Rodinal 1+25 vs 1+50

Rodinal, it’s old as dirt, but people still use it. This awesome little one shot developer has been around since the 1890s and still considered a top choice for black and white photography because it is super easy to use.

The version I have is called Blazenal. It’s chemically identical but has a much better name.

If you have seen my previous experiments I make a strong effort to only change a single variable, while ensuring everything else is the same. In this case, I need two identical or nearly identical frames from the same strip, developed separately. In order to accomplish that I set out for a generic photo that had both highlights and shadows, and something people in general could recognize: A sunset.

I considered doing it indoors in a more controlled environment with strobes to ensure precise exposure and I may consider that in the future, but I needed something universally recognizable and a little more interesting than a lineup of random 80s toys.

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 future I may use a motor drive to narrow that gap.

In the darkroom I separated two strips into their own tanks, and developed each one as normal, except one I did at 1+25 and the other at 1+50. Of course.

Why do this at all? Well, I think the most important formula here is this: Will the extra time it takes to develop at 1+50 be worth it in terms of savings, and can I live with, or do I like the results.


One 500ml bottle could develop 43 rolls of 35mm film, or it could do 86.


To develop 43 rolls of tri-x not including stop and fix at 1+25 is a total of five hours and one minute.

To develop 43 rolls with the same at 1+50 is 9 hours and 19 minutes, but you’ll still have half the bottle left.

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 difference 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 of severity may be more dramatic.





Okay, here are the scans. These scans have no editing to them whatsoever, but you still have to consider your monitor.

Let’s have a look at the histograms.

One of the first things I noticed is that the 25 has a bit more tonal range. The blacks to mid tones are very similar, but then mids to highlights are more dramatic.

You could say there’s more contrast to simplify things, but how much contrast from the darkest to lightest areas is just not consistent across, it varies. It would be more accurate to say more contrast in the mids to highlights, while retaining shadow detail. You can retain more highlights in the 1+50, but at the cost of a little range it seems.

The last thing to mention here is sharpness. If you look closely at this tower here, called the bow tower, you can see the 50 is sharper. It’s not by leaps and bounds but the pattern in the building is more noticeable here.

Scanners can give some great info but I don’t think it’s without its drawbacks. I realized 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.

1+25 Contrast 5

1+25 Contrast 2 1/2

1+50 Contrast 5

1+50 Contrast 2 1/2

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+50 strip, I would have gone with a 20-30 second exposure, and the 1+25 would likely be a 40 to 50 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. I don’t have an exact comparison and my task for next time will be to make sure my strips compensate better but looking at the two strips, and putting the 120 second exposure from the 1+25 and the 80 second exposure from 1+50, the 1+50 looks like it has a little more grain. I can’t be sure though, and while my research does suggest that more grain is a side effect is weaker solutions, I need to see it for myself to be 100%

Alright, now that I have …..what would be the analog version of pixel peep…..grain gawk? Now that I have finished grain gawking at everything, here are some of my thoughts.

What does all this comparing mean for your images though, that’s what this is really all about.

My thoughts are as follows

1+50 is a good dilution if you want to

a) Stretch the use of your developer b) retain higher sharpness and c) lower the contrast of the negative.

Use a 1+25 dilution if you want to a) save time developing, and or b) increase contrast of the image.

I am sure there are other differences and benefits that I missed here, I would love to read them in the comments below, but my knee jerk reaction is that 1+50 has slightly more upsides for me. It’s a flatter negative, so you can control your contrast more, it costs half as much, and it’s sharper.

I think at the very least, it’s a reminder how nuanced film photography is and even if you’ve got your choices locked down, i.e. your camera, lens, film and ISO, you still have other ways to control your final image. Just try not to get lost in the details and remember the point is to get out there and shoot.