silberkorn
Which black-and-white transparencies have a clear base and are suitable for reverse processing? Apart from the genuine black-and-white transparencies Fomapan 100R and Agfa Scala 200X, the only others I know of are Maco PO 100c and Lucky 100, though I’m not at all convinced by the latter due to its tendency to overexpose. What other black-and-white films with clear backing are there?
Regards
Jo
Christoph
All Maco films ending in "c" (as in "clear") have a clear base.
The Rollei R3 also has a clear base, and the new Rollei Pan 25 is said to have one too.
The ADOX 25 and 50 should also be fairly clear; I’d like to test the 50 in the Foma Kit, and perhaps the 25 as well, though it’s too low-speed for most applications.
MirkoBoeddecker
Yeah,
the reason why some films, such as Lucky, are on a clear base isn’t because they’re trying to produce a film suitable for slides, but because the traditional base has become too expensive.
The problem, however, is that the traditional base already has built-in antihalation protection, meaning the films can be cast directly.
Lucky clearly doesn’t care about that and happily goes ahead and coats the film. This makes it a really cheap film to produce, and you can see the result for yourselves.
Technically, it wouldn’t be a problem for Lucky to change this, but then they would have to become almost as expensive as our films.
The ADOX roll films have also always been on a clear base. However, the cost-saving effect was offset by the extra effort required to coat a high-quality antihalation layer (antihalation layer at the back, emulsion at the front). With the decline in production volumes, this extra effort has become relatively more expensive per square metre than the savings made on the base material. This is because the film has to pass through the machine twice, which also increases the risk of errors.
Consequently, these films will in future be cast onto classic base stock again, which will hopefully also resolve the issues with the film ‘popping up’ when loading it.
I’m harping on about this so much so that you understand why there has been a wide variety of relatively inexpensive, slide-compatible film stock in recent years.
It wasn’t the small number of slide developers as a target group that was the reason, but the price difference in the base materials.
This will change in future, and only special slide-compatible films will remain in the high-price segment.
Exceptions are those materials that are still mass-produced. These include (for now) microfilms and traffic surveillance films. Until the government changes the laws here and permits digital processes, these films can be repurposed.
As far as microfilms are concerned, the new ADOX CMS is a case in point. Crystal clear and with the highest resolution – making it perfectly suited for reversal processing.
So you can:
Stock up on Scala residues
Stock up on PO 100 Clear
Use Fomapan R
Develop ADOX CMS 40 in ADOTECH first and then continue with normal reversal processing
Use underexposure on Lucky and push it
Use ORT films
Some of the new Rollei (Maco) films also come from the technical sector. They should work too. Have a look on the Rollei website.
Best regards,
Mirko
Stagirit
For standard films, FP4, Neopan 400 and Tri-X are also suitable; generally speaking, films that do not use thin-layer technology but instead feature a classic emulsion (I’m not sure if this still applies to the current version of FP4).
What irritates me somewhat and which I cannot yet explain satisfactorily is this: when I fix the films without a stop bath in sodium thiosulphate (A300 from Calbe), the base fog is significantly weaker than when using a stop bath and Tetenal Superfix.
I noticed this again the day before yesterday when I developed a roll of Neopan 400 and compared it with negatives from the same batch that I had fixed using Superfix.
So far, I’ve always used acetic acid in the stop bath and haven’t tried ascorbic acid yet, but I intend to give that a go soon.
Gast
Ascorbic acid as a stop bath?
That’s ‘vitamin C’ – don’t you mean citric acid?
Stagirit
I didn't actually mean that, but after a quick bit of research, citric acid does seem like a better option.
Roman
Guys,
Ascorbic acid, citric acid and vitamin C are all the same thing!!!
(I'm expecting more detailed info from Franz now... ;) )
Roman
Gast
Guys,
Ascorbic acid, citric acid and vitamin C are all the same thing!!!
(I’m expecting more detailed info from Franz now… ;) )
Roman
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Unfortunately, you’re just a bit off the mark. Vitamin C and ascorbic acid (more precisely L(+)-ascorbyl palmitate, CAS number 137-66-6) are the same thing, whereas citric acid ((HOOCCH₂)₂C(OH)COOH, CAS 77-92-9) is something quite different. But they’re both white powders ;-)
Martin
Gast
Mirko,
if you go ahead with this and coat Efke on triacetate, but without an antihalation layer, then I will definitely stop buying Efke films.
