This is topic Which is brighter? in forum 8mm Forum at 8mm Forum.


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Posted by Paul Adsett (Member # 25) on May 27, 2013, 02:52 PM:
 
Lately, I have been very impressed with the light output of my Eumig 938 Stereo. Since installing a new Osram Xenophot lamp and adjusting the transformer connection to 110 volts instead of 117 volts in order to get the full 15 volts on the 150 watt EFR lamp, I have been enjoying some brilliant film shows. So I was curious to see how the 938 compared with the GS1200 in terms of light output.
First, let it be clear that the GS1200 has installed in it a brand new Fuji Esc lamp, and that the GS1200 under test has a 2- bladed shutter. The GS1200 also has the Elmo f1.0 12.5mm to 30 mm lens.
The Eumig 938 is fitted with a brand new Osram EFR Xenophot lamp operating at 14.9 volts, and the projection lens is the Kodak Ektar 20mm f1.0 lens (non-zoom). The 938 is the default 3-blade shutter.
I set the projectors up side by side projecting onto a matt white screen. I adjusted the zoom on the GS1200 to produce exactly the same size picture as the 938.
The 938 has a fixed lamp setting, but the GS1200 has a low and high lamp setting. I have no lightmeter readings, but here are my visual impressions:

TEST No. 1 – GS1200 at LOW lamp setting.
The 938 is noticeably brighter and whiter

TEST NO. 2 GS1200 at HIGH lamp setting.
The GS1200 is noticeably brighter than the 938, but the 938 still seems to projects a whiter looking light.

Bottom line is that the 2-blade GS1200 is still brighter overall, but the Eumig 938 with the Xenophot lamp and the f1.0 lens compares remarkably well, and seems to be whiter, certainly so with the GS at the low lamp setting. I have no explanation as to why the Eumig projects a whiter light, unless it has something to do with the lens coatings.
 
Posted by David Kilderry (Member # 549) on May 27, 2013, 11:33 PM:
 
Interesting comparison Paul. I think most of us would like more light out of our Super 8 projectors. My Eumig 940 Stereo has a 1.1 lens fitted and an Osram Xenophot is is very bight. My Elmo ST 1200 is also brighter now with the same lamp and lens fitted. I'll have to line them up and compare.
 
Posted by Antonio Costa Mota (Member # 221) on May 28, 2013, 07:32 AM:
 
I did a similar test between the GS 1200 2 bladed shutter and with a Fuji ESC lamp and also fitted with the Elmo 1,0 lens, and the Beaulieu 708EL-Stereo. This latter projector is fitted with the Osram Xenophot 15v./ 150w. bulb, 2 bladed shutter and
the Schneider Xenovaron 1,1 lens. With the lamps of both projectors on the low setting, the Beaulieu is much brighter.
On the high setting, the Elmo is only marginally brighter. However the light on the Beaulieu is also whiter and the overall
pcture, including edge definition is better. But this has to do
with the much better gate design on the Beaulieu.
 
Posted by Joe Taffis (Member # 4) on May 28, 2013, 07:42 AM:
 
I would like to add my 2 cents to the brightness issue with a question. When I first got my GS1200 the lamp was burnt out. I ordered two new FUJI ESC 24V 200W lamps at a cost of $28.00 each. In the meantime, I went to my local electronics store and bought a EIKO brand ELC 24V 250W lamp for $8.99. I might add that both Steve Osborne and Leon Norris told me that it was O.K. to use this lamp in spite of what has been posted here in the past in regards to possible transformer damage to the GS1200. The cheaper EIKO lamp is much brighter and whiter, so the question is, why use the more expensive one????
 
Posted by Paul Adsett (Member # 25) on May 28, 2013, 09:07 AM:
 
Hi Joe,
Yes you are right on - the ELC lamp is much brighter than the EJL and is possibly much brighter than the FUJI ESC (I have'nt done a direct comparison). I have tried the ELC in one of my GS1200'S and got an extremely bright screen, very white, and with near perfect uniformity. I ran for several hours and had absolutely no problems. The question is though, is it worth the risk of burning out the transformer? Based on my test, it looks like the GS can handle the 250 watt lamp in the short term, but the effects of long term usage on the life of the transformer is not known, unless someone out there has been using the ELC for 20 years or more and can jump in with some more info.
I have often thought of removing the speakers from the back cover, and installing an auxilliary fan, blowing right onto the transformer. Maybe that would really enable the ELC to be run safely in the GS.
 
Posted by Graham Ritchie (Member # 559) on May 28, 2013, 12:53 PM:
 
One cheap way to run a 250 watt lamp safely in a GS1200, is to get your hands on a old slide projector...plenty of those around, that runs a 24volt/300watt lamp. Just run the two lamp wires from the slide projector up to the GS1200 instead and still have the low/high feature.

