8mm Forum: Removal of lamp filters in Elmos....

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Posted by Greg Marshall (Member # 1268) on June 16, 2009, 09:50 PM:

I've been disappointed in the amount of light that my ST1200 allows. I remembered removing the filter that is installed in the machine I had back in the '90's, and did so again with the one I have now, and wow, does it make a difference!

Can anyone shed light (no pun) on this subject? I'm sure the manufacturer put that filter in there for a reason. But, I am not noticing any damage to film passing through the gate, so I'm pretty pleased. Comments?

Posted by Dino Everette (Member # 1378) on June 17, 2009, 02:31 AM:

Isn't that used as a backup for the drop shield when you are turning the switches forward and reverse, etc. Plus my guess would be that it helps absorb some of the heat of the lamp on the gate....I actually have one of mine where I don't have the whole lamp cover and I have run many films through it and haven't noticed any damage...I think you are OK, especially if it is helping with your light out put.

Posted by Gary Crawford (Member # 67) on June 17, 2009, 08:19 AM:

I was on the phone last night with U.S. Elmo expert, Leon Norris...and he told me that he has never figured out what that glass was supposed to do, but whenever he gets a machine for repair, he , with the owners permission, removes that glass...and it adds a discernable amout of light to the screen. He said he had talked with someone who used to work at Elmo and he said he never knew why it was there , either.

I've taken them off my st1200's...with no ill effects.

Posted by Mark Todd (Member # 96) on June 17, 2009, 08:54 AM:

Elmo`s unlike many super 8 machines fan over, and onto the bulb and very well so if the glass is in, whip it out.
Its no worries at all.

Best Mark.

Posted by Joe Taffis (Member # 4) on June 17, 2009, 04:00 PM:

using the 'search' feature here on the forum, type in "elmo light output". Lots of stuff on this topic from long ago. [Smile]

Posted by Dino Everette (Member # 1378) on June 17, 2009, 04:48 PM:

Thanks Joe, and I actually used my newest elmo (sans glass) to screen some very rare one of a kind sound home movie footage of slain politician Harvey Milk last week for a crowd of about 50 people, so it is safe to say she is up n running great, and I ran the audio out through an amp and it sound really great...Now I just need to get an optical print to check out the sound on that one...

Posted by Greg Marshall (Member # 1268) on June 17, 2009, 09:17 PM:

Thanks for all the replys, guys... I feel much better now. The amount of light is significantly better than with that glass in tact. I'm even ready for Scope now. Well, if I had a lens... ha.

Posted by frank arnstein (Member # 330) on July 24, 2009, 11:20 PM:

Hi Greg & others on this thread.

With regards to the Glass piece that is removed by many......
I have a hypothesis as to its true function....

The fan delivers pressurised cooling air to the lamp which flows past the lamp and exits somewhere and dumps the hot air outside.
If there was no glass piece in place, pressurised cooling air would leak out from the hole left by removing the glass. The glass is actually part of the ducting system for the lamp cooling air & to remove the glass is like putting a big hole into your pressurised cooling duct. This will substantially alter the ability of the lamp cooling system & hot air will also leak out directly onto the inside of the gate & aperture. This will heat up the gate and possibly damage film that is in the direct area especially a frame in the aperture.

So thats my theory of why they use the glass plate in the 1st place.
Projected light easily gets through the glass but not air.
Some of these glass plates appear to be cracked in half but thats how they are made. The line is to allow for expansion in the glass. It would soon crack from heat without the expansion join.

What do others reckon about this theory?

dogtor pufferfish

[Roll Eyes]

Posted by Greg Marshall (Member # 1268) on July 26, 2009, 10:30 PM:

Thanks, and that does make sense, however I wish the company would have used a clear tempered glass instead of the milky, opaque-type.... the amount of light loss because of that is significant, enough for me to keep the glass out. Now, because of my decision, I always turn my lamp off before shutting down, and rarely stop a film during projection.

Any other thoughts? Anyone, anyone, Bueller, Bueller?

