Achieving more contrast with D-76

[Adrian Bacon]

1. At last someone who prefers healthy negatives (versus wimpy negatives)
2. Certainly grain ("noise") increases with dev time. But so does the image contrast ("signal"). Not clear whether signal-to-noise is actually degraded.
   I remember a thread where the OP was after intentional grain, and someone gave the advice to develop to low contrast and print on grade 5. Even easier with a s*****r because output range can be expanded almost arbitrarily.

lol... yeah, I like a “healthy” negative.

The appearance of grain is affected by both development time and contrast applied during post/print. If you use an appropriately matching tone curve, grain really isn’t so objectionable. If you under develop and jack the contrast way up (in post/print) it’s going to look grainy. If you over develop and jack the contrast way down, it won’t look as grainy. If you know what the characteristic curve looks like for a given time, you can use a matching tone curve to straighten it back out to gamma 1.0 and end up with grain that is present, but not particularly objectionable. This is assuming your density range is within what you can scan and still keep a lot of discrete tone values per stop of exposure. Once you go under a certain number of discrete tone values, no matter what you do, the grain starts to look chunky. Lots of people mistake it for grain aliasing, but it’s really just not having enough discrete tone values per stop of exposure.

 

[pentaxuser]

Thanks for the reply Adrian. So I infer from what you said that Kodak supplies times for replenished Xtol but Ilford does not? Can you say why replenished Xtol is not even close to stock Xtol but more like 1+1 or even close to 1+2? I thought that replenished Xtol was Xtol stock that on each occasion is topped up with some more stock to replace what effectively has been used? When you start this process isn't the first replenishment close to the original stock? What is it about replenished Xtol that makes it close to 1+1 or 1+2?

I note that Ilford's time for Xtol 1+1 is 12 mins at 68F so at 75 according to the ilford processing temp chart it drops to about 7 mins which is your time for replenished Xtol so the Ilford chart seems to indicate the same development time that you mention on your site which suggests that Ilford is very close to your regime so I am unclear what Ilford being on the high side refers to in your quote

What is the ISO contrast in terms of a number and how do you arrive at it? . In effect I think I am asking how do you establish it and if Kodak figure is lower than the Ilford figure where lies the ISO contrast figure in comparison with both Kodak and Ilford?

It is only by asking questions that I will understand matters and I appreciate you taking the time to answer

Thanks

pentaxuser

 

[MattKing]

What is it about replenished Xtol that makes it close to 1+1 or 1+2?

The development byproducts that remain in the working solution and tend to act as restrainers.
Each time you develop a film, the chemical capacity of the working solution is partially used up, and development byproducts are added to that working solution.
Replenishment involves taking some of the used developer out - thus removing some of the byproducts - and adding some replenisher (in X-Tol's case, fresh developer) - thus replacing used chemical capacity.
If each time you develop a film you take out the right amount of used developer, and add the right amount of replenisher, the working solution will reach a steady state that both performs well and maintains stability.

 

[Adrian Bacon]

Thanks for the reply Adrian. So I infer from what you said that Kodak supplies times for replenished Xtol but Ilford does not? Can you say why replenished Xtol is not even close to stock Xtol but more like 1+1 or even close to 1+2? I thought that replenished Xtol was Xtol stock that on each occasion is topped up with some more stock to replace what effectively has been used? When you start this process isn't the first replenishment close to the original stock? What is it about replenished Xtol that makes it close to 1+1 or 1+2?

I note that Ilford's time for Xtol 1+1 is 12 mins at 68F so at 75 according to the ilford processing temp chart it drops to about 7 mins which is your time for replenished Xtol so the Ilford chart seems to indicate the same development time that you mention on your site which suggests that Ilford is very close to your regime so I am unclear what Ilford being on the high side refers to in your quote

What is the ISO contrast in terms of a number and how do you arrive at it? . In effect I think I am asking how do you establish it and if Kodak figure is lower than the Ilford figure where lies the ISO contrast figure in comparison with both Kodak and Ilford?