Graham.
 
Posted by Mark Norton (Member # 165) on May 30, 2013, 11:49 PM:
 
I did some light tests a while back as I thought the Beauelieu 708EL to look a lot brighter than my GS1200, both with a Schnieder 1.1 11-30 lens and 2 blade shutters.

GS1200 180 lux (Fuji lamp)
Beauelieu 210 Lux.

However with the Elmo 1.0 lens in and a genuine original ELMO ESC Lamp the GS had the edge.

The Elmo lamp gives 20 lux more than the Fuji, the Elmo 1.0 lens gives 27 lux more than the Schnieder 1.1. Tests were done on a 1meter wide screen at 10ft throw.

My conclusion is that the Osram 150w lamp in the Beauelieu has better light focus due to the orientation of the filament. The 250w lamp that some have rightly or wrongly used in the GS1200 has the filament orientated in the same way. I have heard of one person who used this lamp for years in his GS1200 with no problems. Has there actually been a transformer failure due to using this 250W lamp?
 
Posted by Paul Adsett (Member # 25) on May 31, 2013, 03:46 AM:
 
quote:
Has there actually been a transformer failure due to using this 250W lamp?


That's a very good question Mark. I for one have never seen anyone post on any forum that they sustained transformer damage using the ELC. As I said, I ran an ELC in one of my GS'S for hours on end without damage. I would imagine the transformer windings would reach a stable temperature in 30 to 60 minutes.
The big unknown of course is what margin of safety Elmo put into the transformer design. If it was greater than 25% then all may be well with the ELC. But if it was only 10-15% then it may be running close to disaster. Which raises another question. If the GS is fully capable of running a 250 watt lamp why did'nt Elmo use one?
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 02:46 AM:
 
Carrying on this old post, I was particularly interested in Mark's comments regarding the observed brightness levels between the GS and the Beaulieu (both two bladed shutter models).

This got me pondering...as the 250w Osram xenophot lamp has the same orientation of it's filament as the 150w lamp, I was interested to find out if anyone had ever tried upgrading their Beaulieu to accommodate this lamp, and if so, how much brighter again would the image appear?

I think given the all metal separate lamphouse design and strong cooling fan on these machines, then I wouldn't foresee any issues with the film becoming damaged given that the GS can run with this lamp, though perhaps risking damage to the original transformer. Also the same designed machine is capable of taking the HTI lamp albeit with an extra cooling fan on the lamphouse.
 
Posted by Dominique De Bast (Member # 3798) on July 30, 2014, 03:11 AM:
 
Something that is seldom considered is that theorically the more powerfull the bulb is, the worse it is for the film. Personnally, I don't need very to extend the brightness to the max for my personnal projections. As I said in another thread, be aware also that the surface on wich the film is projected is important. The whitter, the best. And, if you wear glasses, like me, test them when you project a black and white film. My glasses darken the picture !
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 03:26 AM:
 
Given that each frame of film only passes the light source for 41.66 milliseconds, I don't think too many chemical changes would take place to the film causing damage from light exposure in that time Dominique.

If this was the case, 35mm film projectors with their huge light boxes behind them, would surely ruin film in each pass wouldn't they?

Anyhow, back to the initial question...
 
Posted by Dominique De Bast (Member # 3798) on July 30, 2014, 04:24 AM:
 
What you say sounds logical. I don't know how it can affect the film. It may be just a French strange obsession as I readed that in French books. I am not sure it is the light that affect (or may affect) films but the heathness.
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 02:29 PM:
 
If heat from a projectors lamp caused adverse chemical changes in the time the frame is in the gate,then how come my 35 year old 35mm slides still have great colour, no noticeable chemical changes through time, heat or light and have spent many more minutes in the gate compared to any cine film as each time they are projected with a 300w lamp source behind them, each slide is viewed for at least 30 seconds?

Anyhow, once again I have digressed away from the initial point in question which was, has anyone tried fitting a standard tungsten Osram 250w Xenophot lamp to a two bladed Beaulieu and if so how much brighter did the image appear?
 
Posted by Dominique De Bast (Member # 3798) on July 30, 2014, 02:59 PM:
 
Andrew, again I have no idea why they say that. Can you really compare slides and cine film ? As you say, you can project a slide for 30 seconds. A cine film would burn if you leave it this time.
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 03:12 PM:
 
Only because a slide projector is designed in such a way as to dissipate the heat to allow the individual frame to be exposed to the lamp for long periods of time in the way a cine projector can by having a still frame facility. Otherwise the machines work in the same manner and everything else regarding light and heat exposure to the frame of film is intercomparable.
 
