How to develop when exposed at "nominal sensitivity"?

MehmetCati · 2006-07-12T13:51:39+00:00

Hallo! Hier nun mal wieder eine Anfängerfrage von mir: Wenn ein 400 ISO Film laut versch. Angaben eine tatsächliche Empfindlichkeit von 320 ISO aufweist un...

MehmetCati

Hello! Here’s another beginner’s question from me: If, according to various sources, a 400 ISO film has an actual speed of 320 ISO and I therefore expose it at 320 ISO, should I use the standard development times for 400 ISO, or do I need to adjust the development time accordingly? :) So, generally speaking: if I perform the film exposure ‘correctly’, do I also need to use a different development time than during the exposure at 400 ISO? Since many developers always provide guidelines for 400 ISO, how do I get a rough idea of a development time if I’m actually performing exposure at 320 ISO or even just 200? Thanks in advance for the answers (even if my naive beginner’s question might be a bit of a nuisance...). Regards, Mehmet

max

Hi Mehmet, Ah, the expert opinions. In my experience, the manufacturer’s specifications for speed are usually more reliable than those for development. That makes sense, really – there are more individual variables involved in development, from the accuracy of your measuring equipment to temperature consistency and water level. (Not to mention the requirement for density in Zone I) Consequently, all the claims about ‘always performing exposure on HP5 at 320 ISO’ are of no use whatsoever on their own, but only in the context of which developer, what time/temperature, and what kind of subjects. Option 1: Plough through the Zone System; it’s all explained there. Alternative 2: the old rules of thumb, such as: -A negative that’s too hard has been developed for too long; one that’s too soft for too short a time. -No shadow detail (on an otherwise good negative) means it has underexposure; blown-out highlights (on an otherwise good negative) mean it has overexposure. What follows as a concrete answer to your question? If you have normal subjects, use the standard development time (for normal gradient). You’ll then get better shadow detail with overexposure (at the expense of a little headroom in the highlights). For high-contrast subjects (glaring light and dark shadows), develop for a shorter time; this compresses the subject’s contrast and is known as ‘N-1’ in Adams’ method. Overexposure has no place with low-contrast subjects. Regards Martin

MehmetCati

Hi Max! First of all, thanks for your detailed reply. I haven’t looked into the zone system at all yet, but I do have two of Adams’ books (The Negative / The Print) on my shelf in their original English editions. They’re really the only unread books I have... :-)) So I suppose I really ought to get round to reading ‘The Negative’... I started developing my own film about a year ago, give or take. I then faffed about for two or three months and have only just started trying things out again. It’s a bit of a shame, as it’s really too warm for the chemicals in summer and I find it easier to heat the chemicals to 20 degrees than to cool them down. For whatever reason... So far, I’ve always performed the exposure on all the films I’ve tried using the ‘printed’ speed and then experimented extensively with different developers, dilutions and times. I’ve pushed the odd AdOX or Ilford now and then, but that’s about it. Just as you say, I then read that the AdOX 400 chm actually has an ISO of 320. It would also make sense to adjust the exposure for the Lucky 400 to 320 instead of 400. In the meantime, I’ve accumulated about 24 Lucky and ADOX films rated at 320 ISO, and I thought I’d develop them this weekend to see what all the fuss is about with these specifications. (Oh yes, I’ve also performed exposure on a few Lucky rolls at 200 ISO) So I thought to myself (I’ve now become quite fixated on Calbe’s A49) that if I can manage the ADOX 400 chm in 9–10 minutes in A49, what would be a good benchmark for 320 ISO that I could use as a guide? That was actually the basic idea behind my question. The developers I’ve mainly been experimenting with so far are: Rodinal LP-Supergrain Emofin A49 D76 Microphen AM-74

What is the specific answer to your question? If you have normal subjects, use the standard development time (for normal gradient). Overexposure will then give you better shadow detail (at the expense of a little headroom in the highlights). For high-contrast subjects (glaring light and dark shadows), develop for a shorter time; this flattens the contrast and is known as ‘N-1’ in Adams’ terminology. For low-contrast subjects, overexposure has no place. Regards, Martin

So I’ll develop using my usual times, which I was happy with at 400 ISO, and see what the results are like with the 320 and 200 films? And the next time I take photos (in similar ‘photographic’ situations), I’ll consider whether I want better shadow detail, for example, and then perform the exposure at 320 ISO

In my experience, the manufacturer’s specifications for speed are usually more reliable than those for development.

Otherwise, I’d rather stick to the ‘printed’ sensitivities and keep experimenting with shorter/longer development times and different dilutions? So the whole ‘actual sensitivity’ of the films is rather nonsense in practice? Purely theoretically, what would actually happen if I exposed an Adox 400 chm at 100 ISO and then developed it according to the times specified for an Adox 100 chm? The same as with an Adox 100 chm? Well then KEEP GOING Mehmet

max

Hi Mehmet, You could also say that the Zone System is a photo lab for accountants ;-).

