[alt-photo] Re: Re : Re: UV Point Light Source

[Tomas Sobota]

Ding,

your system is worth a trip to Paris and having a look :-)

However for whole sheets a bank of UV tubes makes probably more sense.

Tom


On Mon, May 23, 2011 at 5:42 PM, ding dangdong <dingedangedonge at yahoo.fr>wrote:

> I have been using this setup for a little more than four years now.  My
> print
> sizes start from 28x40cm up to whole sheets of Fabriano and i have always
> suffered from light falloff especially observable with cyanotype during
> exposure. Quite a pain because im not at all good at techy calculations and
> stuff so had to resort to a lot of trial and error in solving this little
> annoyance. Right now, i have suspended two bulbs with 55cm distance from
> frame
> and had it enclosed in a DIY folding box of gaffered sheets of insulating
> material (foamcore with aluminum foil on one side much like those folding
> sunscreens for your dashboard). i also have my frame sit on a 'carousel' or
> sort
> of a lazy Susan, a box with wheels that allows me to rotate the frame under
> the
> lights to balance the exposure. Kind of dodging and burning from old
> darkroom
> days. A messy lot of 'systeme D' like they call it here in France that
> leaves a
> lot of room for improvement but so far its working. My base times for
> cyanotypes
> are in the 30mins and gums at 5 mins.
> Anybody out there with better suggestion than my rotating frame?
>
> I apologize for mistakes in my english, not my native tongue. So is French
> even
> if i live here in Paris.
> Ding
>
>
>
>
> ________________________________
> De : Tomas Sobota <tom at sobota.net>
> À : The alternative photographic processes mailing list
> <alt-photo-process-list at lists.altphotolist.org>
> Envoyé le : Lun 23 mai 2011, 10h 10min 34s
> Objet : [alt-photo] Re: UV Point Light Source
>
> Alberto,
>
> After switching the lamp on, you have to wait a couple of minutes before
> using it. After this time (more or less) you see the light change color
> from
> the usual yellow to a greenish hue. That is the visual signal that the lamp
> has started emitting UV. This change is quite fast and you notice it
> easily.
>
> The lamp gets hot, but not extremely since a great part of the 300W
> dissipate as non-caloric UV. More than UV tubes, to be sure. But with a
> separation of 50cm or so from the print, the heat does not reach it
> noticeably. Not even in summer, from my experience.
>
> When you finish the exposure, you have to wait until the lamp cools down
> before turning it on again.
>
> Tom
>
> On Mon, May 23, 2011 at 8:24 AM, Alberto Novo <alt.list at albertonovo.it
> >wrote:
>
> > Philippe Berger wrote:
> >
> >> I use also a Osram UltraVitalux for my Carbon Transfer. It is perfect,
> no
> >> problem
> >>
> >
> > Isn't it too hot, and the light increasing for the first minute or so
> after
> > the switching on?
> > Alberto
> > www.grupponamias.com
> > www.alternativephotography.com/wp/photographers/rodolfo-namias-group
> >
> > _______________________________________________
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