It is only by asking questions that I will understand matters and I appreciate you taking the time to answer

Thanks

pentaxuser

the way replenished xtol works is you put 70ml of fresh stock xtol in your bottle of working solution for every 80 square inches of film developed, and then top off the bottle of working solution with your freshly used xtol that you just developed with. The bottle of working solution has both fresh xtol and used xtol in it and so does not give the same results as fresh xtol, hence, different development times.

in my experience, every emulsion responds differently to replenished xtol and I’ve yet to see a sure fire easy to calculate way to figure what the replenished time will be from the stock times. You can see this just by looking at the times Kodak publishes in J-109. The time from stock to replenished doesn’t seem to fit a known good pattern. Some emulsions have almost no time difference between the two, and others have a relatively large difference.

Ilford does not provide replenished times, but Kodak does for some Ilford films, however those times are for the higher 0.58 contrast, not for the 0.56 contrast that Kodak gives for Kodak films. I’ve found that it’s easier and simpler to just simply settle on a given contrast as a standard and work out a time for a given film through testing. For me, since I process a lot of film for other people, that standard is 0.62 since the vast majority of people don’t give enough exposure, and I want to provide as much speed as I reasonably can.

Specifically, with HP5, Ilford’s time is with their agitation, my time is in a JOBO with continuous agitation, which will produce more contrast if everything else is equal.

in terms of actual numbers, to calculate contrast, you divide the density range of the film by the exposure given, so for example, the ISO standard specifies the speed point as 0.1 log above film base plus fog and that 1.3 log units of exposure (4.33 stops) should result in 0.8 log units of density above the speed point. So, 0.8 / 1.3 = 0.615, round it up to 0.62 for simplicity’s sake.

To determine the contrast of a given film for a given time, a very simple way to do it is to correctly expose an 18% grey card at a given ISO, then subtract 4 stops from that exposure and make another exposure of the grey card at that lower exposure level. Process the film and measure the two density levels. Subtract the lower one from the higher one to get the difference then divide that by 1.2 (4 stops of exposure In log units). That is your contrast level. For example, if I did this and had 0.85 density and 0.1 density for my two points, that would be 0.85 - 0.1 = 0.75. 0.75 / 1.2 = 0.625. Close enough to 0.62 contrast that I wouldn’t even skip a beat. You can do the same thing with Kodak’s replenished times and measure them. They are consistently less contrast than ISO contrast. Again, Ilford tends to be higher contrast than Kodak, but both are consistently lower than ISO contrast.

 

[baachitraka]

...the way you have developed your first film, could be your desired contrast now...and this holds pretty much for the grain.

 

[M-88]

Not at all!!

You've got enough information in this thread already to make you an expert

Problems arise with the normal sequence of adjusting developing time to get the contrast you need for printing when your "printing" involves scanning, however.

In a purely analog workflow, one strives to find a development time that consistently gives negatives that print well on a medium-contrast-grade paper (e.g., grade 2 or 2.5). That gives lots of leeway on either side to deal with negatives from very contrasty or very flat scenes. Scanning throws a whole bunch of other variables into the mix in the form of automatic adjustments by the scanning software, etc. Still, the goal is the same: find a film speed and development time that works for you and gives you prints you like.

None of the manufacturers' recommendations are carved in stone; they are simply starting points. Every black-and-white photographer finds their own combination of personal film speed and development time.

It doesn't have to be complicated either (like the Zone System or BTZS). Just follow Kodak's simple advice:

If your negatives consistently need more shadow detail, expose more (i.e., use a lower effective film speed or E.I.). And vice-versa.
If your negatives are consistently too flat, develop longer, and vice-versa.

Keep playing around with the variables till you find what you need in terms of good shadow detail and negative contrast.

Best,

Doremus

I do get the feeling that it would be nice to try and print something eventually.
I also get the feeling that it would be wise for me to buy a 30 m bulk roll of film, purely for experimental purposes, to get the hang of all the adjustments.

...the way you have developed your first film, could be your desired contrast now...and this holds pretty much for the grain.

My first film was a roll of Kentmere 100. I haven't shot it in two years now... But mostly I agree.

 

[pentaxuser]

The development byproducts that remain in the working solution and tend to act as restrainers.
Each time you develop a film, the chemical capacity of the working solution is partially used up, and development byproducts are added to that working solution.
Replenishment involves taking some of the used developer out - thus removing some of the byproducts - and adding some replenisher (in X-Tol's case, fresh developer) - thus replacing used chemical capacity.
If each time you develop a film you take out the right amount of used developer, and add the right amount of replenisher, the working solution will reach a steady state that both performs well and maintains stability.

