Divided developers for "push" processing?

[p.barden]

I often hear people inquiring about the subject so I'm asking about this more out of curiosity than personal needs.
I often use Thornton's Divided developer and like the result a lot, but my results always suggest some loss of film speed when using it. People sometimes ask about the suitability of Divided D-23 and it's kin for "pushing" film to get an increase in film speed, but it seems to me that these types of developers aren't well suited to pushing film for more speed.
What are the facts in this regard? Can you use a divided developer to effectively "push" film? Seems to me it's not the best option.

[Ian Grant]

Thornton himself suggests the only controls with his divided developer is adjusting the Metaborate level towards 20g/l to increase contrast, and lowering towards 7g/l to decrease contrast.

D23 divided would be no better, Diafine can give around a stop increase, but there are better approaches. There is a substitute formula for Diafine type developer DCB 4 page 257.

Using Phenidone alongside Hydroquinone, instead of the Metol in Thornton;s developer or Divided D23, helps give this speed increase.

Ian

[charlie_chaplin]

PB,
If you are using the divided developer to process sheet film, depending on the film, the divided developer would allow you to inspect development after the second bath and return it to the first if you want to push it further, going a second and even 3rd round if you are trying to achieve higher densities without exploding contrast.
I am guessing you are using this on 35mm or 120 negative roll film because something with as much sulfite as you have in D-23 is meant for those smaller formats. Roll film makes development by inspection nearly impossible.
some suggest this formula could help with speed increase while keeping grain similar to d-23 if you are not going to put this through the baths a second time and just extend dev times.
MCW Rapid Developer containing 5.5 g Metol, 75 g anhydrous sodium sulfite, and 5 g sodium metaborate (kodalk) in 600 ml water has been claimed to give a 50% speed increase over D-76 development with both slightly less and more even graininess depending on the film emulsion.
If you can inspect your film and run it through the baths more than once, then Beutler’s formula might be a better choice (for divided dev) if you want to push your film, especially for a second or third round through the two baths. The sulfite in the D-23 make fog a possible outcome if you go for a second run or an extended dev time.

[p.barden]

PB,
If you are using the divided developer to process sheet film, depending on the film, the divided developer would allow you to inspect development after the second bath and return it to the first if you want to push it further, going a second and even 3rd round if you are trying to achieve higher densities without exploding contrast.
I am guessing you are using this on 35mm or 120 negative roll film because something with as much sulfite as you have in D-23 is meant for those smaller formats. Roll film makes development by inspection nearly impossible.
some suggest this formula could help with speed increase while keeping grain similar to d-23 if you are not going to put this through the baths a second time and just extend dev times.
MCW Rapid Developer containing 5.5 g Metol, 75 g anhydrous sodium sulfite, and 5 g sodium metaborate (kodalk) in 600 ml water has been claimed to give a 50% speed increase over D-76 development with both slightly less and more even graininess depending on the film emulsion.
If you can inspect your film and run it through the baths more than once, then Beutler’s formula might be a better choice (for divided dev) if you want to push your film, especially for a second or third round through the two baths. The sulfite in the D-23 make fog a possible outcome if you go for a second run or an extended dev time.

As I stated in my initial post, I am not asking about DD-23 for my own needs but out of curiosity, having recently seen people recommend it for "pushing" film beyond its rated speed. I have no need for such techniques myself, since I have never needed to "push" any film - it's not something I do. I just wondered why people would recommend DD-23 for pushing, since my experience with it (both 120 rolls and sheet film sizes up to 8x10) suggests that I can expect some speed loss when using it.

[p.barden]

I'm hoping Steve will offer his opinion.

[sanchell]

The first thing to understand is that push processing does not increase true film speed. Push processing underexposes the film, whose speed has already been maxed out by the mfr., and increases the density in the highlights, giving you something to print.

An actual speed increase is measured by increased density in the shadows. Push processing decreases the density in the shadows through underexposure. That said, push processing is a way to capture an image in low light without using auxiliary lighting (handheld flash, Lume Cube, etc.).

For push processing to work, your primary subject must be illuminated. I use available artificial light, street lights, and light emanating from store windows for street photography at night. The attached photo, Dante's Cafe, NYC 2005, is an example of the first. You will notice that the shadows lack detail. Using Ilford HP5+ rated at EI 2400, I captured the image handheld without a flash. This is not a speed increase; this is push processing, and you should be clear about this.

Considering that the mid-tones and highlights have also been underexposed to some extent, the secret to push processing is to find a film and developer combination that will develop them to a printable density. And this is all that so-called push processing formulas and techniques do.

Back to divided developers. Should you ever find yourself in a situation where you need to push process sheet film, I think p.barden's suggestion of multiple times through the first developer using inspection is worth trying. However, why you would ever need to push process sheet film is beyond me.

Dantes Cafe 2005.jpg (122.68 KiB) Viewed 198 times