Exposing/developing for Azo/Platinum

gainer · Apr 27, 2005

Donald Miller said:
Gainer,

I guess that we will just need to agree to disagree...My photographic efforts are directed to the end of making photographs that are worthy of display. By that I mean technically well executed images as well as artisticly fulfilling. That would tend to encompass not duplicating sandstone images and slot canyon images that have been done ad nauseum.

I don't give a damn about space shuttles, lunar flight or any of that other irrelavent crap that you seem to pump yourself up with. But then again what the hell, someone may be impressed. I assure you that I am not...so save this for those who might be immature enough to be impressed.

Speaking of pontificating and being dogmatic...have you ever in your extensive experience encountered the aspect of psychological projection? If you have, I encourage you to revisit the subject. If you haven't then I suggest that it may prove interesting reading.

Pumping up? Talk about the pot calling the kettle black. You still haven't, and I suppose never, will explain how being able to make fine pictures worthy of display makes you an expert on anything else.

If I am cajoled for saying that I was an aerospace engineer in a former life, just think what you might have said if I had told you I was principal oboist of the Norfolk Symphony Orchestra and its official photographer for several years. My pictures have been displayed in the Chrysler Museum in Norfolk. So what?

Jorge · Apr 27, 2005

noseoil said:
Out of context? I think these two images were used to illustrate a point, but don't remeber exactly.

In any event, they seem to be well exposed, developed and conceptualized. Great job, jdef. tim

Tim the prints were made by Don, not jdef. Funny how he uses the prints posted by others to critizise them but when he is asked to post his, they are nowhere in sight.....

On the subject of changing the apparent contrast of graded paper by using different spectra of light I used this for many years when I printed in silver with graded papers and it works. The effect is not great by any means, but it does affect the exposure of the paper by virtue of the light transmitted by the film.

I have a Zone VI VC head and I noticed that when I used pyro negatives (PMK) if I used the green light only I would get better exposures on the highlights, when I used the blue light only I had better separation on the dark tones. In essence I was doing split filtering printing with graded paper.

I dont see why it cannot work with Azo and varying the light source.

Here is an example of a print I did this way.

sanking · Apr 27, 2005

Jorge said:
I have a Zone VI VC head and I noticed that when I used pyro negatives (PMK) if I used the green light only I would get better exposures on the highlights, when I used the blue light only I had better separation on the dark tones. In essence I was doing split filtering printing with graded paper.

This is very similar to what I am observing in exposing AZO with visible light and UV-A light. While the overall contrast range does not vary greatly, the difference in rendition of local tonal values, i.e. in the highlights, mid-tones and shadows, is very different.

Sandy

Jorge · Apr 27, 2005

sanking said:
This is very similar to what I am observing in exposing AZO with visible light and UV-A light. While the overall contrast range does not vary greatly, the difference in rendition of local tonal values, i.e. in the highlights, mid-tones and shadows, is very different.

Sandy

I beleive you are studying this, I think this effect will be more pronounced with stained negatives, specially with your pyrocat HD since the UV/VIS response of the stain is so specific. If my expereince helps you, I did not not see the same response when I used TMX RS and had non stained negatives. But then Azo has a different respons and the stain might not matter.....I dont know since I have never used azo.

sanking · Apr 27, 2005

OK, some more about the 13 watt Feit Electric screw-in Blacklight tube that replaces and provides the same "glow" in the dark as a 60 watt incandescent.

*Quality in light you can see*

*Will liven up your celebrations, halloween, parties, dances and get-togethers for years.*

*Will brighten up an otherwise dull gathering.*

*Posters and colors take on a whole new look when illuminated with this special and unique blacklight.*

*With this great new compact fluorescent blacklight you will be known as "The Party Specialist."

*All whites appear whiter."

*All colors appear brighter."

*Glow in the dark, with a 8,000 hours bulb life.*

And does a real number on AZO.

Sandy

sanking · Apr 27, 2005

jdef said:
Apparently I'm no longer allowed to post to this thread, regardless of the content of my messages. So much for "public" forum.

Jay

Say what?

Sandy

sanking · Apr 27, 2005

Jorge said:
I beleive you are studying this, I think this effect will be more pronounced with stained negatives, specially with your pyrocat HD since the UV/VIS response of the stain is so specific. If my expereince helps you, I did not not see the same response when I used TMX RS and had non stained negatives. But then Azo has a different respons and the stain might not matter.....I dont know since I have never used azo.

Yes, I am trying to study this. But as in many situations, the more you know, the more you realize how little you really know.

But thanks for your observations. I will bank them along with my own and see where they lead.

Sandy

jmdavis · Apr 27, 2005

sanking said:
OK, some more about the 13 watt Feit Electric screw-in Blacklight tube that replaces and provides the same "glow" in the dark as a 60 watt incandescent.
..................
And does a real number on AZO.

Sandy

Is that a good "number" or a bad "number" that it does on Azo. If 13 watts of fluorescent is 2 stops faster than a 65 watt bulb are we taking a 200 watt equiv (more or less). In other words, I'm wondering if the end result might be that a 13 watt blb could basically replace the 300 watt R40. But perhaps its too early for this sort of speculation.

Mike

sanking · Apr 28, 2005

jmdavis said:
Is that a good "number" or a bad "number" that it does on Azo. If 13 watts of fluorescent is 2 stops faster than a 65 watt bulb are we taking a 200 watt equiv (more or less). In other words, I'm wondering if the end result might be that a 13 watt blb could basically replace the 300 watt R40. But perhaps its too early for this sort of speculation.

