Sunday, June 22, 2014

C-41 for everyone

I am involved with B&W Photography since I was about 14 years old. I knew its workflow, from film to print, but I was unable to understand the Chemistry involved, nor I mastered all the details from the capture until a ready print.

Now that I am over 60, I have more time for Photography and I could turn real a dream I always had, to develop color negatives. When I started, I even didn't know that the chemical process of color negative films was called C-41. And I still don't know where the name C-41 comes from. Maybe Color Process number 41, or 4 baths plus 1, doesn't matter...

My first step in what C-41 is concerned, was to buy a developing kit and follow the steps indicated in its brochure. The process is very demanding in what temperatures and times are concerned and it was established for automatic processing, for sure. Not for people doing C-41 in a simple developer tank, I think. But some people seem to like following very strict instructions and they do C-41 according to the standard instructions.

I am sure that, if C-41 had been established for home processing, it would be very different. I am going to try to explain the standard procedure, then you will realize how difficult it is to achieve always the same quality. Of course, this standardization was needed because C-41 films could be developed anywhere and, contrary to B&W, the colors must be the same, disregarding where you let the film be developed. In B&W, the film can be developed with more or less contrast, with more or less grain, a little over or underdeveloped. That could always be repaired at printing. But a color film must have the same quality everywhere.

Standard C-41 process:

Development - 3' 15" at 38,5ºC

Rinse - 3 times, very quickly
Bleach - 4' 00"
Rinse - 3 times
Rapid Fixer - 3' 00"
Washing - 30', flowing water
Stabilizer - 1' 00"

All baths should be at 38,5 ºC. Crucial is the temperature and time of the developer. Manual control is almost impossible, variations will occur if you do not use a thermostatic device. The 3' 15" developing time are also important and this causes stress and not plaisure like it should.

Now, about the chemicals involved:

The developer contains, as developing agent, CD-4, a p-Phenylenediamine derivative, Hydroxylamine Sulfate as stabilizer and Sodium Carbonate as alkali. CD4 is a silver developer that by its oxidation provides the dye components needed to form the color image on the film. It seems impossible to replace CD4 with another developing agent, so far. If a C-41 is developed with a B&W developer, for instance, only silver will be developed. If the film is bleached, all the silver will be transformed back to halides and washed out by the fixer.

The Bleach Bath, in which ferric-EDTA is mainly used, is necessary to remove the silver without washing out the dyes. The Bleach transforms silver in halides and the fixer solves them and on the film we have then only an image formed by three dyes, Cyan, Magent and Yellow.

The fixer removes the halides from the film. After fixing, the film should be very well washed to remove completely the fixer and finally the film undergoes a 1 minute stabilizer bath to protect the organic dyes against deterioration. This bath is a very diluted solution of formaldehyde.

Finally the Fixer, it is the same used for B&W films. And there are mainly two choices: Sodium Thiosulfate based fixer or Ammonium Thiosulfate based fixer, the only difference is that Ammonium Thiosulfate acts faster, 2 to 4 minutes against 10-15 minutes for Sodium Thiosulfate.

OK, if you want to follow this strict instructions, it is up to you. But I have been working in a room temperature process, based on the Dignan's 2-bath C-41 process, to which I added some own experience in order to get better colors. I have been using Dignan's process alone but I was not fully satisfied with the results:

The two younger
Photo 1 - Developed with Dignan's 2-bath C-41 process

Yes, we get 'color' but they are not 100% correct. Of course it is possible to make corrections via Software, but it would be better not to have to, to use the pictures like they are scanned, with minor changes in the automatic scanner settings.

I reproduce here Dignan's recipe, for 1 liter of both baths:

Bath A

600 ml distilled water
1 g Sodium Bisulfite
11 g CD4
9 g Sodium Sulfite Anhydrous
Water to make 1 Liter

Bath B

500 ml distilled or filtered water
45 g Sodium Carbonate (monohydrate), aka washing soda
1 g Potasium Bromide
Water to make 1 Liter

Bleach and Fix are the usual for C-41.

The main difference is tath all baths are at room temperature and you mussn't care about some seconds more or less. On the other hand, you don't need Hydroxilamine Sulfate as CD4 stabilizer. Each time you use the bath A, the quantity will diminished of say, 20 ml. One liter is theorectical enough for 50 rolls, unless bath A goes bad before.

