I don't really understand...

[max_barstow]

<p>Hi,<br>

Have been developing my films for a few months now, and I'm finally getting some results which I quite like (using HP5+ and Rodinal), but I don't really understand what the importance of agitation is, other than for making sure you get an evenly developed film.<br>

What I'm getting at, is why do people bother with different agitation methods, or why couldn't you just shake the canister vigorously for the whole developement time?<br>

Thanks</p>

[evan_goulet]

<p>Agitation brings fresh developer to the film faster than waiting for diffusion alone to deliver it. If you used constant agitation you would lose a lot of control over contrast, and your development times would be significantly shorter. </p>

<p>On highlights in particular, the developer is locally depleted which slows development in those areas. Agitation brings the fresh developer back to the highlights and continues development at a rapid pace. So highlights would have a tendency to overdevelop, and shadows would not have a chance to sufficiently develop.</p>

[max_barstow]

<p>So if you didn't agitate you'd get a very contrasty image?<br>

And how do people work out what kinds of agitation give certain results?</p>

[leicaglow]

<p>I would only add to Evan's excellent explanation by saying that refreshing the developer not only keeps the developer process moving forward by replacing exhausted developer with fresh, but also prevents uneven development from pockets of fresh and exhausted developer. Lack of agitation, and the resulting combination of exhausted and fresh developer, can also cause bromide drag, an uneven streaking causing areas of lower and higher densities. In extreme cases, another effect can occur: Mackie lines. These are areas where the bromide drag is pronounced between the edge of two adjacent high contrast areas. The appearance is a double line and you would see this on edges of power lines, poles, buildings, tree trunks or other sharply defined objects against a bright sky, for example.</p>

[lex_jenkins]

<p>The main purpose of agitation is to ensure consistent results. Agitation provides a flow of fresh chemistry to the emulsion.</p>

<p>Generally speaking increased agitation speeds up the development process while achieving the same results. Continuous agitation requires the shortest development time; intermittent agitation requires longer development time to achieve the same results. "Stand development", a specialized technique in which little or no agitation is used, takes the most time and risks uneven or inconsistent results.</p>

<p>Complicating issues such as contrast or "compensation" are loosely related to agitation, but depend on other factors as well, including the type of developer used.</p>

[max_barstow]

<p>Okay. So if I do HP5 for 6mins in Rodinal 1+25, constant agitation for 1 min, then 10 secs in every 30 secs after that, is that gonna be a lot of development or what? Thanks for the help.</p>

[walter_degroot]

<p>i think the issue has been well explained above.<br>

but 2 other factors can affect results.<br>

years ago a strong and concentrated developer was used , Like straight d-76.<br>

more recently d-76 ( as an example) has been used 1:1 or 2:1,.<br>

this changes the effect and gives somewhat different results.<br>

Those who go too far and dilute the developer TOO much to save money. will get poor results. the developer may be too little to properly or fully develop the film. ( similar to trying to develop 2 or 3 rolls of film in the same mix of developer)<br>

A mixed bath that was intended as a ONE SHOT.. this is a false economy.</p>

<p>the other factor is "air bells" even if you use a "stand" type of develoment, it is important to bang the tank on the table once or twice to dislodge these bubbles.</p>

[yann1]

<p>Not really the topic, but why HP5 in Rodinal ? There are better developper for this film such as HC110, DDX, ID11 ... Rodinal is for slow films.</p>

[janne_moren]

<p>The way I understand this (and please correct me if I'm wrong here):</p>

<p>You have a sensitivity curve for the film, from just where the film starts to react to light, up to where it completely saturates.</p>

<ul>

<li>Your exposure determines where the darkest part of the image starts on the low end of the curve. </li>

<li>Your development time will determine the slope of the curve; the longer ou develop the steeper the slope and thus the higher your contrast as your lightest areas approach the saturation point. </li>

<li>Agitation works as a gamma setting. Little agitation gives you low gamma and thus a lot of midtones with little shadow or highlights. Lots of agitation gives you a high gamma setting, with most parts of the image in the shadow or highlight areas and very little in the midtones. Where the transfer point is set is determined by the development time. </li>

<li>Dilution - I think, I haven't tested this - effectively sets the low end of the possible gamma when you have no agitation.</li>

</ul>

<p>Again, this is just my interpretation; not sure how correct it is, but this mental model has helped me get what I'm doing so far at least.</p>

 

[paul_hoyt]

<p>The other problem with constant agitation, when developing roll film on reels, is the developer starts to swirl around the edges of the reels and the development is not even; you will see a density gradient from the edges towards the center of the film. "<em>So if you didn't agitate you'd get a very contrasty image?</em>". Just the opposite, a very flat negative.<br>

