[pres589]

I thought Clayton's advice on a two-stop push was to take normal time & temp for a given speed and increase by 1.5 at the same concentration. I took that to mean 6 minutes times 1.5 = 9 minutes. I then used MDC results for this kind of push based on D-76 (I know they aren't the same, I'm just looking for another reference) and it was something like 12 minutes. I guessed 11 minutes based on those two figures. What are you thinking for a two stop push from 400 to 1600 for HP5 or Tri-X or TMax 400 at 20c and the normal 1+9 dilution?

I can get it wrong but I'd like to try and get it right the first time. I've got a pile of HP5 for this purpose, not as much of the other stuff. Is there better guidance than what I've been using?

EDIT: Found this; https://www.photo.net/discuss/threads/pushing-hp5-what-do-you-suggest.160439/

Basically, 13ish minutes at 75F, per this guy that seems to work at Clayton. I think adding another minute for ~71F is probably about right.

[abruzzi]

Basically, 13ish minutes at 75F, per this guy that seems to work at Clayton. I think adding another minute for ~71F is probably about right.

If you use the massive dev chart's time/temp converter, and put in 75F for 13minutes, 71F for ??, it says you should go up to 16 minutes 14 seconds. Thats only a time/temp conversion with no reference to chemicals used or whether 13m at 75F was good to begin with. But it is a starting point. I don't know how much normal developing you've done, but especially when you get to shooting outside the recommended range, unless you have a lot of experience, picking some numbers off the net are going to be a crapshoot, and require tests before you have any idea if they work. I've pulled some that worked, and some that made useless negatives. The numbers are more trustworthy when they come off a spec sheet, so Kodak's time for developing TMX with Xtol shot at 100 is pretty darn good.

Massive Dev Chart Film Development, Film Developing Database

[pres589]

abruzzi, thanks, I agree. I can't seem to find "trusted" info from the 'net about what I'm trying to do. I'll give the roll 16 minutes and some change with the goal to have the developer completely out of the tank by 16 minutes, 15 seconds. I'm saving my results as meta-data in Lightroom so I should be able to track how this all works out. I think that's about the best I can do. Shoot, document, and shoot again. I'm cautiously optimistic.

[stevebrot]

I can't seem to find "trusted" info from the 'net about what I'm trying to do.

I would use Ilford's directions for D-76 as a starting point. According to their chart, that would be 12.5 minutes at 20C with normal agitation* for a push to EI 1600 using "stock" D-76 (F76+, 1+9). Remember that a two-stop "push" is actually two stops intentional underexposure from box speed with significant over-development in an attempt to build appropriate density in the highlights (low values fall where they may with resultant increase in global contrast and loss of shadow detail).

Ilford Photo | Development Chart (PDF)

Bracketed exposures of typical subjects along with the same for a test setup (include at least one object representing true white with texture, zone VIII - IX) will give an indication of a working EI for a given time/temperature. Note that the intent is to find a working EI for a given time/temp rather than a time/temp for a desired EI. That last is a more elusive target.


Steve

* For small tank by inversion, Ilford suggests 4x in the first 10 seconds followed by 4x in the first 10 seconds at each minute mark.

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Last edited by stevebrot; 09-26-2018 at 10:41 AM.

[pres589]

Is there guidance somewhere on how to shoot a roll of film at specific "targets" to make it possible to find the effective working EI for a given time/temp? This isn't something I had thought about previously but should have considered before ordering a pile of film and shooting/developing as fast as possible.

[Alex645]

Is there guidance somewhere on how to shoot a roll of film at specific "targets" to make it possible to find the effective working EI for a given time/temp? This isn't something I had thought about previously but should have considered before ordering a pile of film and shooting/developing as fast as possible.

Are you familiar with Ansel Adams' Zone System? It specifically and technically addresses exposure and development times based on your key gray scale target and desired contrast. That's a gross simplification, but the Zone System has become the default answer for B&W wizards for decades.

[pres589]

Not really. I was hoping there was some kind of card I could print or order that I could then take pictures of in various lighting with the camera set to an ISO then test different dev times at a fixed temp to try and determine how close the test dev scheme is to real.

[Alex645]

Not really. I was hoping there was some kind of card I could print or order that I could then take pictures of in various lighting with the camera set to an ISO then test different dev times at a fixed temp to try and determine how close the test dev scheme is to real.

So if I understand, a gray card with Zones 1 thru 10. Zone 1 is black with no detail and Zone 10 is paper white with no detail. Look at this link and scroll down to the "Meter Standard Value" image.

Zone System And Metering | Alan Ross Photography

[pres589]

I don't have to go with the card route. Do you have some other recommendation besides this?

[Alex645]

I don't have to go with the card route. Do you have some other recommendation besides this?

