[tuco]

...
From perusing the Web, I get the impression that the big error with B&W film is underexposure and over development. (I'm seeing a lot of people rate Acros at 80--or even 50 in a contrast-y scene--then develop N-1 or N-2.)
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Why is that a big error? It is called highlight expansion. You'd employ this technique when your scene has low dynamic range with high values only falling one or two stops above the middle gray. With highlight expansion you can move those high values up a stop or so while holding the low values pretty much were they are and get more contrast in the image if that's what you want.

Take the identical picture with Acros at EI 80 and one at EI 100. Go try and tell the difference. This is not positive film! Moving your middle gray up or down 1/3 stop with BW film is nothing.

[Arjay Bee]

Will get back to you

Scanned a couple of the same negs using the canon flatbed scanner and the default scan came out brightly pink tinged (Surprise surprise). Was able to get a 600dppi scan that was about 3500px wide. Ported to Photoshop and Nik silver effex pro and left it at the default setting except for brightening it a little. Cropped the top and cleaned all the dust bunnies off and have upsized it to poster size. Pretty pleased with it - as usual better in real life. Attached is a web sized copy.

[dsmithhfx]

default scan came out brightly pink tinged

Does the canon software do native grayscale?

[CreationBear]

You'd employ this technique when your scene has low dynamic range with high values only falling one or two stops above the middle gray.

Tuco-- thanks so much for the insights...I have to admit that it was mostly your pics that got me obsessing over this--they just seem to have a "snap" that's so far eluded me.


Just to be clear about "highlight expansion," then: for a low contrast scene, expose normally and develop N+1?

[drmoss_ca]

OM2n, 28/2, XP2 @ 1600, Ilfotec HC, X1 scan:

[wkraus]

My father's library, 1973
Photina Reflex, Isco Göttingen Isconar 1:3.5/75, Ilford FP4, lab-developed (film loaded in 1973, completed in 2017), negative copied using Pentax K-1 with smc Pentax-D FA 50mm Macro




I started taking photos with a very simple point-and-shoot camera using Rapid format film as a kid. In 1972 or 73, I picked up my father’s old Photina Reflex TLR camera and put a few B&W films through it but soon concluded I wanted something more flexible. In December 1973 I purchased an Asahi Pentax SP 500 and never looked back... until very recently when I noticed there was still a film in that old camera. I completed the film and had it lab-developed, and while the early frames were mostly no longer usable, a few turned out interesting, if only for personal reasons.

Here's one of the recent ones, taken at f/4:

[dsmithhfx]

My father's library, 1973
Photina Reflex, Isco Göttingen Isconar 1:3.5/75, Ilford FP4, lab-developed (film loaded in 1973, completed in 2017), negative copied using Pentax K-1 with smc Pentax-D FA 50mm Macro




I started taking photos with a very simple point-and-shoot camera using Rapid format film as a kid. In 1972 or 73, I picked up my father’s old Photina Reflex TLR camera and put a few B&W films through it but soon concluded I wanted something more flexible. In December 1973 I purchased an Asahi Pentax SP 500 and never looked back... until very recently when I noticed there was still a film in that old camera. I completed the film and had it lab-developed, and while the early frames were mostly no longer usable, a few turned out interesting, if only for personal reasons.

Here's one of the recent ones, taken at f/4:

Really like the first shot.

[tuco]

Just to be clear about "highlight expansion," then: for a low contrast scene, expose normally and develop N+1?

Not quite. Since you are over developing the film to move your high values up more, you need to slightly underexpose so your low values also don't move up too much. Highlights develop faster and move further than the shadows.

An easier way to expand your tonal scale when your scene is flat is to follow Ansel Adams suggestion in his book, The Negative, by Intensification. That is, soak the negative(s) in a solution of selenium toner diluted 1:2 with Kodak's Hypo Clearing agent for 5 minutes. You can do this anytime after the film has been developed. So you can decide later what frames you want to do this to.

Highlight compression and expansion can be done without a densitometer by trial and error. And highlight compression is easier to practice without a densitometer than expansion, I feel. To do it right you'd first would conduct a speed test of the film by measuring the density of Zone I. And once you have that you need to find a development time that places Zone VIII at a specific density that's different for a condenser vs a diffusion enlarger. That's a lot of work and you need equipment. So I wouldn't worry about highlight expansion just yet. In the image editor you usually can improve a low contrast scenes much easier than you could with wet printing.

For high contrast scenes and highlight compression where you want more DR than normal development, try starting off by over exposing one stop (shoot say 100 film at EI 50) and cut your normal development time down by 20% or so as a starting point. Look at the shadow detail on a light table or something and decide if you got them or not. If the shadows are too thin then you'd want to add more time and of course if the film looked over exposed keep reducing the development time. Do this until you are happy with the shadows. A one-degree spot meter and the zone system of metering helps you with this a lot! When you place a shadow area say 3 stops below the middle gray exposure with a one-degree, it is something you can visually see in the print or scan if it matched how deep of a shadow you expected once you got a feel for this sort of stuff.

Now not all developers are good at the more extreme highlight compression. Just like some are not good at highlight expansion or pushing film. You just have to experiment.

Good luck.

[CreationBear]

You just have to experiment.

Excellent, thanks so much for taking the time to elaborate... There's a darkroom "collective" here locally, so it might be time to take the plunge.

[tuco]

Excellent, thanks so much for taking the time to elaborate... There's a darkroom "collective" here locally, so it might be time to take the plunge.

Good deal. I edited what I wrote since you read it BTW.

[g026r]

Here's a fun one: came in a plain yellow box with a white typewritten label on it advising to handle in low light. Inside of which was a plain black metal daylight-loading cassette with another white typewritten label. Both labels said only one thing about the emulsion inside: "Kodak SO-410," indicating it was a film only available as a special order.

The film leader offered the first clue as to what it was: baby blue, similar in shade to another emulsion Kodak had sold commercially but without that film's standard anti-halation layer. A bit of searching through old references confirmed it: Technical Pan, probably sold for scientific work and possibly pre-dating the adoption of the TechPan mark.

No idea on the age of this, as the box had no dates, but it's probably safe to assume that it was quite expired. Seems to have been well stored, as it turned out wonderfully with only about a stop extra exposure.







Spotmatic II.
Auto-Chinon 55mm f1.7.
Kodak SO-410.

[tuco]

...
No idea on the age of this, as the box had no dates
...

Got a picture of the box? Maybe we can get a feel for its age from that.

[tuco]

Passing through a small town I came across this. I have no clue what's going on. PS, I have new gear coming. I can't wait. A Fuji GX617 pano camera with a 90mm lens ( = 20mm in small format).

Small Town Drama.

400TMY

[g026r]

Got a picture of the box? Maybe we can get a feel for its age from that.

Box and cassette; not pictured is the plain aluminium cannister that stored the cassette inside the box. My guess is late-70s or early-80s.

I had actually forgotten that this box labelled it as photomicrography film. (The handle under low light was on the other side, perhaps? I forget precisely where it was, but clearly not on the label as I originally recalled.) I have a second box with the same SO-410 code and a label that indicates it as being for astronomical work.

[tuco]

Yeah, hard to tell. Certainly custom labeling. But I think your estimate sounds good.

EDIT: One clue could be typewriter print vs say computer print (dot matrix, inkjet/laser) on those labels.