Film-Tech Forum ARCHIVE: Scope lens replacement glass

This is topic Scope lens replacement glass in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Justin Frakes (Member # 10491) on 06-22-2019, 04:18 PM:

Hello again, this year it has been one thing breaking after another. I pulled my scope lens out today and there is a crack in the first glass lens. I'll post some pics of the lens. Thanks for everyone's help.

IMG]http://www.film-tech.com/uploads/uploads0503/20190622_155340-477x1008.jpg[/IMG]

Posted by Mark Gulbrandsen (Member # 72) on 06-22-2019, 04:24 PM:

What kind of light source are you using. Improperly focused igh intensity light could crack those. As far as replacement glass, those are not paper weights. Look on Epay and get replacement lenses there. Schneider or ISCO would be much better.

Mark

Posted by Justin Frakes (Member # 10491) on 06-23-2019, 08:21 AM:

4500w xenon lamp, what am I looking for? Are those numbers on the ring the identifiers for that piece of glass? Thanks I haven't ever had to mess with the lens too much.

Posted by Mark Gulbrandsen (Member # 72) on 06-23-2019, 11:03 AM:

Be sure you have a heat filter in place! The backup is a 100mm lens and The scope lens is a 2X. Look for Schneider or Isco as they are air spaced and not cemented groups. They take heat better, but you still need to have the lamp properly set up and focused accurately. Any hot spots or unevenness in the light when running no film dictate a need for lamp house/lamp alignment. ALSO, NEVER RUN THE WHITE LIGHT MORE THAN 30 SECONDS AT A TIME WITHOUT ALLOWING THE LENS TO COOL!! Run the projector when ever viewing white light! Running the projector cuts the light level roughly in half.

Posted by Jonathan Wood (Member # 4614) on 06-23-2019, 11:22 AM:

I agree with Mark, I’d replace rather than try to repair . I’ve always thought Iscos had the edge in terms of sharpness and colour . There are usually a good selection on eBay although prices have gone up due to use on DSLRs

Posted by Marcel Birgelen (Member # 6801) on 06-23-2019, 05:11 PM:

As for finding a replacement glass for your lens... I doubt it will ever happen, even if the fractured glass itself is just a simple, spherical one. Maybe if you have the exact focal lengths and type of glass and coatings used in the lens assembly, you might find a spare somewhere...

When it comes down to anamorphic lenses, nothing beats ISCO at the moment, although they do come at a hefty price.

Posted by Helmut Maripuu (Member # 2281) on 07-01-2019, 09:30 AM:

Paper tape between the lens and the lens holder? woov! Overheating?

Posted by Louis Bornwasser (Member # 3063) on 07-31-2019, 03:52 PM:

Replace very bad lenses; increase light. Then reduce rectifier to reduce heat.

Posted by Emiel De Jong (Member # 4225) on 08-01-2019, 05:51 AM:

It looks like the scope attachment is still intact, only the backup lens is cracked (the Berthiot 100mm) ? You can remove the backup lens from the scope attachment, and replace it with any brand (Isco, Schneider, Sankor even Berthiot etc.) 100mm lens, I guess diameter 62,5 mm. This should be possible for some 10 - 40 dollars on Ebay I guess. Of course it would be a tremendous improvement in picture quality when you get some better lenses; the Berthiot is an antique, the Sankor scope attachment quite bad.

Posted by Mark Gulbrandsen (Member # 72) on 08-01-2019, 07:17 AM:

Either way, both those lenses are coke bottles, especially that scope lens! I would get some inexpensive Schneiders on Epay to replace them and finally enjoy nice sharp images.

Mark