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Topic: How Do I Modify ST-1200 For More Light?

Dan Lail
Film God

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From: Loganville, Georgia, USA
Registered: Jun 2003

posted January 22, 2005 11:21 PM

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I noticed under the post "How Many Projectors Do You Own?" Brad has converted his Elmo ST-600s to a Marc 350 Lamp & a 24v 250w lamp. I want to convert both my Elmo ST-1200s to a brighter lamp. 24v 250w sounds great! Is this possibly? If so, please let me know. Brad, Kev, Alan, somebody!!! [Confused]

[Confused]

I'll need these [Cool]

[Cool]

it'll be so bright.

P.S. My stripers and Weller are ready.

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Brad Miller
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posted January 23, 2005 02:40 AM

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Damn I keep forgetting to pull that out and take pictures. I swear one of these days I WILL do that.

Are you running a 2 or 3 bladed shutter? If you are still running with a stock 3 bladed shutter, switching to a 2 bladed will make a phenomenal difference in light output (although you want to be running 24FPS material with it).

Also going to a lens with a lower f-stop will increase light. My personal opinion is that the best 8mm lens ever made is the Elmo f1.0 lens.

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Tony Milman
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From: United Kingdom
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posted January 23, 2005 03:22 AM

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Brad,

Yes that would be interesting. I assume the two key requirements are a seperate power source to deliver the hiher current and an improved airflow for cooling?

--------------------
Tony

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Mark Norton
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From: Hampton Hill, Middlesex, U.K.
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posted January 23, 2005 03:50 AM

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Just in case you are considering a 2 blade conversion, I have a 2 bladed shutter on my GS and allthough I was warned it was for 24fps only I find 18fps films are only a bit flickery and if speeded slightly are fine.

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Kevin Faulkner
Film God

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From: Essex UK
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posted January 23, 2005 05:10 AM

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I think the biggest concern on any conversion has got to be airflow. If that temp gets too high at the gate you could get possible distortion of the gate or just plain focus problems as the gate heats up etc. Not what you want with an f1.0 lens. Air flow is not the whole answer. On some of their machines like the Xenons Elmo put a heat filter between the lamp and the gate. This is usually to help remove the infrared end of the light spectrum. Its a Dichroic filter which refelects the infrared back toward the lamp. Good point anyone who removes one from a Xenon for cleaning make sure it goes back in the right way round.

How about letting us see these conversions please Brad.

Kev.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Mark Norton
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posted January 23, 2005 06:19 AM

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A few yesrs back at tadley Phil of Classic had a ST600 that had a 200watt bulb conversion and outwardly there was no difference to a standard machine.
Nice light output for a small machine like that.

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Paul Adsett
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posted January 23, 2005 10:17 AM

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Brad is absolutely right about going to a 2-bladed shutter and fast f1.0 lens. Here is the math for changing from an f1.3 to an f1.0 lens and simultaneously modifying to a 2 blade shutter:

Light output increase= 1/(lens aperture)^2 * 1/(# shutter blades)
= (1.3/1.0)^2 * 3/2
= 1.69* 1.5
= 2.53

so changing from an f1.3 lens to an f1.o lens and modifying from a 3 blade shutter to a 2 blade shutter results in a 250% increase in light output!
This is not just theoretical math, as Kev and anyone else who has done the conversion on the GS1200 will tell you , there is a HUGE difference in light output on the screen, a much whiter picture.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Tony Milman
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posted January 23, 2005 10:33 AM

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Paul

Yes I have this set up now (thanks Kev [Wink]

[Wink]

) and it really does make a big difference.
I was wondering how I could get the lamp out of my video projector and plumb it into the GS......

--------------------
Tony

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Chris Quinn
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From: England, Bedfordshire.
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posted January 23, 2005 10:46 AM

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Me too!!!!

Chris.

--------------------
The other half thinks i'm up to something. Shes right of course.

