Gobo Questions...!!!

[Schniapereli]

OK. 2 questions...

1. At our school, we have no donuts. (Neither the pastry, nor the lighting accessory) But, we have printer's tin, and I also have some tin from a frozen lasagna my mom made. I have searched various places on the internet, and could find the size of the square to make, but could not find the size of the hole. I need to know how big the hole should be on an ETC Src 4 ERS.
Also, I would like to make the donut out of the lasagna tin material, if it will sustain the heat. (we just want to make 1 for the show right now, but maybe more) If the lasagna tin material is not durable enough to withstand the temperature at the gobo slot, then I would make one out of printer's tin, but only if I have to.

2. I have heard of people using tranparencies printed off to use as gobos for Selecon lights. (they put it in the gel slot) So, I was wondering, can this be done with the ETC Src 4 ERS? I know Selecon fixtures are a lot cooler because of the MCM, but the ETC lights are hotter. Can it withstand the heat, and can it be focused enough to get a nice image? Also, how long would it take to burn out...?

[Footer]

With the transparencies... no way, not in a s4, it will melt in .3 seconds... and from the Apollo website were most people get donuts, 2.5" hole to 3" will do ya. Depending on the degree of instrument you are using, the hole needs to be larger or smaller.

[Schniapereli]

Ok, how big would the hole need to be for a

Strand 19*?
Shakespeare 20*?
S4 26*?
S4 36*?
S4 50*?

[Footer]

From logic, 2.5" for small field angles, 3" for larger field angles.

[jmabray]

Ummm... as for the transparency issue - what was said above was not entirely true.

If you have a piece of equipment that Rosco makes called an Image pro - you can do the transparency thing. But you need the Image pro to do it. The image pro is basically a fan that blows air across the "slide" to keep it cool enough - it also has a piece of heat resistant glass in there that blocks the heat from the lamp. This device lives in the Iris slot of a source 4.

go to the rosco website and check it out. www.rosco.com

Jeff

[icewolf08]

Here is the deal with the Selecons. Due to the way the the Selecon is built with the cold mirror the temperature at the gate is theoretically cool enough to use even inkjet transparencies in the template slot. Selecon gives instructions on this on their website. They require you to bench focus the unit in a specific way, and they don't recommend using a transparency for extended periods of time unless you use something like the ImagePro.

In a Source Four the temperature at the gate is hot enough to make steel templates glow red hot. Without the protection of a device like the Image Pro any plastic would melt near instantly. Even things like blackwrap and foil burn up in the template slot of a source four.

[gafftaper]

Yeah those Selecons are very cool... literally. They vent all their heat straight out the top. So after an hour worth of use you can actually touch the lens and barrel. I question how good of an image you would get from a transparency but I believe you can do it.

As for make your own gobo material I would use a slightly heavier material than those thin aluminum lasagna pans. It would probably handle the heat but it's awfuly thin. I've always used cheap pie pans or pizza pans. They only cost a couple dollars and have a little more strength than those aluminum pans.

[FamousLastWords]

Source Fours are Cold Mirrors.

The donut size needs to be 6 1/4" x 6 1/4" with a 2-3" hole, depending on the degrees of the unit for S4.

[Van]

Originally Posted by FamousLastWords

Source Fours are Cold Mirrors.

The donut size needs to be 6 1/4" x 6 1/4" with a 2-3" hole, depending on the degrees of the unit for S4.

If you order them that way. Not all are.

[gafftaper]

A little more on Selecons for those who don't know the instrument:
The Selecon ellipsoidal is "L" shaped. The lamp mounts into an ellipsoidal mirror chamber pointing up at a dichroic filter at a 45 degree angle. The filter reflects visible light, sending it forward to the lens tube, and allows everything else (mostly heat) to pass through and continue up and out the back of the instrument. They round it off with a nice heat sink back there to radiate it the rest of the way. The front of the instrument stays amazingly cool because of this process. They also have really great optics that are as crisp or better than a S4 with a donut... very similar to the new S4 EDLT's It would not surprise me if you could print a standard transparency on your ink jet printer, throw it in a gel frame in a Selecon and get a decent image for a limited period of time.

P.S. Bench focusing rocks on a Selecon. You can flip the heat sink up and look through the dichroic filter (which dims the lamp output dramatically) directly at the lamp. You then simply twist some knobs and center the lamp while you look at it. It's REALLY easy.