Jay, are there any time or temp changes if using carbonate instead of TEA?
BTW, I hope you realize that I was only pulling your leg with the evil scientist/slow down stuff. I really do appreciate the time and effort you've put into your formulas and your generosity in sharing them. Jim
I've not used TEA before, but I guess I will be soon. Is its freezing point a problem? When the developer is mixed, what is the freezing point then?
Originally Posted by jdef
I, for one would appreciate your posting all that info. I know your results are really just a starting point for any other given photographer, but a place to start is always nice.
Jay, ruling out reading error, the bumps in that curve you posted are indicative of an anomaly. It may be that the blended emulsions in the film are not developing properly or that there is a change in tone of the silver and / or the stained image.
I would warrant that a piece of that film processed in a 'standard' developer such as HC110 or D-76 would not have that bump.
Whether this is a problem or just plain unimportant should be determined by the user after careful examination of the prints. But, it just cannot be ignored. It would be nice if you posted a comparison with some standard.
I am already using PC-TEA - Other than images stain, can I expect any other differences? I was hoping PC-TEA would be as smooth as XTOL and it was not. I guess the lack of Sodium Sulfite will do that. I am very pleased with the results of Pyrocat - and had many happy years with PMK (although the grain was too big) I am wondering if this replaces PC-TEA as an improvement and if This will maky XTOL unneccesary.
My photos are always without all that distracting color ...
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If all Jay's film show this kind of behaviour in the graphs, it may indicate that the step wedge that he is using is not evenly spaced, causing the point to be misgraphed. (Not that this is really a problem, it is just that he needs to take it into account in the graphing of the points.) It may be a reading error on the x-axis, not the y-axis...
Originally Posted by Photo Engineer
Maybe it is not so much a hump in the Zone V region as the dip at Zone IX that is causing the concern of PE? Again, it could be caused by a mismatch of the step wedge and the plotting software defaults.
Jay, does that web app that you are plotting with let you input the values for your step wedge, or are you forced to use the Zone step points that it shows on the x-axis?
Kirk - www.keyesphoto.com
Originally Posted by jdef
You say that for roughly equivalent dilutions 510-Pyro is much more active than Pyrocat-HD. I don't see it.
In the curve you show for the development of HP5+ you have a negative density range of .025 - 1.74 with the 1:100 dilution, at six minutes of develoment at 70ºF, with constant agitation.
I just looked at my development of HP5+ in Pyrocat-HD. At the same development temperature and constant agitation here is what my tests gave with the 2:2:100.
5 minutes .12 - 1.56
7 minutes .12 - 1.87
Adding the additional B+F of 0.13 that you are getting with your film/developer combination (which I assume is caused by the higher B+F of the film itelf?) these DRs would be .25 - 1.69 (five minutes) and .25 - 2.00 (seven minutes). In other words, based on these results it appears to me that Pyrocat-HD is at least as active as 510-Pyro, if not slightly more so.
So where am I going wrong?
Last edited by sanking; 05-14-2005 at 12:31 AM. Click to view previous post history.
Sandy - you're using sheet film, right? I think Jay said he was using 220 roll film. That's probably the difference where the differnce in base densities comes from.
The Pyrocat and 510-Pyro look to be pretty close in "activity". His developer was at a 100 times dilution for his run, yours was at 25 times (2+2=4 parts in to 100). So Pyrocat used more stock solution to get to the same ballpark. Of course, we could go and calculate on total amounts of materials in the final dilution and not worry about dilution amounts.
Or, maybe Jay should test it a 1+90 dilution to get the activity crown.
Originally Posted by Kirk Keyes
Yes, I gathered that Jay was using either 35mm or roll film to test and assume that accounts for the considerable difference in B+F in our tests.
Regarding the second point, I normally am only interested in comparing the actual amount of reducer (s) in the working formula, and if memory serves Jay usually does it that way as well. So we would be looking first at the total amount of pyrogallol + ascorbic acid + phenidone in a liter of working 510-Pyro, against the total amount of pyrocatechin + phenidone in Pyrocat-HD. Comparison of the dilution itself by itself is meaningless since the stock solutions don't have equivalent amounts of reducers.
I should also add that the addition of a very small amount of ascorbic acid to the Pyrocat-HD formula provides a significant boost in energy. In fact, I describe a formula called Pyrocat+ on the AZO forum that takes advantage of ascorbic acid to provide this extra boost. The amount is almost miniscule, amounting to about 10ml of a 1% solution of ascorbic acid per liter of working solution, which is 0.01 g of ascorbic acid per liter, if my calculations are right.
However, I am also beginning to think that we may need to re-consider the description of a high-definition developer. Typically the description of a high definition developer is one that contains a very low amount of sulphite, so as to prevent grain solvent action, and around 1.0 g per liter or less of reducer. However, when talking about these high energy formulas that result from the additional synergism between two or more reducers that are super-additive I don't think that the concept of 1.0 g or less of reducer per liter is valid. These solutions re-generate so effectively that in essence they limit the production of adjacency effects because it becomes very hard to get any local exhaustion of the developer, at least with normal and constant agitation. What this means is that the method of development, i.e. type of agitation, becomes highly important with this class of developers if our objective is maximum apparent sharpness through adjacency effects.
Last edited by sanking; 05-13-2005 at 01:50 PM. Click to view previous post history.
Yes - the affect of superaditivity, and then the combinations of more than two developing agents makes this all kind of like a numbers game when trying to determine "activity" levels.
Originally Posted by sanking
Perhaps we should just compare $/L of developing agent instead of total grams/L would be more interesting.