Conventional Fixtures Strange ETC Source Four Ellipsoidal heating

[dshriver]

Hello everyone,

I have a strange situation with my 26 degree Source Four lekos. I have 6 of them and they all seem to have the same issue. They are burning through color gel extremely fast. When dropping a dark gel (like Rosco Congo Blue) they are burning through in 5-10 seconds. This is with the lens tube fully extended. I'm lamped with GE HPL 575s. Thinking that this was odd, I took one of my instruments to Barbizon to have them look at it. We compared it to one of their S4 Lekos. When using the same gel on both my instrument was burning through in seconds but theirs didn't after 5-10 minutes. Barbizon verified that my instrument was adjusted correctly. They couldn't come up with any reason mine was running so much hotter. A call to ETC didn't shed any light (sorry for the pun) on the issue either. So I left that instrument at Barbizon for their tech services department to work on. But do any of you have any thoughts on this problem?

-d

 

[hobbsies]

Try getting some color extenders and heatshield. You can also take a pin and punch a bunch of small holes in the gel in an X pattern accross the middle to help dissipate the heat.

 

[DMXpro]

Maybe the benchmark focusing is off, causing it to focus most of the light/heat at one point, which happens to be right where the gel is?

 

[DELO72]

My only thought is the same as DMXpro- They might be bench focused to a spot which would do it. Also, check the reflector for dust/dirt. If the heat isn't being allowed to pass through the dichroic glass, it could be going forward.

 

[techieman33]

If he took some of the units to barbizon, I would think they would have checked bench focus. Maybe it's that revision of lens tube that has the problem?

 

[dshriver]

In an effort to solve this issue I added 3" color extenders and I installed Rosco heat shield as well. My setup was heat shield on the slot closest to the lamp, then the extender then congo blue at the end of the extender. This was giving me a gel life of about 5-10 minutes.

Barbizon verified that the bench focus was good. The reflector appears fine too. There's no visible peeling or flaking. There is some dust on the reflector but not a terrible amount.

 

[Ric]

I've seen a document on ETC's site which mentions Lens postion in relation to Gel life; perhaps this is the issue?

Found it Page 18 says:-

For maximum gel life with specific lens tubes, refer to the tables below.
And it then details the range of lens movement and best/worse position for each degree lens

For a 26 degree unit,
Lens Tube Soft Focus Back (Lamp “flat”) WORSE
Sharp Focus (Lamp “cosine”) BETTER
Soft Focus Forward(Lamp “peak”) BETTER
Soft Focus Forward(Lamp “cosine”) NOT APPLICABLE

Suprising to see but the Flat focus is the worst for Gel life !

 

[icewolf08]

First off, I have seen this many times. Using dark blues is nearly always problematic. 26 and 36 degree units seem to be the worst culprits on a regular basis.

Congo Blue (R382) has a transmission of 0.56%, that means the gel is converting 99.44% of the light int heat. You better believe that you are gonna cook gel like it is your job. Probably the only way to combat this is with color extenders and Apollo GelShield. In my personal experience, no other heat shield has performed as well as the Apollo product. The caveat is that is costs around $50 per sheet. You also have to install it facing the correct direction.

Your best case setup would probably be to have the lens at soft focus all the way out. Then GelShield in the color slot, color extender, then your color. You might also consider switching to: LHT181 - Congo Blue. The color is very similar and already heat resistant.

Odds are there is nothing wrong with your fixtures, and you could probably get a brand new fixture to do the same thing in the Barbizon show room.


Sent from my iPad using Tapatalk HD

 

[Wood4321]

This is a standard thing for the 26 and 36 degree lens barrels.
I run them sharp, and use a diffusion to soften the beam.
(Usually R119) but your mileage will vary depending on how soft you want the beam.

 

[MNBallet]

For really dark colors like this, it is best to order a dichroic glass. Many people do not even know that you can order it from the same place you get your gel. You can get a small round glass and a holder that fits in your gobo slot or iris slot. that way you don't have to worry about dark colors burning. It's around $10 but it's worth it if you want that deep Congo blue in a light.

Ken Pogin
Production / Tour Manager
Minnesota Ballet

 

[DELO72]

Yeah, once I saw that it was Congo Blue, my thought was- it isn't the fixture, it's the gel choice. 99.5% conversion to heat... OUCH. DEFINATELY go with Dichroic Glass if you need that specific color. You'll save a fortune in gel in the long run. Although with only .5% output... is it worth ever using it? 50 lumens of light from a ~10,000 lumen fixture?

This is where LEDs come in strong.... The other thought- Give ETC a call. I'm sure they can throw you some ideas as well.

 

[kicknargel]

Yeah, once I saw that it was Congo Blue, my thought was- it isn't the fixture, it's the gel choice. 99.5% conversion to heat... OUCH. DEFINATELY go with Dichroic Glass if you need that specific color. You'll save a fortune in gel in the long run. Although with only .5% output... is it worth ever using it? 50 lumens of light from a ~10,000 lumen fixture?

This is where LEDs come in strong.... The other thought- Give ETC a call. I'm sure they can throw you some ideas as well.

It's totally worth it. One of my favorite tricks is to use a deep (almost UV) dichroic lav (not sure the specific color) in a low front angle. Not so much a color wash in itself, but four 1K PARs with that creeps into the shadows and adds a magic little pop to almost any scene (especially musicals).

 

[Sony]

26 degree's eat through gels like crazy.... same thing happens everywhere I work. Use heatshield or dichroics as much as you can, otherwise replace gels often.

 

[dshriver]

Hi Ken,

The idea of a dichroic filter seems like a great solution. However, when I priced them out it was more like $60 per filter for Apollo Dichroic for my Lekos and about $90 for my par cans with an additional $15 for the holder. Am I missing something?

For really dark colors like this, it is best to order a dichroic glass. Many people do not even know that you can order it from the same place you get your gel. You can get a small round glass and a holder that fits in your gobo slot or iris slot. that way you don't have to worry about dark colors burning. It's around $10 but it's worth it if you want that deep Congo blue in a light.

Ken Pogin
Production / Tour Manager
Minnesota Ballet