Re: DIY light source for 10X10" enlarger.

"gr" <greif1nospam@[EMAIL PROTECTED]
> wrote in message 
news:47fd871f$0$7063$4c368faf@[EMAIL PROTECTED]
> jjs wrote:
>> To date I've considered enlarger light sources to be 
>> engineering well beyond my feeble capability, but I have 
>> used and examined only condenser enlargers such as the 
>> Leitz IIa and Omega condenser enlarger, but my task now 
>> is to make a diffusion thpe for the 10x10 enlarger.
>>
>> I want something with No built-in filtration. No fancy 
>> color mixing for VC papers. No electronics. No side-lit 
>> mixing chambers. Just a straight forward light source and 
>> a diffusing layer. I question cold light, mercury va****, 
>> tubes, whatever they are because I just don't plain 
>> understand 'em.
>>
>> I can blunder head-first into this project, but this 
>> group has some smart people with impressive experience, 
>> so I'll put my blunder idea forward.
>>
>> First, I am limited to ~110V AC power although converting 
>> to DC is an option. How about a simple array of 'white' 
>> LEDs at the top, pointing down over the typical sheet of 
>> plastic translucent material found in home supply places? 
>> Or should it be fine ground glass? I am not concerned 
>> about the variability of LEDs over time unless they 
>> change during the time it takes to get an 8X10 
>> negative-to-print just right - maybe a day or two. The 
>> power for the light will be run through a robust 
>> power-conditioner once set aside for a big minicomputer. 
>> Batteries not included.
>>
>> So far so good? Corrections would be most welcome. OR 
>> just let me blunder and if it goes badly I'll post 
>> pictures of the catastrophe.
>>
>>
> Forget florescent lamps unless you run then continuous and 
> use a shutter; even then they can vary intensity quite a 
> bit. Tubes have a warm up vs output curve of 30 minutes or 
> so, CF type take at least 5 min to come up close to full 
> output. An integrator would allow use.
>
> If I was making a quick light box for an 8x10 enlarger, I 
> would use multiple bulbs (4 or 6) (prob small qz halogen 
> to distribute the light more evenly and then 2 white plex 
> diffusers spaced 1-2" apart between the bulb and the neg.
> gr

    The problem with incandescent lamps is heat. Dissipating 
the heat will make construction of the housing more complex. 
If one uses an enlarging meter the variations of flourescent 
lamps with temperature is of much less im****tance. Even 
though flourescent lamps like to run hot the heat involved 
is still much less than it would be for incandescent lamps 
of similar output.


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Richard Knoppow
Los Angeles, CA, USA
dickburk@[EMAIL PROTECTED]