Neutral density with a colour head

[pentaxuser]

OK, does anyone know why the equivalent of ND in the form of CMY should reduce the contrast. Is it because equal amounts of CMY are not completely neutral as appears to have been stated or at least hinted at in other posts?

Thanks

pentaxuser

 

[koraks]

Probably just slight non-linearity or imperfect filtering of the filters in question. Half a grade at a reduction of about 3 stops isn't much.

 

[MattKing]

OK, does anyone know why the equivalent of ND in the form of CMY should reduce the contrast. Is it because equal amounts of CMY are not completely neutral as appears to have been stated or at least hinted at in other posts?
Thanks
pentaxuser

Probably just slight non-linearity or imperfect filtering of the filters in question. Half a grade at a reduction of about 3 stops isn't much.

Reciprocity issues might also be coming into play.
I would also check to make sure that both the before and after examples were fully developed at a developing time that is optimized for the paper - there is a real temptation to under-develop an over-exposed print.

 

[markbau]

Reciprocity issues might also be coming into play.
I would also check to make sure that both the before and after examples were fully developed at a developing time that is optimized for the paper - there is a real temptation to under-develop an over-exposed print.

It never ceases to amaze me how simple threads can go off topic. Here we are talking about neutral density by combining C.M and Y filters and now we are talking about print development times and paper reciprocity.

FWIW, Bergger recommend a development time of "1 1/2 to 2 min in any good paper developer" I time all my print development for 2 minutes, only newbies pull prints "when they look good". Even after 40 years of printing I cannot tell when a print "looks good" under safelight so have always stuck to temp controlled/timed development.
I doubt that there is a currently available paper that does not get to its DMax with 2 minute development in D72/Dektol 1:2 or Multigrade 1:9
With regards to reciprocity, if exposure times are arrived at by trial and error I fail to see how reciprocity can enter into it. Reciprocity only comes into it when some sort of meter reading needs to be adjusted for very short or very long exposure times.

 

[MattKing]

In the interest of clarity....
It all depends on how close to the boundaries of the usable range you were working when you did your tests.
With respect to the developing times, the information included in your most recent post makes it clear to me that you were working well within the recommended range, so I'm sure that the change in contrast isn't related to that issue.
On the issue of reciprocity, the question is more interesting.
It is my understanding that printing papers can run into problems with reciprocity failure when you work with short (less than 5 seconds?) exposures or particularly long exposures. In particular, variable contrast papers can run into contrast change problems, because the different emulsions (one or more of each of the "high contrast" and "low contrast") actually don't differ in contrast, they differ in sensitivity.
If you are working at the boundaries of the emulsions' sensitivities - either high intensity, or low intensity - than the performance response to a change in light intensity may differ between the emulsions - and therefore a change in light intensity may result in a change in contrast.
An exposure time that needs to be less than 5 seconds long may be bumping up against or crossing the reciprocity limits for the more sensitive of the "high contrast" and "low contrast" emulsions, while still being within the reciprocity limits for the other emulsion. When the intensity is reduced, the result may be that each of the emulsions may be better behaved - at least with respect to reciprocity.

 

[Mick Fagan]

It never ceases to amaze me how simple threads can go off topic. Here we are talking about neutral density by combining C.M and Y filters and now we are talking about print development times and paper reciprocity.

FWIW, Bergger recommend a development time of "1 1/2 to 2 min in any good paper developer" I time all my print development for 2 minutes, only newbies pull prints "when they look good". Even after 40 years of printing I cannot tell when a print "looks good" under safelight so have always stuck to temp controlled/timed development.
I doubt that there is a currently available paper that does not get to its DMax with 2 minute development in D72/Dektol 1:2 or Multigrade 1:9
With regards to reciprocity, if exposure times are arrived at by trial and error I fail to see how reciprocity can enter into it. Reciprocity only comes into it when some sort of meter reading needs to be adjusted for very short or very long exposure times.

For starters, I really am happy that you have solved your initial problem.

If you wish to get to the papers DMax quickly, generally speaking, bump the temperature up.

I have been developing Ilford RC B&W papers in my Durst Printo paper processor at either 30ºC or 35ºC for decades now. You want black, I have as black as the paper can do. The paper is in the developer for 45" only, then through a squeegee and straight into fixer for 45".

At 30ºC, standard development time is 22". At 35ºC, standard developing time is 15". Seeing that my paper is always in the bath for 45" then it is almost certainly going to be developed to its maximum black possibility.

