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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Flat Lens is going blurry

   
Author Topic: Flat Lens is going blurry
Craig Kocher
Film Handler

Posts: 10
From: West Hazleton, PA 18201
Registered: May 2004


 - posted 07-12-2004 04:42 PM      Profile for Craig Kocher   Email Craig Kocher   Send New Private Message       Edit/Delete Post 
hello all, may be a stupid question, but we cant seem to figure this one out, hell, even our tech doesnt know whats wrong. It seems that during the first show ( usually around 10am ) the Flat Lens on one of my Christies is going immediately blurry. I can fix it obviously by adjusting it, but then the weird part is, it does this again during the second show, but corrects itself in a few seconds and then I have no problems for the rest of the day, Untill the next morning that is, when the process repeats.

Anyone experience this before? Any Suggestions?

Thanks

Craig

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Wolff King Morrow
Master Film Handler

Posts: 490
From: Denton, TX, USA
Registered: Feb 2004


 - posted 07-12-2004 05:09 PM      Profile for Wolff King Morrow   Author's Homepage   Email Wolff King Morrow   Send New Private Message       Edit/Delete Post 
That is strange. Could it be a thick splice knocking the focus out at the same spot in the trailers? I've seen this happen before. Or maybe some sort of heat expansion in the lense?

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 07-12-2004 05:23 PM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
Perhaps an element is loose, and changes position as the lens heats up? Or the lens mount/turret is loose and changes position with vibration?

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Chris Hipp
Phenomenal Film Handler

Posts: 1462
From: Mesquite, Tx (east of Dallas)
Registered: Jul 2003


 - posted 07-12-2004 06:14 PM      Profile for Chris Hipp   Email Chris Hipp   Send New Private Message       Edit/Delete Post 
I will say it before Brad gets here to yell at you. Post the make and model of the lens to help everyone identify the problem.

I recently had a problem on an ISCO lens where the ring that holds the front element was loose and the focus would drift. Just tightened it up and fixed it.

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Brad Miller
Administrator

Posts: 17641
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 07-12-2004 06:38 PM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
Craig,

Loosen the allen screws that hold your lens into the turret a little bit. Probably a half turn counter-clockwise should be enough. If they are tightened down too far, the Christie turret will exhibit this sort of focusing issue. Just make sure they aren't so loose that the lens can fall out.

If that doesn't work, post again with more detailed descriptions of how the focus behaves on screen.

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Craig Kocher
Film Handler

Posts: 10
From: West Hazleton, PA 18201
Registered: May 2004


 - posted 07-12-2004 10:13 PM      Profile for Craig Kocher   Email Craig Kocher   Send New Private Message       Edit/Delete Post 
Thanks everyone for the advice. Brad, I'm in the Booth Wednesday Morning at 8am so I'll try it then and check back that night. Thanks again everyone, This place is so great, I'm trying to learn as much as possible and this place is definitly helping.

Craig

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John Anastasio
Master Film Handler

Posts: 325
From: Trenton, NJ, USA
Registered: Sep 2000


 - posted 07-13-2004 07:04 PM      Profile for John Anastasio   Author's Homepage   Email John Anastasio   Send New Private Message       Edit/Delete Post 
I once had exactly this problem. It was caused by humidity getting into the lens. The lens was cold, then when the heat of the lamp hit it, the condensation formed on the inside lens element, sort of like taking a cold coke out of the fridge. After it stayed warm for a while, the humidity was driven from the lens and it cleared up.

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Brad Miller
Administrator

Posts: 17641
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 07-13-2004 07:32 PM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
It can't be that. He reports that he can fix it by adjusting it, hence it's not a humidity issue.

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Craig Kocher
Film Handler

Posts: 10
From: West Hazleton, PA 18201
Registered: May 2004


 - posted 07-13-2004 10:52 PM      Profile for Craig Kocher   Email Craig Kocher   Send New Private Message       Edit/Delete Post 
well, I'll know tomorrow morning, Our Tech is coming and were gonna get to the bottom of this...

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John Anastasio
Master Film Handler

Posts: 325
From: Trenton, NJ, USA
Registered: Sep 2000


 - posted 07-14-2004 04:08 PM      Profile for John Anastasio   Author's Homepage   Email John Anastasio   Send New Private Message       Edit/Delete Post 
Agreed, Brad. I wasn't paying much attention... and I agree about the Christie lens screw on the turret. There's really nothing else there to move.

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