So, what is Diafine? Diafine is a fine grain, full or greater film speed two-part black and white developer that possesses some pretty incredible characteristics that you may want to be aware of if you are not already.  It is simple, extremely tolerant of temperate ranges during development and produces excellent results when paired with certain films.  You can also use it for print development too!  I use it with some black and white positive paper when I am in the field to develop my prints.  The trick is to NOT use the same Diafine for films as you do with papers.  

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Diafine film developer is unsurpassed in its ability to produce the greatest effective film speed (EI – Exposure Index), ultra-fine grain, maximum acutance and highest resolution.  If you are not familiar with acutance it is the edge contrast of an image that is related to the amplitude of the derivative of brightness with respect to space.  Still confused?  In short, based on how the human eye works, an image with higher acutance “appears” sharper even though the actual image has not increased in resolution.  As with just about anything, there are thresholds here that if crossed can make an image look bad.  Some people claim traditional developers like D76 or XTOL have higher levels of acutance, but I will leave that up to you to figure out on your own.  Diafine is a fine choice if you are going to be scanning your films for digital outputs.  I personally don't care for Diafine developed negatives for printing in the darkroom, but you shouldn't take my word and form your own opinions.  I prefer Pyro-HD, D76, XTOL or HC110 for my traditional darkroom workflow.  

It is a characteristic of Diafine film developer to permit the widest latitude of exposure without the necessity of time-temperature compensation.  You can even develop different films in the same batch even if they are all rated at different ISO/ASA values!  With traditional developers (e.g., HC-110, D76, XTOL, etc.) you establish your normal development time and then based on your scene you can control the contrast by shortening (n-) or expanding (n+) your development times.  Diafine is a magical formula that does a pretty good job at controlling contrast for you without requiring anything from the photographer.  I think Diafine is the first developer that any new black and white film photographer should use.  It may be the only developer ever needed.  

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If I photographed a very low contrast scene and if I were using a traditional developer I would use N+ development to extend the contrast.  In the reverse, if I photographed a very high contrast scene and needed to retard the contrast, I would shorten my development time using the N- time that I had established.  As you can imagine there is a lot of work and testing that goes into establishing normal, n+ and n- development times with each film and developer combination.  One of the benefits of Diafine is that you don’t need to do any of this testing or development processing and that is why I think it is a good first developer for beginners.  Beginners have enough to worry about when starting and masking the complexity of development is a fair way to start the journey.  However, you will find there is a trade-off for the convenience because you are effectively bypassing any use of the Zone system because Diafine handles it for you.  This can be a blessing in some cases and I think it can also be a detractor at times as well.  I often refer to Diafine as "Zone System in a Box".  

Based on my personal experience I think Diafine is best used in the following scenarios:

• The negative is intended to be scanned and used in a digital workflow.
• A new photographer is getting into b/w film development.
• You photograph a very high contrast scene and are concerned your highlights will be blown out.
• You need to mix the EI ratings of different exposures on the same roll of film.
• You don’t have the ability to monitor and control temperatures in your development process.
• You need a reliable and very quick method to develop your b/w negatives and even some papers.
• You don’t understand or are not employing the zone system for your exposure and development process.
• You don’t want to push process your film 2 or 3 stops for a variety of concerns to include quality issues so Diafine is an excellent alternative.  For example, I would not push Tri-X 3 stops, however, I would EI rate it at 1600 and just develop it in Diafine with what I believe to be superior results.

When it is probably best not to use Diafine:

• If you are using the zone system and want total control over your contrast and development process.
• If you are shooting at box speed or lower with your films.
• If you don't like the results of your prints.  

Diafine Overview

I don’t think Diafine is for everyone, but I find it to be absolutely perfect with certain films especially when you will be scanning your negatives.  If you print archival silver gelatin darkroom prints as I do, you will likely find that Diafine developed negatives don't print the same as your traditionally developed negatives.  I have used it with excellent results with all the Kodak, Ilford and some Arista black and white films when the goal was scanning or editing in Photoshop.  I typically print on Ilford variable contrast fine art fiber papers in the darkroom and get excellent results using my Zone VI cold light head via my traditional developers (D76, Pyro-HD, XTOL).  On a limited basis, I have also used Diafine negatives on silver chloride (AZO) contact prints with Amidol and Ilford Universal developers with good results.  I’ve also contact printed large format sheet film using Foma 111 fiber papers and Diafine negatives with excellent results.  The problems for me are in the enlarged prints.  I simply don't like the look and feel of the prints that I create via the enlargement process.  

