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Author Topic: Uneven focus. Lens or projector?
Christian Bjorgen
Jedi Master Film Handler

Posts: 996
From: Kvinnherad, Norway
Registered: Oct 2009

- posted March 15, 2014 05:54 PM      Profile for Christian Bjorgen   Author's Homepage     Send New Private Message       Edit/Delete Post 
I am having some issues with my ST1200HD that I've had since I got it.

When projecting the focus is uneven. Left is in focus, right is out of focus. If I adjust it's reversed. The "best" way is to have them evenly slightly-unfocused all the way, which is annoying!

Do you have any idea what could cause this? Is is the projector or the lens? (1.1 Elmo lens)

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Well who’s on first? Yeah. Go ahead and tell me. Who. The guy on first. Who. The guy playin’ first base. Who. The guy on first. Who is on first! What are you askin’ me for? I’m askin’ you!

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Winbert Hutahaean
Film God

Posts: 5468
From: Nouméa, New Caledonia
Registered: Jun 2003

- posted March 15, 2014 06:40 PM      Profile for Winbert Hutahaean     Send New Private Message       Edit/Delete Post 
The idea to have both main and balance track is to avoid the above problem. Make sure you projected film with both tracks or even better test with silent film which does not have track on left or right side.

Cheers,

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Winbert

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

- posted March 15, 2014 08:33 PM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
There is an adjustment screw on the lens barrel to get best flatness of field across the full width of the picture.

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The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Rob Young.
Phenomenal Film Handler

Posts: 1633
From: Cheshire, U.K.
Registered: Dec 2003

- posted March 16, 2014 08:35 AM      Profile for Rob Young.     Send New Private Message       Edit/Delete Post 
Yes, Paul is correct and it definitely sounds like this needs adjusting.

However, it is a very small screw and the head can be easily damaged unless you use the right screwdriver!

You'll need a fine Phillips head (that's what we call it in the UK at least) with long shaft; the sort for fine electrical use.

Be aware that only slight adjustment may be required.

If you're careful, you can gently adjust it as film runs to find the most even focus.

But as mentioned, use either silent film or film with both main and balance stripe, so that you're adjusting with "flat" film in the gate.

Good luck! I'm sure this will fix it.

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Vidar Olavesen
Film God

Posts: 2232
From: Sarpsborg, Norway
Registered: Nov 2012

- posted March 16, 2014 09:24 AM      Profile for Vidar Olavesen   Author's Homepage     Send New Private Message       Edit/Delete Post 
Agreed, the little screw fixed my GS-1200 too. It was quite unfocused on one side when I got it too, but slight adjustment and all is well. Even for a clumsy man like me, it was doable

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Jason Schmidt
Film Handler

Posts: 99
From: Saskatoon, SK, Canada
Registered: Nov 2014

- posted December 16, 2015 01:53 PM      Profile for Jason Schmidt   Email Jason Schmidt   Send New Private Message       Edit/Delete Post 
Can someone post a picture of where this screw is precisely located? Can I adjust it with the projector running or is it a screw that I have to swing the lens holder out to adjust?

Do I simply slowly turn the screw and watch what happens on the screen?

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Dominique De Bast
Film God

Posts: 4486
From: Brussels, Belgium
Registered: Jun 2013

- posted December 16, 2015 01:57 PM      Profile for Dominique De Bast   Email Dominique De Bast   Send New Private Message       Edit/Delete Post 
I would be very interested, too, to see a picture as I tried as well to adjust the focus but unsuccessfully. Maybe I didn't try with the right screw :-)

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Dominique

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Jason Schmidt
Film Handler

Posts: 99
From: Saskatoon, SK, Canada
Registered: Nov 2014

- posted December 16, 2015 11:45 PM      Profile for Jason Schmidt   Email Jason Schmidt   Send New Private Message       Edit/Delete Post 
I took a picture with the lens holder swung out. My suspicion is that it is "A" in the picture. Can someone tell me if I am right? Assuming it is "A", what is the process to adjust it? Do I just tighten/loosen the screw while watching the projected image to see if it improves or gets worse?

Also, what is the pin (marked with a green line pointing to it) on top of the lens holder?

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Lindsay Morris
Film Handler

Posts: 87
From: Darlington, WA, Australia
Registered: Jul 2013

- posted December 17, 2015 02:04 AM      Profile for Lindsay Morris   Email Lindsay Morris   Send New Private Message       Edit/Delete Post 
Jason,

It is indeed the screw marked "A" that adjusts the lens carrier to be exactly parallel with the gate backing plate.
It only needs a weenie bit of adjustment either way to get the best possible focus.
If doing it whilst the machine is running IF you are screwing the screw IN (clockwise rotation of the head) you will see the change in focus happen easily.
BUT if you have to undo the screw that "pin" you refer to is part of the lens carrier securing system to keep it closed & sometimes undoing the screw has seemingly no effect as that pin & the friction between it & the small clip holds the lens carrier out.
So if undoing the screw (anticlockwise rotation) as you do it press firmly on the lens assembly to make sure the carrier assembly DOES move inwards & so alter the focus.

