Film-Tech Forum ARCHIVE: Question about D150 "Curvulon" Correction Lens

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Posted by Frank Angel (Member # 248) on 08-03-2011, 08:40 AM:

There was an auction on ebay for the D150 Curvulon attachment (Kollermorgan). There's a very cursory description which mentions that the lens elements are ground so that there is a focus variant of about 10ft between the center and the edges of the screen, correcting the focus for the curve across the screen.

This seems to imply that the lens merely adjusts the focus to compensate for the distance difference between the left and right ends of the screen to the center.

My understanding of what the Curvulon lens did was to correct for the geometric distortion that the curve introduces into the picture. With the lens, the bowing of horizontal lines at the top and bottom of the screen is mostly eliminated and the horizon remains straight from top to bottom....at least that is what I remember being told years ago by a projectionist at the UA 150 in Long Island NY.

Maybe the lens corrects both focus and geometric distortion?

Anyone have any first hand info on this?

Here it is on ebay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200546534595&ssPageName=STRK:MEWAX:IT

I wish I had disposable income to buy this beauty. I'd build a curved screen just so I could use it -- actually I loved the D150 curve at that UA theatre. The Curvulon let them projector standard 35mm prints on it without any focus issues at all. 35mm scope looked really sweet on the D150 screen.

Posted by Bill Gabel (Member # 1105) on 08-03-2011, 09:27 AM:

Here is some info on the lens.
D-150 Curvulon Lens

I have one from the UA Egyptian Theatre Hollywood. It's a Very Heavy Lens even without the backup prime lens in the rear.

Posted by Mark Gulbrandsen (Member # 72) on 08-03-2011, 09:28 AM:

I have one thats a decoration atop my dresser. You are correct in that it corrected geometric distortion. This is simply an attachment lens much like an anamorphic lens and a variety of Kollmorgen 4" diameter back up lenses screw directly on to it. The Kollmorgen back up lens on mine has an added aperature and one would assume that was the attempt to increase focus depth. The lens is way too heavy to mount in anything but a DP-70 and I'm pretty sure all the U.S. D-150 locations were DP-70 equipped. The lens could actually serve as an anchor for a small ski boat!

Posted by Brian Guckian (Member # 1678) on 08-03-2011, 09:44 AM:

Here's a link Frank to an article written by Dr. Richard Vetter himself on the subject, over at in70mm.com:

[EDIT - I see Bill Gabel got there first!]

The projection field curvature was variable according to the spacing between the two lens doublets employed in the design.

Dr. Vetter states that with the appropriate choice of prime lens and the Super Curvulon lens set to the required magnification, the correct net focal length, field curvature and screen image width with precise focus center to edge were obtained.

It certainly would be a valuable acquisition.

A D-150 Super Curvulon lens is used to great effect at Pictureville, Bradford, UK when they do 70mm presentations on their Cinerama screen.

Posted by Bill Gabel (Member # 1105) on 08-03-2011, 09:51 AM:

True most US D-150 locations were equipped with DP-70s. But there was a few locations that were equipped with DP-75s and Century JJ model projectors in the US.

Posted by Lionel Fouillen (Member # 1475) on 08-03-2011, 10:22 AM:

The ODEON MARBLE ARCH in London had Cinemeccanica V8 projectors when it opened with D-150.
Scanned magazine about the installation

Posted by Bob Bregazzi (Member # 5623) on 08-03-2011, 11:05 AM:

The Odeon Marble Arch was the first cinema i ever worked in. At the time i was there (1968. if i remember correctly the D150 picture size was 75'x 29'. At the time i was there Dr. Doolittle was showing in normal 70mm Todd-AO. Fox stipulated in the contract that no picture size could be as big as the D150, hence normal 70mm was about 68', which in itself looked lovely on that screen and I believe the normal 70mm lens were curvature corrected. There were 3 vic 8's. It used to be a beautiful theatre but was carved up into 5 screens.

Posted by Lionel Fouillen (Member # 1475) on 08-03-2011, 12:28 PM:

Bob,
I saw The Temple of Doom and Lawrence' 1989 restoration in 70mm at Marble Arch. As far as I remember, The Temple was projected on the original curved screen on the standard surface you mentioned. Unfortunately for Lawrence, the screen had been flattened, they say at David Lean's request. Too bad it was split in 5 in the 1990's, although the original stage and front rows remain intact but underexploited by the new 35mm-only installation.

Posted by Bob Bregazzi (Member # 5623) on 08-03-2011, 02:24 PM:

yes you are right Lionel, it was at DL's request, he was a wee bit perturbed by the amount of distortion on the desert scenes. I saw "close encounters" and "return of the jedi" both in 70mm. although the cinema was not in the "west end" it was always considered one in the early years, but being of the beaten track turned into a bit of a white elephant.

Posted by Lionel Fouillen (Member # 1475) on 08-04-2011, 05:10 AM:

[YouTube] Odeon Marble Arch
Showing the flatter screen in what's left of the Odeon. In the new projection booth they built in front of the former circle, it seems they kept an original Vic projector, albeit with a new Christie lamphouse. But is it a Vic 8 ? I always thought Vic 8 never were built with single-lens holders. Could this be a Vic X ?

Posted by Louis Bornwasser (Member # 3063) on 08-04-2011, 11:04 AM:

I have used a Magnecom 65 pushed fully together for nearly the same effect. If you have a long enough f/l of the prime, it will pass 70mm film. The previous lens in this house was an old Cinemrama 70 lens. The deep curve screen needed the help. The Magnecom lens used this way caused the center of the picture to focus about 25 deet deeper than the sides.
At least the Schneider didn't change the color, and was much brighter than the Cinerama. Louis

Posted by Hillary Charles (Member # 769) on 08-04-2011, 01:56 PM:

This looks like one of those lenses in action.

The same poster also uploaded some other D-150 related pictures.

Posted by Bill Gabel (Member # 1105) on 08-04-2011, 02:38 PM:

quote: Hillary Charles
The same poster also uploaded some other D-150 related pictures.

Yes, I did that yesterday on that site.

Posted by Hillary Charles (Member # 769) on 08-04-2011, 02:41 PM:

So you're the mysterious "William"! Small world! Thanks for sharing those great photos. [Cool]

Posted by Bruce Hansen (Member # 281) on 08-04-2011, 05:06 PM:

quote:
The lens could actually serve as an anchor for a small ski boat!

Mark. I have a small ski boat. would you like me to give that lens a try?

Posted by Bruce Hansen (Member # 281) on 08-05-2011, 02:29 PM:

OK, way off topic, but this picutre just goes with the above picture:

A frozen strawberry daiquiri is a wonderful thing on a hot summer afternoon. Take THAT, global warming. [beer]

Posted by Mark Gulbrandsen (Member # 72) on 08-06-2011, 03:33 PM:

Bruce... The lens may well indeed sink your boat!

Posted by Louis Bornwasser (Member # 3063) on 08-06-2011, 04:12 PM:

Once had a 4" B&L anamorphic and a 4" diamater Kollmorgen backup chucked together with 2 large radiator clamps and a piece of steel pipe. Weighed 32 pounds and nearly wore out the JJ it was in. (Indiana Theatre, Indianapolis, IN)) Louis

Posted by Bruce Hansen (Member # 281) on 08-06-2011, 07:19 PM:

quote:
Bruce... The lens may well indeed sink your boat!

OK, Never mind. [Wink]