Your first minute of agitation is getting the film wet with the developer. If you presoak your film, the first minute is getting the developer to replace the water in the emulsion. The 5 second shake or 10 second shake replenishes the developer where it may have exhausted in the high densities. What is important is you need to be consistent in the agitation scheme. If you find your negatives are consistently thin, increase your development time, keeping the same agitation scheme. If they are consistently have too much contrast, reduce the development time. If you do not keep to a consistent routine of agitation (how you agitate and how long) it will be very difficult to solve negative problems.</p>

<p>Paul</p>

[chris_waller]

<p>I often use HP5 and Rodinal, but I use it at 1:50 to give me longer development times and thus more precise control. It also gives me a little extra compensation, i.e it holds back highlight development, due to developer exhaustion, while allowing the shadow areas to develop (for the reasons which Evan explained).<br>

I give the tank 6 inversions in the first 30 seconds then one inversion every 30 seconds after that. The important thing is to stick to a strict agitation regime. It's every bit as important as temperature and dilution.</p>

[max_barstow]

<p>What is the point of presoaking film? Also, on that matter, the water from the taps has chemical residues in it, so is that an issue?</p>

<p>I rather like the grain I'm getting with the HP5 and Rodinal. It's kind of soft, quite a bit of it.<br>

Would you get less grain at 1:50? Also, if you're halving the amount of developer in relation to water, does that mean you'll need to double the developing time, or is it not so simple?</p>

[lex_jenkins]

<blockquote>What is the point of presoaking film?</blockquote>

<p>Prepare for a long session of bone-gnawing. We darkroom dogs love to chew on this bone.</p>

<p>Pre-soaking serves almost no point at all that applies to most of us under typical conditions. This practice tends to confuse a lot of folks new to the darkroom.</p>

<p>In fact, Ilford specifically recommends against pre-soaking their films under most circumstances.</p>

<p>Pre-soaking is a throwback practice to the days of processing large format sheet film in open trays for very short development times. Very short development times, often less than five minutes with sheet film in open trays, could potentially lead to uneven development. The pre-soak was believed to make the emulsion more receptive to even absorption of developer.</p>

<p>This may have had some validity for this specific usage with older films, and even with some currently available films made to duplicate those older emulsions. But Ilford, Kodak and most other contemporary films do not need this step. Years ago Ilford reported that an ingredient was added to their emulsions to aid in rapid, even absorption of developer, so the pre-soak served no purpose and might actually interfere with even development.</p>

<p>Another common reason to presoak is to get rid of the water soluble dyes used in some films (typically anti-halation and sensitizing dyes). For some reason some photographers are bothered by these dyes, altho' there is no evidence to indicate the presence of dyes during development interferes in any way with processing. However, some folks recycle their developers and don't want discolored developer. That's a valid enough reason.</p>

<p>Other photographers worry about slightly tinted negatives and go to extreme lengths to get neutral gray negatives. There's no evidence that slightly tinted negatives interferes with printing, but it bothers a lot of folks. So they use pre-soaks, aggressive agitation, extended fixing, two or more fixing baths, hypo clearing agent and other tricks to get rid of the dyes.</p>

<p>Rodinal tends to strip out dyes more readily than most developers. And it's a one-shot use developer. So this negates either of the usual reasons given for pre-soaking.</p>

<p>However, if you intend to experiment with highly concentrated Rodinal solutions for development times shorter than five minutes, a pre-soak *might* offer some advantages with certain films (other than Ilford). However, to minimize variables it's also necessary to pre-fill the tank, use hangers/lifters to place the reels into the tank and remove them, because pour times will lead to inconsistencies with very short development times. So with roll film development it's necessary to mimic open tray development as closely as possible to completely immerse the film in, and remove it from, the developer as quickly and smoothly as possible.</p>

<p>If you're using 35mm or medium format film (especially Ilford) and one-shot developers, with development times longer than five minutes, pre-soaking serves almost no demonstrable purpose. It's darkroom voodoo, like stand development, push processing, "compensation effect" and many other bones which you too may eventually enjoy chewing on.</p>

[chris_waller]

<p>OK, I'll rise to this one. I am a pre-soaker. I accept what Lex says, that its benefits may be marginal and maybe little more than voodoo. I used to have an occasional problem with uneven development and bromide streaking. I started pre-soaking many years ago on the advice of a knowledgeable other and I have never had a problem since, so I continue to pre-soak. I use Ilford films almost exclusively and am aware of their advice on pre-soaking. OK, it's voodoo but it keeps me happy.<br>

On your other question, yes, if the developer is more dilute then you need to develop for longer - there is a table in the info leaflet with the Rodinal bottle that gives the times at different dilutions. On the new production the label on the bottle peels back to reveal the information.<br>

