S
Stelios
Guest
Simple question. Trying to achieve more contrast on my negatives, what are the benefits from either way. More time or more aggitation? (note: talking about 135 film)
Longer development time vs more aggitation
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Roger Hicks
Veteran
Dear Stelios,
More agitation = more true (ISO) speed but less acutance, though both effects are often less important than some would have you believe. Some also say that more agitation = bigger grain but there are conflicting opinions on this.
Cheers,
R.
More agitation = more true (ISO) speed but less acutance, though both effects are often less important than some would have you believe. Some also say that more agitation = bigger grain but there are conflicting opinions on this.
Cheers,
R.
S
Stelios
Guest
Cheers Roger.
So I'll get similar results with either way?
As far as I know more developing will result in more grain too...
So I'll get similar results with either way?
As far as I know more developing will result in more grain too...
Roger Hicks
Veteran
Dear Stelios,
Yes, it's pretty much the same either way, except that increasing contrast through agitation = more speed/less sharpness, while increasing it through time = less speed (at a given contrast) + more sharpness. As I say, on grain, opinions differ. Probably depends on the film/dev combination and on exposure.
Cheers,
R.
Yes, it's pretty much the same either way, except that increasing contrast through agitation = more speed/less sharpness, while increasing it through time = less speed (at a given contrast) + more sharpness. As I say, on grain, opinions differ. Probably depends on the film/dev combination and on exposure.
Cheers,
R.
S
Stelios
Guest
Thanks!
cheers
Stelios
cheers
Stelios
wallace
Well-known
I think that you get better control with changing times than with more or less agitation.
wallace
wallace
Finder
Veteran
Agitation is to simply keep fresh developer in contact with the emulsion. When the developer is exhausted at one site, development stops. Agitation replaces that developer. Development times are related to the period of agitation, so increased agitation will have the effect of increased contrast.
Development is a rate process and so increasing development time will add more density to areas that have received more exposure--as long as the developer is active, hence the reason to agitate. Development time effects highlights at a greater rate than the shadow resulting in increased contrast.
The question would be why you are adding contrast? If you are trying to compensate for underexposure, then making better exposures is your answer. If you are trying to compensate for low-contrast subjects, then development time is a better solution as it is easier to control (I can increase development by 20% and understand the change to the film contrast/gamma, but what is increasing agitation by 20%?)
Film speed is a specific density above base plus fog. It is achieved base on exposure AND development--and it is only "true" based on a process.
BTW, density, in the case of having your negatives too dense, is a probably the biggest factor is granularity and sharpness. Really understand your process. If you are trying to compensate for underexposure through development, you will not get the best out of your negatives. Figure out your personal E.I. Things like lens transmission, shutter efficiency, shutter inaccuracy, and operator error (even consistent operator error) can cause incorrect exposures. You should also be matching your contrast to the output, either a paper grade (or range of grades in case of Multi-grade) or scanner response if you are scanning.
What exactly are you trying to do or solve by increasing film contrast?
Development is a rate process and so increasing development time will add more density to areas that have received more exposure--as long as the developer is active, hence the reason to agitate. Development time effects highlights at a greater rate than the shadow resulting in increased contrast.
The question would be why you are adding contrast? If you are trying to compensate for underexposure, then making better exposures is your answer. If you are trying to compensate for low-contrast subjects, then development time is a better solution as it is easier to control (I can increase development by 20% and understand the change to the film contrast/gamma, but what is increasing agitation by 20%?)
Film speed is a specific density above base plus fog. It is achieved base on exposure AND development--and it is only "true" based on a process.
BTW, density, in the case of having your negatives too dense, is a probably the biggest factor is granularity and sharpness. Really understand your process. If you are trying to compensate for underexposure through development, you will not get the best out of your negatives. Figure out your personal E.I. Things like lens transmission, shutter efficiency, shutter inaccuracy, and operator error (even consistent operator error) can cause incorrect exposures. You should also be matching your contrast to the output, either a paper grade (or range of grades in case of Multi-grade) or scanner response if you are scanning.