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• In many cases, Diafine provides a full stop of film speed increase or better versus the manufacturer’s rated speed.  For example, I have found that I can shoot Tri-X at a range of 400 to 1250 with great results.  The best general results are at EI 1250 as suggested by the manufacturer.  An EI of 1600 can have mixed results and this largely depends on your light conditions and contrast.  I can even change my ISO from frame to frame on the same roll if I want and there are no changes to my development process.  This isn’t going to change the contrast or exposure of your photos, it simply gives you the freedom and ability to adapt to varying lighting conditions.  This is a huge advantage for many photographers allowing them to have a single roll of film loaded and have the ability to modify the ISO on the fly.  If you are using large format sheet film this isn’t probably as attractive or even necessary really.  In short, this allows someone to photograph sports with high shutter speeds as well as landscapes or even portraits all with the same film and no modification to the development process.  I have used this technique with 120 and 35mm films.  Large format is sheet-by-sheet so that doesn’t really matter.
• The temperature range is very forgiving between 70F and 85F.  I typically aim for a target between 70 and 72 with my tap water and chemicals (Part A, Part B, Fixer).
• Development time is standard with a minimum of 3 minutes for each part (A and B).  I typically let mine soak a little longer, but that is my personal preference based on my own testing.  My best results have come when I moved my times from 3+3 (soaking A for 3 minutes and B for 3 minutes) to 4+4 for most films.
• Films of different speeds can be developed together in the same tank at the same time.  That can be very helpful and an incredible time savings too.
• Diafine can be continually re-used with a known shelf life of a year or longer making is extremely cost effective and very easy to use.
• It is a compensating developer.  This means that shadows develop fully with excellent detail and highlights won’t be blown out.  You will probably find in your own work that you will want to work with your mid-tones once you get your scanned image into your editor.  I use Photoshop and it only takes a few seconds with a Levels or Curves adjustment to dial things in right where I want them and no loss of detail or blown out highlights.  When you combine this technique with layers and masking you have an endless formula that will produce top-notch results.  In the darkroom, you just print for highlights first and then dial in your variable contrast filter for your shadows.  However, as I stated above, I don't like Diafine negatives for enlargement work.  But don't let that deter you from exploring and forming your own opinion.  
• Diafine negatives scan very well and in fact, if that were my goal, Diafine is the best tool for the job.  I typically just set the black and white points in my scans and that is the only adjustment I make.  On a side note, I scan at 16-bit Grayscale with all my b/w negatives.  Some people will tell you to scan as positives and invert the image but in my personal opinion this simply bloats the file size and I don’t like the visual result.

After you use Diafine for a while many possibilities start racing through your mind.  Once you get your mind around varying exposure indexes and application within your photography you can literally get lost in this stuff (in a good way).  You simply have to expose the film, develop it, take good notes and find combination’s that match your requirements and style.

Optimum Results

Optimum results are obtained if all solutions, including the wash, are maintained at the same temperature. Care must be exercised to prevent any amount of Solution B from entering Solution A.  I do a pre-wash in my Diafine development process and I always measure the temp of my chemicals (A, B, Fixer) and then try and match the temperature of my running tap water for optimum results.

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Contrast Control

Diafine is known as a “two-bath” developer. Film are developed to a fixed amount or degree of contrast. If you develop at 3 minutes versus 4 minutes there technically is not supposed to be an impact on the results.  I have personally found and believe that if I let my film soak up solution A a little longer than the 3 minutes that when the development takes place in solution B I tend to get better results for most films.  Density and contrast ratings for Diafine negatives range between .65 and .75 gamma.  

Diafine by its very nature limits highlight development and that is why you won’t see blown out highlights.  You will effectively get an extended tonal range in most of your images.  In some cases, you can control contrast by lowering the EI (exposure index).  This is most usable in high contrast scenes.  I will include an EI chart below, but I think you will typically find a two stop increase for most films and in some cases like Tri-X and HP5+ even three stops is possible under certain circumstances.  I think one of the greatest advantages to using Diafine is that your highlights won’t get blown out and your shadow detail can be very good when scanning is the goal.

