ELC bulbs - any reason not to buy the 700 hour version, and how long would that last?

Jeff Bannow · Dec 13, 2010

I'm planning on storing a quantity of ELC bulbs for our Durst and Omega enlargers. It seems prudent to start stocking up on what we can while we can, although I hope they continue to be available. I'm planning on buying a bunch and vacuum sealing them for storage, as well as a few replacement sockets and other bits.

Seems like a much better deal to buy the 700 hour version of these, as opposed to the standard 50 hour life bulbs. There must be a catch here though - why even offer a 50 hour version? I feel like I'm missing something important.

50 hour
700 hour

Additionally, how many bulbs would you consider a lifetime supply?

Jeff Bannow · Dec 13, 2010

Well, I answered my own question! The difference is on lumens output, and in color temp.

From Osram/Sylvania's website:
ELC - 800 Lumens - Average Rated Life 50 Hour -Color Temp 3400k
ELC-3/X - 550 Lumens - Average Rated Life 300 Hour -Color Temp 3250k
ELC-7/X - 450 Lumens - Average Rated Life 700 Hour - Color Temp 3200k

So, I guess I need to stock the regular 50 hour bulbs. How long would you estimate these 50 hour bulbs would last?

AgX · Dec 13, 2010

In general: the more shortlived versions of all incandescant lamps are designed to be effectively underrated for the voltage they are actually advised for. That results in a higher current and a thus light output. Well, one could achieve that by a higher wattage, but by employing effectively a higher voltage than usual for such a design, the spectral output is shifted to the blue side. Thus, as long one does not want to generate IR radiation those lamps are more effective in bringing out visible (as well as photographically active) light.

The catch is that they fail much earlier.

Jerevan · Dec 13, 2010

If you were using the lamp for 15 minutes total every day for 365 days you'd use up two lamps a year. It is really hard to say how many is enough.

Jeff Bannow · Dec 13, 2010

Jerevan said:
If you were using the lamp for 15 minutes total every day for 365 days you'd use up two lamps a year.

That makes sense. Does the bulb actually last 50 hours in enlarger use though, being turned on and off all the time.

I'm not sure if I need to think about 10 bulbs or 100 bulbs here.

Jerevan · Dec 13, 2010

50 years of constant enlarging gives you 100 bulbs, with the above 15 minutes a day. 150 and you're in the clear, I guess.

Me, I'd buy 20 and if the bulbs are going away, then stock up or switch to whatever technology that is useable at that point in time. Some people are moving to LED, like this guy: http://www.deadbread.com/crumbs/23c.html

Jeff Bannow · Dec 13, 2010

Jerevan said:
50 years of constant enlarging gives you 100 bulbs, with the above 15 minutes a day. 150 and you're in the clear, I guess.

Gee, only 150! Now I feel better.

Too bad both my wife and I print, so that would be 300 bulbs ... time to take out a loan!

AgX · Dec 13, 2010

The industry employs a special switching routine for household lamps.

But those enlarger lamps, as well as the late special lighting lamps, would need another switching routine.

ic-racer · Dec 13, 2010

You can actually test each type for intensity on the baseboard. Did you keep any of those color analyzers? The 'white' channel is essentially a baseboard meter. The kids enlarger uses 12v bulbs, so I tested 5 different types I got from the internet and various hardware stores around town. The brightest one on the baseboard was not the one with the highest wattage. The reflector shape and filament orientation made a difference in directing the light at the filters before it got to the diffusion box. The Omega lamp aims at a relatively small opening to shine on the filters, so the type of reflector may make a difference (or not) but it would be easy to test.

Also 3400k will give theoretically slightly more contrast with the max magenta filtration because there is more blue light to come through. You could test the lamps with a step wedge and maximum magenta, but its probably too small a difference to pick up with a 21 step wedge.

Jeff Bannow · Dec 13, 2010

Hmm, I've got an enlarging meter, so that would be a possibility ....

I could also check for even illumination as well then.

Steve Smith · Dec 13, 2010

Jeff Bannow said:
I'm planning on buying a bunch and vacuum sealing them for storage

They're vacuum sealed already. What will a second vacuum seal achieve?

Steve.

Steve Smith · Dec 13, 2010

Jerevan said:
Some people are moving to LED, like this guy: http://www.deadbread.com/crumbs/23c.html

Some of us here are doing it too: (there was a url link here which no longer exists)

Steve.

Jeff Bannow · Dec 14, 2010

Steve Smith said:
They're vacuum sealed already. What will a second vacuum seal achieve?

Steve.

Hmm .... I suppose that's true!

Jim Jones · Dec 14, 2010

Many years ago I wired a low voltage power transformer as a voltage reducing autoformer to greatly extend the life of 16mm movie projector lamps. The color shift and reduced light output were acceptable in this application. In an enlarger, the transformer could be used for composing and focusing, and bypassed for exposing. The electronics in some modern enlargers might make such a modification inappropriate.

ELC bulbs - any reason not to buy the 700 hour version, and how long would that last?

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