Agitation, dev. time impact - a little confusion..

[alexz]

Well, I had my point of view on these as what influence/control what during development, but recently begun to doubt myself.
So, as per my understanding and largely due to my understanding of "expose for shadows, develop for highlights" (for negative) saying, I assumed the once during development, first shadows are processed by the solution then it comes to highlights, hence shadows can hardly be controlled during development at all (because occur at the beginning of the process), while varying dev. time we can control highlights.
Am I wrong ? Should it be just opposite ?

Another confusion of mine: agitation. I used to consider agitation control as an additional tool for subtle contrast control tool, for highlights in particular. I.e. if I expect highlights might be critical due to particular shooting conditions, I tend to approach more moderate agitation (aside of considering to reduce dev. time).
However, in some other thread I was advised to consider somewhat increasing agitation regime in order to improve shadow details.

Anybody would care to elaborate ?

Thanks in advance, Alex

 

[Roger Hicks]

Dear Alex,

Highlights (densest part of neg) develop first. More development brings out more shadow detail. If the shadow detail is too thin, you need to over-develop, thus leading to excessive contrast. Therefore you expose generously ('for the shadows') and develop so that the highlights don't get too dense ('for the highlights').

More agitation will always give you more shadow detail for a given contrast.

All of the above can be verified experimentally, i.e. it is solid sensitometry, not opinion.

Hope this helps.

Cheers,

R.

 

[alexz]

Thank you Roger, have no reason not to believe you, but that confuses me even more...
In one of my previous threads I referred to my recent stint with Microphen pushing Tri-X to 1600. I begun with certain dev. time taking Massive Dev. chart as the base time to start with. Came out with severely blown out highlights and nearly blocked shadows. I begun to reduce development time (trying to keep agitation regime the same) gradually moving through another 2-3 attempts until reducing dev. time by 15-20% yielded much more pleasing highlights and reasonable contrast (yet opening up shadows a bit more wouldn't hurt either).
So that I assumed that shorter dev. times restrains highlights, but since shadows get developed first (as I thought), not much can be done to save them but the actual exposure.

Now, according to what I gather from your explanation, one needs to be large on exposure in order to be able to use reasonable short dev. times thereby keeping overall contrast under control. Did I get it right ?
If so, there is very little control on highlights because tey get developed at the beginning...
Or I'm getting lost even more ???

 

[Pherdinand]

The highlights, or the shadows, they don't "get developed at the beginning". Development continues until you take the film out of the developer.
Highlights develop faster than shadows. If you double the development time, as a simple example, the shadows do not get twice as bright, but the highlight gets many times brighter.
Trust Roger on this.
It is not linear.

This is why pushing film will increase contrast - the highlights develop much stronger, while the shadows only develop a little bit more.

there are exceptions, like using diafine, where development stops when the solution A component is used up completely in the film, thus contrast does not increase with prolonged development time.

Agitation increases contrast as well, since fresh chemicals come into contact with the film speeding up development. This is why with very high contrast film e.g. technical pan you are not supposed to agitate during development.

 

[Roger Hicks]

Now, according to what I gather from your explanation, one needs to be large on exposure in order to be able to use reasonable short dev. times thereby keeping overall contrast under control. Did I get it right ?

If so, there is very little control on highlights because tey get developed at the beginning...

For the first para, spot on. Take a look at

http://www.rogerandfrances.com/photoschool/ps iso speeds.html

For the second, you seem to be forgetting that development is a continuous process. You control how much the film is developed (both shadows and highlights) by increasing and or all of (a) dev concentration (b) temperature (c) time (d) agitation.

Cutting any of the above will give less density and less contrast, but for constant contrast, you will get slightly more toe speed with more agitation and less time. How much more will depend on the film and developer.

Overall, your aim is to develop for long enough to get adequate shadow detail ('expose for the shadows') without excessive contrast ('develop for the highlights').

This is why Tri-X at EI (NOT ISO) 1600 is a problem except with very low-contrast subjects. You'd get more shadow detail and less contrast with a faster film such as Delta 3200 (true max ISO 1250, contrast doesn't build too badly until EI 2500-5000 and may still be tolerable at EI 10,000+).

You may also find this useful:

http://www.rogerandfrances.com/photoschool/ps neg density.html

Cheers,

R.

 

[alexz]

Thank you guys, now that slowly appears to get into my mind.
You both caught me on that fact that I forgot that developing process is a continuous one and usually progresses all the time the chemicals are in. Now, shorter dev. time (given constant temp. and agitation approaches) will keep the highlights from blowing out while being just enough to open up the shadows if the film has been exposed properly (for shadows).
That indeed makes sense.
Besides, that also warrants the fact that increased agitation contributes to shadows allowing shadows details to open up while avoiding stretching dev. time.

Thank you a lot, that clarifies the issue.

 

[vdonovan]

This is a great thread, a very clear and sensible discussion.

 

[charjohncarter]

This subject has fasinated me, and I can never find an answer; so thanks Roger and Pherdinand. I had read someplace that agitation controls contrast, but in my experience if it does, it is minor. It seems to me you get the same contrast increase by just developing longer. If I'm off the beam on this please tell me. Sometimes I think the only reason for agitation is to get even development. The stand effect does exist, but it doesn't seem to be useful in very many situations.

 

[Roger Hicks]

(1) I had read someplace that agitation controls contrast, but in my experience if it does, it is minor. It seems to me you get the same contrast increase by just developing longer. . . (2) Sometimes I think the only reason for agitation is to get even development.

