Pro's and con's of HID conversion

[Paul Adsett]

Do the Xenpow 150 watt HID lamps have an integral UV filter?

[Brian Fretwell]

The Wikipedia entry for HID lamps (https://en.wikipedia.org/wiki/High-i...discharge_lamp) states:-

"Most HID lamps produce significant UV radiation and require UV-blocking filters to prevent UV-induced degradation of lamp fixture components and fading of dyed items illuminated by the lamp. Exposure to HID lamps operating with faulty or absent UV-blocking filters causes injury to humans and animals, such as sunburn and arc eye. Many HID lamps are designed to quickly extinguish if their outer UV-shielding glass envelope is broken."

I would think the very short exposure of the dye in films would not lead to extra fading.

[Paul Adsett]

Some really excellent comments by HID users here, - keep 'em coming!

A couple of things not yet mentioned, which should go in the + column:
1. The 150 watt HID lamp dissipates far less heat than the equivalent 150w Halogen bulb - or so I am told.
2. Use of the external HID power supply removes a ton of current load from the GS1200 transformer which will now be coasting along just supplying current to the electronics and solenoids and motors, so it will run a whole lot cooler and will now probably last forever!


The same advantage also of course applies to Graham and Tom's 250W ELC lamp conversion of the GS1200, where they also use an external power supply.

Anybody know if the HID lamp puts out a lot of UV light?

[Dominique De Bast]

It's always better to see it in real but you can get an idea : Elmo GS1200 with 150W HID Xenpow conversion - YouTube

[Graham Ritchie]

Sorry folks not convinced

Maurice does mention "that the films are improved as it emits a colour temperature of 6500K which has a good degree of "blue" content"

Now this blue content is where HID falls down in my view, I have as yet to see any visual evidence here or elsewhere to show the HID is a improvement, more the opposite to be honest. Sure you are getting more light, but do you really want a lamp that is biased towards blue? projecting through a "good" color print?.

There was a video of a film convention in England, I can't remember where, but its on the forum somewhere that shows the HID in action with various film clips. Everyone of those clips had that blue look I myself have some of those prints and they don't look that bad.

So once again, sorry folks for being a bit of a party pooper, but until someone can show me some visuals that will convince me otherwise I will stick to my Osram Xenophot lamps for home use.

[Dominique De Bast]

I confirm what has been said above. You need to adapt the way you project by keeping in mind you cannot easily stop the projector during a show as you would do with a convetional lamp in case of problem. You have to make sure (more than with other projectors) that your film is in good condition (I remember, for example, a standard/regular 8 film that had old tape splices, they almost all broke during the first projection-with my Siemens-, so definitely not a good idea to project such a film for the first time with a HID machine). These projectors are ideal for features. I did project several standard/regular 8 films over the last months mounted on large spools and it is fantastic to see those films with the HID lamp. As Lee says, it's not impossible to switch the lamp off in case of need (altough it's not recommended at all, as I understand). I had a problem during one of my projections (with the LPU, not with the projector but the result was the same : I had to stop the projector to fix the trouble). What I did was to switch the lamp first, let a few more meters of film running then stopping the projector and quickly put the shutter on the "masking position" and...no frame burnt. For projecting short films, which I did seldom, with this projector, the best way I found was to have several take up spools ready for each film and rewinding everything after the show. As John, I project mainly standard/regular 8 films with the HID projector (I only tried once super 8 to test the machine) and I'm more than happy with it and it would be nice to have HID projectors for super 8 and 9.5 as well if I can get that one day. To summarize, more work for the projectionnist but the result certainly worths it.

[Paul Browning]

Maybe the car HID version would be a better alternative, it was nearly as bright as the beaulieu 708 el which is brighter than the gs 1200, cheaper to buy, readily available and would probably not need any extra cooling, the mod would need a reflector for the lamp to sit in and fixed in position, not that difficult to do ............

[Maurice Leakey]

[QUOTE=Mark Mander;n40573]....Bulbs more expensive..../QUOTE]

True, at £72 each.
However, they are supposed to have a life of 750 hours compared with the stated life of 50 hours for an ELC.

