How important is it to be accurate with development times?

[psychfunk]

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?

[Gerald C Koch]

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.

[tkamiya]

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.

[desertratt]

The correct time and temperature are important. But you have to modify the listed development time to your own situation. You may be too heavy or too light on the agitation and there could be some other factors. Some people prefer a thinner negative, some like them more robust. I attended the Leica travelling school years ago and they said the ideal negative was one that you needed to print with a #4 grade paper. That's way too thin for me. I think they meant "in theory" the thinner neg is best. Kodak used to fib about the speed of their b&w films so the majority of people would overexpose. The idea was b&w take better to overexposure than underexposure and by overexposing, at least the customer got something. The guidelines are only a starting point. This is my input from spending 50 years in darkrooms.

[psychfunk]

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?

[ic-racer]

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?

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.

[Allen Friday]

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.

[psychfunk]

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.

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

[Bill Burk]

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,

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.

[tkamiya]

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.