Mike

Yes, I meant "good" in the sense that the 13 watt Black Light tube is very efficient at exposing AZO. With approximately 1/5 of the wattage of a 65 watt RH40 flood the black light tubes is approximately two stops faster, when printing a Stouffer step tablet. That is pretty impressive.

However, the difference in contrast I observed when using the NuArc 26-1k and a bank of BLB tubes to expose AZO to a Stouffer step wedge (with extremely short exposure times!) was not present in my tests with the 13 watt fluorescent tube. But the original test was not an error because I went back and repeated it with the BLB bank and still got the same result, i.e. much more contrast than with the RH40 flood?

Also, and very contrary to my expectations, I did not find any difference in contrast between the use of the RH40 flood and the 13 watt black light tube in printing pyro stained negatives. This really has me baffled. And, although the black light tube prints a stained negative faster than the 65 watt RH flood, the difference in speed is not nearly so great as it is with unstained negatives. I did find, however, some significant differences in the shape of the characteristic curves produced by the two lights that would definitely result in a different rendition of tonal values.

Sandy

Kirk Keyes · Apr 28, 2005

sanking said:
However, the difference in contrast I observed when using the NuArc 26-1k and a bank of BLB tubes to expose AZO to a Stouffer step wedge (with extremely short exposure times!) was not present in my tests with the 13 watt fluorescent tube. But the original test was not an error because I went back and repeated it with the BLB bank and still got the same result, i.e. much more contrast than with the RH40 flood?Sandy

Sandy - have you thought about reciprocity failure? Not in the usual sense of longer exposure reciprocity that we experience with low light levels, but on the other side of the scale - extremely short exposure reciprocity.

Azo, which is designed with relatively long exposure time, as all printing papers are, maybe it is showing a reciprocity failure with the really short exposure time that you needed to use with your brighter bank. The 13 watt fluorescent tube, even though it was only a few stops brighter than the R40 bulb, is appearently not significantly bright enough to show the reciporcity effect.

I don't have any books on hand to look up a graph of contrast vs. exposure (and over a wide range of exposure), but I'm sure I've seen one somewhere - James and Mees I think may have one. Perhaps someone here has one handy to look into it.

Kirk Keyes · Apr 28, 2005

Jorge said:
On the subject of changing the apparent contrast of graded paper by using different spectra of light I used this for many years when I printed in silver with graded papers and it works. The effect is not great by any means, but it does affect the exposure of the paper by virtue of the light transmitted by the film.

Jorge - that's really interesting. It's a technique that I don't think I've ever seen discussed as a printing tool, even though the books on sensitometry all mention this effect. I love seeing theory being put into use in practice!

Kirk Keyes · Apr 28, 2005

Donald Miller said:
My photographic efforts are directed to the end of making photographs that are worthy of display. By that I mean technically well executed images as well as artisticly fulfilling. That would tend to encompass not duplicating sandstone images and slot canyon images that have been done ad nauseum.

Donald, sorry you feel my prints are not as worthy of display, as are yours apparently are. I happen to enjoy sandstone, the slot canyons, and the other images I presented on my web site. And I'm sorry if you do not see any difference between them and the other ad nauseum photos you've seen - I happen to know there is a technical difference that you missed on some of those photos. And it has to do with understanding the properties of light, colors, and they way they are captured on film. Too bad you didn't recognize that so you could have appreciated it...

And ultimately, if all my photos do is invoke a feeling of "I wish I had been there to see that", then I am succesful.

By the way, where are your prints? Do you have any photos online? I would like to see some of your fine Azo prints. And my offer of a print exchange still stands. I promise my print will not be a color print, and not of a slot canyon.

Kirk - www.keyesphoto.com

mark · Apr 28, 2005

Kirk,
For what it is worth I found your images quite good. Assuming that the images look better in real life I am certainly impressed.

sanking · Apr 28, 2005

Kirk Keyes said:
Sandy - have you thought about reciprocity failure? Not in the usual sense of longer exposure reciprocity that we experience with low light levels, but on the other side of the scale - extremely short exposure reciprocity.

Reciprocity failure is one possible explanation and was suggested on the AZO forum.

Another thought is that there may be some uneveness of illumination caused by a slight interval between when the tubes actually come on. This seems very possible when the exposures are 1/10 of a second or less.

Sandy

Kirk Keyes · Apr 28, 2005

sanking said:
some uneveness of illumination caused by a slight interval between when the tubes actually come on. Sandy

Unevenness? From the flickering of the lights, as part of the light bank starts up faster than another part?

sanking · Apr 28, 2005

Kirk Keyes said:
Unevenness? From the flickering of the lights, as part of the light bank starts up faster than another part?

Yes, that is what I mean. With the light integrator set to 0.1 seconds I see this as a distinct possibility.

Sandy

Kirk Keyes · Apr 28, 2005

sanking said:
Yes, that is what I mean. With the light integrator set to 0.1 seconds I see this as a distinct possibility.Sandy

If the bank is consistant, try rotating the step wedge 180 degrees and make a second contact print. I would suspect that the bulbs may have some consistancy to their ignition/firing order.

Or, use a second contact frame, and hold it at a distance from the bank to cut down on the intensity of the light. Perhaps you could get the contact frame far enough away from the light bank to drop the exposure time to a few second?

noseoil · Apr 28, 2005

Thicker glass to absorb more UV light?

Kirk Keyes · Apr 29, 2005

http://unblinkingeye.com/Articles/articles.html

Thanks for the link. I like the one of the waterpocket in what looks to be granite.

Exposing/developing for Azo/Platinum

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