U of S | Mailing List Archive | alt-photo-process-l | Re: intensity of bulbs

Re: intensity of bulbs

  • To: alt-photo-process-l@usask.ca
  • Subject: Re: intensity of bulbs
  • From: "Gordon J. Holtslander" <gordon.holtslander@usask.ca>
  • Date: Mon, 23 Feb 2009 19:22:38 -0600
  • Comments: "alt-photo-process mailing list"
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I use 4 foot 40 watt tubes on my UV unit. I used 4 foot tubes because
they were the cheapest UV tube I could find.

My UV unit is made from 5 plain double tube strip lamps - holds ten
tubes. The lamps are screwed to a piece of plywood so that the spacing
between the tubes is consistent - they are about an inch apart. The unit
is around 2 ft by 4 ft. The whole unit is on hinged to the wall so the
the tubes face the counter surface when its "hinged down" . When I print
the unit sits 4 inches above a couter top. - it has chain stays with
turn-buckles to hold and insure its level. When I'm not printing I hinge
the whole unit up and latch it to the wall. I can get away with having
such a huge unit. When I'm not printing it does not take up any counter
space - just some wall space. I use the same counter top for coating
paper and much of the other work in my darkroom.

I had considered using high intensity tubes and ballasts - but I didn't
think the slightly shorter printing times justified the expense. Might
be worth it if the cost of high intensity tubes and ballasts is much
cheaper now.

If I didn't use strip lamps I could have the tubes much closer together
-(the strip lamp design governs the lamp spacing) allowing a more
intense output, but my printing times haven't been as issue yet ...

Gord

geoff chaplin wrote:

>The length of the tubes is primarily determined by the maximum size of the
>print you wish to make - plus a margin to avoid light fall-off at the ends.
>I use 24" tubes to print 20" negs without a problem.
>
>At the same distance from the tubes the light intensity is proportional to
>the power of the tube (assuming the same type, efficiency etc). So a 40w
>tube would be twice as bright as the 20w tube.
>
>Geoff Chaplin
> ジェフ　チャップリン
> 
>geoff@geoffgallery.net 
>www.geoffgallery.net  
>Skype: geoffchaplin1611
>UK mobile (英国の携帯電話): +44(0) 7770 787069
>Japan mobile (日本の携帯電話): +81(0) 90 6440 7037
>Japan land line / fax (日本の電話とファクス): +81(0) 166 92 5855
> 
>
>-----Original Message-----
>From: Barry Singer [mailto:bsinger@sasktel.net] 
>Sent: 24 February 2009 07:18
>To: alt-photo-process-l@usask.ca
>Subject: intensity of bulbs
>
>A cursory search of the archives doesn't help me answer this question.  
>Perhaps some one can help?
>
>Does a 24" bulb at 20 watts have the same intensity as a 48" bulb at 40 
>watts?
>
>Barry
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