High Acutance Develper
In his book "Photographic Processing Chemistry" (1974 Focal Press), L.F.A. Mason lists a typical High Acutance Developer.
This may possibly be the formula for Hyfin, which was Ilford's High Acutance developer, available from 1961 until the early 1970's. Mason calls it a typical formula:
High Acutance Developer
Sodium Sulphite (anhyd) 5g
Sodium Carbonate (anhyd) 5g
Water to 1 litre
Development times 15-25 minutes
Requires a minimum of 600ml of chemistry per 35mm or 120 film.
Mason notes that additions to the formula have been proposed, either 0.1g/litre Potassium Bromide or 5ml of 0.0001% Potassium Iodide solution. (He may be referring to other similar formulae like FX-1 etc)
Hyfin was sold in packets containing 5 sachets of developer each one making up 600ml of solution. I have two packets of Hyfin & will weigh the contents of a scchet next time I'm in the UK.
Hyfin instructions were:
Pan F & FP3 - 18 minutes @ 20°C
Continuous agitation for the first 10 seconds then 5 seconds every minute.
Gives 1 stop more effective film speed
In the early 60's there were 3 High Definition devopers availabe in the UK, lford's Hyfin, Kodak's High-Definition Developer & Johnson's Definol.
It's no co-incidence that Hyfin & HDD are very similar to Beutler's High Definition developer, sold as Neofin Blue, and another similar developer is Crawley's FX-1 formula.
The major differences are that Beutler has 1g Metol/litre & Crawley's FX-1 only 2.5g Carbonate + 15ml 0.0001% KI, compared to the formula above. The decrease in the Metol level compared to Beutler is likely to increase the edge effects & acutance further.
The addition of Potassium Iodide is likely to have little or no effect now as most modern films contain far higher levels in their emulsions, particularly Tmax & Delta films. It may have been more important with certain films Crawley speculates that it was needed in HDD for Pan-X
Mason would have known Crawley and his work, Ilford began manufacturing his chemistry for Paterson around 1963.
Last edited by Ian Grant; 08-02-2009 at 06:32 AM. Click to view previous post history.
Ok, here goes the chemistry.
If you add a tiny amount of iodide to a developer which uses a low level or no iodide, then the iodide goes onto the grains instantly, but then is released imagewise proportional to development. It therefore concentrates in areas of high development and causes edge effects.
With a high iodide emulsion, the iodide is already there in the emulsion ready to be released imagewise to do the same thing, but additional iodide acts to supresss this effect, kind of like buffering the iodide ready to be released from the grain. Also, todays emulsions vary in iodide content, and so it is hard to choose the level of iodide appropriate for use in a developer and so results (accentuation or supression) might vary from film to film. In addition, it is important to remember that some modern emulsions are core shell with iodide in the core but not on the surface. These react in a totally different manner.
So, there is no one answer except to say that adding iodide is a bad idea as a general rule. It may work, it may not work at all, or it may work counter to expectations. It is therefore considered best left out with modern emulsions.
That is why I have said before that older developer formulas may not be best for modern emulsions and vice versa don't use modern developers on old style emulsions.
Does this help?
Does 'old style emulsions' include FP4 Plus, HP5 Plus, Tri-X etc. or are you referring to the Efke type films?
Originally Posted by Photo Engineer
Last edited by Tom Kershaw; 08-03-2009 at 08:08 PM. Click to view previous post history.
Reason: correcting grammar
Originally Posted by Tom Kershaw
I hesitate to guess. Try it yourself and let us know.
Anecdotally Agfa Rodinal would seem to be a reasonably popular choice for developing T-max type films, however this developer was originally formulated in when, the 1890s? Your comment would suggest Rodinal may possibly be best suited to films such as FP4 Plus or CHS100, or are your comments more directed towards developers such as FX-1? According to A&T (FDC): Stock solution A: metol 5g, sodium sulphite anhydrous 50g, potassium iodide 0.001% 50ml, water to make 1 lt. Solution B: sodium carbonate anhydrous 25g. water to make 1 lt
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IIRC, Rodinal has no iodide and lets the emulsion determine the resultant imaging characteristics. This is probably best under the circumstances. The lack of Iodide is probably in Rodinal's favor and was the result of understanding the ideas put forth in my post above.
- And so Rodinal exposes the true characteristic of the emulsion?
Originally Posted by Photo Engineer
I am not a big Rodinal user so I would have to run extensive tests to give a definitive answer. Why don't you try some tests yourself and see what you come up with.
In a way Rodinal must bring out the true nature of the film, it's such a simple developer. Kodak made their own version Kodelon, as did Ilford, Johnson's etc.
My own experience of FX1 with the Iodide solution was that with FP4+ and HP5+ it seemed to do.... nothing.
Nothing bad happened, but the developer didn't seem to behave any different to a similar metol based developer without the Iodide.
Ditto with FX2
I never tried them with Pan F, maybe that was the one I should've tested?
So, my humble opinion is that FP4+ and HP5+ do not respond like 'old emulsions' to these old acutance developers.
The only developer that I found that seemed to increase the acutance of FP4+ to any noticeable extent and give some prominent edge effects, much more so than dilute Rodinal, was Paterson Acutol. I'd love to know the formula for that, especially now it is no more...
One day I am going to give FX1 one last go and dunk some ADOX 25 in it.
This is pretty much exactly what I was getting at with my "modified D-23" post. Very little metol, very little sulfite. I think I will try it out. I just need to get some sodium carbonate. I guess the sodium carbonate is to take the place of the sulfite's role in D-23 as an activator. Thanks for posting this.
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