Design Finding correct beam angle for Image Multiplexer

petercav17

Active Member
Fight Leukemia
Hello all,

For a show that I am lighting in a venue with limited open dimmers, I want to have a gobo wash. However, I can really only spare 1 or 2 dimmers.

To accomplish this I have picked up an Image Multiplexer from City Theatrical which is basically a prism that multiplies an image x6, and I'll put it and a gobo in a Source Four mid center and with some barn doors (shutters won't work) and I'll be able to wash the whole stage.

I have tested this, it works great (looks amazing with twin spin) and is fairly bright.

My issue is that the 36 degree barrel leaves a dead zone in the middle, but a 50 creates an ugly overlap in the middle. I don't have any zooms, so I'm considering 2 things:
- Use the 36 and add a second unit that projects a single gobo into the dead zone
- Use the 36 deg. and a color extender to get the prism farther away from the lens in hopes of making the image a bit larger so it'll cover that center zone. (or would that not work/do I need the 50 deg. for this?)

Has anyone done this before? Used a different method? Thoughts are much appreciated. Thanks!


Below is a crude drawing of the senario, note I only drew 4 of the 6 beams, sorry I used MS Paint

imga.png
 
This may sounds really silly, but in the time it took for you to write this post and draw a picture, couldn't you have tested your idea of using a color extender?

I have not worked with this product before, but I would guess that if it is designed to be used in the color frame slot, then the optics won't quite be right if you put it in a color extender. What would be most interesting is seeing how it affects the focusability of the fixture. In general though, adding a color extender isn't going to change the field angle of the fixture.
 
This may sounds really silly, but in the time it took for you to write this post and draw a picture, couldn't you have tested your idea of using a color extender?

I don't have any color extenders in stock, so I didn't want to buy some if I wasnt sure that it would work. Thank you though, confirmed my suspicions about the field angle thing.

As to the focusability - I have no clue what would happen, I really want to try this just out of curiosity.

I'm trying to think out of the box, forgive me if this whole thing seems a little far-fetched.
 
Or you could ask your buddy to borrow a S4 zoom and try it (me).

See I was going to ask you about an S4 junior to hit the middle - didn't know that you had zooms!

I'm planning to use a zoom then, unless you've got a different idea John.
 
My guess would be to use two gobos one in the 36' multiplier and one in a 50' lens to wash over the entire area. Soften the focus of the image multiplier and have the 50' a little sharper and brighter.
 
Consider it done. You can borrow both. I do like Robert's idea too, and think we should try all possible combos; then pick the one you like best.
 
Consider it done. You can borrow both. I do like Robert's idea too, and think we should try all possible combos; then pick the one you like best.

Great thanks John and everybody for the input.
 

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