Pyrocat HD and 400 speed films

[cmpatti]

I've become enamored w/ Pyrocat HD, and I'm kinda' starting from scratch on my selection of film. I'd like to find a 400 speed (or so) film that is (1) available in 8x10, (2) able to get sufficient contrast w/ Pyrocat HD for use with Azo & platinum (I'm trying for dual-use negs), and (3) inexpensive. I've read good things about TMY in Pyrocat (and TMY has the additional benefit of very favorable reciprocity characteristics), but it's about $3/sheet, and I'd like to find out whether one of the cheaper films will work for me.

So, what experiences do folks out there have w/ Pyrocat and some of the less-expensive 400 speed films?

 

[LFGuy]

No experience here with 400 speed film, but try this:

(there was a url link here which no longer exists)

 

[Ole]

HP5+.

So, now I've said it... I think Ilford should be paying me a commission for this - or at least giving me free film

 

[Tom Duffy]

Ole's full of crap
Tri-x professional is the way to go, it's not wimpy like HP5+.

Seriously, i don't think Ole's answer or mine help very much. Both films are pretty expensive.

I've read that Arista 400 speed film is a clone of HP5 and is available for much less than the name brand products.

 

[Tom Duffy]

I meant to add that Arista is available from Freestyle photo sales in California.

 

[lee]

I use Arista from Freestyle in LA quite a bit and it is HP5+ without a doubt. It is about 1/2 Ilfords price.


lee\c

 

[Donald Miller]

We have a sponsor that sells 8X10 400 speed sheet film. Actually a couple of them as I look at it. The Classic 400 from JandC Photo is priced at $86.00 for fifty sheets. The price on Kodak TriX (B&H Photo) is $137.50. Maybe this fits into the catagory of the Samson and Goliath dialogue that has been addressed elsewhere on this site.

 

[cmpatti]

Well, it seems like Arista and JandC Classic 400 are inexpensive choices. Can anybody provide any experience with these films developed in Pyrocat HD for Azo and/or platinum printing?

 

[Donald Miller]

Chris,
Sandy King the developer of the Pyrocat HD formula posted some test results of the Classic 400 film. I believe that LF Guy directed your attention to that post. I don't know of anyone personally who has shared their experience when using this film on Pt-Pd. There may be some folks on the Azo forum that have some experience with the Classic 400 film. Azo and Pt-Pd seem to require similar negative contrast ranges.
Another film that I have used for Azo is the PhotoWarehouse 125 ISO film. Most folks seem to think that this is HP4 in a plain wrapper. I do know that this film will build density sufficient to the task of Azo and Pt-Pd. Jorge also shoots this film on his 12X20 for Pt-Pd. The price of this film is certainly attractive. I believe that I bought 100 sheets (8X10) for $125.00.
I have also used the Classic 200 (JandC Photo) it will build enough density for Azo and Pt-Pd. Good luck.

 

[sanking]

My personal opinion is that TMAX 400 is the best film for palladium printing, with TRI-X a close second. These two films are very responsive to N+ development and will reach the high CI needed for palladium, especially when photographing in very flat lighting conditions. Ilford FP4+ is equally responsive but its relatively slow speed can be a problem in low lighting situations. Unfortunately TMAX 400 and TRI-X are not available in ULF formats except by special order, and they are very expensive when obtained this way.

BTW, AZO and palladium require negatives that are quite different in terms of density range. For AZO printing we need a negative with a DR of about 1.3 while palladium requires a density range of about 1.7-1.8. However, if we develop a negative in a staining developer for the ES of AZO it will have a greater effective density range to UV light, making it suitable for palladium. For persons interested in printing with both AZO and palladium this is one of the major advantages of staining developers. All staining developers have this characteristic but with Pyrocat-HD there is a much greater difference between the effective printing density to blue and UV light than is the case with the pyrogallol based developers such as ABC Pyro, Rollo Pyro and PMK.

Just for the record the DR needed for various processes is:

1) Silver gelatin - 0.8 to 1.05 with VC or graded papers.
2) AZO- 1.2-1.3
3) Platinum - 1.4
4) Carbon - 0.8-2.5, with contrast control by strength of dichromate sensitizer
5) Kallitype and Palladium, 1.7-1.8
6) Vandyke, Salted Paper and Albumen, 2.2-2.5

Sandy King

 

[Donald Miller]

Sandy,

Thank you for sharing that information. I noticed on your reply to my latest question in which I asked about the 1.4 density that Clay had posted on Ed Buffaloe's site that you mentioned that Clay's information was based on reading a negative through the "blue" channel on a densitometer. That you went on to indicate this reading translated to a 1.8 when read through the uv channel. That this reading was the cause for my excessive negative contrast when used for printing on Azo. Would the conversion of blue to uv that you addressed be an accurate linear conversion factor of "blue" to "uv" readings?

Additionally, as I observe the Kodak spectral sensitivity charts for Azo the peak spectral response occurs in the range of 360-410 nm with drastic fall off at that point. It is my understanding that this is "near band uv". What is the factor that I am missing (considering the differing negative densities) in regard to the response of Pt-pd (which I have not used) and Azo. It appears that both process/materials respond to uv?

Any information that you can share to clear up my murky view on the matter would be greatly appreciated.