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Kevin Faulkner
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posted January 23, 2005 10:47 AM

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As I said though before, watch that added heat.
Yes just doing the 3 blade to 2 blade conversion will give you an extra 1/3 increase in light output and that is very noticeable. The 1.0 lens will do the rest. With the ST1200 you cant change the shutter to a 2 blade as its a differnt design to all the other machines. The main drive is via the shutter blade assay rim and it would mean major surgery to do a conversion although I dare say its not impossible [Wink]

[Wink]

Kev.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Paul Adsett
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posted January 23, 2005 12:27 PM

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Even better than an f1.0 zoom lens is using an f1.0 prime (fixed focus) lens. The fixed focus lens has far fewer optical components than a zoom lens, so it has much better light transmission and less light scatter, and therefore better contrast. I use an f1.0 Kodak Ektar prime lens on my Eumig S938, and again it is a huge difference over the Eumig supplied f1.3 zoom lens. I would love to use this lens on my GS1200, but it has a very short back focal length and I can't get it close enough to the film plane.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Dan Lail
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From: Loganville, Georgia, USA
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posted January 23, 2005 02:34 PM

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Brad, I'm using a three blade. Kev says it's very difficult to change blades on an ST-1200. My lens is a 1.1 zoom. 250watts is 100watts more than I have right now. [Cool]

[Cool]

I have The Wizard Of Oz and Aliens both Deranns that project darker than than other prints. A brighter lamp would really be nice for all prints. [Smile]

[Smile]

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Tony Milman
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posted January 23, 2005 02:53 PM

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Dan

What size image are you projecting? I sometimes switch between the low and high setting on the GS or use my 150W ST1200 and OK it is darker but to be quite honest unless you really step up say to the Xenon I am not sure that you will be bowled over by the improvement. Yes it is brighter but to me it isn't enough to get too worked up about.

--------------------
Tony

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Heinrich Kronschlaeger
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posted January 23, 2005 03:06 PM

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I modified three 100 W projectors for 24 V/250 W. A friendly electrician built a transformator for me ,adjustable from 14 up to 24 V , power 300 W . I inserted a power pack for direct current (for the fans) into the transformator-housing, also adjustable ( bought at Conrad.de ).. From this external trafo I put connections to the projector: Alternating current for the lamp and direct current for the fans. I tried to find the right fan, the first I used was a small one , it was too high-speeded and it produced sound-interferences . Then I found the right one : " Papst " - fans (7 - 15 V), 9 x 9 cm , from Conrad. I placed one at the back plate (I put off the loudspeaker ), one at the front of the projector , exactly in front of the lamp. Then I drilled many holes there into the removable cover, also in the metal lamphouse, if available. A bit of the light turns outside . Inside the projector I had to build a new cable for the new lamp ( a new socket too ). The lamp 24 V/250 W fits exactly on the mounting plate for 100 W lamps. The brightness is much higher than with a 100 W lamp. Very well suitable for such a change are Eumig, Yelco, Noris and Elmo. Costs for me (in Euro): Trafo 80 (friendship price), housings for the trafo 20, power pack 15, 2 fans 2x 25, cable, sockets etc., 15. It is advisable to let the work check up from an electrician.
Kindly regards
Henry

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Paul Adsett
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posted January 23, 2005 03:21 PM

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Hi Heinrich,
Very interesting info, I may have to try upgrading my Eumigs to 250watt lamps! I think ,as Kev points out, that heat dissipation is the key issue. If you are going to upgrade to a 250watt lamp from a 100 watt lamp you will need 2.5 times the cooling air mass flow rate to preserve the same temperature rise in the projectors lamp housing. If you can get hold of an air velocity meter this can be used as a basis for measuring the mass flow rate of the air in the existing projector. You multiply this value by 2.5 to determine what mass flow rate you need for the new (or additional) fan. [Roll Eyes]

[Roll Eyes]

Then look up the performance curves for available DC or AC fans to select one that will do the job [Eek!]

[Eek!]