The antihalation provided by triacetate is simply NOT enough; the result would be overexposure in any situation with significant contrast. I refer to:
Kisselbach, Theo; Darkroom Handbook, Seebruck am Chiemsee 1961, p.25
There, on the subject of ‘halo-free’ film, a lovely illustration is shown ‘from the monastery church at Altenberg near Wetzlar’, once with just a grey base – dreadful!
I’m slowly getting fed up with the empty promises used to hype up first the clear support and now the next ‘improvement’ that’s actually a step backwards.
Either an anti-halation layer AND triacetate, or leave everything as it is.
Roland
cfb_de
Hi Roland, hi Martin,
@Martin: Killjoy! :-)
@Roland: Then just do without the Efkes. For my part, I can only say that I’m absolutely delighted to finally be able to buy these wonderful films again *without* the drawbacks of the PET base.
There is absolutely no question of increased light spill (I’ve been making a direct comparison between ‘old Efke’ and ‘new Efke/ADOX’ for several years now), the triacetate base has significantly better flatness, shows no light-piping and is nowhere near as scratch-sensitive on the reverse side (where, on the PET base, a floppy ‘NC’ emulsion was applied thanks to Schröder).
Everything points to a return to sensible base materials. The only reason for PET would be – apart from the poorer antihalation protection! – and setting aside all the associated disadvantages, a socially motivated consideration for the three people who reverse transparency films from it.
It’s not without reason that I’ve been nagging Mirko for years to cast the Efkes onto proper base material again. Bad for Fotokemika, but good for us, that thanks to “Rollei” this is apparently finally possible again.
Best regards,
Franz
MirkoBoeddecker
Roland,
That’s not quite right.
1) All KB films have always been cast on this triacetate base – without any halo effect issues, even though they are far more demanding than roll films, as all flaws became disproportionately more noticeable with increasing magnification.
2) I’ve never complained about the advantages of the PET base; that was someone else. It always annoyed me. Films coming unstuck, light leak at the edges due to poor winding and the light-piping effect, roll films that lived up to their name...
3) We’re leaving everything as it is, namely going back to how it always was until five years ago!
Modern base materials cannot be compared to those in the book you quoted.
B U T: If you can get me some clear roll film base, I’ll make a mould just for you reversal developers, freeze it and have it made to order.
There is no clear roll film base left to buy anywhere in the world.
Without Agfa and the aerial surveillance films, that’s it for now.
So we need to make some changes and are now positioning ourselves to ensure it’s as future-proof and affordable as possible. Pre-financing 50,000 square metres of PET is more expensive than buying the required quantity of triacetate at a higher price and having less work with the antihalation protection. Not to mention that 50,000 square metres of roll film is probably enough to cover the entire planet until the sun falls into the Atlantic...
Best regards,
Mirko
Gast
Franz, Mirko,
The fact is that Schleussner supplied the film with a triacetate base and additional anti-halation colorant, not just one or the other.
If I’m not mistaken, Mirko has actually praised these tried-and-tested anti-halation colorants here on the forum.
When Mirko writes that the film was always like that, he perhaps means before 1960, but ADOX continued production until 1970, so why should we technically revert to the way things were back then?
After all, Agfa was also producing both until recently, not just one or the other.
Roland
Gast
ADOX was also a pioneer in antihalation technology.
The KB 21 was the first 35mm film to be coated with a double antihalation emulsion. It was a world leader at the time and, thanks to this Duplo AH emulsion, the most sharpest film in its class.
Our tests of the Lucky have not yet gone beyond Dmax determination and general photographic parameters.
I didn’t say the film was bad.
Mirko, you wrote that yourself here, back in the Lucky context.
MirkoBoeddecker
Roland,
Until the switch to PET in 1999 (suggested at the time by a competitor), the films were always coated on triacetate for cost reasons.
All other films are manufactured in the same way (Agfa, Foma, Fuji, Kodak, Ilford).