I have tried to warm bath B (where development takes place), and I found out that this improves the colors. But then, I measured the pH before warming and after warming and it was clear that the warm bath had a higher pH. This showed me that, instead of warming the bath, we may achieve the same result by increasing its pH. So I decided to add some Sodium Hydroxide to Bath B and the colors shifted to a much better approach to the real colors.

City Walk
Photo 2 - Developed with Dignan's 2-bath process at higher pH

And here are the recipes I have used:

Bath A

600 ml distilled water
1 g Potassium Metabisulfite
11 g CD4
9 g Sodium Sulfite
Water to make 1 Liter

Bath B

500 ml distilled water
50 g Sodium Carbonate anhydrous
1 g Potassium Bromide
5 ml of a 10% Solution (10g for 100ml) of Sodium Hydroxide
Water to make 1 Liter

In bath A, I am using Potassium Metabisulfite instead of Sodium Bisulfite because it is easier for me to buy at local stores and it does the same as Bisulfite. It is added as first as Oxygen scavenger to prevent the Oxydation of CD4 when this one is dissolved in the water. Finally Sulfite will act as preservative of the solution, whose pH should be 6,5 or less.

In Bath B I use 50g of Sodium Carbonate anhydrous and not 45g of monohydrate because I use a 5% solution for other B&W developers and this doesn't change the result and keeps pH after use, it may be reused several times. The small amount of Sodium Hydroxide, 0,5g/L, provides a change of the pH from 11,6 to 11,8 or 12.

I have learned, by my own experience, that the paper of an alkali in a developer is somehow similar to its paper as washing powder for tissues.The alkali soaks and softens the film in order to allow the penetration of the developer in the layers of the film. Using Dignan's process alone was not developing well the red color in prints that corresponds to the cyan layer which is at the bottom of the film. With a higher pH, this layer (and the others) gets well developed.

Daily walk
Photo 3 - All 3 colors Blue, Green and Red well represented

To finish this long article, let us see how you may develop your C-41 films.

Prepare 1 Liter of bath A and divide in 2 bottles, each one of 500ml. Mark one as the work solution and the other as replenishment. Each time you develop or each 2 or 3 times, fill the work solution with the replenishment.

Prepare only 500 ml of bath B. This bath is not 'consumed' because it receives water from the previous rinse bath, balancing what it loses when leaving the tank.

Prepare also a 500 ml bleach bath for C-41 and 500 ml Fixer. Personaly I prefere the so called Blix bath, Bleach and Fixer in one bath only. This bath will last very long, you only need to filter it from time to time. Keep it in a amber bottle because it may be affected by light but leave the bottle open, it needs air for long life, It is not wrong to through it from a bottle to another several times to aerate. The recipe for Blix may be found here.

C-41 at room temperature
Photo 4 - This is all you need to process your C-41 films at room temperature

And the workflow can be this one:

- Pour Bath A into the developing tank and agitate for 1 minute and give some taps on the work bench with it to free the film from possible air bubbles.
- After 10 minutes pour the bath A back to its bottle.
- Pour Bath B into the tank without rinsing or washing.
- Use semi-stand development with bath B, 1 minute constant agitation and then 3 gentle inversions or rotations per minute.
- After other 10 minutes, pour the bath B back to its bottle.
- Rinse very well 3 times with water
- Pour BLIX into the tank also for 10 minutes.
- Wash very well and hang the film to dry.

Note: I am not using the stabilizer bath, because the stuff (Formaldeyde) is not very healty and I prefer to wash very well and accept that my negatives will not keep forever. Me too!

Important: Please check latest recipes for the 2.nd bath of 2-bath developer that proved to be better.Here:

Friday, June 20, 2014

Digital darkroom

I have been involved, but not too much, in a recent discussion at Flickr, where some people were for and other were against digital post-processing of pictures captured on film. Sometimes I also think that it doesn't make much sense to start with analog and end with digital, unless we want to store the originals for the next 50 years or more by using film.

Digital pictures stored in digital media like harddisks, movable or solid state, or any other physical support, will not survive that long, I think. The only digital media capable of storing for a long time is the internet, some site like Flickr or other having thousands or millions of users that may support the site to be sure that it will not close. Even if they close, copies will be in some other site and may be found through the Way Back Machine.

Let us assume, however, that digital is not safe enough to store our originals and we prefer to shoot on film and keep this as the backup from which the higher quality prints can be made, either on paper or on digital form. We can see a digital image as a print of an ideal high definition image stored on film. This is not always truth but a good film camera with the right film well processed is comparable or better than the best digital cameras.