. Then you have the job of the mechanical interface to the projector. It all sound like a very enjoyable project! [Wink]

[Wink]

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Dan Lail
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From: Loganville, Georgia, USA
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posted January 23, 2005 04:02 PM

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Tony, I'm projecting onto an eight feet wide by six feet high screen. I did notice a marked difference between the 100w lamp on my ST-800 and the 150w on the ST-1200. I'm also using a Xenophot lamp and run it in the brightest setting for dark prints. [Wink]

[Wink]

Excellent info Heinrich! [Smile]

[Smile]

I need photos! Looks like I going to have do the modification myself. [Eek!]

[Eek!]

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Tony Milman
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posted January 23, 2005 04:03 PM

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Paul

Perhaps it would be a good idea to take the temperature at the gate witht he 100w in place and then ensure the temperature remains at or below this level post conversion

--------------------
Tony

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Brad Miller
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posted January 23, 2005 04:28 PM

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Actually, in the past a buddy and I converted Elmo ST-600 and an ST-1200 to 2 bladed shutters. (One of the ST-600s still has the Gemini short arc lamp modified and installed.) If I remember correctly, we bought two 3 bladed shutters and knocked off 1 blade from each. Seems like we had to drill a couple of holes in them to make them mount (and keep balance), but basically sandwiched them together.

Also very important, I do specifically remember having to sandwich a piece of cardboard in between the shutter and plastic pulley to prevent the pulley from getting melted by the heat transmitted to it by the shutter.

And yes we had two fairly large squirrel cage blowers on the projectors, one forcing air in, one sucking air out. Anyway, it's been about 15 years since I did any of that so my memory is pretty foggy, but I assure you it can be done. [Cool]

[Cool]

We also had a Eumig S926 that was originally modified for a 250w 24v lamp, then later upgraded to the Gemini as well. (I may be confusing some of the steps in upgrading to the 2 bladed shutter and larger lamp on this machine with the above post.)

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Joe Taffis
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posted January 23, 2005 07:04 PM

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This is all very interesting, but..., I wonder why the Elmo builders didn't incorporate these modifications for more light into their original designs...two blade shutters and such...they surely must have believed that the light output while projecting a film was fine the way it was when these machines were being sold new. With a throw of under 20 feet the projected image looks fine with no modifications to my Elmo machines. Are you guys concerned with showing film from a longer distance, in a big hall, or am I missing something here?

--------------------
Joe Taffis

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Paul Adsett
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posted January 23, 2005 07:12 PM

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I think the thing is that more brightness will always produce a more impactive picture, and certainly if you are projecting scope films thru an anamorphic lens you need all the brightness you can get.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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John Clancy
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posted January 24, 2005 02:19 AM

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Joe, light output is probably the main reason why many get carried away with video projection. The light output from even cheapo video projectors far exceeds the average Super 8 projector and causes many to believe they are watching better imagery than they are. The same is true with Super 8. The brighter the light the better the picture (perceptibly).

--------------------
British Film Collectors Convention home page www.bfcc.biz. The site is for the whole of the film collecting hobby and not just the BFCC.

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Mark Norton
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posted January 24, 2005 05:14 AM

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Looks like there are a lot of machines converted to the Marc 350 watt Lamp out there. I heard that wittners used to sell a conversion kit, does anyone know if it is still available?

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Ugo Grassi
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posted January 24, 2005 06:01 AM

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Hi Mark,
if you want to convert a machine for a discharge lamp, the best solution is to use an Osram HTI w32 250. The Mark 300 or 350 is an old lamp, with a short life (50h).
I made this conversion on one of my GS1200. I think the job is easier on this machine than the others.
http://www.osram.com/pdf/service_corner/technicalinfo/250W32e.pdf

--------------------
Bye
Ugo

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Mark Norton
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From: Hampton Hill, Middlesex, U.K.
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posted February 02, 2005 02:11 PM

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Just a thought, has anybody ever liquid cooled a discharge lamp?
Surely it would overcome problems of fan noise and high temperatures at the film gate. Or what about LED Light?

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Kevin Faulkner
Film God

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From: Essex UK
Registered: Jun 2003

posted February 03, 2005 05:47 AM

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Led light! now thats an interesting thought. The white Led can now pump out quite a bit of light but you would have to concentrate the light form a large number of them onto the gate.

Kev.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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