8mm Forum: Elmo GP-E focus?

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Posted by Richard Kemp (Member # 1621) on July 24, 2009, 08:10 PM:

Hi

Just ran a Regular 8 film through my (new / second hand) Elmo GP-E ~ put it through 3 times just to check my impressions: the centre of the frame was in sharp focus, left frame completely blurred, right frame less blurred but still fuzzy! Extracted lens, but could see nothing wrong with it, so I put it back and ran the film again: same result.

Then removed Regular 8 film and swopped settings to Super 8, ran Super 8 film - whole projected frame now clear, balanced and in focus - so it was not the lens (relief: i bought this projector for the lens because my old GP-E developed a lens imperfection).

Can anyone tell me why my GP-E projects in Super 8 okay but throws a distorted image in Regular 8, please?

Many thanks,

Posted by frank arnstein (Member # 330) on July 27, 2009, 09:27 AM:

Hi Ritchard
On the Elmo GP-E,
When Regular 8 is selected, at the film gate a fine hair spring pulls the outer film side guides outwards, away from the aperture. It presses on both ends of the outer swivelling guides & forces them out. For Super 8 films the film guide needs to be in the IN position to properly locate the film & frame in relation to the aperture.
However, if the small, fine tension spring happens to unclip from either side guide retaining hooks, the guide won't move back out when selecting Reg 8, leaving a narrow channel for the film. So the Reg 8 film will be compressed from the sides causing it to form a curved shape as it it forced through the gate.
This will give the "out of focus at the sides" symptom you are experiencing.
To fix this.. open the film gate and inspect the lotation of the outer guide spring ends. Are they in their locating hooks?
If so, is the guide moving in and out when changing guages?
Probably its not.... & until you refit the spring ends properly, you will only get Super 8 films to focus properly.
Its a quick fix if the spring isn't lost but merely unclipped at either or both ends.
Good luck with it and let us all know what you find.
GP-E ElmoS are a very sensitive projector and everything has to be spot on or it will soon chew up your films. They are great when properly set up & with the 150w Halogen, put out a brilliant picture.
dogtor pufferfish [Wink]

[ July 27, 2009, 10:45 AM: Message edited by: Kevin Faulkner ]

Posted by Richard Kemp (Member # 1621) on August 04, 2009, 05:35 PM:

thanks Frank,

expert advice!

will update [Wink]

Ric

Posted by Richard Kemp (Member # 1621) on September 28, 2009, 06:54 PM:

Hi Frank

Problem : at last I got round to comparing the 2 GP-E's and apologies for delay. Both seem to mirror one another on selecting from Super to Regular, the sprung 'hair clip' type arrangement to the left of the film gate draws back to fractionally widen the film path ok

So I can't see any reason why GP-E number 2 should distort the Regular 8 film as it passes the film gate - real mystery! [Confused]

Is there any other diagnostic I can run please?

Thanks

Posted by frank arnstein (Member # 330) on September 30, 2009, 03:26 AM:

Hi Richard

It's back to the drawing board then,

Try to determine if the film pressure plate is sitting flat in the film gate when the lens holder is shut.
I have found a few pressure plates to be bent or bowed, leaving a gap at the bottom or sides.
Especially on projectors that swing out the lens to the side. They are great for cleaning apertures but are delicate & we can't just slam the lens holder shut.
They sometimes catch as they close & then will bend if forced or slammed shut.

Try it without film in it. Look along the entire edges of the pressure plate when the gate is shut, and see if its flush at the top, bottom & sides. Try it in the Reg 8 position as well. See if the pressure springs are being compressed properly & evenly to provide good flattening of the film as it slides through the gate.
Report back with the results for further discussion by the forum.

dogtor pufferfish

[Roll Eyes]

Posted by Richard Kemp (Member # 1621) on September 30, 2009, 04:37 AM:

thanks Frank: will update [Wink]

Posted by Richard Kemp (Member # 1621) on September 30, 2009, 04:58 PM:

quote:
Try to determine if the film pressure plate is sitting flat in the film gate when the lens holder is shut.
I have found a few pressure plates to be bent or bowed, leaving a gap at the bottom or sides.
Especially on projectors that swing out the lens to the side. They are great for cleaning apertures but are delicate & we can't just slam the lens holder shut.
They sometimes catch as they close & then will bend if forced or slammed shut.

Try it without film in it. Look along the entire edges of the pressure plate when the gate is shut, and see if its flush at the top, bottom & sides. Try it in the Reg 8 position as well. See if the pressure springs are being compressed properly & evenly to provide good flattening of the film as it slides through the gate.

OK - I found something:~

The pressure plates are attached to the opening section of the lens retaining unit, they are held in place by two sprung screws, above and below the film gate;

On the good GP-E, the pressure plate moves outwards slightly, couple of millimetres, when the lens unit is closed, compressing the springs ever so slightly;

On the problem projector there is no movement whatsoever of the pressure plate, on closing the lens unit. This might suggest the pressure plate is not actually pressured at all, allowing the Standard 8 film to bulge out of focus, when the film path narrows on selecting that gauge?

