Enlarger Contact Printing is Good Bad ugly?

[Tin Can]

AZO is sensitive to both UV and Visible Blue light, and both give curves of about the same shape. So, use whichever source is convenient for you. However, light sources designed for alternative printing put out too much radiation for AZO.

Sandy

Thank you Sandy. I trust your opinion.

[Paul Metcalf]

Well, pick your light source as you please, the paper will tell you what it likes.

[Tin Can]

Well, pick your light source as you please, the paper will tell you what it likes.

I see, that is interesting, perhaps UV does act faster. I did notice in my initial tests with a Time-o-Lite contact print box AZO was very slow compared to RCMG and I compensated with time.

Since AZO is fixed grade would there be any advantage to using UV light source?

Thanks for the chart and input.

Obviously I will need more testing.

[Drew Wiley]

You can even enlarge onto Azo given a reasonably powerful colorhead or alternative strong source and a fast enlarging lens. That merely refers to its speed and
spectral sensitivity. Tonality is always a bit different between enlargements and contact prints.

[Paul Metcalf]

So now you match your light source with the paper sensitivity, and you can see where the overlaps are. With an incandescent light, it's the blue end of it's spectrum that Azo paper is the most sensitive to, but it's the least available component frequency from that light source, hence long exposures. For some (and I surmise quit a few Azo users) these longer exposures are not an issue. You'll have to try some different approaches and see what you like. From my experience, I can't tell any difference in tonality between the different light sources as long as there is sufficient coverage of the image, and that coverage has a significant amount of parallel light rays (i.e. the light source isn't really close to the contact printing frame). I believe Michael Smith uses a 300 watt incandescent a few feet above the contact frame and typical exposures are in the tens of seconds (his negatives, not yours though). I didn't like a 300 watt bulb in my small darkroom because of the heat (and brightness). A 100 watt bulb put my exposures in minutes. Out of curiosity I tried a black light (spiral) and with it mounted on the ceiling of my darkroom (7-1/2 ft ceiling - can you say parallel light rays?!) my typical exposure is less than 20 secs, sometimes as short as 10 secs. Which can challenge dodging and burning. I've stuck with the black light for my main exposure, and I do occasionally use a pen flash light with a black cone (to make a pencil light) to paint low density areas when I screw up my exposure LOL. Good luck, contact printing on Azo is very satisfying.

[cdholden]

For AZO and other silver chloride papers I always use a tungsten bulb. The chloride emulsion is sensitive to visible light, much slower as you know than bromide, but prints very well with a light bulb. I don't know why UV light would be better but then there are many things I don't know.

Is your choice of tungsten light source on silver chloride papers based on something you can describe in the print visually or just a time control?

[DG 3313]

+1 with VC paper

Super Chromega