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This topic comprises 2 pages: 1 2
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Author
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Topic: Help needed determining a scratch origination
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Cory Johnson
Film Handler
Posts: 46
From: La Crosse, WI USA
Registered: Aug 1999
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posted 05-07-2001 12:23 AM
Pro 35 projector with a DTS reader mounted on top. I am 100% sure it is something on the projector itself, so I will leave the platters out of this. What is basically happening is we are getting a faint, vertical scratch(es) on the very right side of the film, (the side opposite of the sound track). Now, the projector has been doing this for as long as I can remember, however, it was never a big issue before because the size of the screen cropped it off so it was not noticeable. However, we got stadium seating and a bigger screen as of late and know the screen is the correct aspect ratio and the scratches are visible. I will try and describe them as best as I can.
- Only seem to appears after a couple of showings, but always "develop" over time.
- Once they are there, they don't really get any worse.
- Appear about a foot from the right hand of the screen on a descent sized screen (50ft ish).
- Are vertical and vary from a single, vertical scratch about 8 inches long to a bunch of smaller vertical scratches lined up very close to each other.
- Are patterned. What I mean is they appear in the same location on each film. Always towards the middle of the frame seems the worse.
- If you look physically at the film, you have to look VERY closely at it and you can see some "buff" marks at the spot of the scratches. Almost like a very light contact with a harsh object.
- I have tried a different film gate and it didn't change the scratch nor its characteristics.
- doesn't cover the entire film evenly, nor the frame evenly. Some reels you can't see the faint scratch, others it is very visible.
I have check every possible thing I can think of for this so any help is appreciate. Our techs don't know what could be causing it because all of the equipment looks good when inspected. Thanks in advance.
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Paul G. Thompson
The Weenie Man
Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000
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posted 05-07-2001 05:41 PM
Emusion side scratch? or non-emulsion side scratch?If it is a non-emulsion scratch, check the runner plate of the trap. It may have been dropped. Take the film trap out, and look for a "polished" surface on the curve that holds the intermittent sprocket shoe. It it is, chances are you found the problem. Very common with the Pro-35. Just spring it back a little, and you should be ok. If it is diagonal scratches on the emulsion side, the loops are probably too big and it is hitting the framing shaft, or that stupid roller the film lays on between the intermittent sprocket and hold-back sprocket. Take it off, shaft and all, and 99% of your emulsion scratches will go away. I have taken all of mine off 15 years ago, and threw them away. The machine will run perfectly fine without them.
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John Wilson
Film God
Posts: 5438
From: Sydney, Australia.
Registered: Dec 1999
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posted 05-07-2001 07:05 PM
Cory,When you bypass the dts reader (when not needing to use it), does the film rub on the top guide roller of the dts reader? Even lightly touch it? If it does (even more-so when it only just touches it,) that roller will not move and a 'green' print will see light scratches appear over time. dts readers are sometimes mis-aligned to the film path and use the fact that they are actually running through the reader to get 'on track', but when bypassing, the film is on another trajectory and this will put the right side of the image onto the roller. That's my take...
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