thread machined into it, and the lens housing has a large spring loaded ball that precisely fits the groove. You focus by rotating the whole lens. Simple and foolproof with zero backlash and the ability to really fine focus the lens. David's idea about a locking screw sounds good to me. The only problem might be that just the action of tightening the locking thread might disturb the focus of the lens if there is any slop at all in the fit of the lens housing.

Posted by Winbert Hutahaean (Member # 58) on September 22, 2008, 02:05 AM:

Hi all,

I think the distance between our eyes and the screen will be contributing to this focus issue. The nearer we sit the more out of focus is noticed. We are talking about the projection of 8mm wide film in 100 inches screen.

I have my dedicated theater with only 3 meter distance between the seater and screen due to room limitation. Every time I set the focus from the projector, everything looks good, and when I go back to the seat I have a feeling to be out of focus again.

I sit too close to the screen! [Wink]

Posted by Maurice Leakey (Member # 916) on September 22, 2008, 06:11 AM:

I quote from "The Focal Encyclopedia of Photography."

"The front row of seats should be one screen width or more from the screen - never less. This is the shortest distance from which the eye can take in the whole screen at once.

The back row seats should be eight screen widths or less from the screen - never more. This is the geatest distance from which the normal eye can distinguish detail without strain."

Posted by Graham Sinden (Member # 431) on September 22, 2008, 07:03 AM:

Yes, Elmo's may have several design flaws. But I bet every GS1200 owner would NEVER swap their machine for a top of the range Eumig, Bauer, Chinnon, Fuji, etc.

Graham S

Posted by Joe Taffis (Member # 4) on September 22, 2008, 04:33 PM:

I agree Graham, and I don't own a GS. The heavily built ELMOs are tolerable of my home-made modifications and fiddling where others would not be.

Posted by Steve Klare (Member # 12) on September 22, 2008, 06:26 PM:

Every machine ever made at any time for any pupose has design flaws, it's purely a function of the human being at the drawing board. Sure, there are better designs and worse designs, but there are no perfect designs.

I've never had the pleasure of meeting the GS-1200 face to face, but between my mid range Elmo and Eumig machines, the ease of access makes the Elmo my favorite. The fact that it's so easy to get in and clean, lube and inspect the film path from end to end makes it easier to be confident when I thread it up.

My Eumig has never done me wrong, but I just feel more at ease using the Elmo.

Posted by Paul Adsett (Member # 25) on September 22, 2008, 07:30 PM:

Sorry guys, I could'nt resist! [Big Grin]

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