So if you no longer want to use ADOX because we no longer have a clear base and switch to another brand, you’ll end up with exactly the same product.
It’s true that ADOX films used to be coated with an additional anti-halation layer. Back then, however, the base films were also less effective at preventing halation.
This is down to the adhesion of the emulsions and the chemical inertness of these relatively expensive colorants. Today, there are better products to choose from.
Your concerns are unfounded. The antihalation protection is already built into the base and is entirely sufficient – probably even better than the one we used to have to laboriously apply to the clear base.
Lucky didn’t do that, and that’s the difference between ADOX clear bases and Lucky clear bases.
There have been certain changes in the market for technical films that have caused demand for this clear roll film base to drop so low that it is no longer manufactured.
Should halation issues really arise, one could consider an additional coating, but that would be a one-off and would make the film (unnecessarily) more expensive.
If you want to test it out, do a comparison between 35mm and 6x6, but remember to compensate for the enlargement factor when shooting by using a focal length extension, or compare a 6x6 crop with the 35mm format!
Best regards,
Mirko
Gast
Mirko,
I’ve got nothing against using triacetate fabric – that’s what I’d like to see too – but not if the benefits are more than offset by cutting corners elsewhere.
Perhaps I put that a bit harshly, but if the results end up being worse than they are now, that’s it – I’m out of it.
Roland
MirkoBoeddecker
Roland,
How long have you been using these films?
As I said, most users have been longing to go back to the tried-and-tested base for years and are fed up with PET.
As no one has had any issues with light sensitivity with this base material, I’m a bit surprised by your reaction.
I’m very keen to see your test results, though, if you decide to give it a go yourself.
I’ll have a go after Christmas at comparing the density of the two films using the densitometer.
Best regards,
Mirko
RomanJRohleder
Namd,
Let’s be honest – how many of us have ever reversed an Efke film?
Out of perhaps 50 R50s, I’ve only run one (plus someone else’s) through the Fomakit so far. Given the advance warning of the PET base being discontinued and if there’s a need, I’d freeze the stock and be absolutely chuffed to have any film processed in a standard negative lab.
No light piping, less critical regarding scratches, less hassle with halos when using a grey base, and flatness like Western films. Oh yes, Franz has already reported most of that.
As far as I’m concerned, Mirko can calculate my 10-year supply and stock up on it. Or the Czechs could make a real effort and produce the R100 in decent formats instead of those ridiculous stamp-sized rolls.
Somehow I prefer the latter; I’ve actually been writing an email to the Czechs about this for a year now; at some point I’ll really get round to it. ;-)
Roland,
PET substrates must be clear, whereas a triacetate substrate can also be produced as a greybase (see AP400/APX400 or the Fortes and Ilfords).
Where do you see the advantage of PET in this regard? It always requires a protective coating or other treatment during processing, whereas triacetate can already meet most requirements for antihalation in its raw film form.
Or is this a case of reading backwards from the old Schleussner advertising slogans, along the lines of “Because back then triacetate plus AHU coating was the best in the world, triacetate base is rubbish”? I can’t quite follow it; I’m missing the piece of the puzzle.
The only obvious catch to the story? Rodinal won’t be bubbling out of the Jobo in dark blue anymore.
Christoph,
Efke R50, EI50, 12 mins in the initial development stage using the Foma kit. Works fine.
Roman
Gast
Mirko,
I’ve been using ADOX for as long as I can remember; the KB 17 was my very first black-and-white film back in 1960, and my very first film ever was an ADOX Color NC17 that came as a gift with the camera.
I’ve also been using your triacetate-based Efkes (since 1998).
If I’m not mistaken, the films back then still had double antihalation protection.
To be clear, I’m not concerned about a clear base; I simply don’t want the films to become any worse than they are now in terms of antihalation – around 1970, they were truly excellent.
Roland
Gast
Roman,
let me make this absolutely clear: I want the quality standards of 1970 back, ideally triacetate with AHU varnish, because the AHU varnish plays a far greater role than the triacetate substrate.
Roland
Gast
Roland,
Not to mention checked suits, ties and slicked-back hairstyles!
Holiday trips with film cameras, German Railways officials in smart blue uniforms and weather that was always fine.
Germany must become once again what it never was
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