Michael Smith and Paul Chamlee are perhaps the most experienced photographers using Lodima/Azo who are working today. I am not sure if they have done any "objective scientific studies" as to using an enlarger when printing on Azo paper, but they have reported the times needed to be inordinately long. I can tell you that the work preliminary to our study of the tonal range of Lodima has shown that the EV of the light source at the contact printing frame is in the range of about 11 to about 12-13 depending upon the bulb and the height of the bulb from the frame-normally 36 to 40 inches. Needless to say, the bulb used is dependent upon the density of the negative. Since Michael uses film that is subject to increasing base plus fog he normally uses a 300W spot bulb at 36 inches from the negative-and even then I am told that his print exposure times are becoming longer. Many of us who use Lodima find that a bulb varying from 60Watts to 120 Watts is perfectly adequate. Although it is best to keep the distance from the bulb to the frame constant at 36 inches ( best I think to have a "standard" to compare other values to ), there are times that a certain negative is a bit thinner. Consequently, in order to have time to burn and dodge, the bulb can be raised ( or a bulb of less output can be used at the same 36 inches ) so as to increase the time of exposure and hence provide more time for burning and dodging. Moreover, if one finds that one's negatives developed to a certain ES print easier and consistently when the bulb one prefers to use is at a height 40 inches from the contact frame-no harm. There is some testing involved in order to define the light intensity that works best in YOUR darkroom using YOUR materials developed in YOUR usual manner. After all, "it" is all about tailoring one's methods to fit the response of the materials used. For your reference, doing paper testing of Ilford and Adox MCC ( for contact printing ) whilst using the enlarger as a light source at 30 inches provided an EV of 8.5 to 9. Thus, the need for increased light intensity to expose Azo/Lodima for contact printing. I have no data using Lodima for enlarging.
I hope the information was useful. I will ask Michael to chime in as he wishes. He has used Azo for many years and can provide all manner of advice and counsel.
There ARE some enlarging heads that have been configured so as to be able to enlarge on Azo/Lodima. Durst USA provides information on such an enlarger which is in regular use by a photographer on the West Coast.
The other thread got me thinking it might be fun to try just for kicks. I'm familiar with Michael A. Smith's extensive history with Azo/Amidol and Lodima so I probably should have looked there first. I remember even my contact printing times being long with Azo, although I never had the wattage I really needed. Anyhow this was just a thought experiment. Thanks.
Since we are jointly interested in Azo papers, here a a link to an enlarging head for Azo. Note the EV values at ASA 100 and compare such to the ones I furnished above. Those are very intense lights in the Durst machine! Keep you hands out of the light path! :}
there are people who enlarge on azo with a normal enlarger &c ... but
their enlarging times from what i remember were like 10 minutes,
maybe longer ... azo/lodima/gaslight ( silver chloride ) paper is very slow ..
years ago i did tests for paper negatives, it was 5-7 stops slower than any other paper i had ..
( regular developing out rc and fiber papers, processed in normal developer ) ...
i remember reading ( maybe on michael and paula . com ) that michael smith got one of those
durst enlarger bulbs and was really enjoying enlarging some of his earlier work that was not ULF ...
he'd be the person to email regarding enlarging, and what the starting point times would be
with a cold light head or a condenser enlarger .. ( that is if you don't want to buy a durst head )
good luck !
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