Wednesday, February 27, 2013

Caffenol Strong, new findings

Some days ago I developed a 120 B&W film in the recipe that I called Caffenol Strong. If you are following this blog, please see 2 posts earlier. I forgot adding KBr (potassium bromide) and the result was a very dense and foggy negative. Some of the photos could still be saved, like the following:

Old windmill
The color is the inverse of the negative blueish color, maybe automatically tonned by scanner or software. The fact is that this Caffenol gives, with Fomapan film, a «sepia» or, if you wish, a coffee stained positive image.

The amount of KBr is crucial for both avoiding fog and accutance of the photos. Also the developing time is considerably influenced by this amount. I have been using 1 g/liter of KBr but today I decided to use just 0,5g/liter to have a decent development time of less than one hour.

I am still waiting for the film to be fixed with common salt (sodium chloride) because the ammonium thiosulfate is producing strange white spots (black in negative). Salt fixing takes a long time, some hours depending on temperature and concentration. The film is now clear after 3 hours but needs 3 hours more to be considered fixed. I hope I can show the results of Caffenol Strong + Salt in the next post.

Friday, February 22, 2013

Building a rig to make macros of slides or negatives

One of the problems with the scanners is the time you need to scan a single picture, even at low resolution. The digital camera, a not so bad one like my Sony A290, is able to reproduce slides and negatives with acceptable quality and very quick. Yes, I know, there are a kind of tubes with a macro lens for that, but I wanted more control on the process. So, I made the rig below:

The rig to reproduce slides and negatives
On the right side you may see the scanner Epson V500 used to reproduce the slide below. It is more sharp than the one made with the rig, but that could be my fault. The scanned build took quite a long time to scan at 1200 dpi. The camera made the reproduction in a fraction of second and the image is similar to a 2400 dpi with the sacanner. The colors are better and durst was more filtered than with the scanner.

Scanned with Epson V500
Macro made with a Sony A290
Finally, the rig was made up from a standard cheap slide rule bought at ebay and some pieces of iron and wood and screws. The backlight is from a led array for photography.

Wednesday, February 20, 2013

Caffenol Strong

Some months ago I was trying to make a Caffenol two-bath developer like I did with Parodinal+Vit C. Starting point was equal amounts of coffee and Vit. C as bath A and then soda + potassium bromide as bath B. Before having some result I had to go on increasing coffee and vit. C concentration of the bath A until I reached 200g/liter each. But then, I realized that the amount of bath A transported into bath B was as little as 10ml/Liter. So I tought, why not adding the 10 ml of that solution directly  to the soda bath. So I did and the result was as expected, this developer worked in about 30 minutes at 20ºC.

Some days ago, I remembered I still have some bottles of bath A, made some months ago. The developer was still good, which means it can be stored for several months (I added some grams of sodium sulfite as preservative too).

One of the pictures shot last weekend and developed in Caffenol Strong, the name I gave to this weak/strong developer.

Scanned as color negative

Amazing is that the negative has a blueish color that, inverted, resembles coffee stain in the positive image (maybe a question of film too). The other advantage is a pH about 10,8 with very long developing time and, as far as I can observe, very fine grain compared with other relatives.
Bath A - dissolve 5 g/L of sodium or potassium sulfite or metabisulfite; add 200g coffee and 200g Vit. C and stir. Let stand until the foam vanish.
Bath B - 50g/L sodium carbonate + 1g/L potassium bromide
Work solution: 10ml of bath A in 1 L bath B or equivalent.
Developing time is about 30 minutes at 20ºC with Fomapan 100 ISO. 
If one uses only 500 ml of this developer it will contain 1g coffee and 1 g Vit C.
This is almost a miracle, isn't it? Like the 1L car of Volkswagen.