Thanks Matt. My difficulty is why based on this replenishment regime and thus removing some of the byproducts then adding fresh developer thus replacing used chemical capacity you don't end up with or very close to what is the same as "new" Xtol which is what you use as one shot? Can it really end up more like Xtol 1+1 or in some case nearer 1+2?

pentaxuser

 

[pentaxuser]

Thanks Adrian as you will see Matt has also explained what the replenishment regime does and based on his explanation as to what the replenishment process actually is and does I have asked him how this results in replenished Xtol being different enough from fresh Xtol to be closer to 1+1 or even 1+2

I also note that in the Ilford literature it says that its times result on a Gbar of 0. 62 which is the same figure you quote as your ISO figure so does this mean that Gbar 0.62 is less than your 0.62 and what is it that makes it different and by how much if you were to translate your 0.62 into Ilford Gbar 0.62?

Thanks

pentaxuser

 

[138S]

Can it really end up more like Xtol 1+1 or in some case nearer 1+2?

No the same. Developer consumption depends on how dense is the negative, one roll may use more developer than the next one.

Kodak says that a minimum 100ml of stock dilution should be used for a 35mm roll one shot, in this way available developer will be able to make all negative black, but a particular film may spend less. With Replenishment you add 70ml of Xtol for each roll you have processed so you save 30% of the chem.

how much if you were to tranlate your 0.62 into Ilford Gbar 0.62?

There is no direct formula to convert one to the other, because for each film curve it's different, but difference is small. Difference is how you select the points to make the gradient calculation.

See here C.I. average gradient (g bar), gamma... pages 8 to 10:

https://www.kodak.com/uploadedfiles...en_motion_education_sensitometry_workbook.pdf

 

[MattKing]

Those development byproducts are very powerful.
It is not all that different from the results one obtains by adding a restrainer like benzotriazole.

 

[pentaxuser]

No the same. Developer consumption depends on how dense is the negative, one roll may use more developer than the next one.

Those development byproducts are very powerful.
It is not all that different from the results one obtains by adding a restrainer like benzotriazole.

QUOTE]

So 138S the replenished Xtol is the same as one shot Xtol?

Matt What does your statement mean in terms of the question I have just asked 138S. I note you have already said that these development by products are removed when you replenish

I am simply trying to get clarity on what in practical processing terms changes.

Finally how close, in your opinions, is Ilford's Gbar of 0.62 to that of Adrian's measure of ISO contrast of 0.62. As you will see if you read my posts to Adrian i make the point that at stock solution and at 75F Ilford's Xtol comes close to about 5 mins 30 secs whereas it would appear that at 1+1 Ilford's 12 mins at 68F is slightly above Adrian's time for replenished Xtol at about 8 mins as opposed to Adrian's 7 mins albeit that this is rotary processing so the times if we use the Ilford recommendation to subtract 15% and then convert to 75F gets us very close to Adrian's 7 mins

So it would appear that Adrian's contention that replenished Xtol is closer to times needed for one shot at 1+1 would seem to be right but this is only the case if steady state replenished Xtol is not the same as stock Xtol used once and dumped.

So it all comes together as an explanation if all the byproducts are not removed from the Xtol via replenishment which is what you may be saying Matt. I just need confirmation of this

Thanks

pentaxuser

 

[138S]

Those development byproducts are very powerful.
It is not all that different from the results one obtains by adding a restrainer like benzotriazole.

Well, the important by-product is Bromide, which is has a similar restrainer effect than benzotriazole. For paper Br may change tone to warm and benzo not, but for film they do a similar job, IIRC.

 

[pentaxuser]

138S, I hope you can reply to my question?

Thanks

pentaxuser

 

[MattKing]

So 138S the replenished Xtol is the same as one shot Xtol?

Matt What does your statement mean in terms of the question I have just asked 138S. I note you have already said that these development by products are removed when you replenish

I am simply trying to get clarity on what in practical processing terms changes.