What exactly are you trying to do or solve by increasing film contrast?
katcons
Established
Maybe a more relevant variable in talking about contrast would be the developer used?
Juan Valdenebro
Truth is beauty
In general, extending development time is stronger for contrast than more agitation.
But some developers give a film a more straight curve, and some others an S shape curve, so with the former ones you gain contrast easily when extending times, and with the latter ones that contrast compensation effect is not that intense...
When I was a student, for the first two years the use of HP5+ and ID-11 was mandatory, so we could learn to vary contrast changing developing time. Tri-X in Rodinal (1+50, 18ºC) is a more forgiving combo: less sensitive... But the only thing that really matters, is your own testing. It's easy, fast and reliable. All films and developers work, so pick one and one, and use them until you know how to use them on sunny and overcast days...
Cheers,
Juan
But some developers give a film a more straight curve, and some others an S shape curve, so with the former ones you gain contrast easily when extending times, and with the latter ones that contrast compensation effect is not that intense...
When I was a student, for the first two years the use of HP5+ and ID-11 was mandatory, so we could learn to vary contrast changing developing time. Tri-X in Rodinal (1+50, 18ºC) is a more forgiving combo: less sensitive... But the only thing that really matters, is your own testing. It's easy, fast and reliable. All films and developers work, so pick one and one, and use them until you know how to use them on sunny and overcast days...
Cheers,
Juan
Roger Hicks
Veteran
Very true. I was assuming that this was a change in standard development, to get the contrast right for 'normal' printing. I'd certainly use time, rather than agitation, as the variable if I already had negatives I was happy with.
As an aside, very few shutters run fast, so this tends to increase the effective EI. I have one Pentax SV where the shutter runs a stop slow across most of the range. And of course, leaf shutter efficiency varies with aperture.
Cheers,
R.
Roger Hicks
Veteran
Not really. Any dev will deliver a wide range of contrasts with variation in time/agitation/temperature. Sure, there are low-contrast devs (POTA, D23, D25) and high-contrast devs (D19) but in the middle ground (D76, ID11, DDX, Microphen, Perceptol, Xtol, FX39) it shouldn't matter that much.
Cheers,
R.
charjohncarter
Veteran
As Finder says: agitation is to keep developer from being exhausted in areas on the negative that are highly exposed. Agitation can also be skillfully used to control the amount of development of these highly exposed areas. Ansel Adams used HC-110 (1:120) and reduced to length of time between agitations to achieve highlight compensation. This method still allows the shadows and midtones to develop fully. But you want to increase contrast not compress it.
Juan Valdenebro
Truth is beauty
Although agitation can of course affect contrast because of highlights density, we can't use agitation only to use a film for different light situations: a deep gray overcast day and midday harsh sunlight on snow... It's developing time what we use.
Cheers,
Juan
Cheers,
Juan
S
Stelios
Guest
plenty of answers! thanks everyone. I guess I should make clear that I am using Rodinal 1+50 for TriX (mostly, some Neopans and FP4 here and there) and I simply wanted to have contrastier negatives to print on grade 3 or less. I like to have the option of more contrast with grade 4 and 5. That is off course subjective. At first I tried aggitating (inverting to be precise) more. Used to be 3 inversions every 30secs, then I tried to double this by 6 inversions per 30secs. My standard time would be 15mins on 20C. This all is just a test, I might go back to 3 inversions per 30secs. Or I could just try Rodinal in 1+25. I just wanted your opinion on aggitation vs extending time. Thank you for all your answers, this is quite helpfull.
Juan Valdenebro
Truth is beauty
With Rodinal 1+50 you'll be able to do it... Develop for some more minutes... If you did 15, try 18 or 20... I use Rodinal 1+50 from 6 to 60 minutes for different films and light situations...
Cheers,
Juan
Cheers,
Juan
charjohncarter
Veteran
I agree when it all is boiled away longer development time is the easiest and most controlled way to increase contrast.
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