Now, we take pictures with a film camera and we need a digital processing work flow to produce our prints on the screen or on paper by means of a printer - inkjet or laser printer. But once we have transfered the film image to the computer, the digital picture may be retouched and transformed with an image software. I am using, for instance the free software Photoscape. Some examples of picture manipulation with Photoscape:

Original, Fujicolor C200

Example 1, Agfa look

Example II, cinema look

Example III, cross processing look

Example IV, Kodak Portra look 

Example V, Fuji Provia look

Example VI, Fuji Velvia look

Wednesday, June 11, 2014

C-41 at room temperature II

So, here am I, and back to color! I will try to post more about color from now on.

As I already said in former posts, see as reference this post, it is possible to develop C-41 films at room temperature. The last film I developed gave more acceptable results. I am talking from Dignan's 2-bath developer that I have been using for quite a long time, but I am not completely satisfied with the color rendering of that method, still the idea of developing C-41 at room temperature beeing a great target.

Some time ago, when trying to apply Dignan's method with a warm 2.nd bath, I measured the pH before and after heating and I found out that the heated bath has a higher pH. So, I am trying to achieve better results using room temperature at higher pH for the second developer bath, adding some Sodium Hydroxide to the it.

After preparing a 5% solution of Sodium Carbonate (50g per Liter) with 1g per Liter of Potassium Bromide, I added, with a dropper, the equivalent to 1g/L of Sodium Hydroxide.

I used semi-stand developing technik for the 2.nd bath, that is to say, 1 minute constant agitation and then some turns per minute. I choosed this technik because I already tried stand and constant agitation. I gave following times: 10 minutes for the first bath and 10 minutes for the second, better more than too short, remember that overdevelopment will not happen because the amount of developing agent (CD4) is limited.

Example 1

Example 2

Example 3

Example 4
The color rendering is much more real than I get by just applying Dignan's recipe. I thing, by now, that I can live with this result, although it could be tweaked a little more. But I already have a better red. Dignan's alone gives magenta instead of red. Remember that the red sensitive layer is the last one, after green and blue, and a possible explanation is that a higher pH allows the developer to penetrate more deep in the film.

Another improvement I may report is what grain is concerned: less grain, I think the semi-stand development is aproved by now. And no surge marks, which occur in stand development.

Tuesday, June 3, 2014

Agfa Synchro Box

From Camarapedia, this paragraph to introduce the camera:

«Agfa Synchro Box 600, also known as Agfa Synchro Box, is a medium format box camera manufactured by Agfa Camerawerk AG, München, Germany between 1951-57. It is a version of Agfa Box 50. The Synchro term in the name is for flash sync shutter.»

With this old piece of museum you may play and experiment several thinks, like pinhole photography and other possibilities.

The original camera shoots in 6x9 format, in older times it was a great advantage, you could make direct prints without the need of an enlarger. I played a lot with this camera as I was about 13 or 14. An oncle told me the essencial of photography and even offered me a device to make direct prints very confortable at the darkroom.

Today I have several Agfa boxes and one of them is used for experiments. The first think I made was to take the single lens attached to the film loading device. It was not easy, the spring that holds the lens is very strong and finally I made a drastic choice, I broke the lens. But if you are more patient, it is possible to remove without violence.

The next, I oppened the front part (just pulling it out), and removed the front glas which is only introducing noise to the pictures, it is not a lens. I also removed the piece containing the two apertures and a yellow filter. It is also possible to remove the shutter that can be used in another DIY camera.

After all, I broke a close-up lens with a 55mm ring and used only the ring without glass as a 55 mm screw adapter for other lens. This ring was centered arond the camera front ring and filled with epoxy. The box was so transformed in a interchangeable lens camera.

If I use a +10 close-up lens, I get a more or less foccused image. The next, I reduced the image to the size 4,5x6 cm, cutting so the parts less foccused of the image and doubling the number of pictures per roll, 16. One turn per picture, a liitle more at the beginning, a little less to the end.

Finally, you may use, with the 55mm adapter a wide angle lens from Holga. This will have the advantage of enhancing the aperture angle and the image becomes sharper.

Modified Agfa Synchro Box
Fig. 1 - A new camera based on the Agfa Synchro box

Playing with an Agfa Synchro Box
Fig. 2 - The image above was made without the wide angle Holga lens.

Playing with an Agfa Synchro Box
Fig. 3 - A picture made using the wide angle Holga lens .

The vertical lines in the photos are made by the black paper mask. This mask can be fixed inside the frame and will not produce these "vintage" drag marks.