So I’ll develop using my usual settings, which I was happy with at ISO 400, and see what happens with the ISO 320 and 200 films?

Exactly. Definitely for the 320s. That way, in the worst-case scenario, you’ll get negatives that print well with blown-out highlights (if the sky lacks detail, there’s still 1000 and a bit of headroom). If the 320s turn out well, I’d treat the 200s the same way.

So the whole ‘actual speed’ of the films is pretty much nonsense in practice?

No, and no. 1. For the Zonis, most of them actually want a negative density of 0.15 (+base & fog) in Zone I, i.e. 4 stops below mid-grey, which has certainly proven its worth in practice; the industry usually rates it at 0.1 based on slightly different criteria. 2. For everyone else, it has turned out that the rule of thumb ‘expose for the shadows, develop for the highlights’ isn’t so easy to put into practice, at least with automatic exposure (how did that go again? Place deep shadows in the metering area, press AE lock, and then achieve underexposure by 3 or 4 stops?!?!?!?!?), so it’s more practical to allow a range of 1/2 (that would be 320) to 1 (200) stops in the shadows and just get on with taking the shots. As long as you have a normal subject contrast between 1:30 (5 stops) and 1:100 (7 stops), it’s all fine. Most development specifications are, in fact, already designed for a reasonable gradient. Whether the overall density is slightly higher or lower makes no difference in practice. Mind you, as long as you can print your negatives well, the development is fine. You only need to shorten the time if you’re constantly faffing about on paper between 00 and 1, and still not getting any nice grey tones. As an online alternative to the negative and in short form, I’d recommend the following: http://www.schwarzweiss-magazin.de/swmag_frame_kurse.htm – specifically, for those in a real hurry, courses 3, 4 and 5 from Part 3. These are more realistic for 35mm practitioners than Part 2. A brief digression on the creative side: I was personally quite astonished at how fussy I became about contrast when I started printing myself. I certainly don’t take those “beautiful old town pictures” in bright sunshine anymore (it’s great light for photography, after all), because no film (not B&W, not colour, and not digital either) can capture the town hall door in the shade properly if the main subject in front of it is also supposed to be recognisable in the sun (yes, I know about exposure bracketing and Photoshop). I’d rather wait until the “Hamburg softbox” (a cloud in front of the sun) arrives – it’s amazing what becomes possible all of a sudden. Best regards, Martin

MehmetCati

Hi Martin! (Sorry, I called you ‘Max’ earlier) First of all, many thanks for your comments. Your link in particular looks very helpful to me. I’ll have to print it out straight away and read it as bedtime reading. Up until just now, I’ve developed six rolls of 320 film, using my tried-and-tested 400 ISO settings. Somehow, the negatives don’t seem to have turned out that great in comparison; they don’t really ‘jump out’ at me like the comparable ones. I really must print them to see what I can actually get out of them. I find it very difficult to judge the negatives on their own. Well, somehow I have the feeling that I still have a lot of theory to read up on. If the prints don’t really convince me, then I have to say that I’m really happy with the specified speeds.

2. For everyone else, it turns out that the rule of thumb "expose for the shadows, develop for the highlights"

is something I’m completely unfamiliar with! I’ll make a note of that and give it a go.

As long as you have a normal subject contrast between 1:30 (5 stops) and 1:100 (7 stops), it’s no problem at all. Most development specifications are actually already designed for a reasonable gradient. Whether the overall density is slightly higher or lower makes no difference in practice.

I reckon so too now. So Martin, thanks again. I think your post is really great. It’s really helped me out. Otherwise KEEP IT UP Mehmet

fotohuisrovo

A clear explanation, even for beginners.

The developers I’ve mainly been experimenting with so far are: Rodinal LP-Supergrain Emofin A49 D76 Microphen AM-74

Although it’s worth noting that LP-Supergrain and AM-74 are the same thing. So that saves a bit on testing costs. Best regards, Robert

max

Hi Mehmet

Sorry, I called you Max earlier

No problem, that’s the advantage of having several first names. One last thing, because this is very often cited as a successful standard procedure: Forum user x: “I always expose film xxx by one stop and shorten the development time by yyy.” Of course, I don’t know the specifics of how other people develop their optimal processes. However, this approach suggests that forum user x frequently photographs high-contrast subjects and is frustrated that even at gradient 0 they are still not optimally printable, whilst medium-contrast subjects remain printable even when underdeveloped at gradients 3–5. This is generally typical of people who head out with their camera in fine weather (sunny), or for whatever reason do not want to or cannot wait for the right light (holidaying in the Mediterranean, and the sightseeing tour continues), and so naturally this is exactly the right approach (and in line with what I wrote above). Regards Martin