Re: sun vs. UV lights in cyanotype

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From: Christina Z. Anderson (zphoto@montana.net)
Date: 01/29/03-10:23:55 AM Z


Thanks, Sandy, for this tip. Would you also say that your exposure this way
(direct sun vs indirect) is twice as long, 4x as long, or what? I've just
always done my exposures out on the back deck, facing the sun, which in MT
is extremely strong (at 5000 feet elevation). However, the frame gets very
hot. I now possess a UV lightbox, and find my Ware cyanos (dense negs) are
taking about 16 minutes. I mean, I love doing them at all hours now that I
have a light box, but the sun exposure was always such a more enjoyable
process, running up and down the basement stairs and sitting outside while
exposing and such. However, I have never thought to use the north sky.
Chris
----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, January 29, 2003 9:12 AM
Subject: Re: sun vs. UV lights in cyanotype

> Chris,
>
> With all processes I have used you get more contrast by exposing in
> the shade with the frame pointed at the north sky than by exposing in
> direct sun with the frame pointed directly toward the sun.
>
>
> Sandy
>
>
>
>
> >Yes, Sandy,
> > This is why I brought this up. I was always under the impression
that
> >sun at a 90 degree angle to the contact frame would produce the sharpest,
> >nicely contrasty print. Uv would be more of a diffuse source of light.
Now
> >that I have said James said this, I should perhaps clarify his quote: p.
> >109, "You can also achieve lower contrast appearance in your image by
using
> >the sun as your UV source. Cyanotype exposed by sunlight tends to
provide a
> >longer tonal range than does a mechanical UV light and thus creates a
lower
> >contrast image by a light to dark association.". IT seems in essence he
is
> >talking about apparent contrast, the tones relating to one another, a
longer
> >tonal range equating with an apparent lower contrast. But still, it
seems
> >fishy.
> > However, you are saying, below, that the north sky produces greater
> >contrast??
> >Chris
> >
> >----- Original Message -----
> >From: "Sandy King" <sanking@clemson.edu>
> >To: <alt-photo-process-l@sask.usask.ca>
> >Sent: Wednesday, January 29, 2003 8:54 AM
> >Subject: Re: sun vs. UV lights in cyanotype
> >
> >
> >> If James really says that I think he is wrong. With all of the UV
> >> processes I have used the sun gives greater contrast than the UV box.
> >> But even with the sun there is a marked difference in contrast
> >> between exposures made in the shade (greatest contrast) with the
> >> contact printing frame pointed at the north sky, and those made with
> >> the frame pointed directly at the sun (less contrast, but sill more
> >> than with the UV box).
> >>
> >> Sandy King
> >>
> >>
> >>
> >> >Do those who do cyanotype regularly find the sun gives less contrast
than
> >> >the UV box? Christopher James says this--that you get a longer tonal
> >range
> >> >in the sun and hence lower contrast.
> >> >Chris
> >>
> >>
>
>


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