 

[sanking]

Donald,

Regarding your first question, it is not possible to give an exact linear conversion factor for the Blue to UV reading because it changes with increasing highlight density, and it also varies with films. However, in general it would be pretty safe to say that a blue channel reading of log 1.3 will read a bit more than log 1.7-1.8 in UV mode. However, a blue channel reading of 1.0 would read only about 1.25 in UV.

About the issue of AZO sensitivity, it is true that this paper has its maximum sensitivity in the UVA range, and drops off rapidly in the near visible range. However, because of the speed of the paper most people do not use UV light to expose. The use of a UV lights of the type we use in alternative photograhy would result in impossibly short exposures. So in practice most people are exposing with lights that emit very little if any UV radiation and it is only the light in the blue range over about 420 nm that is effectively available to the process .

That is at least what I believe to be the case based on my conversations with a number of AZO printers.

Sandy

 

[Donald Miller]

Sandy,

Thanks for your timely response to my earlier question.

I guess my questions still remain. If the spectral response of Azo is in the UVA or near band UV range, as Kodak indicates, then the reflector flood lamps that I and others use must be emitting some UVA energy (or so it would seem to me). Perhaps the percentage is small in relation to total light output and that would seem to bear out the problem with short exposure times using a purer uv source for Azo exposure.

That still leaves me with the question of the differing density effects as you have described them insofar as Pyrocat developer is concerned. If, as information available would seem to indicate, then the relative UV effects on exposure by a stained negative would seem to apply to both Pt-Pd and to Azo. The relative "speed" of the two materials would seem to have no bearing on the fact that they both expose to UV.

Bob Herbst in his tests (www.unblinkingeye.com) seems to show with step tablet exposure comparisons on Azo and Pt-Pd materials/processes that there is only 1/2 step greater density range recorded on Pt-Pd materials. That, if I am reading the results of his conclusions correctly, the silver chloride emulsion is capable of greater dmax then Pt-Pd and that Pt-Pd seems to show a greater ability to record and differentiate higher tonal values when compared to Azo.

Would this ability to distinguish high negative densities by Pt-Pd be the sole reason for the greater negative contrast range used by Pt-Pd photographers? However, I still question why a seeming differing effect on the transmission of UV should not apply to Azo as you seem to indicate that it does.

Thanks for any insight that you can share.

 

[sanking]

Donald,

I thought my last response addressed directly your question. AZO has sensitivity well into the visible light range, and it is the radiation in the visible range that is providing exposure, not UV light. Your reflector flood lights probably emit little or no UV radiation, but the AZO material is exposed nevertheless because it also has considerable sensitivity to light in the visible range.

What I am saying is this. You can expose AZO with a UV light source, which matches the greatest spectral sensitivity of the paper, but your exposures will be really short, too short for most contact printing conditions. Or you can also use the spectral sensitivity of AZO that is in the visible range and make the same exposure with lights of much greater wavelength, *but* your exposures will be much longer.


Regarding Bob Herbst's tests, note simply that AZO is capable of a much greater reflective density range than platinum or palladium. The maximum reflective density possible with platinum or palladium is around log 1.5, whereas AZO is capable of readings approaching or in excess of log 2.0.

Finally, I do not indicate that there is a differing effect on the transmission of UV light as it applies to AZO. If people were routinely using UV light sources to expose AZO, instead of light sources in the visible range, then we might assume that the density range requirements of negative for AZO and Palladium printing would be about the same. But the fact remains, folks are exposing AZO with light sources that produce little or no UV radiation.


Sandy

 

[Donald Miller]

Sandy,

Thank you for your further elaboration on this matter. I did not wish to give the impression that I was being contentious of your statements. If I appeared to be, then I apologize.

I did not understand what, to me, appeared to be conflicting statements. I was taking the Kodak released information to be the literal limits of the materials characteristics. I understand now that the Kodak information indicates the peak sensitivity and not the actual limits of the spectral response as I had previously assumed.

Once again, thank you.

 

[sanking]

Donald,

Bear in mind that I am just making observations and don't want to come off like some kind of expert. I don't know a lot about AZO but what I know for a fact is that most people are using light sources for exposure that put out very little or no UV radiation. And if you look at the spectral sensitity curve for AZO you will see that it has quite a bit of sensitity in the visible range at about 400 nm in the violet, and still quite a bit at 450nm in the blue.

Yesterday someone contacted me in response to a message I left on the BTZS web site regarding BTZS testing of stained negatives. He had tried this with AZO using the blue channel of his densitometer and the resullts did not match the times he knew to be correct from practical testing for N development. I can see that this would be a problem wiht AZO since the exposing light used by most people does not match the maximum spectral sensitivity of the paper itself.

Sandy

 

[Donald Miller]

Sandy,
Your information has informed me and filled some gaps that had existed in my understanding about exposure on Azo. Among those has been the matter of enlarging smaller format negatives on Azo. I know that Durst Pro USA has come out with a light source for that purpose. Michael Smith has indicated, furthermore, an individual is developing a light source for enlarging on Azo.

My thoughts have been that if Azo responds only to UV (my misunderstanding) and considering the length of time that exposures take that it would take incredible wattages to accomplish this considering the restriction of the enlarging lens aperture and the diminishment of light intensity by the distance removed from the easel.

Now I can see that considering the fact that Azo is very responsive to UVA (as indicated by your information of unmanageable short exposures in UV exposure units) that it would take a much smaller wattage device then what I had first thought. Once again, thank you for informing me.

Best regards,
Donald Miller