Posted by Dominique De Bast (Member # 3798) on July 30, 2014, 03:33 PM:
 
I would think that it is a big difference if there is less heatness in one case than in the other. I remember that among the advices of choosing a (cine) projector, there was the "finger test". You should be able to put your finger on the gate after several minutes of projection without burning it. Some projectors are, regarding this, better designed than others.
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 03:54 PM:
 
Which top Super 8mm sound projector do you know of Dominique, where you can comfortably place your finger onto the steel gate aperture after several minutes of full brightness projection?
 
Posted by Dominique De Bast (Member # 3798) on July 30, 2014, 04:11 PM:
 
The Beaulieu was said passing the test but I don't recall having test it myself. I know that I have one projector that doesn't heat too much the gate but I don't remember if it is my Beaulieu or not (as you know there are several models so I should check wich model they were refering to but I cannot do that now as I am not at home at the moment). I have always found that the heating of the bulb was an interesting point. Just imagine if you can one day replace a classical bulb by another (like a led) with the same brightness and the same quality but without needing to cool it via the fan, that would be, for someone who can modify machines a source of noise avoided by removing this fan. And you could cover more the lamp room which on some projectors (Fumeo for example) send a lot of light in the room via the areation.
 
Posted by Andrew Woodcock (Member # 3260) on July 30, 2014, 06:49 PM:
 
My question was aimed in sarcasm Dominique. I, for one, don't recall ever owning a Super 8 Sound PJ worth it's stripes that doesn't get extremely hot around the gate area within minutes.

If one exists, I don't know of it!
 
Posted by Dominique De Bast (Member # 3798) on July 31, 2014, 12:02 AM:
 
I will keep your question in mind and try to find back which of my projectors succeeded the "finger test". That will however take time as I will not start before September and of course wait the occasion as I use a different machine regularly to try to maintain them working. I will also check if there is a reference of the Beaulieu model that is supposed to pass this test.
 
Posted by Andrew Woodcock (Member # 3260) on July 31, 2014, 03:45 AM:
 
Ok Dominique, I will be interested in the outcome from your "French book" on projector finger testing. [Wink]

I will be astonished if even the standard Beaulieu passes this "finger test" as even the outside of the lamphouse cover gets extremely hot after around 30 minutes, let alone the actual gate.
 
Posted by Dominique De Bast (Member # 3798) on July 31, 2014, 04:33 AM:
 
The book giving the Beaulieu as a winner for the finger test is titled "Super 8 et video légère" if I am not mistaking and is written by Michel Karloff. Again, I am not at home at the moment so I cannot give more details (From memory it was published in 1978 but this has to be checked). Of course, it is not because something is written in a book that it is true. From the day I readed the "finger test", I tried on several projectors and in the Super 8 gauge maybe one or two I own succeeded. Something interesting to notice is that the author of the book says that some makes are not quoted in purpose. He doesn't name them but I remember that Eumig is among the banned one, which I found unfair for the Austrian company.
 
Posted by Brian Fretwell (Member # 4302) on July 31, 2014, 06:10 AM:
 
I've always thought it was the high energy part of the spectrum, blue and ultra violet that cause dye fade. Photos exposed to sunlight have the red (which absorbs the blue/uv fade first). I wonder if Xenon lamp projectors cause more fade than tungsten ones which would have less U/V and blue.
 
Posted by Andrew Woodcock (Member # 3260) on July 31, 2014, 01:21 PM:
 
I will take it that nobody has ever tried using the Osram Xenophot 250w lamp in the Beaulieu then as I haven't had any response to the question.
 
Posted by Dominique De Bast (Member # 3798) on August 31, 2014, 01:31 PM:
 
After checking in "Cinéma Super 8 et vidéo légère", it seems that I made a confusion. Michel Karlof says that the cooling system of the Beaulieu 708L is oversized (I try to translate) but the "thinger test" (after one hour of projection) is succeeded by the Fuji SH30. What was intersting in reading the part concerning the Beaulieu (the best Super 8 projector for the author of the book) is that it can accept 32,5 mm non zoom lenses. The interest is that these lenses are brighter. It is written that a 1.3 fix lens can be 50 % brighter than a 1.1 zoom lens (I don't translate the technical explanation). I suppose that such lenses are rare and Wonder if any member has tried one on his Beaulieu and if so, which what result ?
 
Posted by Alan Rik (Member # 73) on August 31, 2014, 01:37 PM:
 
I have used a 22mm Ektar 1.0 lens fixed which is Super Sharp and very bright on the Beaulieu. If I had a longer throw that is the lens I would use on the Beaulieu but since I only have a 20ft throw I need the 1.1 Schneider.
The fixed focus lens is also great on the Eumig S938/940. I tried that as well.
 


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