POP info-"Bullet proof negative" comment

[mark]

I am intrigued about this process and it sounds like fun. What I need is a bit of clarification regarding some comments Ole and CJarvis made in their Retrophotographic discussion. Maybe someone can help me out.

I do not have a densitometer. What does "bullet proof" negative mean? Would a negative that is exposed and processed for alt processes or AZO be adequate for this paper?

 

[Jorge]

Yep, you need a negative with a DR of about 1.4 to 1.6. So a negative for Azo or pt/pd would work fine.

 

[Francesco]

I take bullet proof negative to mean a negative so dense that exposure times under an enlarger head would be in the tens of minutes - in other words, they will not respond at all to enlarging. My negative destined for AZO are very dense but will only require, in my case, between 20 to 40 secs using a 300 watt bulb.

 

[sanking]

I am intrigued about this process and it sounds like fun. What I need is a bit of clarification regarding some comments Ole and CJarvis made in their Retrophotographic discussion. Maybe someone can help me out.

I do not have a densitometer. What does "bullet proof" negative mean? Would a negative that is exposed and processed for alt processes or AZO be adequate for this paper?

A "bullet proof" negative is one that has been overexposed by one or more stops and that has also been developed to a high density range. It is a very dense negative with a lot of contrast. Such negatives will usually print well with alt processes and AZO but exposure times can be two to four times as long as would be required had the negative received normal exposure.

Many people seem to think that you must have bullet proof negatives to print with the alternative processes and AZO but this is not correct. For these processes you don't need any more density in the shadows than for regular silver printing, but you do need negatives with more contrast, i.e. of higher density range.

Sandy

 

[David A. Goldfarb]

Just to follow up on Sandy's comment, I think the desire for "bulletproof" negs with more shadow density as well as increased contrast probably has to do with some of the films that people who like contact processes often use. If you use a film with a long toe and high Dmax (Tri-X, Classic/Forte 400, and I'd guess Super-XX might work this way as well), overexposure pushes the whole range up the curve, off the toe, and into the straight line portion, resulting in better shadow separation, and as long as the film doesn't shoulder at the highlight end, this can produce better results.

 

[sanking]

Just to follow up on Sandy's comment, I think the desire for "bulletproof" negs with more shadow density as well as increased contrast probably has to do with some of the films that people who like contact processes often use. If you use a film with a long toe and high Dmax (Tri-X, Classic/Forte 400, and I'd guess Super-XX might work this way as well), overexposure pushes the whole range up the curve, off the toe, and into the straight line portion, resulting in better shadow separation, and as long as the film doesn't shoulder at the highlight end, this can produce better results.

I am sure that is why some people overexpose film but it does not always achieve the desired end, in fact more often than not it does not.

Overexposure to push shadow density into the straight line part of the curve works really well with some film/process combinations, Super-XX and AZO coming to mind as a superb example.

Unfortunately it does not work nearly so well with other combinations and is actually counterproductive with many. For example, TRI-X has a very long toe but an upward flaring curve in the highlights so if you overexpose to put important shadow density in the straight line part of the curve it makes highlights very difficult to print in AZO (or other silver gelatin papers) without getting blown out. This perhaps explains why TRI-X has never been very popular with AZO. On the other hand the flaring curve in the highlights is great for Pt./Pd. because it compensates for the highlight shouldering of the process so it makes sense to overexpose TRI-X with Pt./Pd.

And of course you don't want to overexpose films that have very short toes (HP5+, FP4+) or films that have almost no toe (Delta 100, TMAX-100, TMAX-400) with any papers, irrespective of the shape of the paper curves, because with these films the shape of the curve is such that overexposure simply adds to printing density without achieving any enhancement in print quality.

In short I don't recommend overexposure for most film/process combinations unless you really understand how the film and paper curves interact with each other. But folks who already know that don't need someone else's recommendation anyway, now do they?

Sandy

 

[Alex Hawley]

Many people seem to think that you must have bullet proof negatives to print with the alternative processes and AZO but this is not correct. For these processes you don't need any more density in the shadows than for regular silver printing, but you do need negatives with more contrast, i.e. of higher density range. Sandy

I just jumped off of the overexposure wagon for my Azo work. For a while, I was overexposing by 3 to 4 stops, albeit not on purpose. Most of the time, I was getting the classic "bullet-proof" negs that were taking about 3 minutes to expose on Grade 2 Azo. When the new Grade 3 came out, being a full 2 stops slower, I had to move my light bulb down to just 24 inches over the print frame to keep a reasonable exposure time.

Most of the time, my overexposure was working OK but there were cases where it didn't. That made me realize my mistake.

One step in proving this all to myself was shooting a series using the sunny 16 rule plus one stop using J&C 400 and J&C 200. It worked! The Azo prints are just as good as the "bullet-proof" ones and the exposure times are reasonably short. The only reason I'm opening up one stop past the Sunny 16 setting is to get the extra density for Azo, But that's one stop and one stop only.

 

[Ole]

As has already been said, a "bulletproof" neg is one that is so dense that it would be better for blacking out the darkroom windows.

That is not necessary at all. But many printing-out processes, and several others, work better with negatives with higher contrast than would be used for enlarging. This can often be acheived by using a staining developer, which builds highlight density by stain in addition to silver. In my case I developed the 18x24cm film in ANSCO 130 (1:1, paper developer), then bleached and redeveloped in pyro to build more printing contrast. The redeveloper I used also added a lot of base fog, which had no other effect than to prolong the exposure needed. I'll try another mixture next time...

 

[cjarvis]

Indeed, my "bulletproof" negs were overexposed and overdeveloped. My print time for POP under BLB tubes is 20-25 minutes--a little less in full sun. I should say that I hate my bulletproof negs. For me a better all-around negative that I can use for POP, platinum or cyanotype has been a normally-to-a-tad-underexposed and slightly overdeveloped...maybe +1, which leads to my next thought...

I have found that since switching from Plus-X upon its dicontinuation to HP5+, my hit rate is much higher. HP5+ is considerably more flexible.

 

[c6h6o3]

I have found that since switching from Plus-X upon its dicontinuation to HP5+, my hit rate is much higher. HP5+ is considerably more flexible.

TMY is a lot more flexible than HP5+. So is Efke PL100.

 

[mark]

I think I get it and have ordered some POP. I am sure I will have many more questions after it gets here.