That help??

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Lindsay

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Jason Schmidt
Film Handler

Posts: 99
From: Saskatoon, SK, Canada
Registered: Nov 2014

- posted December 17, 2015 08:35 AM      Profile for Jason Schmidt   Email Jason Schmidt   Send New Private Message       Edit/Delete Post 
That helps, thanks, I'll try clockwise first during operation tonight to see if that helps.

For counter-clockwise, where exactly do I press firmly? There seems to be two solid pieces, the lens and the assembly, not sure how I can press firmly on the assembly that will do anything since it just one big hunk of plastic.

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

- posted December 17, 2015 09:59 AM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
The whole design of the lens holder of the Elmo GS1200 and ST1200 is, IMO, very poor indeed for such high quality machines. This tiny little screw is expected to provide a precision adjustment of lateral focus, and those 2 screws that locate the whole lens holder to the chassis via oversized holes are expected to be used to get vertical focus? Try doing it sometime!
No Elmo really shortchanged the design of their flagship projectors in the most important area of all, lens alignment.
Look to Beaulieu to see how it should be done.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Lindsay Morris
Film Handler

Posts: 87
From: Darlington, WA, Australia
Registered: Jul 2013

- posted December 19, 2015 11:07 PM      Profile for Lindsay Morris   Email Lindsay Morris   Send New Private Message       Edit/Delete Post 
Jason,

Just push gently on the lens barrel to ensure that the gate assembly moves inwards closer to the film.
Not all machines need the gentle help but it pays to ensure you have moved the lens assembly ever so slightly after you have adjusted that screw outwards.

Quite a few 35mm projectors had a similar system for evening up the focus & used screws not much bigger than the ones on the Elmo's

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Lindsay

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Jason Schmidt
Film Handler

Posts: 99
From: Saskatoon, SK, Canada
Registered: Nov 2014

- posted March 11, 2016 04:16 PM      Profile for Jason Schmidt   Email Jason Schmidt   Send New Private Message       Edit/Delete Post 
I've been fiddling with the side to side focus here and there and I still can't seem to get it right, so I'm wondering if perhaps there is an element of vertical focus adjustment needed.

How is the vertical focus adjusted? Is it one of the screws in the photo I posted earlier in the thread?

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Tom Photiou
Film God

Posts: 4837
From: Plymouth U.K
Registered: Dec 2003

- posted March 11, 2016 04:21 PM      Profile for Tom Photiou     Send New Private Message       Edit/Delete Post 
To be honest with you, here is my thoughts, these screws are set from factory and dont usually need touching. We have three of these machines, only one showed this fault, we switched lens's and in our case this was the problem, a dodgy lens.
However, over the weekend i shall pop back on hopefully with more info and images on partial focus on these projectors.

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

- posted March 11, 2016 04:21 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Paul's statement above comes from a professional engineers perspective, and he is so correct on all points he makes here.

Much of the "flagship projector" design by Elmo here, left in many of the original design flaws that were apparent and complained of on their earlier ST model range.

Considering the sophistication and complete electronic overall given to the GS 1200, the mechanical aspects of this machine were neglected by comparison.

In their nativity, Elmo presumed there were no improvements necessary to "keep up with the pack" I feel.
It was a huge mistake, because had they had given the very same attention to detail to their mechanics on these machines as they did with their electronic innovations, they would have created without doubt, the all round best Super 8mm Projector the world would have ever seen.

As things turned out, others better them for the reasons of importance ultimately to their owners.

With regard to the aspect in question here regarding one non upgraded aspect of original design,
Paul quotes:

"Look to the Beaulieu, to see how it should be done"

Who could disagree with such a sensible statement from a true "Engineers" perspective?

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"C'mon Baggy..Get with the beat"

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Mark Todd
Film God

Posts: 3846
From: UK
Registered: Aug 2003

- posted March 11, 2016 04:28 PM      Profile for Mark Todd     Send New Private Message       Edit/Delete Post 
You tend to find if the lock tight blu set stuff has come off the screw wiill slowly adjust itself one way or the other.

It needs locking back up once its just right.

Best Mark.

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

- posted March 11, 2016 05:58 PM      Profile for Andrew Woodcock         Edit/Delete Post 
Shouldn't even be relying on a "loctite" adhesive for these critical factory settings Mark.

These adjustments should be adjustable and mechanically lockable. To engineer out any errors caused through many years of useage

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"C'mon Baggy..Get with the beat"

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