8mm Forum: Reducing screen size

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Posted by Jason Schmidt (Member # 4526) on December 08, 2015, 06:43 PM:

Much has been said of increasing screen size given a limited sized room. My question is, what techniques can be used to reduce screen size when the projector is quite far from the screen? I want to project in a room that has a balcony and when shooting from the balcony the smallest I can get the picture spills over the edges of the mounted screen by maybe a foot or so.

I am using a 15-25mm zoom on the setting to get the smallest picture. The picture is plenty bright but again the issue is the spill over, so I'm hoping to make the picture slightly smaller without having to bring the projector down off the balcony and into the audience. Any ideas?

Posted by Janice Glesser (Member # 2758) on December 08, 2015, 07:28 PM:

Jason you don't say what model projector you are using. I would think a 30mm lens would do it. If you can't find a 30mm lens to fit your projector...then you might try finding a telephoto converter lens used for cameras and camcorders to place in front of the projector lens (.5x or less). However it then might make the picture too small. Of course there is always the alternative to get a bigger screen [Smile]

Posted by Steve Klare (Member # 12) on December 08, 2015, 07:30 PM:

Elmo made a long throw lens (25-50mm) for using their S8 machines in auditoriums. I'd love to have one myself for basically the same reasons you do (I can't project 'scope films and stay on the screen without moving the projector forward.).

The catch is these are fairly short in supply and fetch the kind of price that keeps me moving the machine instead of buying one!

Posted by Jean-Marc Toussaint (Member # 270) on December 08, 2015, 07:39 PM:

And if I may add to Steve's comment, Elmo made two long-throw lenses with different f-stops: 1.4, the most common and 1.2, the better one. Prices for the later are usually on par with the short-throw 1.0 (ie - 300 USD).

Posted by Jason Schmidt (Member # 4526) on December 08, 2015, 07:40 PM:

Sankyo 460 is what I'm using right now.

Posted by Paul Adsett (Member # 25) on December 08, 2015, 08:26 PM:

I used to have the Elmo 25-50mm f1.4 auditorium lens. It was a good lens, but nowhere near as bright or sharp as the Elmo 12.5-25mm f1.0 lens. For that reason, in public shows,I always use the f1,0 lens and move the projector closer to the screen if I have to.

Posted by Steven J Kirk (Member # 1135) on December 08, 2015, 09:45 PM:

Some say the ultimate lens for Super 8 is the Schneider xenovaron. This is 11-30mm range and would give a great result. It might be a long term project to find one with the correct barrel. There are adapter sleeves that fit but also versions of the Schneider for Elmo, Eumig, Bauer. In the mean time find a 16mm converter or zoom attachment and put it on a stand in front of your machine. But you will lose light with this set up.

Posted by Andrew Woodcock (Member # 3260) on December 08, 2015, 11:59 PM:

I use the Schneider Xenovaron lens in all but one of my projectors natively (no adapter or sleeve).

My room is only around 25ft long but to fill a 10ft diagonal, I tend to be hitting around the centre spot of the zooming range.

By putting it on 30mm it is remarkable just how small still the picture is.
I would have predicted that you could easily use this lens up to distances of around 40ft away from the screen so long as the screen itself is a decent size.

Anything much beyond 50ft with any standard Super 8mm Projector, and you're probably into the realms of too much light dropping off due to throw distance anyway.

Posted by Maurizio Di Cintio (Member # 144) on December 09, 2015, 03:01 AM:

I second Janice's advice: it works great after finding a way to hold the converter perfectly lined up in front of the basic lans. Only please note: since we are talking about telephoto converter here, what is needed is not a ".5" (that would double the screen size!) but a 1.5x or 2x converter. There will be some light loss...

Posted by Maurice Leakey (Member # 916) on December 09, 2015, 03:42 AM:

To save the cost of a new lens would it be possible to move the screen closer to the projector?

Posted by Jason Schmidt (Member # 4526) on December 09, 2015, 08:23 AM:

The issue with this space is that the screen is fixed andas big as it can be.

I'll look into the telephoto converters, I used to have some for my camera but sold them awhile ago.

Posted by Jason Schmidt (Member # 4526) on January 20, 2016, 09:24 AM:

Would this be suitable?

http://www.ebay.ca/itm/52-49-46mm-Conversion-Lens-Double-Tele-Converter-1-5-X-Wide-Wide-055x-/111760869601?hash=item1a057788e1:g:HFgAAOxy4YdTProy

Posted by Janice Glesser (Member # 2758) on January 20, 2016, 01:45 PM:

I've never used a combo lens before... might work, but there may be more optics than needed and could darken the light output. I would look for just a telephoto lens converter.

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