Film-Tech Forum ARCHIVE: LTI Lamps that you would go for........

This is topic LTI Lamps that you would go for........ in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Peter John Anthony. C (Member # 2500) on 10-18-2005, 11:48 AM:

Hi friends!

Could you please help me out with your experience and knowledge by differentiating between LTI 4.2K HEH or 4.2K GS and LTI 4.5K HS lamps?
1.Which of these lamps last longer?
2.Which gives more brightness?
3.Which of the lamp emits more heat?
4.Cost related which is better?

Most important if you want to select from these lamps which one will you favour for?
Above are some points struck to my mind, any other suggestion will be most appreciated…

Thanks,
Peter

Posted by Monte L Fullmer (Member # 2797) on 10-18-2005, 12:44 PM:

quote: Peter John Anthony. C
differentiating between LTI 4.2K HEH or 4.2K GS and LTI 4.5K HS lamps?
1.Which of these lamps last longer?
2.Which gives more brightness?
3.Which of the lamp emits more heat?
4.Cost related which is better?

HS bulbs are cheaper than the HEH bulbs
HS bulbs have longer warranty hours than the HEH bulb
There is no difference in Lumance output (rated on the box) between the HEH and the HS bulb
I'm running both the HS and the HEH bulb and IMHO that the HS gives out better light than the HEH bulb, but my bulbs are the 2k variety. I've heard that the 4.2K HEH gives out better light than the HS variety.

Not familiar with the GS series. It all depends on your lamphouse model and required bulb.

thx-Monte

Posted by Louis Bornwasser (Member # 3063) on 10-18-2005, 08:17 PM:

GS is "gap shortened." This is a design issue that yields an increase in light at the expense of long life. Major bulbs establish a loss of 20% of light as the warranty life. GS bulbs have reduced warranty and useful life. Louis

Posted by Peter John Anthony. C (Member # 2500) on 10-20-2005, 08:00 AM:

Thanks Monte & louis!!!!!!!!!

What do you suggest me should i buy HEH or HS bulbs.....

Which emits less heat???

I hav got a feed back that HEH emits lots of heat & its life is very less compare to HS ...

please advice sir thanks

Posted by Monte L Fullmer (Member # 2797) on 10-20-2005, 02:30 PM:

HS being cheaper than HEH's, that'd be your call on that one, pricewise.

Yet, have to ask a question on your concern about heat:
Is the heat film-related, or just lamphouse temperature?

Film heat, especially if your running those 4.2k bulbs, is a careful factor on bulb focusing. (what you do, with motor running, pop open the dowser and put the light on the screen without any film through your SCOPE lens and aperture. Draw the bulb back to where the corners begin to darken and you have a good "hot spot" in the centre of the screen. Then, move the bulb forward to where the corners lighten back up and continue to move forward until the light output just begins to lessen, then stop. This should get you the decent light output, but will drastically reduce the heat on the film) But unfortunately, film is going to get warm with that much wattage and you really can't get away from that kind of heat.

Lamphouse temperature is to enlarge your exhaust system to draw more out of the lamphouse area.

thx-Monte

Posted by John Pytlak (Member # 331) on 10-20-2005, 03:17 PM:

Articles about heat-related issues:

Heat Damage Part 1

Heat Damage Part 2

Bottom lines:

Be sure lamp alignment is correct (string or laser)
Be sure distance from lamp to aperture is correct
Align for best illumination uniformity
Don't "hotspot"
Use effective heat mirrors to remove damaging infrared energy
Keep that hear mirror cool (an overheated mirror/filter is less effective in removing IR)
Be sure lamp is properly vented to stay cool and increase lamp life

Posted by Peter John Anthony. C (Member # 2500) on 10-21-2005, 01:25 PM:

Heat related to Lamp house console only, i have heat filter...
Thanks Monte and John for supporting with your valuble suggestion....

Peter