Lamp Questions

[ship]

Originally Posted by lxdeptnz

Fair enough. I realise that the colour temps are different. What I wanted to know, which I found out from a lamp supply company, was that a MSD 250 lamp is approximately equal to a 1kW parcan. Even though the colour temp of the discharge lamp is higher, so it's whiter and hence appears brighter.

Thanks
David

I’m not your supplier but recognize that the in general balance in some sense between that of a arc source 250w lamp might be similar to that of a 1Kw PAR lamp. This is balance of what light comes out in comparison to what the light looks like only. I in a Leko did not find a similarity, but than of course I have alway rallied behind the fact that a FLK lamp is not a FEL lamp where output and color temperatuer balance. The only balance is that of a FEL lamp in light loss due to a huge filament as to how the FLK becomes similar. How this relates to a 1Kw PAR lamp to a Mac 250, don’t know. I certainly consider them as opposing classes and would not consider them the same to my extent at least. Than of course I would not be attempting to use them for the same intent.

Let’s now take the FFP PAR 64 lamp in comparison to that of a MSD 250/2. The Luminous output of a GE standard FFP Narrow Spot is 12,000 Lumens at 330,000 Candle Power once it hits the reflector. The Mac 250 Krypton states 4,600 Lumens (after the lenses) at a 20.6° beam angle that is roughly similar to that of the FFP at 26x14°. The actual candlepower of this fixture as opposed to the other versions is not stated in my ready reference but should be a lot less. Still it’s possibly similar enough in some assumption of color temperature as balanced against luminous output.

If that’s what the vendor says, perhaps that’s by experience they have found comperable. Than again, perhaps as a last week washing machine sales person, they are blowing smoke up your rear. Test their assertion in seeing what that balance really looks like. It’s going to be different, but in overall effect is it similar? Can you tell the difference between a EHG and FLK or GLA lamp on stage in a 360Q fixture? Nope for the most part. Lots of leeway in lighting effectively.

Answer than is, don’t know. Appears brighter certainly, comprable? That’s for end users not me to say.

[moojoe]

I just found this post, and have found it very very interesting.

Ship, how is this book you spoke of in post 1 coming along, seems like it could be increadibly useful.

[ship]

When I can take about six months to a year off of work, I'll let you know. Until than, about three years behind schedule in the appendex alone.

[sarahfromstaller]

I'm new to the forum, so I hope this hasn't already been covered. I did a search and didn't see anything quite like my problem.

I just started working at a theatre that has been putting Osram GLA lamps in our Altman 360Qs when the old EHGs burn out... However, we have a large pile of caps that need to have the lamp socket replaced, and more and more caps that have GLA lamps in them are being added to this pile every show. Has anyone else noticed a correlation between these lamps and corrosion in the sockets or is this just the normal amount of wear in old units? It just seems to me that they're breaking faster than I've seen at any other theatre I've worked in, but I might just be crazy.

Any thoughts or comments would be greatly appreciated.

[ship]

It's certainly possible that your GLA lamps to some extent are causing already warn out lamp bases to fail at least in a way you note over that of the stuff that is also wearing out that you have not noted yet.

Long sentence yes. Consider the GLA at 575w but 115v verses that of the EHG at 750w but 120v. I consider this about the same reletive amount of heat on the lamp base.

Given this, it's more likely than not that as you change lamps over to the GLA - much better investment, that the lamp bases were either warn down but not noticed or on their last legs thus blowing now.

Given most of your fixtures were probably bought at about the same time, all thus should wear out also within the same in theory period of time.

Is it the GLA wearing out your bases over that of the theater's standard of a EHG? Possibly in some extent, but most likely the lamp bases are at about the end of their life.

No mention to what extent the bases before the GLA lamps are inspected thus no accurate way to tell if it's the lamp or just an old fixture. You are no doubt noting the wearing out after the fact of the GLA going bye bye. The GLA no doubt will have lasted much longer given the lamp base providing power to it were any good.

A Bone pile of fixtures to work on is a good thing. Once you get high temperature lamp bases in the fixtures - given you don't attempt to use old lamps in re-trashing them the new wired fixture will last a good long time. Just a question of the rotation of the gear I thing in sending it in for service call.

A fixture taken out of a show in placing it in the bone yard with a large NFG tag on it is a bad thing. No time to fix while in prep for the show. Instead the sooner the better in what you make work long before the show opens.

[Radman]

Thanks as usual for your in depth explaination!

[sarahfromstaller]

Thanks, ship. That must be what's happening. They're all pretty old and have never been properly maintained. It's just killing me right now because I just started a tech week, I'm literally hanging the inventory for this show (not a big inventory... just a big show...), and I'm designer, ME, and electrics crew all in one, which means I don't have time to fix stuff, but I need everything fixed. I tried to do a maintenance call and fix some instruments last week, but the guy who was in charge of ordering stuff hadn't gotten the parts on time. Oh well, it will all come together... right? :roll:

[ship]

The magic of opening night and time next show to fix the details you note.

[propmonkey]

so i got this cdrom in the mail from orsam. it seems pretty neat. i havent used it yet but it appears that you can select different lamps and compare them side by side. i think people should get a copy of it if they can.

[JohhnyK]

Hey Ship,

I was wondering if you knew the heat output at the back of a 360Q with an EHG 1k... we use Ushio & Osram lamps.

Thanks