Numbers added for clarity.

(1) Spot on, subject to the point that with more agitation and less time, you will get slightly more toe speed at a given contrast. It really is pretty slight: 1/3 stop would be good.

(2) That is the main reason. Yes, minimal agitation will give increased edge effects, but as with the speed/contrast balance, it is easy to overestimate or overstate their importance.

The big problem is that most photographers DO exaggerate quite small differences. Sometimes, yes, a subtle difference will lift a picture from good to great, or at least from mediocre to good; but a lot more often, it ensures that the picture remains mediocre because the photographer is so obsessed with technique that he forgets the aesthetic side. In other words, subtle technical differences are totally irrelevant next to the fact that it's a boring picture.

Cheers,

R.

 

[Quinn Porter]

This has been helpful. Thank you.

 

[Pherdinand]

your latest paragraph is so very true, Roger, that it hurts🙂

 

[charjohncarter]

Thanks for that Pherdinand, it does hurt. Once not too long ago, I decided to improve my technique for development etc to such a point that I could take a photo of a freeway and it would be an Ansel Adams. The problem was; I was somewhat satisfied (you are never completely satsified) with my technique, but the images were duds. I guess you need both, the love/soul side is more important.

 

[Tom A]

Sometimes I think pictures from those early days of photography have become famous, just because they survived! Technically perfect shots are nice, but there has to be "soul" there, otherwise all it is, is technically perfect photo! I like some of Ansel Adams shots, but not all, however perfect they are! Heresy, I know!
As for developing those pesky negs: I am a great proponent for split type developers, Diafine, Farbers D76 and Td 201. The advantage is that the volume of developer is very slight (around 5-6 ml/roll from the A bath) and it will exhaust itself in the highlights and keep them within "paper" tolerances. However, they are not very good for over/under exposed negs as there is not enough developer to correct for screw-ups!
Some of the modern "thin" emulsion films does not work well with this process as they simply do not absorb enough of the developer (A bath) to fully develop. The only one that I have found works consistently well with films like Tmax (both old and new), some of the Fuji (Presto 100) and the really slow EFKE/Adox 25 asa films, is the Td 201. Economical too - about 50 rolls in 2x2000ml (2000 ml A and 2000 ml B).
The Td 201 is in Anchell's "Film Developing Cook Book" - essential reading for bl/w shooters. You mix it yourself, but you also cut the cost per roll to $0,15. Fast too: 3 min in A and 3 min in B with continious agitation. Go to Flickr and type in Td 201 in the tag search and there are a lot of samples.

 

[kaiyen]

Roger - I would not have thought agitation could gain 1/3 of a stop in toe speed. That is quite remarkable. Wow.

(I re-read that and it sounds quasi-sarcastic. It's not - I am really surprised)

 

[Roger Hicks]

Roger - I would not have thought agitation could gain 1/3 of a stop in toe speed. That is quite remarkable. Wow.

(I re-read that and it sounds quasi-sarcastic. It's not - I am really surprised)

That's the most I can imagine as theoretically possible, with the right film/dev combination, not the most I've ever seen. No offence taken, and I'd be surprised too. All I was trying to do was give a ball-park figure. One-sixth stop, yes,fairly easily (anything less is experimental error). Or maybe 1/4 stop. But 1/3 stop, as you say...

Cheers,

R.

 

[kaiyen]

I'd be okay believing 1/6 of a stop 🙂

it's slight, regardless, and that would be an interesting and arduous task of balancing contrast control, agitation to keep fresh dev on the shadows/toe, and getting the overall time right. Does not sound like fun.

 

[Roger Hicks]

I'd be okay believing 1/6 of a stop 🙂

it's slight, regardless, and that would be an interesting and arduous task of balancing contrast control, agitation to keep fresh dev on the shadows/toe, and getting the overall time right. Does not sound like fun.

Bloody right, sport.

Long-toe film, high-energy developer... Maybe.

But as you say, is life long enough?

Cheers,

R.

 

[charjohncarter]

Thanks Tom A. and Kaiyen, but after thinking about Rogers 1/3 of a stop shadow density increase (for the last five hours), I'm thinking that isn't bad. I'd like that. My question is: is there a concomitant increase in highlight density?

 

[kaiyen]

Would you seriously work that hard to get the extra 1/3 stop in toe speed, which is only kind of related to film speed (you won't necessarily achieve actual increase in film speed just because you achieve increased toe speed - it might not reach into the shadows).

The reason why Roger and I are saying that life is too short is that, even if you lived to 100, the amount of effort required to get enough fresh developer over the shadow areas to get 1/3 of a stop (and 1/3 is kind of ridiculous) in the toe (and only at the beginning of the toe via agitation but still control contrast through timing would be...insane. And only viable if you are shooting sheet film or an entire roll - ENTIRE roll - at the same contrast range. Otherwise you'd never be able to accurately achieve that level of control to determine if you've hit it or not.

that's some serious effort.

 

[charjohncarter]

Ahh, Kaiyen if you are addressing me, I don't think I said I was willing to work hard. In fact, I have never worked hard. But if it was a matter or increasing shadow density with a couple of extra inversions during my regular development process then what the heck. If you had read my other posts you would see that I really don't think agitation does add much to shadow density that increased development time wouldn't. And I'm sure you will correct this and it is a small point, but you forgot to close your parenthesis.