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I hope someone can help me. The image from my GS1200 is sharp at the top but blurred at the bottom. It’s not the lens as I’ve swapped the lens from my GS800 and it does the same. I know there is the little screw that can be adjusted for the vertical focus but is there a screw to adjust the horizontal focus and if so which one?
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Phillip, believe me you are not alone with this problem. For a very high end projector the design of the GS1200 lens focusing system can only be described as a joke. There is NO precision adjustment designed in for top to bottom focus uniformity. Instead, the lens holder is bolted to the chassis by 2 screws through OVERSIZED holes on the lens holder, the idea being that you align top to bottom focusing by looking at the projected picture and move the lens holder very slightly to get best focus before fully tightening the 2 screws. Left to right focus uniformity is done by adjusting the little set screw at the bottom right of the hinged part of the lens holder which presses against the rear gate plate. The problem is that because of the oversized holes, adjusting vertical focus also affects horizontal focus, so we have 'crosstalk' between these two adjustments! Now you also have the problem that the lens itself is not precisely located in the barrel of the lens holder(there is a suggestion of a V- groove location for the lens in the lens barrel, but it really is ineffective to getting precise positioning of the lens) and the focusing is done by a sloppy snail cam engaging the pin on the lens barrel. Talk about backlash! The whole thing is really an abortion, and getting totally even focus across the screen is a hit and miss proposition which you should be prepared to spend hours on before you hit the sweet spot. Its even more difficult with an f1.0 lens with its miniscule depth of focus. And even then, once you have got focus uniformity as good as it can be, there is no guarantee its going to stay that way for long because of all the slippage and slopiness that can occur with this design.
What on earth were Elmo thinking here? They spend a fortune on the bells and whistles of the rest of this amazing projector, and next to nothing on the most important part - the optical system alignment and stability! They should have looked at the rear sprung gate design and spiral lens thread system used on the Bolex 18-5, the easiest , simplest, most precise, and best focus arrangement of any of my projectors.
Excuse my rant!
Good luck, it can be done, but its a tedious and frustrating process.Last edited by Paul Adsett; September 24, 2024, 06:06 PM. -
Yup, as I pointed out in the pet peeve thread, the manufacturers were more focused (no pun intended) on sound quality than optics.Comment
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Hi Paul, which screws do you mean, the ones on the lens hinge? Although I don’t think I’ve the time or patience to try, I’m hoping classic home cinema will swap it for another machine but have not heard anything from them.Comment
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Hence my stance in a recent thread about not trusting anyone with projectors, even when buying them "serviced." I always assume that I'll have to put lipstick on a pig.
To be in this hobby in the year 2024, you also need to be a projector repairman.Comment
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About two years years ago I bought a Sankyo 762 that was "serviced". The amplifier is utter trash. Lots of hiss, hum and popping plus it runs too fast. "Serviced" my a**!Originally posted by Brian Harrington View Post
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Yes Phil, the 2 screws on the lens mount hinge that bolt the hinge to the chassis of the projector, located vertically below the front hinged cover retaining clip. If you just loosen those 2 screws you can shift the lens holder positiion considerably.Hi Paul, which screws do you mean, the ones on the lens hinge?
If you are otherwise happy with your GS1200, the focus issue is not reason to sell the projector, as it CAN be corrected. Its just that it can be a PIA to do it!Comment
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It sounds like he bought it from that dealer and wants to return it for a problem free one, if such a thing exists.
I would try to do the adjustment to avoid the hassle of returning it and getting another clunker. But that’s just me.Comment
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There is a seller on the bay who waxes poetic about how he services projectors. I haven’t seen any negative feedback, but he sells very common low end stuff he calls top of the line and best of the best.Originally posted by Dave Bickford View Post
Dave, did you get it from a dealer?
The one thing I can say is that I have a few machines where I got a refund because it wasnt as described and the seller didnt want it back. One is an otherwise good machine without a focus knob that I havent figured out how to fix yet. It broke during delivery because the guy packaged it so poorly.
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Dave,
Have you tried contact cleaner on the amplifier?
Adjusting the correct potentiometer will fix the speed.Comment
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