8mm Forum: How Do I Modify ST-1200 For More Light?

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Posted by Dan Lail (Member # 18) on January 22, 2005, 11:21 PM:

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]

I'll need these [Cool]

it'll be so bright.

P.S. My stripers and Weller are ready.

Posted by Brad Miller (Member # 2) on January 23, 2005, 02:40 AM:

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.

Posted by Tony Milman (Member # 7) on January 23, 2005, 03:22 AM:

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?

Posted by Mark Norton (Member # 165) on January 23, 2005, 03:50 AM:

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.

Posted by Kevin Faulkner (Member # 6) on January 23, 2005, 05:10 AM:

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.

Posted by Mark Norton (Member # 165) on January 23, 2005, 06:19 AM:

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.

Posted by Paul Adsett (Member # 25) on January 23, 2005, 10:17 AM:

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.

Posted by Tony Milman (Member # 7) on January 23, 2005, 10:33 AM:

Paul

Yes I have this set up now (thanks Kev [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......

Posted by Chris Quinn (Member # 129) on January 23, 2005, 10:46 AM:

Me too!!!!

Chris.

Posted by Kevin Faulkner (Member # 6) on January 23, 2005, 10:47 AM:

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]

Kev.

Posted by Paul Adsett (Member # 25) on January 23, 2005, 12:27 PM:

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.

Posted by Dan Lail (Member # 18) on January 23, 2005, 02:34 PM:

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]

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]

Posted by Tony Milman (Member # 7) on January 23, 2005, 02:53 PM:

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.

Posted by Heinrich Kronschlaeger (Member # 145) on January 23, 2005, 03:06 PM:

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

Posted by Paul Adsett (Member # 25) on January 23, 2005, 03:21 PM:

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]

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

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

Posted by Dan Lail (Member # 18) on January 23, 2005, 04:02 PM:

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]

Excellent info Heinrich! [Smile]

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

Posted by Tony Milman (Member # 7) on January 23, 2005, 04:03 PM:

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

Posted by Brad Miller (Member # 2) on January 23, 2005, 04:28 PM:

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]

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.)

Posted by Joe Taffis (Member # 4) on January 23, 2005, 07:04 PM:

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?

Posted by Paul Adsett (Member # 25) on January 23, 2005, 07:12 PM:

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.

Posted by John Clancy (Member # 49) on January 24, 2005, 02:19 AM:

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).

Posted by Mark Norton (Member # 165) on January 24, 2005, 05:14 AM:

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?

Posted by Ugo Grassi (Member # 139) on January 24, 2005, 06:01 AM:

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

Posted by Mark Norton (Member # 165) on February 02, 2005, 02:11 PM:

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?

Posted by Kevin Faulkner (Member # 6) on February 03, 2005, 05:47 AM:

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.

Posted by Jan Bister (Member # 332) on February 03, 2005, 11:33 AM:

I must confess that when I read Joe's post wondering about why Elmo etc. didn't incorporate features such as the 2-blade shutter into their designs, I'm glad nobody did... the increased light output vs. a 3-blade shutter is certainly nothing to scoff at, but I wonder if I'm the only one who would be bothered by the reduced amount of light/dark cycles per second? ... Am I? [Confused]

Here's the thing - I grew up in Germany (moved to the States about 9 years ago) so I was always accustomed to watching PAL TV with 50 fps... and I always noticed some flicker as well, though at the time I didn't think it was all that bad! Fast-forward a few years, and suddenly I'm watching NTSC TV at 60fps and I'm simply stunned at the difference that an extra 10 light/dark cycles make in providing a much steadier picture with less flickering... so easy on the eyes, I can almost understand why Americans are such TV junkies. [Big Grin]

Since then I've been back to Germany to visit my parents, and believe it or not, I cannot watch PAL TV anymore without getting a headache after a while... an hour at most, maybe.

But before I digress... one of the reasons I love film is, you have a rock-steady projection image with 72 light/dark cycles per second (at 24fps), and that's all the more important since the picture is so large vs. a TV screen. Now, going back to a 2-blade shutter and putting up with only 48 cycles per second on that huge screen... I could not do it!!! I would want to scream. Maybe I just have unusually sensitive vision - I can even tell the difference between 75fps and 85fps on my PC monitor - but I can't be the only one who wouldn't be bothered by the increased flicker of a 2-blade shutter. [Eek!]

