How important is it to be accurate with development times?

This evening my sister gave me a roll of 120 film labelled HP5+ so I could process it for her.
I souped it in HC-110 dilution H for 10.5 minutes, agitating once a minute (standard practice for me).

It turned out to be Delta 400...and the negatives turned out absolutely fine. Not a problem.
I looked for dilution B on Massive Dev Chart, which says 7.5 minutes, and doubling that for dil. H would give 15 minutes...

So, to what extent is accuracy actually required when processing film? Was it to do with the dilution of my developer?

Check out the following site for information and times for HC-110 www.covingtoninnovations.com/hc110. If you want good results you must watch time and temperature closely. If you do your own printing this will be very helpful. Fewer test strips etc.

If your film was exposed EXACTLY the same and you develop it EXACTLY the same way, you get EXACTLY the same result.

But, a lot of things can happen in a photo shoot. Our shots aren't EXACTLY the same every time. Contrast range of the scene is different every time. So first off, you aren't dealing with identically exposed film, unless you are in a controlled environment and/or you are super careful with your exposure.

Then your developer... Dilution can be off a bit. Temperature may be off a bit. Agitation may be different a little.

The only thing you can really do is to do the best you can to be consistent.

Dilute it carefully and accurately.
Use the same thermometer every time.
Learn to agitate the same way every time.

Practically speaking....
I use D-76. My stock mixture may be fresh or 6 months old. My dilution may be 5 to 10% off. My agitation may be off by 10 seconds and may not be identical. I do use the same thermometer though.... I get the total development time to say within 10 to 15 second accurate.

This is good enough for me. Any variation, I can compensate at printing time.

I used to use water bath and maintain temp to +/- 0.5C. I used to be extremely accurate on timing including agitation.
It made no appreciable difference for me.

Thermometers can be off by a couple degrees easily, so use the same thermometer every time. Make sure the developer isn't dead. Other than that, I wouldn't worry too much.

I think I phrased the question wrongly: Does having a more dilute developer and therefore longer development times give a greater timing latitude?

I'm not familiar with Delta 400, so let's take HP5. I would develop for 5.25 minutes in dil. B, and 10.5 in dil. H. The difference of a quarter of a minute at dilution B can really change the negative, because HC-110 is so active. Is this effect lessened by greater dilution?

psychfunk said:

This evening my sister gave me a roll of 120 film labelled HP5+ so I could process it for her.
I souped it in HC-110 dilution H for 10.5 minutes, agitating once a minute (standard practice for me).

It turned out to be Delta 400...and the negatives turned out absolutely fine. Not a problem.
I looked for dilution B on Massive Dev Chart, which says 7.5 minutes, and doubling that for dil. H would give 15 minutes...

So, to what extent is accuracy actually required when processing film? Was it to do with the dilution of my developer?

Click to expand...

If you print on multigrade paper, or have an extensive range of graded paper on hand, there is like a 30% plus or minus leeway with development times. How much leeway you actually have depends on the scene's range and your usual paper grade.

Having your development time off 10 percent with dil. B will be pretty close to being off 10 percent with dil. H. 15 seconds off with dil. B is a much higher percentage of the total development time than 15 seconds with Dil. H., so the effect would be more noticeable with Dil. B.

ic-racer said:

If you print on multigrade paper, or have an extensive range of graded paper on hand, there is like a 30% plus or minus leeway with development times. How much leeway you actually have depends on the scene's range and your usual paper grade.

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This is the news I was looking for. Thanks all for your input.

psychfunk said:

I think I phrased the question wrongly: Does having a more dilute developer and therefore longer development times give a greater timing latitude?

I'm not familiar with Delta 400, so let's take HP5. I would develop for 5.25 minutes in dil. B, and 10.5 in dil. H. The difference of a quarter of a minute at dilution B can really change the negative, because HC-110 is so active. Is this effect lessened by greater dilution?