Posted by Graham Ritchie (Member # 559) on July 27, 2009, 05:29 AM:

Frank is spot on, I have said the same in a previous post in the past. That hot air has to be blown out the top, not having some of it heading towards your gate and films, The last thing you want in a projector is a lot of hot air blowing all around the place. The best bet is to get some more heat resistant glass made to fit.

Graham.

Posted by Gary Crawford (Member # 67) on July 27, 2009, 09:33 AM:

My experience has been that st1200 light can be boosted a lot by 1. getting that glass filter out of there 2. buying osram xenophot lamps...these things give out a lot more light than other 150 watters. 3. find and invest in an elmo f1.1 or , even better, an elmo f1.0 lens. they really allow more light onto the screen. I found that those improvements brought brightness almost up to what I was getting from an elmo GS with 200 watt bulb and three blade shutter.

Posted by Joe Taffis (Member # 4) on July 27, 2009, 04:13 PM:

hi all, Greg, you say your glass is "milky/opaque". Here is a pic of one of mine I just popped out for this pic...it's from an ST1200D mag/opt, and it is perfectly clear...so I leave it in the lamp housing. [Confused]

Posted by Greg Marshall (Member # 1268) on July 27, 2009, 07:10 PM:

Guys, thanks for the posts.

Gary, I have installed the Osram Xenophot lamp, am currently leaving the filter out... and have been looking for a 1.1, as mine is the 1.3. One day, I'll run across one, reasonable.

Joe, that is not like the glass that I removed from mine. My unit is a ST1200HD mag/opt, and the glass I removed from mine is a light greenish/milky-greenish/opaque piece of glass... it does have the expansion crack, but you certainly cannot see through it... so you can imagine how much light is not allowed through. Yours is clear, with the expansion crack. Did you replace it with that, or did yours come with it?

Posted by Dan Lail (Member # 18) on July 27, 2009, 07:51 PM:

Well I just removed my lamp filter and can se more brightness in the picture. Thanks.

Posted by frank arnstein (Member # 330) on July 28, 2009, 12:58 AM:

Hi again to all on this interesting Elmo thread.

I believe that all these Elmo hardened glass "windows" were originally clear & fully transparent.
Due to the intense heat that the glass is exposed to & repeatedly over many years, the glass may change its chemical composition & it turns opaque. We could think of the glass as "burnt" & it should be replaced, not just removed & then left out.
Imagine the total amount of heat that is blown onto the aperture & gate area after half an hour of projecting a 150w Halogen lamp?
I would think it could "cook" whatever frames are in the gate or near the aperture, especially if you stop for a minute during the film near the end.
It's interesting to try & visualise the flow & movement of heat through the parts of a projector. We can't see the heat but its there every time we run our projectors & it must be disposed of in the most efficient way possible or we will have a film BBQ that we don't really want.

dogtor pufferfish

[Wink]

[ July 28, 2009, 07:19 AM: Message edited by: frank arnstein ]

Posted by Paul Adsett (Member # 25) on July 28, 2009, 12:48 PM:

So how come the GS1200 does not have one of these fixed filter glasses? I would have thought that if Elmo decided it was necessary to have this glass on the 150 Watt ST1200 that they would also have put one in the 200 watt GS1200.

Posted by Greg Marshall (Member # 1268) on July 28, 2009, 02:18 PM:

I don't own a GS (yet).... they don't have any type of glass filter like the ST's?

Posted by Paul Adsett (Member # 25) on July 28, 2009, 03:46 PM:

No, there is no glass filter on the GS. When you go to still frame, a solenoid is activated and drops down a glass filter and perforated metal plate behind the gate, but it is lifted out of the way for normal projection.

Posted by Greg Marshall (Member # 1268) on July 28, 2009, 05:59 PM:

From what I've read, I'm thinking it's the same type of filter that drops down in the GS, that's permanately in the ST.

And, Paul, BTW, whenever you want to sell your scope Grease print, please let me know.