With regard to exposure times, I am in complete agreement with you. If you are working to extremely long or extremely short exposure times and get there by trial and error, then what you see is what you get.

For quite some time I was in the postcard exchange and often was making around 50 prints or more from the same negative; one after the other. My exposure times using a 5x4" negative and really extended bellows, possible with a DeVere enlarger, were sometimes in the vicinity of 2" to 2.8" with particularly dense negatives maybe heading towards 5". I usually had pretty good technical standard of my prints. As to the subject matter, that was up to those who received prints.

Anything under 1" is usually a bit iffy, as the lamp itself needs to get up to speed. After that, anything up to 10 to 15 minutes or even longer when during mural sized prints, also works.

Durst 8x10" enlargers I have used with 1,000W heads, work around short exposure times by keeping the enlarger head lights on all of the time. They have a shutter blind, which does allow consistent short exposure to be used. We often used very short exposure times when duplicating film under an enlarger.

Mick.

 

[MattKing]

With regard to exposure times, I am in complete agreement with you. If you are working to extremely long or extremely short exposure times and get there by trial and error, then what you see is what you get.

I'm in agreement as well - as long as you realize that if after obtaining a satisfactory result you then substantially reduce the light intensity in order to increase the exposure time, the reciprocity behavior of the various components in the emulsion may require you to change the contrast settings in order to match that satisfactory result.

 

[btaylor]

I have been developing Ilford RC B&W papers in my Durst Printo paper processor at either 30ºC or 35ºC for decades now. You want black, I have as black as the paper can do. The paper is in the developer for 45" only, then through a squeegee and straight into fixer for 45".

At 30ºC, standard development time is 22". At 35ºC, standard developing time is 15". Seeing that my paper is always in the bath for 45" then it is almost certainly going to be developed to its maximum black

That is really interesting— I have a Durst Printo and I have done a fair bit of RA4 processing with it but it never occurred to me to run B&W RC through it at elevated temperatures. It would be out in daylight in a minute and a half— thanks for this info, can’t wait to try it.

 

[Mick Fagan]

That is really interesting— I have a Durst Printo and I have done a fair bit of RA4 processing with it but it never occurred to me to run B&W RC through it at elevated temperatures. It would be out in daylight in a minute and a half— thanks for this info, can’t wait to try it.

You will love it. After a bit of trial and error, I found that if the B&W paper comes out directly into a tray of water first, after which I pick it up with tongs and place it into another cleaner tray of water for about 30", hand rocking with a bit of vigour.

Meanwhile, immediately after I put the paper into the intro unit, I've switched on my separate roller transport paper dryer. By the time the paper has exited and been in the two water baths, I pop it through the now up to temperature dryer and I have a properly processed print that is dry and can be carefully examined for whichever direction I think I should go. Essentially, 3'.00" dry to dry is about where it is; neat eh?

I've printed shed loads of Ilford B&W RC paper through roller transport machines, 30ºC IIRC was pretty much where we were at. Those processors, were dry to dry, slightly slower than RA4. This was so the paper spent a bit more time in the dryer part to ensure it was really dry when it came out. As we often used 1.2m wide Ilford B&W RC roll paper, when it rolled up it would stick unless it was really dry.

The Durst Printo is wonderfully consistent with Ilford RC B&W paper and the chemistry lasts pretty well, regardless of what you use. For the last few years I have been using Either Ansco 135 warm tone paper developer, or E72, which is supposed to be a more environmentally friendly Dektol type of paper developer.

The E72 is really neat as the dilution can help slightly with contrast from the get go. 1+1 for high contrast 1+2 or 1+3 for lower contrast. Fresh developer at 1+1 at the start of a printing session, prints come out sparkling; makes one feel great.

If you use Kentmere paper, be prepared for a big suprise, exposure times are really, really short through the Durst. IIRC that paper has developer incorporated into the emulsion and it lets you know immediately.

The elevated temperatures do have a bit of an effect on longevity of the bath, but I've found fresh developer for each session works best. I have used developer the next day, but if you wish for it to shine, fresh is best. I use commercial B&W fixer as that works out to be cheapest. I get whatever I can purchase cheapest, I don't think there is really any difference between products in that part of things.

Cleaning the developer rack after each session is par for the course, as is ensuring the developer bath is full all of the time. Meaning you keep oxidation from discolouring the rollers to a minimum.

I mix my developers from raw chemistry, in case you were wondering.

Mick.

