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  #21  
Old 8th September 2014, 10:29 PM
Mike O'Pray Mike O'Pray is offline
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Basically, Michael, the two fix process is a very efficient method for fixing. You use both slots so the second slot is always very free from fix and ensure the prints wash easily. If you overuse the one bath then you might not fix the print properly but with a second bath you ensure the print is properly fixed. Once you have reached the limit of prints that say Ilford gives for a one bath fix then you dump that first slot and then the second slot become the first and you make up a fresh second slot.

That way you have a safety margin which is the second slot of much fresher fixer. I cannot recall his explanation but Ralph Lambrecht who wrote the book "Way Beyond Monochrome" explained why the two bath process was actually more economical in terms of fixer than the one bath.

As you have a 4 slot processor then it is definitely worth trying.

Mike
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  #22  
Old 9th September 2014, 07:16 AM
SanMiguel SanMiguel is offline
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Thanks Mike that's very helpful and sounds like its worthwhile.

MartyNL I'm using an older Stopclock, so my test strips are 1/4 stop. If I think the optimum time lies between two strips then I go into real-time mode and either do a second test strip manually or just set the time for a print accordingly. It's a great piece of equipment - takes a lot of the mental strain out of timing both test strips and prints.

Michael
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  #23  
Old 9th September 2014, 04:12 PM
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MartyNL MartyNL is offline
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I quite like this site
http://www.davidkachel.com/assets/fpsecret.htm
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MartyNL

“Reaching a creative state of mind thru positive action
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  #24  
Old 9th September 2014, 05:27 PM
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Argentum Argentum is offline
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Michael,

You may not be aware that Ilford filters (very good filters by the way) are what is called "Speed matched".

What this means is that when you change contrast/filter the print time remains constant. However, in reality this doesn't quite work out as an exact truth, largely because it relies on you being able to visually assess an exact print tone density which most of us can't or the required density doesn't exist in the subject.

Having said that, you should know that the Ilford filters you are using are speed matched on a highlight tone of around 0.3 LogD which in everyday speak means a highlight print tone which retains some textural detail.

Knowing that means that when trying to get your print time correct you should be using a highlight tone with some textural detail in it as the primary part of your image test strips to use for print time assessment.

When that highlight tone in the test strip is looking about right for print time, you can then change contrast/filter which will affect mostly the mid and shadow tones leaving the print time about the same. It will also adjust the contrast of tones above the selected hightlight tone but not as much as the mid and shadow tones.

So: Set print time based on a highlight tone with some texture to keep print times relatively constant and adjust contrast for shadows.

That's the theory but in reality there is always a little tweaking to be done but using a highlight tone with some texture in it is the best for getting to a decent starting time for a work print.

Note that if your negatives are much too soft or much too hard in contrast then it makes printing much more difficult and more changes in print time may be required in combination with contrast filter changes.

See graph at http://www.film-and-darkroom-user.or...5&postcount=62 which was made with ilford filters on MGIV

See how the different contrast grades cross over at the same point, Log of Density 0.3 which is the speed point for ilford filters on MGIV (or thereabouts)

(note that enlagers using dichroic filters will have a different speed point unless specifically calibrated for same speed point which most aren't)

Last edited by Argentum; 9th September 2014 at 05:35 PM.
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  #25  
Old 9th September 2014, 06:55 PM
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Argentum Argentum is offline
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I would add that depending on how you do your film exposure metering and the subject brightness range of your subject when taking the photograph, the resulting negative density of a highlight with texture in it is very likely to be different for each subject you photograph. This is especially true if you are exposing film for the shadows.
On the other hand if you are exposing film for the highlights (which is what an incident meter does) then your negative highlight densities will be far more consistent and the benefit of that is that you will get more consistent print times from one subject to the next.
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  #26  
Old 9th September 2014, 06:55 PM
Mike O'Pray Mike O'Pray is offline
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Quote:
Originally Posted by MartyNL View Post
Thanks for that. It certainly reinforces my point about why selling packs of 10 sheets of paper makes no sense at all for sellers or buyers.

Mike
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  #27  
Old 9th September 2014, 07:31 PM
Richard Gould Richard Gould is offline
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Quote:
Originally Posted by Mike O'Pray View Post
Thanks for that. It certainly reinforces my point about why selling packs of 10 sheets of paper makes no sense at all for sellers or buyers.

Mike
I would agree abouts packs of ten, but packs of 25 seems the norm from Adox, and 25 sheets in the larger sizes isn't bad
Richard
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  #28  
Old 9th September 2014, 09:07 PM
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Jakecb Jakecb is offline
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That's a useful link Marty and lucid advice from Argentum et al as usual too. I'm learning a lot in my darkroom but most of the time just by trial and error and often not knowing some of the whys to what I'm seeing. Good luck with your work Michael

By the way I bought that Monochrome book too and it has a lot of maths in it! Scary
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  #29  
Old 10th September 2014, 01:26 AM
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Quote:
Originally Posted by SanMiguel View Post
(although I'm aware that a x2 factor is mentioned with regard to grade 4 and above filters, this clearly isn't exact, or at least not for me and my setup).
The graph I linked to in my earlier post shows that in fact the x2 exposure time for grade 4 and above is bang on.
This was a real test I made to produce that graph and not some theoretical ideal representation.

BUT its only bang on for the speed point tone. Any non speed point tone will change with a change of contrast setting. And that means that if you have not set print time for that highlight tone, and were perhaps concentrating on something a bit darker, then in all probability it will appear that x2 for grade 4 and up is wrong because the tones will change more than you expected.

Also I have found that actually using twice the time instead of altering aperture (theoretically the same but not in practice)
is a more reliable way of using grade 4 and up. Reasons for this are aperture adjustments not being as accurate as you might think and also reciprocity effects that paper suffers from as well as being able to judge what should stay the same tone as you adjust contrast.

Getting the absolute correct balance between print time and print contrast is very tricky. The more you practice, the intuitive it becomes.

Last edited by Argentum; 10th September 2014 at 01:40 AM.
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  #30  
Old 10th September 2014, 10:30 AM
SanMiguel SanMiguel is offline
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Lots to think about here. Argentum I get your graph - very illuminating (excuse the pun) and many thanks for taking the time to explain all this. Regarding my own learning curve I'm not past the toe yet but this is all very helpful.

Interesting that most articles I've read advocate setting the print time based on the highlight tone (as per Argentum) and using the grade choice to settle the shadows, while David Kachel's article (thanks MartyNL) suggests the opposite.

And its reassuring to hear that getting the print time/contrast balance is tricky. I can see that Kachel's systematic approach to print-making has a lot of merits, particularly for a novice. At the price of paper I can see my Comask coming in handy.

Jakecb re trial and error I know exactly where you're coming from. But the more I read I'm realising that its not entirely a black art and although I'm still in the tunnel I can see a faint glimmer of light in the distance. At the minute its a balance between reading around the theory and practice in the darkroom - and I'd forgotten the pleasure you get from producing your own print, which you just don't get with the 'other way'.

Michael
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