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- dave
Crab juice, or Mountain Dew?

At last week's ITEA Seminar Series in Los Angeles, Dwight Lindsay of Schneider Optics announced a new version (3.0) of their very useful free "Theatre Design Pro" software, that helps in choosing lenses and designing auditoriums:
http://www.schneideroptics.com/software/theatre_design_pro/

Part of the charm of theatres is that each one is different -- in screen size, viewing and projection angels, throw and so on. To custom design and make optical systems for a particular cinema design is incredibly complicated as well as expensive. Even Multiplex operators that build "identical" auditoriums within cinemas find: 1) they are seldom really identical, and 2) the design needs to change anyway, whether the original design is used once or a few times.

Don't leave with the idea that today's projection optics are assembled from glass pieces out of a bunch of parts bins. These are very complicated optical designs, some of which take months and years to optimize and produce. Both ISCO and Schneider make products for a lot of industry segments, including cameras, medical imaging and other high technology lens requirements -- cinema projection lenses are among the most complicated designs they make.

What we can do is design cinemas within bounds that use incredibly good optics like the Isco Ultra Star Plus and Schneider within their design and performance limits. We can accommodate a certain amount of downangle projection now and minimize to tolerable levels, if not eliminate, keystoning effects now. Stadium seating designs have brought a whole new bunch of challenges to film and image projection.

Pat

Isco (and other)lens adapters also allow some "perspective correction" for correcting moderate keystone distortion:
http://www.iscooptic.de/english/products/adaptered.htm http://www.iscooptic.de/english/products/adaptergold.htm

People have tilted the screen itself to help reduce keystoning. Both ISCO and Schneider make a device that holds the lens on an angle to reduce keystoning (but it causes other problems.) Cheap lenses used in short throw theaters show a noticable pincushion; Again the ISCO and Schneider lenses do a better job at keeping focus in extreme situations.

It always seems like the building is designed from the lobby outward and the projection equipment is crammed into the leftover places that it shouldn't be.

Example: two auditoriums of the same size back-to-back where the projectors must be placed off-center in the narrow booth so that a human can walk between them, which creates not only keystoning, but reflections off of the port window bounce through the other port onto the other screen.

I think they are hanging out with the TRAVEL GHOSTS.

When one uses a PC adatper, they are trading keystone effects for linearity affects (probably the lesser of the two when most people judge a picture).

When on shifts a lens, you have limits on both the entering pupil of the lens and the exiting portion of your lens system (including the PC adapter or turret). This is more of an issue with shorter focal length lenses (as are used in the bulk of "modern" theatres.

That said, Schneider just redesigned their PC adapter so the technology is being supported and is progressing. ISCO uses two eccentric cylinders that can allow about 5mm of shift at any point. Schneider has a slider for the lens tube so one can slide the lens about +/- 5mm (and maybe more). After that, with the Schneider adapter one can rotate the whole adapter to place the lens in the desired location. If one is merely trying to compensate for vertical keystone, then lock the adapter down with the slider in the vertical orientation and adjust until you picture is centered.

For those that have not used PC adapters, you haven't lived until you try to use one with a Scope lens! It WILL try your patience.

Steve

Steve

Angles, angels and ghosts, OH MY!

<For those that have not used PC adapters, you haven't lived until you try to use one with a Scope lens! It WILL try your patience.>

I use an Isco PC adapter with an Isco Blue star anamorphic on a Bauer B11. The major problem is that almost each time I place the lens with its bracket (the B11 hasn't got a turret)it rotates somehow, although I handle it very, very carefully, so the image is a litlle crooked on the screen and I have to correct it.
I'm not sur I could express it clearly, my english being too poor.

Philippe

How is the lens rotating? Is the ISCO adapter slipping? Or is your indexing ring slipping? I have a modification for the PC-Cine adapter that will stop it from slipping (and not render it useless) but it does require disassembly and some milling. ISCO could have gotten the lock mechanism a bit better on it. Why they haven't corrected the locking design is a mystery to me except they are bound to be low production as compared to other items.

When we design a multi-format booth (beyond the Flat/Scope lenses) then we use PC-Cine adapters quite a bit so all formats are centered on the screen. A recent installation had 11 lenses (5 on one projector and 6 on the other) and PC-Cine adapters are must to get all of those to center up. (the formats supported are 1.37, 1.66, 1.85, 2.39-Scope, Silent and 16mm on one projector).

Steve

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