My rant on shooting box speed. Am I out to lunch?

[Milpool]

You might be surprised, though. In examining literally thousands of negatives - perhaps over 10 thousand at this point (yikes!) - both my own and other people's, the single biggest sin I've seen committed is underexposing the shadows. For people anxious to just get going, I have often repeated the "1/2 box speed, 20% less development" rule of thumb. They pretty much always come back saying that their negatives are much better. Nothing takes the wind out of a beginner's excitement than to tell them they need a densitometer and a year of testing before they really will know what they are doing

For my own part, I more and more have gravitated to the view that the purpose of computing exposure (and thus selecting the proper EI) is to achieve a negative that gives me the most possible interpretive choices in the silver printing process. I haven't touched my densitometer in years because with a new film/dev/agitation combo, the 1/2 ASA -20% rule above gets me close enough to get going. From there, I just eyeball it.

I'd much rather make pictures than tests - some of my favorite images were test pictures taken at the "wrong" EI, developed at the "wrong" dilutions, the "wrong" time, or agitated the "wrong" way. These mistakes led to a refining of how I expose a given film/dev/agitation scheme but they still are glorious in their results (at least some of the time).

(I still would love to see some of your pix ...

I've got some in the gallery here if you want (go easy on me - they aren't scans or anything, just iphone snapshots of the prints).

Media added by Milpool

www.photrio.com

 

[Autonerd]

Shoot at box speed, but don't push or pull. Keep things simple.

That's basically what I said to the Reddit OP. But in a *lot* more words.

 

[BrianShaw]

There's a bit of history involved but the ISO speed criteria are rooted in print quality. It's based on the minimum shadow exposure for excellent quality, not the minimum exposure to get an acceptable image.

It began with a lot of work on what constitutes an excellent print (see L. A. Jones) which led to print judgement speeds. It turned out for the "first excellent print" negatives there was a relationship between the shadow contrast and the overall contrast (see fractional gradient). Since the fractional gradient speed was cumbersome to measure directly, later work on methods of estimating this speed led to the Delta-X criterion, which is built-in to the ISO criteria.

Thanks very much for the correction and the education!

 

[Paul Howell]

The idea of box speed being carved in stone is not what Kodak, ILford, Agfa, or going back the way back machine GAF or Defender ever said. All said that the posted film speed was a starting point adjust as needed. Looking at Foma's posted data sheet for 400 and 100 only get to box speed with high energy developers like Microphen. Foma 200 a hybrid of traditional and T gain does a better job of getting to box speed with most developers. Tmax and Delta 3200 seems to best out at 1600 to 1200 ISO, but ILford and Kodak DX codes for 3200, they intend their 3200 speed films to be push. Although with DDX or Tmax developer you can get closer to 3200 than with other developers. When I was a working PJist I favored high flm speed, TrixX at 400, pushed to 600 to 800 was common. For news I sacrifed shadow detail for speed. On the other hand fine arts photoogs like AA who hated dark empty shadows and often sacrfited speed for shadow detail. What is best, what ever work for you.

 

[Slixtiesix]

Many years ago I read Barry Thornton's essay on the "No-Zone System". He explained at length that you usually need to overexpose BW negative film, because the vast majority of films do not reach the box speed, as advertised by the manufacturer, and therefore would turn out underexposed if used at box speed. According to Thornton, a slight overexposure (which technically is the correct exposure), will lead to better tonality and finer grain.