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Author Topic: Dark corners
Brian Paymer
Film Handler

Posts: 31

Registered: Jun 99

 - posted 07-02-1999 09:27 PM      Profile for Brian Paymer     Send New Private Message       Edit/Delete Post 
I've got an auditorium where no matter how much I de focus the bulb I can't get rid of the dark corners in scope mode. It doesn't show up in flat mode. Any tips here would be appreciated.

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Brad Miller

Posts: 17687
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

 - posted 07-02-1999 11:22 PM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
I am assuming this is a short throw/large screen setup?

I'll bet if you unscrew the backup lens from the anamorphic and remove any dummy rings (so the two lenses will be closer together) that will solve your problem. Many flat/backup lenses come with a huge (about an inch long) ring to mount as a flat lens and many engineers do not remove this when mounting to an anamorphic.

Assuming this is your problem, the image is actually hitting the inside barrel of the lens causing your dark corners.

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Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

 - posted 07-03-1999 01:24 AM      Profile for Aaron Sisemore   Email Aaron Sisemore   Send New Private Message       Edit/Delete Post 
Another cause is the distance between the projector head and the lamphouse, if you have a way of sliding the lamphouse or the lamp unit inside the console) you should be able to fix the vignetting (the technical term for the dark corner problem) rather easily.


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Brian Paymer
Film Handler

Posts: 31

Registered: Jun 99

 - posted 07-03-1999 11:53 PM      Profile for Brian Paymer     Send New Private Message       Edit/Delete Post 
It worked! Thank you guys. I would never have guessed it to be something as simple as an extra lens ring.

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