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Topic: good results with scope image at 12'?

Dave Ganoe
Expert Film Handler

Posts: 119
From: Point Marion, PA
Registered: Jun 99

posted 01-18-2001 06:33 AM

Is is possible to get a nice, clear, and in focus scope picture with the projector only 12' from the screen. I tried using a variable anamorphic, and another scope attachment but the results are not watchable. I tried an assortment of base lenses also but the result was still the same. Any advice? Oh, I can't move the projector any further from the screen without knocking down a wall or two in the house. Thanks.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-18-2001 07:21 AM

Yes, you definately can. Any ISCO or Schneider lens will easily focus that close. Also the older Bausch & Lomb scope lenses can be modified to focus that close as well. If you unscrew the lock ring and then unscrew the focus barrel off the lens, marking both the main barrel and focus barrel exactly where it lets go so it can be put back together correctly.There are two small guide tabs on each side of the main lens barrel that need to be shortened. Remove these one at a time and file them shorter with an aperature file, being sure that you leave no burrs. Do this to both tabs and then re-assemble the lens barrels. It should focus down to about 10 to 12 feet.
Mark @ GTS
Mark

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Pete Lawrence
Expert Film Handler

Posts: 192
From: Middleburg, PA
Registered: Aug 1999

posted 01-18-2001 08:44 AM

I had the same problem, only I was trying for 25 feet. The modification that Mark describes certainly did gain a little, but not enough with the lenses I had. The problem is that the B&L red-ring scope attachments I have also have a raised edge on the moveable front element. This edge comes up against the outer lens shell and stops the front element from sliding in far enough to focus close. I would have to machine away some of the outer shell to get it to focus any closer. I now use a pair of Vidoscope (spelling?) attachments that seem to work ok at 25 feet, but I don't think they would make it at 12 feet. The other objection to the B&Ls is I have yet to see one where the lens cement hasn't yellowed. Another thought is if you don't want to spend the big bucks for a ISCO or Schneider and aren't running over about 1KW on the lamps you can use one of the larger diameter 16mm scope attachments. I've tried it and it works great. All of them will focus real close. You just have to work out some mounting method and watch out that the light isn't clipped at the corners.

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Jeff Stricker
Master Film Handler

Posts: 481
From: Calumet, Mi USA
Registered: Nov 1999

posted 01-18-2001 12:49 PM

I have adapted a 16mm anamorphic (type 16D) lens to a old B&L 3 1/2" standard lens using various PVC plumbing supply parts (file to fit!!). I'm running a 15' throw and get great results. The focusing collar on this lens says it will go as close as 2 meters.

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 01-18-2001 01:24 PM

I've set this sort of throw distance up for many people. I find the large barrel ISCO anamorphic lenses work the best, although Schneider's "closeup attachments" work well too. With the ISCO, I've found I can get the prime lens closer to the anamorphic, so there are no dark corners. With the Schneiders sometimes an extra coupler is necessary in order to get the lens close enough to the film to focus. I've never been pleased with other brands of lenses in home screening rooms.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-18-2001 04:20 PM

I don't remember modifing the barrel but its possible that I did. I had a B&L red ring scope lens once that was sharper than any other lens around at the time. That was about 20 years ago. Even Dwight Lindsay from Schneider saw an a - b comparison of it next to the Schneider of the time and was quite surprised that it looked better.
I agree that most older anamorphics are Coke bottles by comparison to newer lenses but this one was exceptional for some reason. I don't think the elements had yellowed yet. I was told that it is not the cement but the glass formula that the B&L's were made from has a built in chemical reaction and all of them will eventually yellow. The reaction was obviously unbeknownst to B&L at the time.
Mark

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timothy johnson
Film Handler

Posts: 50
From: minneapolis, mN 55419
Registered: Jul 99

posted 01-18-2001 04:52 PM

for sure, my home theater (35mm) set up has an isco scope lense thrown at 17 feet, ultra crisp and sharp..love isco...

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 01-18-2001 09:36 PM

I have focused the VidoScopes (silver with the black ring) down to 10' The shortest focal lenght is 2.5" with them
The B&L Glass discoloured from the effect of the higher UV in xenon light sources

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John Eickhof
Jedi Master Film Handler

Posts: 588
From: Wendell, ID USA
Registered: Jan 2000

posted 01-18-2001 11:48 PM

If you have a B&L, Vidascope or Mosty, The actual housing needs to be cut back about 1/4" and the slots that the indexing pins engage must be lengthened. It is not wise to grind on the indexing pins as this may deform them enough to change the astigmat relationship between the front element & the rear. Basically, you do as Mark suggested, remove front lock collar, then remove index pins (they should be punch-marked with one or two marks to indicate location, then scribe
a small line on the shoulder of the inner tube that holds the front elements, remove it and take the barrel to a good machinist and have him trim off about 1/4" of the exposed threads, and elongate the slots fot the index pins about 1/4". Make sure he dresses up the thread ends to make threading the lock ring back on easy. You can clean the lens thoroughly, and re-assemble, then dial it in!
Good luck. If you can't find anyone local to do this, let me know, I can do it for a nominal fee here at NTE!

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John Eickhof President, Chief Slave
Northwest Theatre Equipment Co., Inc.
P.O.Box 258
Wendell, ID. 83355-0258
208-536-5489
email: jeickhof@nteequip.com

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 01-19-2001 11:03 PM

Mark:

Beating a Schneider anamorphic has never been that much of a trick. Throughout the years they have had miserable problems of keeping their elements properly aligned. They also have clung to the 4-element design whereas ISCO's 4, 5 and now 6 element anamorphics are getting increasingly superior. The ISCO Blue-Star is just plain phenominal!

The Schneider "integrated" "ES" is actually a pretty good piece with shorter focal lengths and I like their ability of detaching the anamorphic piece like the larger ones. Also the Schneider integrated anamorphic has a nice focus/lock mechanism.

The full size Schneider anamorphic (the "WA") seems to have a greater than 2X expansion.

Steve

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"Old projectionists never die, they just changeover!"

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