Click to expand...

psychfunk,

I enjoy development times 9-15 minutes in D-76 1:1 and would hesitate if the indicated development times were less than 5 minutes. At short development times you can get uneven development.

I am careful in all my measures... like tkamiya, except I am not very careful with time. The timer is across the room when I start it and then I put film in tray (or developer in tank). So my accuracy on times can be off by a minute easily.

Take sheet film for example. Start timer... turn around and leaf one sheet in the developer after the other. 30 seconds - 45 seconds can elapse before all the sheets are in developer... At the end of the cycle, take one sheet out at a time... Although Fred Picker would rotate a sheet to keep track of which was the number one sheet, I don't track the first shot in... I am far more concerned with smoothness of motion than exact time in developer. I would rather have to print a shot on Grade 2 because it got one minute more development than another shot of the same batch... than have to retouch a scratch on the print.

Long story short... Yes. Greater dilution, longer time. One minute time error 15 minutes instead of 14 will be hardly noticeable. While if the total time was 5 minutes and you gave it 6, the difference could be a paper grade change.

Here's sort of a guide.....

Long story short (if you want a longer version, read up on zone system), your negative gets twice as dark every time you extend the development time by 20 to 30% and contrast goes up by one grade. That means if you are printing, your exposure time under the enlarger gets twice as long every time you develop your film 20 to 30% longer. This is not exactly correct but it'll give you sort of a visual on what happens.

You can certainly successfully print these images although that long of an exposure time may become painfully boring after doing it so many times.

This works by percentage by most part. So longer your dev time, loser accuracy you can afford in terms of absolute seconds.

Seriously though, don't stress so much about timing issue. Get it reasonably accurate, say 15 seconds (in my case) and you'll really not notice any difference.

Here is a different viewpoint: I say that it depends mostly upon the film, itself. If you have a standard film like Delta 100 or TMY 400 it matters to be within, say, 10% of the ideal. If you are using a microfilm like Kodak ImageLink that accuracy matters even more, assuming you are aiming for continuous tone and not extreme contrast. In sum, inherently contrasty films demand even more accuracy with development.

Taking an atttitude that variable contrast paper will always save the day is faulty thinking. You should get your situation in order and be able to produce consistent results time after time. Naturally, psychfunk, if you dilute you get to have a more lengthy development time in order to achieve the same gamma (contrast relationship between the negative and the actual scene). This can mean more accurate development because it's easier to time 10 minutes than to time 3 minutes (because of the inflow and outflow of developer which does, and does NOT, 'count' as actual development time). With a 10 minute development time, the time needed to fill and empty the tank does not matter as much as with the 3 minute development time. - David Lyga

for years labs didn't process every film
by itself make sure the time &c were exact to the chart.
they would process a handful of different films / speeds together &c even though
at home you wouldn't. if you look at charts they sometimes
say pushed 1stop of pulled one stop same processing as normal ...
time temperature dilution &c are always important ...
they give a starting point for you to figure out what you will actually do
after you process a roll ... and you are on your second, third. fourteenth ...
i process all my film together, asa 25 - 3200 in the same developer for the same
time without agitation .. i don't sweat the small stuff .. but all that said
i know my working methods and i know what to expect ...

The goal is the print, and the print is the summary of all the previous steps in your process.

While you have 'leeway' of +/- 25% in contrast with multigrade paper, you are best off if you leave that 'leeway' to creative choice rather than saving your ass, so your goal is always to make negatives that print well on something in the middle from Grade 2 to 3, let's say.
That leaves room on BOTH sides of 'normal' to increase or decrease contrast fairly dramatically.

Think of the film processing as a bolt, and the paper being a nut. To make them fit together they have to be the same thread. Same with negs and paper - the better you fit the negative tone curve to the paper tone curve, the easier it will be for you in the darkroom come printing time. Your rate of wasting paper will be significantly reduced, which is a real benefit in this day and age, where paper is really expensive. I print with Ilford papers, usually 11x14, and that paper is almost three US dollars per sheet now. Film is comparatively inexpensive compared to that.

tkamiya said:

If your film was exposed EXACTLY the same and you develop it EXACTLY the same way, you get EXACTLY the same result.

