Film-Tech Forum ARCHIVE: ISCO lens problem

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Posted by Chris Hipp (Member # 1788) on 09-08-2003, 06:13 PM:

one of my scope ISCO lenses looks extremely "hazy" on screen. It almost looks like the throw is off and it is ghosting all over the screen.

I tried adjusting the throw as the tip section says to do so and I have checked the shutter for warpage or damage but all is fine. I cleaned the lenses and port glasss.

The Flat image is clear.

What could be wrong?

Posted by Brad Miller (Member # 2) on 09-08-2003, 06:53 PM:

Have you cleaned your lenses? Odds are it is the rear element that has is dirty from using XeKote to clean the projector with or someone smudged the lens with their hands when threading. Alternatively you could have a fogged lens due to humidity.

The focus setting once set will never, ever need to be touched again.

Posted by Chris Hipp (Member # 1788) on 09-08-2003, 06:58 PM:

I have cleaned the lens , front and back, the best I can with Rosco lens cleaner. How would I know if it was humidity? Would it be fogged up like a windshield?

Posted by Brad Miller (Member # 2) on 09-08-2003, 07:08 PM:

Yeah, I've seen lenses literally look like a "fogged windshield" from humidity issues. Can you tell which surface is fogged?

Posted by Ron Yost (Member # 1850) on 09-08-2003, 08:21 PM:

I'm assuming it's in a turret and you can't (or aren't supposed to) remove it to have a look right through it? If it's fogged by humidity that would be one sure way to tell.

Ron Yost

Posted by Chris Hipp (Member # 1788) on 09-08-2003, 08:25 PM:

OK, I'll check if it is fogged up. It is in a turret, I dont see why people make such a fuss about taking the scope lens out. I've done it several times to replace the pins and I've never had a problem aligning it when I put it back in.

Posted by Gordon McLeod (Member # 33) on 09-08-2003, 10:58 PM:

Chris I noticed most of your posts start with "I don't get it" or something similar
When people offer advice when asked then maybe one should think it comes from experience and comments like I don't get it are or why so tend to make one hesitate offering advice

Posted by Chris Hipp (Member # 1788) on 09-09-2003, 12:41 AM:

I didn't realize I was being so negative; that certainly is not my intention. I'm appreciative of any advice that anyone offers me and I try to help out anyone that I can. Sometimes I don't understand something or I would like something explained in more detail.

Posted by Paul G. Thompson (Member # 655) on 09-09-2003, 01:25 AM:

Chris, I have seen a couple of old B&L and some Sankor anamorphics that had a problem like you described. The lens looked fine....the elements were not dirty as I peered at them.

How old is the lens, and did you try it in another projector?

The problem corrected themselves when I threw the lens away and replaced them with better junk. [Wink]

I suspect the coating may have deteriorated in such a manner as it would render such a crappy picture.

Hmmm....my 4,000th post.... [beer]

Posted by John Pytlak (Member # 331) on 09-09-2003, 09:21 AM:

You may have gotten moisture or oil INTO the lens. Here's a Schneider "white paper" about proper lens cleaning procedures:

http://www.schneideroptics.com/info/white_papers/lens_cleaning.pdf

Here is Isco's site:

http://www.iscooptic.de/english/indexeng.php

If you have internal contamination or damage, you will need to have the lens professionally disassembled and cleaned.

Posted by Luciano Brigite (Member # 1104) on 09-09-2003, 09:46 PM:

Make sure the front and back elements are not loose
I had two lenses that couldn't get focused, they were clean .Turned out that the ring that keeps the elements in it's place loosened up and the element moved while being cleaned or due to vibration, only a very small move is enough to cause problems with anamorphics.Why it did happen.. I have no idea.both lenses can be considered old by now.

Posted by Will Kutler (Member # 770) on 09-09-2003, 09:52 PM:

At one new 20plex where I was employed, several Schenider lenses all wnt bad at once and really produced a headache (in terms of both trying to get films on screens, as well as patrons who got headaches from a badly focused picture). Anyhow, for some reason on this new batch of Schneiders, the elements were all loosening up making it imposible to focus, or maintain focus. But Schneider did correct the problem.

Posted by Chris Hipp (Member # 1788) on 09-10-2003, 02:59 PM:

Well, I checked it out today. I cannot see any moisture inside the lens, in fact it looks prefectly normal. I switched it out with another projector and the problem stayed with the lens.

I'm thinking that maybe someone got some lens cleaner or maybe sprayed windex on the lens and it got on the inside.

I guess I'll have to send it back for repair.