[Mark Mander]

So plus points are,
Faded prints can look better

Sharper image

Black and white prints look better

Dark prints are improved

Minus side
careful use if your machine doesn't have a dowser

Bulbs more expensive

Not really recommended use for start stopping the machine multiple times(lamp on and off)

Mark

[Maurice Leakey]

....It's not the power in turns of wattage, it's the colour temperature that delivers the much improved images on the screen......

I heartily agree with John, as I said above, it's the bright white light from an HID 150 that is so impressive, even faded colour films are improved as it emits a colour temperature of 6500K which has a good degree of blue content.

Color temperature black body 800-12200K - Color temperature - Wikipedia

[John Burgess]

I have converted two Kodak 8 (st 8) projectors so I can only speak for that gauge. I must say I was astounded at the difference achieved by HID, a lot of st 8 prints can be a little on the dark side and this lamp certainly brings them to life. It's not the power in turns of wattage, it's the colour temperature that delivers the much improved images on the screen.If possible you ideally need a dowser to shut off the light when stopping the motor, although as Lee pointed out you could use the shutter to do the job. I would certainly opt to convert Paul , even with a small throw you will appreciate how much much improvement HiID can make to your films.
John

[Tom Photiou]

My own thoughts on this are these, my room, (and i suspect many other users rooms) is a humble average spare room measuring around 14ft x 12ft. For 16mm i use the 25mm lens, and in this size room the bright image from the 250w lamp is more than ample even on scope films, you should be able to see this in my screenshots on other threads, or reviews on the other channel. Obviously these machines weren't designed for home movie use but for larger venues, therefore to me, it would be pointless doing a conversion on a 16mm for home use unless you have a decent large size room.

For super 8s, again, while i know there would be an improvement, it would be more suited to people who have a much larger room than that of the average UK home, or for those who do film show events for various party's or other venues in which case it would be an good advantage. With my projector just 14ft from the screen i feel the image using the 150w lamps and the 1:1 and 1:0 lens is more than enough. I have seen people put up images showing the standard light against the HID, the standard light was yellow, the HID light was bright white. I do err on this, if i demonstrated the lighting on my Eumig 810 using the standard 100w bulb and the 1:3 lens and then put up the HID then your going to see an improvement. I'll show you the same same improvement putting up the 100w bulb 1:3 lens of a Eumig against my Elmo HD with a 150w bulb and 1:0 lens.
I'm not dissing the HID, (i have considered it myself), im just saying for the average user in and average size room, i think if your using a good lens with the 150w or 200w bulbs, it seems to be a bit of over kill.

[Maurice Leakey]

As 16mm projectors are obviously larger than Super 8 projectors they are much easier for conversion to HID 150.

My Bell & Howell 644, which was converted professionally, is a delight to use, no different to use from when it had its original 1000 watt lamp.

The bright white light from an HID 150 is certainly an improvement over a conventional lamp.

[Mark Mander]

I've also had an Elf 16mm done and the results are much improved over the super 8 machine I have,mainly due to the larger gate, I personally think the conversion is better suited to 16mm machines ,Mark

[Lee Mannering]

Hi Paul. My own conversions of the humble Eumig is born of love for the little wonder up against the big boy machines such as the highly regarded Elmo GS1200 machines. Running a HID machine will require the operator/projectionist to raise his or her game as you will need to pay more attention as any projectionist would to the film when projected. By design these HID lamps should be left on until cool down at the end of your show but they do cool quicker than a regular lamp so will re light under 5 minutes.

Other than my Eumig conversions which have been sold outside the UK I request buyers call for a training session when collecting which has worked well.
Yes you are better to spool up for a show but I often run 200ft reels of say STD 8 next to the Elmo HID and you will get used to the idea that HID needs more attention or risk burnt frames.
Unlike the Elmo GS the little Eumig 800's do not have a dowser so if you do need to stop mid way switch the lamp off or turn the shutter inching knob to close the lamp light. You soon get the hang of it.

Other precautions are having long white leaders on films and something to block the bright light in front of the lens. Even with the Elmo GS dowser in place you will still see light on the screen at home.

Other than that its all good news. As with my recent visit to the cinema and a 26ft screen my own Eumig HID performed well and has one big benefit over the GS a big choice of quality lenses to fit any setting. I do love my HID GS1200 by the way.