 

[markbau]

For starters, I really am happy that you have solved your initial problem.

If you wish to get to the papers DMax quickly, generally speaking, bump the temperature up.

I have been developing Ilford RC B&W papers in my Durst Printo paper processor at either 30ºC or 35ºC for decades now. You want black, I have as black as the paper can do. The paper is in the developer for 45" only, then through a squeegee and straight into fixer for 45".

Mick.

This is worth a further discussion. One of the many great habits I got from Tim Rudman's classic book was testing for maximum DMax (or as Rudman elegantly calls it " a paper yielding its maximum black"). In my experience most modern papers (Ilford MG classic, ADOX MCC) easily get there with 2 minutes development in developers like Ilford Multigrade 1:9 or D72 1:2) I'm sure very high developer temps would get to maximum black in even less time but maximum black is maximum black.

What I am particularly interested in is extended development time. If we agree that a given paper reached Max Black in 2 minutes, we can then develop that paper for 3 minutes. Even though we reached Max Black in 2 minutes, anyone who has printed will know that the print that received 3 minutes development will appear more contrasty, my question is, is this really more contrast? The highlights will be pretty much the same in the two prints. In other words, what are we actually seeing when we develop the print longer? The black isn't blacker.

I'm often torn between increasing contrast (via filters) by 1/2 a grade versus leaving the same filter but increasing development time. Do you think that both methods result in the same sort of contrast increase?

 

[MattKing]

In my experience, extending the development doesn't increase the contrast. Extending the development darkens the near shadows and lower mid-tones (in relation to the other tones in the print).
The result is different, but it isn't (IMHO) a difference in contrast. It is a difference in distribution of tones.
A change in contrast filters also changes the distribution of tones, but it is a different difference (if that makes sense).

 

[Mick Fagan]

Highlights are in the main made by exposure, or controlled by exposure. If you don't expose long enough, you won't have your fine highlight details.

Shadows are controlled mostly by your chosen contrast grade, the exposure time you give will alter them as well, but whatever contrast grade you give the paper is the greatest controller of shadows.

Complex, eh?

Many moons ago, I had the satisfaction of using a pair of 4x5" enlargers with Ilford multigrade heads. I was paid to do prints on what was state of the art equipment, mostly I would have done it for free as they were so easy and their ability to control shadow detail as you were printing, was amazing. Just watching the head change colour as you were printing, was magical enough; seeing the end product, was the icing on the cake.

Reasonably often we would be doing high key prints, this is where you realise that exposure gives you the highlight detail and altering the contrast for the shadow means you can stop the shadows becoming jet black. In other words, you (within reason) can control visible detail in shadows.

This doesn't mean I don't do longer developing times in my own darkroom, it just means I have never considered it as that great a tool for print excellence. Changing development time can and does make a difference, but not enough for me to worry too much about.

I concur with Matt, in post number 61.

Mick.

 

[markbau]

Whilst we know that exposure controls highlights and contrast grade controls shadows it’s actually not quite as simple as that. If we increase exposure, shadows will get darker, not as dark as a contrast increase but they will be darker than the first print. If we change contrast the highlights will usually be left untouched but areas around them will darken hence the whole print being more contrasty. When I first learned of Dr Beers developer as a way of getting in between grades when using graded papers I scratched my head a bit because I found the same result could be obtained by simply increasing development. So for years I used this method until VC became my papers of choice. I personally think that increased development is a valid contrast control tool but probably not as useful now when we have 1/2 grade filters and colour heads where contrast can be infinitely variable. The split grade people do the same thing. Anyway, interesting to discuss.

 

[Doremus Scudder]

Mark,

Most modern papers really don't change contrast much with extended development. What really happens is that the entire response curve gets shifted toward faster paper speed; exactly the same thing as adding a bit more exposure. I often use increases in development instead of small tweaks in exposure to fine-tune a print. Often, 15 seconds of extra development will make a noticeable difference.

It's interesting how "printing down" gives what amounts to more contrast in many cases. If a lot of important print values are blocked up on the toe of the paper (i.e., the highlights are all crowded close together), then adding a bit more exposure (or development) will pull these up into the straight-line section of the paper, separating them more. This is, indeed, more contrast for those particular values. And, as long as the shadows aren't negatively affected by the exposure increase, the print is usually better. This, however, more properly belongs in the process of finding the exact right print exposure, not nailing down the contrast. Note that adding more or less contrast with filtration won't help find the optimum exposure.

Best,

Doremus