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theoretically. this is exactly right!

When I am teaching film development, I like to compare time and temp charts to stripes on the road. They are guidelines.

You will NEVER develop 2 sheets or 2 rolls of film identically, The objective is to have an idea of where your errors may be and to have a handle on what you are going to do in development BEFORE any chemistry gets poured. How long is it going to be in each chemical, how long and when you will agitate, how long it takes to pour in and out, where the timer is, where the cap for the developer bottle is...etc, etc. Get your act together before and don't do anything "on the fly"

David Lyga said:

This can mean more accurate development because it's easier to time 10 minutes than to time 3 minutes (because of the inflow and outflow of developer which does, and does NOT, 'count' as actual development time). With a 10 minute development time, the time needed to fill and empty the tank does not matter as much as with the 3 minute development time. - David Lyga

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Bold font above added by me.

The best method for developing film is to lower the reels into an already full tank. So, a normal developing cycle would entail using three tanks, each filled with developer, stop bath, and fix (along with a possible fourth tank if you care to do a pre-wet). Obviously you need complete darkness for when the tanks are open.

I fully agree with you, Thomas. The film is in quickly and out just as quickly. That mimicks the advantages of sheet film development. - David Lyga

Development time is not as important as many would believe. The main concern should be consistency. The accuracy of short developing times - like 3 or 4 minutes - is much more critical that longer times - like 16 or 20 minutes. The needed accuracy is more or less proportional to the total time. If you go a bit longer, you get a bit more contrast; shorter, you get a bit less. Differences in agitation can easily give development changes equal to as much as 15 percent changes in time. Therefore it is important to develop a consistent technique and then find the development times that work well for you.

I've done this experiment once. I think I used Tmax400 and XTOL for this test.

Take an image with full range of tones. Have a gray card in there also.
Shoot it 1 stop over, 1 stop under. 2 stops over, 2 stops under. Then repeat the process 2 more times.
Develop each with what the chart says. +20% dev time and -20% dev time. Then +20 MORE % and -20 MORE %.
Print each image so that the gray card looks identical.

Except for the fringe cases where -2 stop exposure and least developed AND + 2 stops and most developed, all results looked basically the same. I really had hard time telling them apart.

Try it.... it's amazing how flexible and forgiving this whole thing is....

Sure it's flexible. The kicker is that if you make negs that print well at a medium grade, you have a lot more artistic freedom to BOTH lower and raise contrast, with the same neg. If your negs are higher contrast, or lower contrast, to begin with, you pretty much lose flexibility in one direction.

And, lets not forget that if you know what to expect in the darkroom, a lot of guesswork is taken out, which means less paper wasted, along with a lot more hair left on our scalps.
While its nice to have a safety buffer, it would be wasteful not to try to make negatives that are consistent, both density and contrast wise.

Thomas Bertilsson said:

Sure it's flexible. The kicker is that if you make negs that print well at a medium grade, you have a lot more artistic freedom to BOTH lower and raise contrast, with the same neg. If your negs are higher contrast, or lower contrast, to begin with, you pretty much lose flexibility in one direction.

And, lets not forget that if you know what to expect in the darkroom, a lot of guesswork is taken out, which means less paper wasted, along with a lot more hair left on our scalps.
While its nice to have a safety buffer, it would be wasteful not to try to make negatives that are consistent, both density and contrast wise.

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Yep.

Over the past 4-years or so of learning and refining my processes I have found that the better I get at producing "normal" negatives, the easier my life is and the quality of my first proofs has literally increased by several orders of magnitude because of that.

Nice, "normal", consistent negatives are the bomb and the bees knees.