As to whether it gives less grain, that's a moot point. I use the higher dilution because I typically downrate HP5 to 160 ASA. Any reduction in grain is due to the reduced development.</p>

[max_barstow]

<p>Sorry, what's a one-shot use developer?</p>

<p>My bottle doesn't have times for HP5 at 1+50, only at 1+25.</p>

<p>When you rate a film's ASA differently to the factory default, if you set it higher, that doesn't actually change the film in any way, but the metering instead?<br>

And what's the point of downrating, getting longer exposures? Couldn't you just over-expose it at 400 ASA?</p>

[chris_waller]

<p>One-shot develoeprs are those which are diluted, used to develop the film, then poured down the drain. Some developers are reused, increasing the development time for each subsequent film to allow for the gradual loss of activity. Some developers can be replenished by adding fresh developer.<br>

Film is downrated to change the contrast of the negative. One gives more exposure, then reduces development. The net result is a neg of lower contrast. It's a useful technique when the light is very bright and contrasty.</p>

[kari v]

<p>"And what's the point of downrating, getting longer exposures? Couldn't you just over-expose it at 400 ASA?"</p>

<p>Metering at ISO 200 is the same as "overexposing" ISO 400 by one stop. Take your pick. ;)<br>

You can shoot HP5+ at 200-1600 and get good results by adjusting development. 3200 is certainly doable but getting into pushing your luck territory. Depends on the lighting conditions.</p>

[max_barstow]

<p>I presume a stop is one bar on a light-meter?</p>

<p>How can you work out (roughly) how much developing time to add as ISO goes up (lets say every 100) to get a similiar look to that which you get at 400? That's probably badly phrased...<br>

And do you get more grain if you change the ISO so it's higher?</p>

[martial_baribault1]

<p>Presoak was really to prepare old emulsion to developpment as many of them could not even take water you could litterally roll a drop of water on it without really wetting it.It was set to prevent air bubbles from forming on film wich would end with an undevelopped spot. Following manufacturer recommendations is always the best policy for optimum results.Films have evolved and so is processing them and if manufacturer has new processing recommendations, you should follow them as, in the end, they want optimum results to be attained with their products and as easy as possible. I don't think anybody would use ASA3200 at ASA64 just because 50 years ago it was almost the only film speed available.<br>

I won't pass under silence that repeatability is achieved by standardized procedures wich includes time/temperature/agitation. differences between a film developped in winter darkroom and summer ones can be quite high resulting in dramatic shifts in speed & contrast.A good agitation comes regularly at least every 30 seconds (15 is better)and shall include reversing the tank if possible. if you use a rod and lift ,rotate the rod while lifting. It should be smooth yet happily disturb chemistry and prevent flow pattern wich is the reason why reverse agitation is so good . violent constant agitation never helped much except in the heydey of rushing in the press room to get that photo on the deadline, it wasn't pretty but it was there, It never won yearly contest but it won the day.I personally never really liked those but all the Paper peoples were happy.I still remember printing wet negatives half fixed(just cleared ) to meet that deadline.Longer fixing & washing were for ...after the latter had been achieved.</p>

[max_barstow]

<p>Thanks so much for all the help, really is useful :)</p>

[dweezil]

<p>I've done the test a few months ago with exactly this combo (Hp5 + rodinal).<br>

What I did was shoot 4 rolls of this from the same still life and the all of the films developed them in rodinal 1+25 for 6 min.<br>

One roll without agitation, the second one with 6 min continious agitation (jobo), the third one was done using my regular agitation scheme: 30 sec continious then 10 sec every minute, and a 4 th one with a random agitation scheme.<br>

I can not see any difference between the regular and random scheme and very little with the continious agitation. That last one is slightly more contrasted.<br>

The stand developped film was under developped. What I can say about this is that agitation does matter up to a point. The most important is the amount of agitation. How you agitate, the movement, the intervals don't count as much.</p>

[loren_sattler]

<p>I presoak for reasons not mentioned so far; to maintain consisten processing temperatures. I have gotten in the habit of reading the temperature of the developer coming out of the 35mm or 120 tank after development. The difference between summer and winter is significant due to room temperature. During processing, I leave the tank in a tray of water at 68 degrees. An 8 x 10 tray is not very deep. Presoaking makes it easier to control the tank temperature especially tall multiple reel tanks.</p>

[max_barstow]

<p>This is something which has had me confused. The place where I got all my chemicals, developing tank etc. said that it only mattered what temperature the developer went in at, not what its constant temperature was.<br>

Surely the temperature of the water (in both the presoak and the tray) will also change? Isn't there some very accurate way of controlling this? Or does it not really matter too much?</p>