Film-Tech Forum ARCHIVE: standard vs. reverse anamorphic

This is topic standard vs. reverse anamorphic in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Scott Norwood (Member # 30) on 02-08-2012, 12:07 PM:

For the lens experts:

Given the choice, and all other things being equal, will a reverse-anamorphic lens with a 75mm prime lens give a better, worse, or equal quality image to a standard anamorphic lens with a 150mm prime? Is screen brightness affected either way?

I have not dealt with reverse anamorphics personally (I always thought of them as being a drive-in-specific item). Are they a reasonable option for an indoor house?

Image quality aside, the primary disadvantage that I can see is not having the correct lens for full-aperture silent (which, for a common-height screen, should normally be approximately equal to the prime lens used for scope). The other major disadvantage would be the difficulty of finding reverse anamorphic lenses on the used market (which might not be more difficult than finding 150mm lenses on the used market). Is there any other reason to avoid the reverse-anamorphic option?

Posted by Victor Liorentas (Member # 5272) on 02-08-2012, 12:38 PM:

One advantage I can think of for a 75mm route is,it's easy to find a 75mm prime at state of the art quality level.
The 150mm will be difficult to find and it will be decades older in design. The newest lens designs were for short throw multiplexes and I think go to about 95mm...

The reverse anamorphics I have seen look pretty good and I think the prime lens is more important but then again a decent 150mm with the best newer anamorphic should be very good.

I wish Isco made a 110mm Ultrastar HD prime. [Frown]

Posted by Barry Floyd (Member # 385) on 02-08-2012, 01:38 PM:

I picked up a Schneider Reverse Anamorphic adapter off of Ebay about two years ago for less than $200.00. Guy selling it had no idea what it was - nor the value of it. I replaced an old ISCO reverse anamorphic with the Schneider, using the same Schneider prime lens that I already had screwed to the ISCo, and the difference was literally night and day. My throw is 354 feet and my picture size is 25x59, and yeah mine is used in a drive-in.

Posted by Marin Zorica (Member # 1716) on 02-08-2012, 02:48 PM:

Reverse or nor is not so much difference, since they are both same except reverse anamorphic is in fact normal anamorphic but reversed, also you can nottice on reverse anamorphic that distance marking are going in opposite way. But tha thing is prime lens, that 150mm prime lens will get better picture than 75mm since 150mm has bigger f stop and thus more light will pass true it, normally in case both 75mm and 150mm lens are equal quality.

Posted by Steve Guttag (Member # 268) on 02-08-2012, 05:09 PM:

Scott, don't listen to these guys, they don't know what they are talking about...what horrible advice!

Any of the forward anamorphics (ISCO Ultra, Ultra-Star, Blue-Star or Schneider Cinelux-WA) will trounce ANY reverse anamorphic. All of the reverse anamorphics are 4-element units too.

An ISCO Ultra or Schneider CU 150mm with a good anamorphic will yield a superior picture than the 75mm (any model) and any model of reverse anamorphic. This is so easily demonstratable with target film or even just looking at a picture you all should be embarrassed for making such absurd statements.

While it would have been nice for the 100mm+ to get a lens redesign, they were already exceptional lenses that had the latitude needed for 35mm and 70mm projection. As one goes shorter, the difficulty of the lens dealing with the film pulsating and the depth of focus becomes more difficult (magnification increases) so progressively the benefit to a better lens is realized.

-Steve

Posted by Victor Liorentas (Member # 5272) on 02-08-2012, 05:37 PM:

I was only kidding of course but the rest of you should be ashamed! [Big Grin]

Posted by Phillip Grace (Member # 2262) on 02-08-2012, 10:47 PM:

FWIW I've had some experience with two types of reverse anamorphic. It was a temporary indoor installation with a long throw, (about 150 ft) and we could not source backing lenses of the appropriate focal length (about 180mm) for conventional scope in time, so had to go with the reverse anamorphics. The Kollmorgen KA 298 R, and its Isco equivalent had pretty poor transmission and some vignetting, but the Kollmorgen KA 299 reversible - huge thing with 4 inch barrel diameter - was a much better unit. I was advised at the time not to use reverse anamorphics with focal lengths shorter than 80mm due to vignetting issues, which would seem to have been good advice. That having been said, on an A/B comparison later, conventional anamorphic projection with fairly modern lenses was far superior. Of the older types of backing lenses, the long Isco Super Kiptars are pretty good.

Posted by Manny Knowles (Member # 1171) on 02-08-2012, 10:55 PM:

I never got a good result with Kollmorgen - and I had about 12 of them back in the dark ages. (Pun intended.)

Posted by Scott Norwood (Member # 30) on 02-09-2012, 10:16 AM:

Thanks for the comments. I won't recommend reverse-anamorphics. I'll have to find a pair of 150mm primes when the theatre (re-)opens later this year. I will post in the FS/WTB section when the time comes.

Posted by David Kilderry (Member # 142) on 02-10-2012, 03:01 AM:

Scott at the focal lengths you are talking about a regular anamorphic is the best solution. A 150mm backing lens is still efficient especailly with a modern design.

What is not mentioned here is at very long drive-in focal lengths, a reverse anamorphic is often a better option. We were faced with an 8 inch backing lens and regular anamorphic. There are no efficient 8 inch lenses available used so in this case we used a shorter length backing lens and reverse Kollmorgan 4 inch diameter anamorphic. At our drive-in it produced a sharper and brighter image than the alternative.

Posted by Lindsay Morris (Member # 1430) on 02-10-2012, 09:00 PM:

David's experience mirrors my own at a small country drive in that it had a non standard screen for scope.(undersized for width)
Image on W/S was quite good but utter crap in terms of illumination on scope as seeing the cues was a real problem.... it was that bad . [puke]

As the W/S almost filled the screen width wise I tried a reverse anamorphic using the W/S lens and took the aperture plate out completely for scope so the image fitted and slightly overshot the screen on the sides but when compressed down it just left a small black bar top and bottom...maybe considered "Film Done Wrong" but improved the light on screen and dragged the cues back in from almost outer space and made the operator's nights a tad less traumatic.
All they have to do now is swing the scope anamorphic up into place and hook out the aperture plate for W/S when they want to change formats from W/S to scope.
Up side is that focus stays pretty much spot on as the backing lens is never removed.
[Smile]

I still have a pair of Kalee 190mm (7.5") F 1.9 ex DI lens that have 70mm barrels made back in the 1960's and cost the earth then but now nobody wants them.

Posted by Louis Bornwasser (Member # 3063) on 02-14-2012, 08:20 AM:

There are 3 issues here:

1. Absolute image quality: the 150mm "wins"

2. Light: the reverse anamorphic wins.

3. Image size at very long throws: the reverse anamorphic wins, since there is no alternative. Louis