Re: UV-exposure units/ UV LEDs:diagrams

My UV array consists of six bulbs and exposure time is also around five
minutes, depending upon the negative.

I tried exposing with an enlarger and after a day and a half I still had
nothing, so unless you are going to replace the bulb, I would suggest it as a
non-starter.

Cheers -

george

--- "Gordon J. Holtslander" <holtslander@skyway.usask.ca> wrote:

> Hi:
>
> I do a lot of alt process work. I contact print with a bank of UV
> flourescent
> lamps 3 inches above my printing frame. My exposure time for cyanotypes is
> around 5 minutes.
>
> If you were to use an enlarger the time may be far too long to be practical
> and the UV light may damage the negative.
>
> I don't want to discourage people from trying this, but I think the exposure
> time will likely be in the range of hours - an hour is only between three and
>
> four stops longer exposure than my contact print time.
>
> To get an idea of exposure someone should compare the exposure time they need
>
> for a contact print to that of an enlargement. How many stops longer is an
> enlargement compared to a contact print..
>
> A stop is doubling the exposure time. The difference between 5 seconds and
> 40
> seconds is 3 stops more exposure. 3 stops more exposure than 5 minutes is 40
>
> minutes.
>
> A quicker method may be to make enlarge negatives or enlarged reversal
> negatives
>
> see http://unblinkingeye.com/Articles/NbyR/nbyr.html
>
> Gord Holtslander
>
> On Saturday 04 November 2006 5:13 pm, earlj@comcast.net wrote:
> > The idea of using an enlarger for alt process work is very intriguing, and
> > I think that it just might work. The first question that pops into my mind,
> > though, is how the heck do you focus the enlarger? Won't the focus be
> > different at 395 nm than at the wavelength of your 'normal' incandescent or
> > fluorescent light source?
> >
> > Earl Johnson
> > Inver Grove Heights, MN
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Received on Tue Nov 7 05:55:51 2006