Rectangular 4x5 or 5x7 cold light heads available anywhere?? (for devere)

Sparky · Apr 20, 2011

Howdy folks... havent' posted in some time... but I'm wondering if anyone knows of a source for a rectangular cold light head to install in my devere 504. I have a dichro head that I gutted and use a round aristo head in... but it's always a huge pain, since the lamp is a little far from the neg stage owing to the modification and I don't seem to ever get my 4x5 negs fully covered (!!!). So I'm trying to rectify the situation... if I can only find a rectangular or square lamp. I suspect the head cavity can accomodate a 5x7 lamp too... any suggestions??

ic-racer · Apr 21, 2011

I think all the 4x5 cold cathode units were round.

ChuckP · Apr 21, 2011

Aristo and Zone VI made some rectangular 5x7 heads. Unfortunately they are probably hard to find used. Not sure if the various model sizes are still available on the Aristo website or another website. I probably have an old catalog somewhere that shows the sizes if you need them. I also have the Zone VI catalogs but I'm not sure they have the head dimensions. You will probably need around a 6x8 space to fit the head into.

Sparky · Apr 22, 2011

I'm starting to wonder if I shouldn't just hire a neon sign fabrication firm to make up a custom one for me...! I don't think there's much in the way of guts to the lamp heads other than a warming unit and/or a transformer... should be adaptable as long as the total tube length isn't much greater..(?) - and I guess it needs to be filled with the appropriate gas (?)

ic-racer · Apr 22, 2011

Maybe that is a good idea, but I couldn't get my professionally manufactured Aristo head (14" x 14'" covering 8x10") to provide an even field. So, I suspect a home-made unit will be even more difficult to make even. My unit was originally mounted about 1.5 inches above the negative. I could not move the whole lamp assembly lower, but I was able to move the diffusion plastic one inch lower, so it was about 1/4" above the negative carrier. This improved the edge coverage. I also made a center filter to go on top of the diffusion plastic. That helped even more. Perhaps you could try either one of those methods. ( http://www.largeformatphotography.info/forum/showpost.php?p=319386&postcount=28 )

There is a thread out there (LF forum maybe) with neon and cold cathode manufacturer links etc.

For a more practical solution, there are plenty of 4x5 dichroic heads out there, why not go that route?

Sparky · Apr 22, 2011

No - well it HAD a dichroic on it I kept blowing up the power supply - the devere's electrical systems are notoriously like those on jaguars...!! so I gutted the dichro head (was WAY more trouble than it was worth...!!!) and dropped in a cold light - but it's a bitch because I have to place my MC filters UNDER the lamp so I have to lift up the lamp and drop in a filter each time I need a grade change...

Sparky · Apr 22, 2011

so that's kind of why I'm trying to find a good permanent solution now... i guess the spacing from neg to diffuser to cold light grid is pretty critical - but it seems the further you place the cold light from the diffuser, the smaller a 'circle of illumination' it sees... even if it's more uniform IN that circle...

ic-racer · Apr 22, 2011

I don't want to seem like a broken record but, there are many suitable dichroic head bulbs that run right off the mains; you don't need a regulated power supply. Running a quartz halogen lamp off the mains with no regulation will be way, way, way more stable in light output than a coldlight.

Also, along the lines of getting a cold cathode custom made, realize that a cold cathode tube is distinctly different from a neon tube or a fluorescent tube. But here is a place that specializes in cold cathode lighting and even makes a flexible cold cathode light strip: http://www.cathodelightingsystems.com/products/132/flexible-cathode-light-strip

Sparky · Apr 22, 2011

well I would actually challenge you on that.... how is it physically different from a 'neon tube' filled with the appropriate gas? that's PRECISELY what it is. Think about it for a second. I think people tend to mythologize equipment too much sometimes... but anyway- basically - to make my quest clearer - I found that cold light gives me far better exposure times (i.e. 200-300 sec vs 2500 sec and reciprocity from hell) when making big prints... so I'm kind of committed to that... I MAY consider LED - but I don't think it has even close to the same output in the actinic band (UV ish) that cold cathode does....

ic-racer · Apr 22, 2011

Sparky said:
well I would actually challenge you on that.... how is it physically different from a 'neon tube' filled with the appropriate gas?

Certainly they are very close, but would a typical neon shop be able to create one? I don't know. Maybe a typical neon bulb will work fine with some cooling vents.

http://www.cathodelightingsystems.com/pdf/CLS_Cathode_vs_Neon.pdf

ic-racer · Apr 22, 2011

This is exactly what you need:

That is the coldlight made for the DeVere 504. Search for CATHOMAG.

The picture is from a ebay.uk auction, it went for £21.00 said to be working and with stabilizer.

Sparky · Apr 23, 2011

well - I appreciate the info... though they're salesmen at work there... I guess I wouldn't have a problem taking my chances with a neon fabricator... I'll just figure out (perhaps an even better one) the gas that's most active in the blue end while still having enough green activity to make the VC filters still function...

Sparky · Apr 23, 2011

Thanks - yeah a cathomag might be a great plug and play solution... maybe I can wire it up to my metrolux (the main reason I don't want to go dichro or any other source)... if I can FIND ONE..!

Rectangular 4x5 or 5x7 cold light heads available anywhere?? (for devere)

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