Burning gel

[Techiegirly]

I did a search and read previous posts to pick up some tips about this situation but I have a very specific problem and I need more specific answers so here goes:

I work in a childrens theatre that runs year round the same show sometimes 6 days a week 4 shows a day depending on the time of year. During a busy time I'm literally changing out gels in 10 of our units (6" Fresnels) that have R74 (night blue) every other day (or every 4 shows or so). 1 of the Fresnels in particular burns through VERY quickly. Sometimes I have to change him out before I change out the other 9. The theatre is very small in that most of the lights aren't more than 10 or 15' from the stage and they can all be seen from the audience. The Fresnel I struggle with constantly is such a headache because this set of Fresnels are used all alone basically at one point in the show to create night time so I can't see myself poking holes in the gels although I've been tempted to with mixed enthusiasm.

I was thinking of using a gel extender but have done a Google search and had no luck finding any. Do they even exist for this particular fixture? If they did exist would it even work? The light is about 12-15' off the ground above the stage, wouldn't a BUNCH of light end up showing through and make this idea look pretty stupid and useless? I couldn't use a top hat because the light is so close to the stage, it would ruin the focus.

Is it the light itself? I assume so since it burns through more quickly then the other 9 lights with R74 they are all pretty much used as often as one another in that they are a group on the board and mainly get used together. Does it need to be bench focused? Can a Fresnel even be bench focused? I feel so stupid asking that...

What if I took the lens off? Would that make the difference? Isn't that unsafe if say the lamp were to break suddenly the lens would provide a barrier of protection certainly wouldn't it?

I've run every idea through my little brain and I'm dying for a solution. Since this show is a permanent install I think it's important to solve this issue since we go through so many sheets of gel per week. Keep in mind we use heat sheild. We put the R74 in one frame and then the heat sheild in another frame behind it. I feel as though the heat sheild might be helping but really I can't say for sure since the only gap in between the 2 is very tiny (think 2 gels frames loaded into a Fresnel...not much space).

Any ways...what would you do?

[gafftaper]

Don't remove the lens, it won't focus well and as you suggested it'll be a safety hazzard.

You can't bench focus a Fresnel, just clean the lens and reflector.

Not sure what size accessory slot you have on your fresnels but I think 7 1/2" is fairly standard. City Theatrical makes a wide variety of color extenders. Select Lighting Accessories and then color extenders about $27 each.

Have you tried using a pounce wheel on your gel to let a little extra heat escape?

You could try one of the heat shielding gel products... might help a little.

The best bet would probably be to convince the powers that be to replace the gel with a dichroic glass filter. Might cost you $100-$200 each but in the long run you would save a lot of money on both gel and labor. I think Rosco, Gam, and Apollo can all make them for you in whatever size and tint you want. Here's the Rosco product page. Here's Apollo. It's going to be expensive but would probably pay for itself pretty quick at the rate you are burning gel.

[Techiegirly]

As I said in the post we use heat sheild but it's not really working in my opinion. I was considerng a pounce wheel but am afraid light may show through. These 10 lights are used alone on one part of the show for several minutes so I fear that even tiny holes will create an issue.

At very least if I could convince "the powers that be" to buy just 1 dichroic glass filter for the "problem" fresnel we would probably save tons of money in the long run. Thank you, I didn't even know this was an option

[gafftaper]

Either call your local dealer or call Rosco/Apollo directly for more info. It's one of those things that you won't find a published price on as it's going to be custom done.

Get a price quote. Calculate how much it costs in gel and labor per week to keep going like you are... put a stop watch on yourself to see how much time it takes you to cut and change that gel. Show the boss how long it will take to break even and how much money you will save over a year.

The best part is dichroics last forever, so 10 years from now they can still be using those same dichroics on another show with no loss of color.

[DarSax]

No sweat on all the questions!

First, you can't bench focus a fresnel, to answer your question.

Second, I'd wager that its the focus of the fresnel. I couldn't say off the top of my head if you can put the focal point of the lens in the actual gel (or might depend on the fixture), but I'd put money on the fact that the focus is the reason the gel's burning through so quickly.

Meaning unfortunately, I don't know a solution to your problem if the focus is necessary. I'd check that first, though. If you can alter the focus, even slightly, your problem might be assuaged greatly. (SAT word for the win!)