Thanks

pentaxuser

Creative quoting here
I'm not exactly sure which question you are referring to.
The important thing to understand is that as you replenish, you are removing some of the development by-products (primarily bromides, as 138s says) and leaving some of them in the working solution. At the same time, you are putting back enough chemical capacity to restore the working solution to the same level of activity. Once you reach a steady state with respect to the level of chemical activity and the amount of development byproducts in the working solution, that chemical capacity and the level of those byproducts are, not surprisingly, quite steady.
The level of chemical activity of that steady state working solution is quite similar to the level of chemical activity of more dilute fresh developer - similar to the level of chemical activity found in 1+1 or 1+2 dilutions of fresh X-Tol. As a result, the developing times for replenished X-Tol are similar to the developing times for those dilutions of fresh X-Tol.
However, even if the development times are the same (meaning that the contrast obtained is the same), it doesn't mean that there aren't subtle but appreciable differences between the results concerning things like acutance, grain and tonality. For those reasons, diluted fresh X-Tol isn't the same as replenished X-Tol, even when developing times happen to match.

 

[138S]

138S, I hope you can reply to my question?
Thanks

Replenished xtol is not exactly the same than one shot, but very similar, and mostly the same if time correction is well adjusted, but a perfect correction requires some work.

Imagine you use a yankee tank, you develop say four 4x5 sheets, first time you have the same than with one shot or even a more intense development because developer will exhaust less than with one shot, as you have developer in excess.

Second time you add fresh developer but the resulting mix is a bit less active than the first time, as some used developer is there.

After some batches the developer activity achieves an stability, by using test strips you can correct development time to perfection (https://www.ilfordphoto.com/1672109) if you want.

______

In practice... say you want to use Xtol stock for finest grain in a tank that needs 500ml for two rolls... then you are to waste 60% of the developer one shot...

For the next batches of two rolls you may reuse developer by discarding 140 to 200ml and adding the same amount of fresh developer. You may have to extent developing time a bit for the same effect, but you may reuse developer indefinitely by replacing 70 to 80 ml per roll each time.

______

So, finally, "one shot" is more consistent than replenishing, difference may be narrow, but "one shot" may waste a lot of developer depending on your tank system and desired dilution.

Also it has to be pointed that a negative slightly underdeveloped is no problem, it can even be benefical many times. Not the same than underexposed, underexposure easily damages, but for Large Format we underdevelop many times for benefical effects, personally I underdevelop quite a lot (N-1 at least) half of the times.

IMO some underdevelopment from developer strength variability is not a concern. Presently I develop sheets in trays 1:1 and I waste little developer, so I don't need anymore replenishing, but time ago I was using it with the yankee tank, with perfect results.

 

[pentaxuser]

Thanks both and that largely clears matters up and cover the fact that the Ilford times for 1+1 allowing for temperature and Adrian's rotary processing is now very close to Adrian's times. I now also appreciate why Xtol 1+1 one shot is not quite the same as replenished Xtol.

In the absence of a direct reply I think I can assume that Ilford's Gbar of 0.62 has to be very close or even the same as what Adrian refers to as ISO contrast. Initially and in the absence of an explanation I was puzzled by Adrian's time having made what is clearly the wrong assumption that when you replenish Xtol you are effectively restoring it to the same as fresh Xtol which was what started my questions in this thread

pentaxuser

 

[Adrian Bacon]

Thanks Adrian as you will see Matt has also explained what the replenishment regime does and based on his explanation as to what the replenishment process actually is and does I have asked him how this results in replenished Xtol being different enough from fresh Xtol to be closer to 1+1 or even 1+2

I also note that in the Ilford literature it says that its times result on a Gbar of 0. 62 which is the same figure you quote as your ISO figure so does this mean that Gbar 0.62 is less than your 0.62 and what is it that makes it different and by how much if you were to translate your 0.62 into Ilford Gbar 0.62?

Thanks

pentaxuser

what others have said.

with respects to GBar, I’d have to go look up the points used for measurement as I don’t remember off the top of my head. I’d imagine it would be similar, but again, that is Ilford’s recommendation for non-replenished xtol. Kodak does have a time for HP5 with replenished xtol, but is for the lower 0.58. The thing I don’t know about Kodak’s stated contrast is if it’s for gbar or contrast index. I do know that when I use Kodak’s times, a correctly exposed middle grey card is typically between 0.70 and 0.80 density above film base plus fog, whereas ISO contrast should be ~0.85 above film base plus fog.