Posted by Paul Adsett (Member # 25) on February 03, 2005, 12:04 PM:

Hi Jan,
Yes I have the same reaction when I visit the UK. But apparently the flicker does not bother the Brits. When I remark about the flicker on their TV they wonder what I am talking about!
Regarding the 2-bladed shutter on the GS1200, I have made this conversion on one of my machines, and the incresed brightness is very noticeable. I have found that the flicker only becomes noticeable if you project a small picture. And remember, your local Muliplex projects with 2-bladed shutters.

Posted by Mark Norton (Member # 165) on February 03, 2005, 12:26 PM:

I too have a 2 blade conversion in my 'new'GS 1200. My earlier example had the standard 3 blades and in a direct comparison to my other projector, a ST180, yes the extra 100w from the GS gave a brighter picture, allthough both looked good.
Now against the 2 blades the ST180 really is just a pale shadow and now I only use it on my camping holidays running off the car battery using an inverter.
I eaven now show all my 18 fps film on the 2 bladed machine, yes there is noticable flicker in very light scenes, but speeded up slightly this is hardly noticable.
For what is actually free exrta light from the bulb a 2 bladed conversion is the way to go.

Posted by Tony Milman (Member # 7) on February 03, 2005, 12:34 PM:

Mark,

You now have my attention. You take you r projector on holiday [Eek!]

I am truly humbled

Posted by Jan Bister (Member # 332) on February 03, 2005, 12:41 PM:

Paul: yeah, that's what I meant... the Brits just don't know any better (sorry, folks) [Big Grin]

and although I was once in the same boat, now that I do know better you couldn't pay me enough to go back... no 2-blade for me, thanks [Smile]

Are you sure about the big multiplex cinemas using 2-blades though? I swear they all operate on 3-blade, as I really notice practically no flicker on the big big screen. In fact, I once heard many moons ago that some theatre systems use no shutter at all but use a special lamp that actually turns on and off 72 times per second in synchronity with the intermittent motion of the 35mm film. [Eek!]

I'm not sure if that's true (or even possible), it's strictly hearsay and I may well have been fed a bunch of crock there. [Wink]

Posted by Barry Johnson (Member # 84) on February 03, 2005, 12:49 PM:

Simple,but often overlooked is the original lamp alignment.I have increased light output on many machines by simply paying attention to this small but important feature. [Cool]

Posted by Tony Milman (Member # 7) on February 03, 2005, 04:13 PM:

Jan,

Apparently in the UK they use Strobe lights at Disco's but only the Yanks notice

Posted by Jan Bister (Member # 332) on February 03, 2005, 05:47 PM:

LOL!!!!!!! [Big Grin]

Posted by Brad Miller (Member # 2) on February 08, 2005, 12:21 AM:

quote:
Are you sure about the big multiplex cinemas using 2-blades though? I swear they all operate on 3-blade, as I really notice practically no flicker on the big big screen. In fact, I once heard many moons ago that some theatre systems use no shutter at all but use a special lamp that actually turns on and off 72 times per second in synchronity with the intermittent motion of the 35mm film. [Eek!] I'm not sure if that's true (or even possible), it's strictly hearsay and I may well have been fed a bunch of crock there.

Since I install and service 35mm and 70mm commercial equipment, trust me when I say YUP, you're looking at 2 bladed shutters! The only place 3 bladed shutters are used is in very special screening room situations where there is plenty of light to throw away.

Posted by John Clancy (Member # 49) on February 08, 2005, 01:43 AM:

Jan and Paul, you must have been watching duff television sets if you were picking up flicker. Likewise when I visit the States the appaling standard of televisions provided in hotels, bars etc. does make me wonder how anyone in America can ever stand to watch television at all. However, I realize what I'm watching is cheap rubbish and despite the fewer lines resolution modern NTSC reproduction is actually very good.

With a two-bladed shutter, a big enough image will mask any flicker some may pick up. Personally, I rarely use 18fps so it's not a problem.

Posted by Jan Bister (Member # 332) on February 08, 2005, 09:12 PM:

I beg to differ as I just have very good vision, that's all ... please trust me on it. [Wink]

Yeah, TV overall is rather poor nowadays; the HDTV standard is long overdue and still only beginning to establish itself among average consumers.

Brad: I'm honestly surprised... but my guess as to why there isn't any flicker to be noticed even with a 2-blade shutter is that the actual duration of the dark phase is very short whereas the light phase is pretty long... unlike TV where the picture is really a series of lines that light up one by one only to rapidly fade out again, before the TV has even completed one full field. (Two fields make one full, interlaced frame.)
Am I right? [Smile]

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