I have personally found that Diafine works really well in high and normal contrast scenes.  If you are photographing a low contrast scene you are likely to get really flat and unappealing results.  The way that I deal with low contrast scenes when using Diafine is to simply expose the scene at the film's box rating.  For example, if you were using Tri-X in a low contrast scene use the box rated ISO of 400 versus the EI rating of 1250.

For darkroom printers, I would strongly suggest establishing your proper proof time.  In a nutshell, l you need to take 4 blank exposures for your 120 films or 6 exposures for your 35mm film and develop it with your standard Diafine process.  If you are a large format photographer then just a blank sheet of film will be all you need.  Then contact print the negatives on your standard paper in 3-second exposure increments.  You want to find the transition from gray to maximum black (D-MAX) and this is your proper proof time.  You will want a time more than 10 seconds but also less than 30 seconds.  I have an old medium format enlarger that I picked up locally off Craigslist for $25 and use it as my proper proofing system.  That way I just leave the head at the same level, same lens, same aperture, etc. and just don’t have to worry about setting it up each time.  For example, my proper proof time for T-max 100 and Ilford MGIV FB paper is 19 seconds.  Once I get the time close by the 3-second method I dial it in via 1-second increments.  You need to inspect the paper when it is dry and under a bright light to ensure you have selected the best time.  Once you have that time you can use it to make your contact proof sheets for that film, developer and paper combination and you can also use it as a benchmark to judge your development and exposures in the future.

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How Does Diafine Work?

I am not a chemist so I will give you an overview in lay terms of how I believe Diafine works.  To start out with, as mentioned above, Diafine is a two-part developer.  Because of the separation of the development process, you are able to achieve many of the benefits of Diafine.  I should note that I use Amidol as a two-bath developer for some select large format contact prints, and my ability to snatch the print at the right moment is extremely valuable.  

The first part of the solution known as the A bath soaks the film and prepares it for development.  Technically no development takes place when in the A bath.  You can google around and people will tell you they left their negative in the A bath for 15 hours and it developed.  Is that true?  I have no idea and really don’t care…. I don’t have that kind of time and I employ quality control in my development process.

Then you go straight from solution A bath where your film is absorbing the developer into its emulsion layer to B which is the accelerant.  Now you may see why I tend to soak my A bath for a little longer than the prescribed 3 minutes.  I am attempting to soak my film with the A solution for optimum development when the film hits the B solution.  Most of the development of your film when it hits solution B takes place very quickly within the first 10 seconds or so.

One thing you may notice is that no stop bath is used when developing with Diafine.  This is because development is already complete and there is no need for this step. I rinse after my A and B bath and then use my Fixer and onto the final wash before being done.

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Exposure Index (EI)

I have mentioned EI or exposure index a few times already in this article.  Simply put EI is your own speed rating for your film when used with Diafine.  When certain films are developed with Diafine we know by experience the general EI.  This is where the two-stop increase comes from.  I have tested many different films under varying circumstances and as a result, I have my own personal EI for each film.  This is the process and part of the craft.  I keep good notes and the experience and knowledge increases over time.  It is something that you earn by experience and while I can give you guidelines, they are simply just that.  Create and test your own EI ratings.

For example, I tend to use Tri-X 400 with an EI of 1250 in Diafine but I am not afraid to use it at box speed for low-contrast scenes or at times push it to 1600.  I typically use HP5+ at an EI of 800 but I am not afraid to use 1600.  I tend to rate my Pan F 50 at EI 32, Delta 100 EI of 80 and Delta 400 at 320 but I am not afraid to make small changes if needed.

Manufacturer EI Chart

You can use this chart as a starting place for your EI ratings.

General Advice on Films

There is probably no better combination than Tri-X and Diafine and if you want to try Diafine that is where I would suggest you start.  T-grain films don’t typically perform as well as classic films so you may want to keep that in mind.  Tabular films would include standards like T-max 100, T-max 400, P-3200, Delta 100/400/3200.  Conventional films would include Ilford Pan F+, FP4+, HP5+, Kodak Tri-X, Plus-X and Fuji Neopan.  If you follow the Diafine forums you will find people talking highly about Tri-X, Fuji Neopan films and eastern European films like Efke and Fomapan. 

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