Possibly I can investigate correcting this but I don't want to overdo it: too tight and the pressure plate is going to be scraping film :-o ?

But what do you think please?

Thanks

Posted by frank arnstein (Member # 330) on October 01, 2009, 07:09 AM:

Hi Richard

It sounds to me like you found the root cause of the problem.
Well done & much praise to you.

When the pressure plate is closed, the springs should be compressed slightly, to give some pressure to the plate against the film. Not too much presure though, as it puts a lot of strain on the intermittant mechanism if the film won't slide through easily.

To increase the pressure, the gate will need to close a bit more.
There is an adjustment on the stop. In some cases, the lens holder hinge screws need loosening to realign the pressure plate in the gate & ensure all edges clear properly. Make sure it doesnt catch on the gate film guides as it swings shut.

Let us know how you go after doing those checks & adjustments.
Perhaps other forum members will also give further advice.

Its great to know you actually found something visibly amiss.
Now all you have to do is follow it through to a logical & successful conclusion.

I think I can speak for most members reading this thread, that we are proud of your skill in spotting the suspicious pressure plate & all await your next installment eagerly.

"From humble beginings great Projector Technicians develop"..

dogtor pufferfish

[Smile]

Posted by Richard Kemp (Member # 1621) on October 01, 2009, 08:38 AM:

thanks Frank

fingers crossed! - it's only because i had the two GP-E's side by side that i was able to spot the inconsistency [Wink]

will update

*October 3 2009* : so far so good - upper retaining screw was frozen in place, freed with WD40, have now adjusted pressure plate tension - next the 'acid test', pass some film through the projector.

[ October 02, 2009, 10:20 PM: Message edited by: Richard Kemp ]

Posted by frank arnstein (Member # 330) on October 03, 2009, 07:09 AM:

So far, So good Richard.

Don't stop now.
Your on a winning streak.

We all want to know how it ended up with actual film.

dogtor pufferfish [Roll Eyes]

Posted by Richard Kemp (Member # 1621) on October 03, 2009, 04:07 PM:

Frank wrote:

quote:
So far, So good Richard.

Don't stop now.
Your on a winning streak.

We all want to know how it ended up with actual film.

Thanks Frank - well i wouldn't be on a winner without your input!

I put a piece of Standard 8 'found footage' through which i use as a 'test'

First half of the footage was a big improvement on last time, but there was still some focal fuzziness on the left of the image, so I stopped the projector and gave a couple more turns on the pressure plate retaining screws -

Then the lens unit wouldn't shut, so i took a couple of turns off the screws: still no joy, so retracted the zoom lens (to its pre-use position). That seemed to do it but I don't know what was preventing the lens unit closing - too much pressure from the pressure plate or just plain awkwardness due to the zoom?

Anyway, when i resumed projection all of the frame was tolerably in focus: impossible to be 100% certain about image sharpness because of the 'home-movie' quality of the footage, but a vast improvement on previous attempts to use this particular GP-E for Standard 8 projection

The image projected from this GP-E always requires a 'pull down' for the framer, which is not healthy, but does not seem to stress the film transport unduly

The film gate is fuzzy round the edge which probably means it needs some TLC cleaning attention, with canned air unable to shift some of the debris?

So far OK - I did not detect distress to film emulsion or base due to increased pressure from the pressure plate: still early days though, at least I can progress from here though [Wink]

Many thanks!

Posted by Richard Kemp (Member # 1621) on October 06, 2009, 02:21 PM:

update

GP-E film gate cleaned and paths re-lubed. 50' Foma asa100 Standard 8, newly back from lab, put through projector - brilliant - didn't even need to freeze frame to check for focus, a-ok

thanks [Wink]

Posted by frank arnstein (Member # 330) on October 07, 2009, 12:48 AM:

Hi Richard

Let me be the 1st to congratulate you on your success with the Elmo GP-E.
They are a very fussy machine and you must have got it spot on at last.
Goes to show that you never give up on these tricky jobs but persevere and try again later.

Well done Richard, I am very proud off you.
If only you could come to Projector Heaven & assist me here with all the Projector fixing that needs to be done.

regards from Down Under

dogtor pufferfish [Big Grin]

Posted by Richard Kemp (Member # 1621) on October 07, 2009, 02:31 AM:

thanks Frank,

well thank goodness there are people around like you who know what they are talking about!

still, i won't be home and dry till i have put the film through again to check for scratches but it seemed to run smoothly, i'm sure it is all okay now

if you think the GP-E is touchy you (don't) want to try my first projector: Chinon IQ 8811 'Universal' - it eats film, destroys splices, and constantly loses the film loop: the Elmo's and Eumig's i have worked with since have been a dream in comparison, but the fact i had a lens defect on the original GP-E threw me back on the Chinon (for a film transfer) - i hope never to have to go there again - it almost wrecked the entire project: years and years of location work :-o

great forum too and thanks for the invite - if things get much worse in Blighty, who knows [Wink]

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