Film-Tech Forum ARCHIVE: Schneider 100 mm

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Posted by Miguel Ercolino (Member # 2030) on 12-08-2003, 04:05 PM:

Hello this is my first post, and excuse me for any mistake but English is not my primary language.

I am having troubles with 100 mm Schneider prime lens installed in Cinemeccanica turrets, I have focusing problems, i focus the lens but every time that the turret change lenses the image appears blurr again, i dismounted the lens and the prime lens sounds like a "maraca" when you shake it, i send to repair it and the middle lens is not firmly attached, anyone has the same trouble, or Schneider know the problems.

Thanks for your response
Miguel

Posted by Steve Guttag (Member # 268) on 12-08-2003, 04:29 PM:

Loose elements can happen but is not the norm with Schneider. However what I have found is that with two-part lens assemblies (the ones where they can be separated about half way through the lens...they can unscrew...especially if they are heated up a bit. Make sure your lens (I can't remember if the 100mm is a two parter...most of the lenses above 100mm are two-parters) is indeed screwed together tightly. The rear part (the part where it steps down closes to the film, may be loose and just justs a little twisting.

Steve

Posted by Richard Fowler (Member # 893) on 12-08-2003, 04:43 PM:

The newer Schneider and Isco lenses are air spaced with spacer rings to locate the lenses within the lens tube. The lens tube will be two parts at 100mm which you should tighten with the lens pointed upward to help reseat the lenses on their internal spacers....in most cases this will resolve this. I find people will pull on the lenses if moving the turret manually which will sometimes cause this problem.

Posted by Randy Stankey (Member # 64) on 12-08-2003, 05:00 PM:

Years ago I had this same problem. I don't know the exact fl. of the lens but there was a loose element inside. It did rattle around inside there like you say.

For several weeks the booth kept getting calls to fix the focus in one house. ALL of us guys, SWORE that we focused the image perfectly. In a few minutes it would be out of focus. We kept getting blamed for it. After many hours of screaming and hollering we finally suspected the lens. Upon examination, it was found to be bad. When it was finally sent back for repair/replacement the problem was solved.

Posted by Ron Yost (Member # 1850) on 12-08-2003, 06:25 PM:

Why aren't they made more securely in the first place? IMHO there shouldn't be any possibility of glass elements working loose, under normally expected operating conditions, to the point where the image suffers.

Pretty poor engineering and/or cost-saving production methods, I'd say. These are top-line, not exactly inexpensive items, after all. [Smile]

Ron Yost .. owned a -very- sloppy Schneider at one time.

Posted by Gordon McLeod (Member # 33) on 12-08-2003, 06:28 PM:

Actually it isn't sloppy engineering it is improper handling at the users end is the often problem

Posted by Mark Gulbrandsen (Member # 72) on 12-08-2003, 07:18 PM:

Actually it was pretty common going back 8 or 9 years for the Schneiders to work themselves loose. I've had to crawl around more than once to find len elements, spacers,rings and other parts on booth floors. Schneider finally started applying a bit of paint or some type of sealent to the rings when they were assembled. This loosing up is caused by repeated heating and cooling of the lens and this is normal for all lenses. In that case the threaded rings managed to really work loose. Don't recall ever having a problem with ISCO's though.
Mark @ CLACO