Posted by David Kilderry (Member # 549) on July 28, 2009, 11:27 PM:

Many 35mm xenon lamphouses have glsss heat filters, both split and solid, but not all of them. Some manufactureres deemed them necessary and others did not. It does not seem to correlate to the size of the xenon either.

We run our 5,000 watt xenons without a filter (Strong X60C, D and Super 80 lamphouses) and the heat on the film is much higher than any non-xenon Super 8 projector could ever generate. We don't have problems with scorch, buckle or warp either.

I am certainly going to check mine in the ST 1200 now.....

Posted by Greg Marshall (Member # 1268) on July 29, 2009, 12:02 AM:

The old Eprad xenon lamphouses I used to work with had the split, heat glass in them. The Christie lamphouses I have worked with did not... the Christies were 2000, 3000, and 6000 watt units, and we never had a problem with blistering, etc., as well. The gates got hot, especially with the 6000's, but we never had any problems.

Posted by Dino Everette (Member # 1378) on July 29, 2009, 01:20 AM:

I used to take the lamphouse off before realizing it was easy to remove the glass. So much so that I have misplaced the lamphouse for my mag only ST [Frown]

Posted by David Kilderry (Member # 549) on July 09, 2010, 10:01 PM:

Have any of you who may have removed your ST 1200 glass filter noticed any shortening of lamp life since you did it?

I am satisfied that no damage will occur to the film through increased heat, I just wonder about lamp cooling and its affect on lamp life.

David

Posted by Rob Young. (Member # 131) on July 10, 2010, 07:00 AM:

Just to second the point, but the glass is totally clear on my 30 year old ST1200HD.

Think if it is opaque, something's definately gone wrong with it.

Posted by Greg Marshall (Member # 1268) on July 10, 2010, 10:08 AM:

David.... I really haven't noticed if I'm replacing the lamp more often or not.... it's a non-issue to me, as I'd certainly rather have the increased amount of light anyway.

Posted by Gary Crawford (Member # 67) on July 12, 2010, 08:52 AM:

I took all the glass filters off my 1200's...and have noticed no ill effects.....no real heat buildup...no problem on the film gate... the only thing I did notice was more light on the screen. The filters have been off for many months.

On the light issue. I have a 16 foot wide scope screen that I use for outdoor shows at home. I've always been limited to using 16mm on there...Kodak Pageants with marc 300 lamps. I had tried a couple of my Elmo st1200hd's on that screen..but there just wasn't enough light. However, year before last ( I think) I followed Steve Osborn's advice....took out the glass filter...got hold of an Elmo f1.0 lens...put in the osram bulb....put that wonderful Rectimascope scope lens on it..and the picture on that screen from super 8 became at least acceptable...especially on sharp prints that are not printed dark. And of course, I had the option of stereo sound out there in the yard. Last year I finally got hold of my first GS1200.... I had a two blade shutter put in...new 200 watt Fuji bulb which Steve Osborn said was brighter than the standard 250 Elc ( and he was right)...used the f1.0 lens with the Rectimascope scope lens.... and I can say that you can hardly tell the difference in brightness from the 16mm... Whiteness , yes..the Marc 300 puts out a whiter light....but the GS really fills that 16 foot wide screen nicely and the newer prints such as Indiana Jones and the Last Crusade..and The World is not Enough.....look great. It's opened up my Super 8 library to the outdoor shows at last without compromising light or quality...and adding great stereo sound. People can't believe it when I show them later that the picture came from that tiny super 8 frame. And one other note...the picture would be a lot brighter and sharper if I didn't have to project from inside my sun room through a double pane sliding glass door.

Posted by Tony Stucchio (Member # 519) on July 12, 2010, 08:12 PM:

Rectimascope? I don't like the sound of that!
[Big Grin]

Posted by David Kilderry (Member # 549) on July 12, 2010, 09:50 PM:

Gary, excellent, just what I wanted to read, thanks. I will pull out my filter and look to sleeve my 1.1 lens in the Elmo. It is scope that I really wanted more light for too. I will also get a few Osram lamps as the last Phillips I put in looked darker than the lamp it replaced.

David

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