[Sean]

Originally Posted by Techiegirly

As I said in the post we use heat sheild but it's not really working in my opinion. I was considerng a pounce wheel but am afraid light may show through. These 10 lights are used alone on one part of the show for several minutes so I fear that even tiny holes will create an issue.
At very least if I could convince "the powers that be" to buy just 1 dichroic glass filter for the "problem" fresnel we would probably save tons of money in the long run. Thank you, I didn't even know this was an option

Try using "Gel Shield". It's essentially a plastic dichroic from Apollo. It costs ~$40 per sheet, but it is pretty expensive.

Is this unit flooded or spotted more than the other 8 in the system? I'll bet its focus is not quite the same.

Visit City Theatrical's website http://www.citytheatrical.com for color extenders, etc. You can get them from any real theatre supplier.

--Sean

[Techiegirly]

Originally Posted by Sean

Is this unit flooded or spotted more than the other 8 in the system? I'll bet its focus is not quite the same.

Visit City Theatrical's website http://www.citytheatrical.com for color extenders, etc. You can get them from any real theatre supplier.
--Sean

I'm going to check the focus on the fixture as soon as I can. I don't think the world would come to an end if I "accidently" "bumped focus" a tiny bit, especially if I never told anyone I did, they'd never notice. As I've said it's permanent installation so I feel obligated to not change a single thing especially focus. I've accidently bumped focus before and paniced until I fixed the problem as best I could.

I checked out the color extenders and I'm afraid they'd change the focus of the light. I think I'm stuck as far as getting an extender. I believe this light is flooded so an extender wouldn't work for my given situation, correct? Especially given it's closeness to the stage???

[Sean]

Originally Posted by Techiegirly

I'm going to check the focus on the fixture as soon as I can. I don't think the world would come to an end if I "accidently" "bumped focus" a tiny bit, especially if I never told anyone I did, they'd never notice. As I've said it's permanent installation so I feel obligated to not change a single thing especially focus. I've accidently bumped focus before and paniced until I fixed the problem as best I could.
I checked out the color extenders and I'm afraid they'd change the focus of the light. I think I'm stuck as far as getting an extender. I believe this light is flooded so an extender wouldn't work for my given situation, correct? Especially given it's closeness to the stage???

\

You'd have to put one in and see. They make 3" and 5" long accessories, I believe.

If you're handy with a drill and have a couple of "extra" colorframes you could make your own, shorter extender.

Just get some long bolts, say 1/8-1/4" diameter or smaller. Build a standoff by drilling four holes in both frames, one in each corner (but not at the edge, or else it won't fit in the light). Bolt the two frames together, keeping the frames separated a bit by using extra nuts. Then wrap the now open sides with blacktak/wrap. Not pretty, but it might help your problem.

Also, you could use a barndoor. Some of them are designed to hold a colorframe. It's usually about 2" further from the lens, so that may help as well.

When did the LD see this plot last? Is it possible that the fixture's spot/flood has slipped? Gravity would slowly flood the unit out, and could be the source of the problem.

Off to bed....finally!


--Sean

[Pie4Weebl]

if that light was the only one having an issue, I think it would make more sense to replace the fixture instead of spending $200 on a gel. I know lee posts the prices of the glass versions, sadly that sheet is in St. Louis and I am back in Chicagoland. Try cleaning it and check the focus. Make sure there is no black tack covering the exhaust vents on it so heat can properly escape that might do the trick.

[derekleffew]

How did I come so late to this party? Techiegirly, you said you've tried heat shield in the past, with poor results. The Apollo "Gel Shield" really is superior, but any shield needs airspace between it and the color. A 3" color extender will not affect the focus of the Fresnel, even at full flood, which is most likely is as that puts the lamp closest to the lens. Another thought, do you have access to any barn doors? Most would allow you to put the "shield" in the color frame slot in addition to the barndoor, then there's a place for the R74 at the front of the barndoor. Leave all the doors wide open.

I've never had any luck with "pouncing" gel in deep colors, to me it just gives the color media a place to start to burn quicker.

You never told use what make, model, and lamp of the Fresnel in question. We are all assuming, I think, an Altman 6" FS, 65Q, with a 750W BTN lamp. Fixture is not rated for any higher wattage than that, so you better not have a 1000W in there!

Another option, now that it is after 01/01/08, is Apollo's new Gel Miser!

Lastly, you need not go to the expense of a dichroic filter. Devon Glass #148 (website colors are not accurate, call for a sample) is fairly close to R74, and glass is much less expensive than dichroic. I think Rosco also has a line of plain glass.