Kodak D-76 Dilution 1+2 vs Stock

Kodak D76


Arguably Kodak’s most widely used black & white film developer, D-76 is not a one shot like Rodinal or HC-110, but instead a powder you mix all at once, then use at full strength and reuse it, or dilute it and dispose of it.

But which is better? In today’s experiment we take a look at the dilution differences of Kodak D-76.

In my comparisons, I only change a single variable if I can help it. In today’s experiment I needed two identical frames from the same strip of film, and developed in separate tanks. I needed a photo that had both highlights and shadows and something you could recognize, a skyline sunset.

I used a handheld light meter to gauge a good average, and also compared that with my cameras meter, a Nikon FE and both gave the same result. I chose to overexpose slightly. I got a reading of 1/160 and I went 1/125. In hindsight I suppose I could have used exposure compensation but it worked out fine, and we are more concerned about how they compare to each other anyway. I shot all my frames quickly. Both photos that you’ll see in today’s example were shot within a minute of each other.

In the darkroom I separated two strips into their own tanks, and developed each one as normal, except one I did at 1+2 and the other at full strength, or if you really want to be specific, 1+0.

Why bother looking over these differences? Control. Control of the negative and control of your wallet.

Typically, D-76 comes in a bag that mixes into 1 gallon, or 3.8 liters. Now this is interesting because D-76 is a reusable developer.  You can get a replenisher to further its life as well, but only if you work with it at full strength. Kodak’s datasheet says that if you dilute, it is not recommended you reuse or replenish. Now I am sure, someone out there who’s been using D-76 since I was knee high to a grasshopper will tell me there’s a way, but for this demonstration, we will go based on Kodak’s recommendation.

So, 3.8 liters of stock D-76 you can develop 16 rolls of 35mm film. Here’s where it gets tricky. You need to add 15% to your time for every 4 rolls you develop to compensate for the exhaustion of the developer. The first four rolls of tri-x in our example would be developed at 6 minutes 45 seconds (27min). Rolls 5 to 8 would be 7 min 46 seconds( 31 min 4 sec). Rolls 9 to 12 would be 8 min 56 seconds (35min 44 secs). And finally rolls 13-16 would be 10 min 16 seconds (41 min 4 sec). The grand total for all of that is 2 hrs 14 min 54 sec

A 1+2 dilution called for a 13 minute development, but that never goes up. After 16 rolls it’s 3 hours and 28 minutes. That is only 73 minutes longer but it should be noted that the last four rolls of full strength development runs at a time only 2 minutes and 44 seconds less. More of your time is saved in the first few rolls when the chems are still fresh. If I used dilution 1+2, I can also develop 38 individual rolls, over twice the amount.

Before I show you the scans, there are a few things to keep in mind here. Like exposure differences shot to shot due to the slight variation of shutter speed and the setting sun. The slight curve differences of the film when being scanned, as well as the crop of each frame, not to mention any slight variation in the exposure of the scanner. Lastly the temperature differences in the developer. I tried to get to 68F exactly but there’s probably a half to one degree variation.

I should also mention that different films will yield different results. I’m using Tri-X because it’s an old, readily available, popular black & white film. It’s a forgiving film. So while you may get the same KIND of results with different films, the degree or severity may be more, or LESS, dramatic.



When I got the negatives out of the tank, I’ll admit I had a hard time telling the difference. It was easier after it dried. What strikes me as interesting is unlike Rodinal in my last experiment where you mostly saw the difference in the highlights, things seem to be more uniform here. Stock has more detail in the highlights, while the 1+2 has more detail in the shadows.

Let’s have a look at the histograms.



They are both pretty similar all the way across, which is in line with my visual inspection. If you shift the histogram over they are pretty close except for the shadows and a tiny bit in the mid tones, if anything the highlights seem to be least affected. Interesting.

The last thing to mention here is sharpness. If you look closely at this tower here, called the bow tower, you can see the 1+2 is sharper. It’s not by leaps and bounds but the pattern in the building is more noticeable here.

1+2 #5

Stock #2.5

Stock #5

Stock #2.5

Scanners can give some great info but I don’t think it’s without its drawbacks. The only way I was going to see the whole picture was to come back here into the darkroom.

I made a series of test strips and here’s the breakdown of that.

My goal here was to see how the image renders on paper and how the grain looks in the highlights. I made 4 strips, 2 from each negative.

Using my enlarger I set out to make a small section of the biggest enlargement. To do this I set my enlarger all the way up to the top. In this case 22 inches long is as big as I can get with my current setup. My test strips were 5x7 glossy RC sheets. I did one strip with a 2 ½ contrast filter at 10 second intervals and the other with a number 5 filter at 40 second intervals. Doing this for both negatives, and developing in Dektol.

I did the number 2 and a half strips just to see what a generic exposure looked like. Some of this is just about personal taste but from the 1+2 strip, I would have gone with around a 20 second exposure, and the stock would likely be a 25 second exposure.

I thought if I did a long exposure with a #5 contrast filter I could bring out as much grain as possible in the highlights, thus being able to see how it was affected. I would expose the hell out of the highlights, and the tiny black grains would poke through, so to speak.

Unlike my last experiment with Rodinal, there isn’t nearly as much of a difference in either case, whether you are comparing stock to 1+2 or with contrast filters, the differences are not nearly as striking, usually just one increment over. So for example eighty seconds through a contrast 5 filter with the 1+2 negative looks pretty close to a 120 second exposure with a full strength negative.

Okay, now that I have finished grain gawking at all these samples, what do I think?

Well, first off this was my first time trying out D76, and I have to say I really like quality of the negative and look forward to doing a direct comparison to another developer soon. As far as the battle between whether to use it stock or dilute it, my vote is dilute it. The visual difference isn’t dramatic in scan or in print, and you’ll get more than twice the life from it.

I am sure there are other differences and benefits that I missed here, but my gut says to dilute it when I can, like when it’s fresh and I am shooting at box speed, and go full strength when it’s been on the shelf for a few months, or I need to soup it at 1600.

I hope I saved you some time here so you can do more important things, like get out there and shoot. This is a fun experiment but let’s not get too lost in the details.