 

[cliveh]

Well have you got your development time/temperature correct?

 

[jvo]

remember there is the science of photography, there is also the art of photography...one objective, one subjective. you adjust to deal with both as you see fit. one will never overcome the other and achieve a satisfying result.

p.s. have fun

 

[138S]

what others have said.

with respects to GBar, I’d have to go look up the points used for measurement as I don’t remember off the top of my head. I’d imagine it would be similar, but again, that is Ilford’s recommendation for non-replenished xtol. Kodak does have a time for HP5 with replenished xtol, but is for the lower 0.58. The thing I don’t know about Kodak’s stated contrast is if it’s for gbar or contrast index. I do know that when I use Kodak’s times, a correctly exposed middle grey card is typically between 0.70 and 0.80 density above film base plus fog, whereas ISO contrast should be ~0.85 above film base plus fog.

Contrast Index and GBar are "Stated Contrast", what the manufacturer "says", and in depends on how they selected the points in the curve

"Contrast Index is the slope of a line between two particular points on the D-Log E curve. These two points are the minimum and maximum densities on the curve that are normally used to make high-quality negatives. The minimum point falls somewhere on the toe of the curve, meaning that the shape of the toe influences Contrast Index. Thus, it is unlike gamma, which is the slope of the straight-line portion only". https://www.kodak.com/uploadedfiles...en_motion_education_sensitometry_workbook.pdf

I'd add that selecting what "somewhere" also is a factor.


But points for ISO contrast (ISO speed calculation) is very well determined.

I do know that when I use Kodak’s times, a correctly exposed middle grey card is typically between 0.70 and 0.80 density above film base plus fog, whereas ISO contrast should be ~0.85 above film base plus fog.

Yes... kodak recommended times are a bit longer than ISO, I guess this is a "commercial" safety belt for pitfalls in the development like lower temperature, lack of agitation, seasoned/reused developer, filling time... if one underexposes and later he underdevelops then he may blame the developer's manufacturer, a bullet proof too dense negative can always be reduced with Farmer's, and nobody will say that the developer was flawed.

If you check the TMX datasheet the 8:30 time they recommend for Xtol stock, small tank, it delivers around CI = 0.68 or 0.69, a bit higher than the 0.62 ISO states.

 

[Dusty Negative]

I am watching this thread with great interest. I have always struggled with HP5+ and never quite understood the origins of its iconic status. Yet, I keep trying, perhaps because I'm drawn to the mystery of its popularity. I get pretty good results with stock D76* and stock Xtol. Contrary to internet advice, my 1+1 output with those developers is muddier and grainier. DD-X has been flat & grey regardless of the dilution and development time. Basically, HP5+ is by far the trickiest film I have ever used.

On the other hand, Adrian here suggests that you can develop HP5+ and Tri-X to nearly the same contrast and grain. I hold his advice in high regard, but I can't shake off the feeling that there's something off about HP5+ because the question about compressed midtones and the flat look keeps coming up, and it's hard to ignore the pronounced difference between developers with this film.

Also, it performs waa-a-ay better in 120 format for me, vs 35mm. Obviously all films look better in medium format, but HP5+ is, again, special.

* "Stock D76" is Ultrafine D76 for me, not Kodak's

Have you ever shot it at 1600? I actually gave it up for Tri-X (for the exact reason you mention) but stumbled on a box the other day and shot it at 1600 as kind of a Hail Mary. It was gorgeous.

 

[M-88]

Have you ever shot it at 1600? I actually gave it up for Tri-X (for the exact reason you mention) but stumbled on a box the other day and shot it at 1600 as kind of a Hail Mary. It was gorgeous.

Right now that is what I do with Tri-X and HP5+. Or at least shoot at EI800, because shooting at box speed gives bland results no matter the agitation technique.

 

[Bill Burk]

I once tested a wide range of times. The main idea is to use D-76 1:1 until about 17 minutes then switch to D-76 stock for 12 minutes (same as 17 1:1) then 24, 36 and 48 minutes. Somewhere in that range of times you should find enough contrast to do anything.

http://beefalobill.com/images/tmxfamily.jpg

 

[M-88]

http://beefalobill.com/images/tmxfamily.jpg

This is great, I should print it and hang it on my wall.