Film-Tech Forum ARCHIVE: Christie lens swap problem.

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Posted by Jason Black (Member # 684) on 02-19-2004, 03:46 PM:

Since our flat Schnieder lens recently bit the dust, we ordered and rec'd a replacement. It's an Isco-Optics lens. The Isco is about 1.5" longer han the Schnieder it's replacing.

I set it in place with the focal knob at it's midpoint, get the iamged focused tight and crisp across the screen, tighten down the allen heads to secure the lens.. only to find out that the extra length makes the outer lens ring hit the 'stop adjustment' screw collar.

Trying to compensate by moving the lens back does not give me adequate adjustment range. Could I file the collar down so that the lens clears it? I dont' see that this would hurt anything. The collar is like a flange on the adjustement nut, or so it appears.

I just looked in the manual section and couldn't find exactly what I'm talking about, but anyone familiar with Christie's probably knows what I'm referring to.

Thanks!

Posted by Mark Gulbrandsen (Member # 72) on 02-19-2004, 07:52 PM:

Is the actual lens group of elements this long or is there just a ring that you couold unscrew from the front of the lens.
BTW: Its also cheaper to have your bad Schneider lens repaired than it is to replace it. Shouldn't be too hard to juggle things in a large multiplex to work around the bad lens till its returned.

Mark @ CLACO

Posted by Jason Black (Member # 684) on 02-19-2004, 10:29 PM:

Mark,

I'm thinking that the defective lens will be rebuilt at our shop, then sent to another location should the need arise. We've had a real problem with Schnieder lenses with elements rattling loose. Part of it, IMO, is the turret setup and teh way it hits the 'bump-stop'.

AFAICT, there is no outer ring that I can unscrew to allow additional clearance. I will double check that in the morning when I get to work. I'll also try and take a digi-pic of the 'shoulder bolt' that I referred to earlier.

EDIT
Mark,
There was, in fact, a removable "collar" on the new lens. I found this out as soon as I checked it out again when I got to work today. I unscrewed the front 'collar' or 'hood' and now have plenty of clearance. The image is rock solid from top to bottom again!

[ 02-20-2004, 04:05 PM: Message edited by: Jason Black ]