Sorry, I have found there is no substitute to experience and taking notes. There are just too many variables from the film age and stock to the developer type, temp, dilution, age, agitation method, water pH, etc; not to mention your subjective aesthetic response and the subject matter and lighting. Also what paper will this be printed on, using what paper developer, or will it be scanned, and if so what are the variables there?

Now that I've been a photography teacher for more years than I was a photographer, I realize that simple answers can and should be followed by dozens of questions. The more I teach, the more I realize how much I do not know and how much more I have to learn, and the best teacher is still a student at heart.

I know that's not the recommendation you wanted from me.....but hopefully others will have other suggestions that may "click" with you.

[pres589]

On, no worries, I was really asking for your favorite method to get to the solution. Card or something else. Sounds like card time.

It sounds like the roll of HP5 that I shot at 1600 needs to wait in the fridge for a while OR I get a more common developer like HC-110.

[stevebrot]

Is there guidance somewhere on how to shoot a roll of film at specific "targets" to make it possible to find the effective working EI for a given time/temp?

I gave a suggestion much earlier in this thread, but I will share it again in more complete form. The intent is to challenge the dynamic range and is based loosely on aspects of Ansel Adams zone system. My setup includes:

• A black plush toy
• A small camera bag made of dark gray ballistic nylon
• An eleven-step exposure wedge
• An 18% gray card
• A pure white terrycloth washcloth

Here is how I use it to assess recommended time/temp for box speed:

1. Shoot most of a roll using one's common subjects
2. Reserve 5 or more frames for bracketed exposures at 1/2 or 1 1/3 stop increments covering two stops either side of metered exposure*
3. Use the test setup for the bracketed exposures, metering off an 18% gray card for the base exposure. Avoid the wider apertures help insure similar lens contrast for all frames in the bracket. It helps to include a note in the frame indicating the bracket used (1+, 1 1/2+, and so on) as well as metered EI.
4. Process the film using the intended developer/time/temp/agitation
5. Fix and dry the negatives and closely inspect the whole roll (use a magnifier loupe) with an eye towards overall density, blocked highlights, shadow detail, and highlight texture. Give particular attention to the bracketed test series. A good exposure will result in each section of the exposure wedge being visibly distinct from its neighbor(s) and texture/detail should be visible for the near black plush, the camera bag, and the white washcloth. Loss due to over/under-exposure or dynamic range compression will generally be obvious.
6. If any of the bracketed exposures perform better than the metered EI, shoot another test roll with the EI adjusted up or down to match the better bracket shot.

The situation for push-processing is similar except that loss of low values is somewhat unavoidable for over a one-stop push.


Steve

* There are differing opinions regarding direct vs. indirect lighting for the formal bracketed test shots. I have used both direct sunlight at noon and indirect noon light from a south-facing window (window not exposed to sun, but is exposed to south sky). The important thing is to measure either from a gray card or from an incident light metering.

[stevebrot]

Are you familiar with Ansel Adams' Zone System? It specifically and technically addresses exposure and development times based on your key gray scale target and desired contrast. That's a gross simplification, but the Zone System has become the default answer for B&W wizards for decades.

More specifically, Adam's book "The Negative" covers the topic in full detail. I have the earlier edition (gray cover), but believe that the content is essentially similar in later editions.


Steve

[stevebrot]

It sounds like the roll of HP5 that I shot at 1600 needs to wait in the fridge for a while OR I get a more common developer like HC-110.

Nope! Your developer is fine for a 2-stop push. You will face similar questions with HC-110 with the added challenge of dealing with its syrupy consistency.


Steve

[tuco]

Is there guidance somewhere on how to shoot a roll of film at specific "targets" to make it possible to find the effective working EI for a given time/temp? This isn't something I had thought about previously but should have considered before ordering a pile of film and shooting/developing as fast as possible.

You can take shortcuts and learn by trial and error with the zone system with scanninig. But normally the procedure is first to do a speed test to establish a working EI. Many developers are not box speed. A densitometer and a one degree spot meter is usually needed.

You find what EI puts zone 1 at a density of 0.10 above the film's base + fog. Once you have a working EI you need to find a development time that places zone 8 at a specific density. That density depends on a target contrast index for either a diffusion or condenser enlarger. If you only scan, I would target a diffusion enlarger's density. I don't remember those numbers right now but you can look them up. You'd have to do this for each film you use. That's a lot of work.

Now you would meter a scene by "placing" a tonal value below or above your middle gray with a one-degree spot meter. Placing shadows 3 stops below the middle gray (zone 2) is typical but if you wanted to see more detail you might place them 2 stops below. Similarly you might want to favor highlights were you might place them 3 stops above your middle gray. A reading from a spot meter is a middle gray value.