I only have a McBeth reflection densitometer, made in probably the early 80's, of unknown calibration. So I guess it's back to the Zone 1 method. So far it is evident already that this Fuji HR-T green is much lower than the ASA 80 as described by a few guys in the LF forum. Seems I need to move my test range a good bit lower.
Please keep in mind that HRT is not panchromatic film and it's green sensitive. The film is not sensitive to warm colors like oranges and reds. So red objects that have a high luminescence might show up as black on your film. You can make this an advantage by processing Fuji HRT under a safelight and process by eye. I've done some test and with HRT and I've rated my film at ASA 200 with XTOL. Also the film has no anti-halation backing and there's an emulsion on both sides. The emulsion gets really soft and best processed in hangers or with flat bottom trays.
Man, that's wild, According to the zone 1 test I just did, I'm getting a film speed of 25, maybe a hair faster--40 tops. That is with D-76 1:3 6 minutes at 70-72 degrees. I wonder why there's such a big difference? You say 200, some on the LF Form say 160, a lot more say 80, and I'm getting 25. Very strange. But I've already tried shooting an actual photo at 80 and it was underexposed bad. I'm asking around to friends for a computer mouse I can cut up and make a shutter tester out of, but my shutter SEEMS pretty close already. That's the only variable I can think of. My meter is dead on the money. It's a Luna-Pro that I put a 1.35 volt voltage regulator in, and it is in line with my 2 SBC's and my Sekonic.
Originally Posted by Mainecoonmaniac
OK. If it were standard film and developer, I'd be able to help more...
Did you use a "Tungsten" light source? That might be way slower than daylight if I put 2 and 2 together right about red sensitivity (because Tungsten bulbs are "sort of" on the reddish yellowish side of the spectrum).
Next, I'd seriously develop longer. This could account for less speed than expected. Maybe you'll eventually find your time should be 10 to 16 minutes.
And finally since you kind of estimated the speed at 25 - use that as your Exposure Index to base your calculations for the high "Zones" exposures.
No, any more development than 6 mins 1t 70-72 degrees just runs up contrast and gives no help on speed. Am in the middle of fabricating my shutter tester to eliminate shutter as the problem, but so far I'm leaning towards a final ASA of 32. I realize this is only ortho film, but that's no reason not to expect a proper tonal range on most outdoor scenes.
One thing I'd like to pick MichaelR1974's brain about is that he calls D-23 a compensating developer, while having once taken issue with me when I called Microdol a compensating formula. Since Microdol is bacically a D-25 derived formula, and D-23 and D-25 are both 100G/7.5G per liter base mixtures, then if one is compensating, then is not the other? And how in the World could D-76 bear any similarity to D-23 in final results? D-76 is a Metol/HQ formula with 6 or 8 other things in it. At this time, I'm avoiding going the pyro route because it'll cost me 35 bucks to get the first drop of it here from the Formulary. Plus the fact, my bare fingers spend a lot of time in the tray. I hear that pyro can be some nasty stuff to keep your fingers dipped in.
Whoa, whoa, whoa, and whoa.
A didn't say D-23 was compensating. I said it wasn't compensating. The other people in that D-23 thread said it was compensating, and I disagree. Also, Microdol would be more accurately referred to as a D-23 derived formula, not D-25. In any case, these are not compensating developers. If you want a truly compensating developer you need low concentrations of specific developing agents and sulfite - and a relatively strong alkali along with weak buffering. Crawley's FX-2 is an example.
Re how does D-23 work like D-76, it waas designed by Henn to work that way. D-76 does not have 6 or 8 other things in it. The published formula is:
Now, consider at the working pH of D-76, Hydroquinone is not directly active, but rather plays a relatively minor role in "regenerating" the Metol. Grant Haist, while working on a solution to the pH instability of stored D-76, showed that by omitting the Hydroquinone and increasing either the Metol or Borax by 0.5g/l, the working characteristics would be indistinguishable from D-76, although capacity may or may not be lower. Hence the formula for Haist's version of D-76:
A good generalized description of the original D-76 in Haist's book is 2g Metol free base in a 10% Sulfite solution, with just enough Borax added to neutralize the acidity of the Metol salt.
D-23 was originally developed as an alternative. More Metol, no Borax. Since the working pH is lower, development times are different and solvent effect is slightly increased. As a result it is said to produce slightly finer grain than D-76 with approximately 10-20% speed loss, which was determined to be of little consequence in the face of improved consistency, which was of benefit to commercial labs.
The point is, you can end up with virtually identical results from different formulas. Just because one formula contains more compounds doesn't inherently mean anything without looking at the interactions between those compounds. Further, the type of film is an important variable.
D-25 was a lower pH version of D-23 (by adding bisulfite) for extra fine grain, since DK-20 was too solvent for more modern films at the time. Microdol was an evolution of D-23 with the addition of Sodium Chloride, which seemed to produce the extra fine grain effect of D-25 but with less chance of provoking the formation of dichroic fog with evolving films. The formula is commonly assumed to be 5g/l Metol, 100g/l Sulfite, ~30g/l Sodium Chloride. However the actual formula has never been disclosed. Nor has the formula for Microdol-X, which included at least one extra compound - an anti-plating/anti-sludging agent.
Pyro is a different subject. Assuming we're talking about staining developers, there are different formulas that produce different results (and Pyrocat HD is a Catechol staining developer, not Pyrogallol). It is also important to note it can be the colour/intensity of the stain itself which produces compensating characteristics on certain printing papers, not the shape of the silver curve. Experimentation is required.
I'm not sure what you're trying to achieve. That might help you choose the right developer. If this film you are using is a high contrast emulsion, then a compensating developer, or a special low contrast developer might help. Otherwise you simply dilute your D-76 or D-23, try to reduce agitation somewhat, and develop to a low gradient. You will lose film speed, but that may or may not pose a problem.
EDIT: I should add since you're using x-ray film, film speed and contrast could be all over the place under tungsten or daylight conditions etc. If you're doing your step wedge tests with tugsten light for example, I'd expect very poor speed.
As an engineer I felt compelled to go through a similar path (step wedges, density tests, varied development) for several of my favorite films about 20-25 years ago. It was an interesting learning experience but I would not recommend it in this case. X-ray film is not designed to give you a conventional rendition so a more pragmatic approach should serve you better:
Originally Posted by Tom1956
1. Shoot five frames of a normal scene at different ISO values +/-2 steps from the suggested ISO (about 100) and develop for the suggested time. Pick the ISO that results in the most satisfactory shadow detail. Remember that this is orthochromatic film so the shadows will be lighter in daylight. Development time should not affect the shadow detail much.
2. Using the ISO for the shadow detail you favor, shoot the same scene in the same light and develop for the recommended time and +/-20 and 40%. Dilute the developer for all cases if any of these times is less than about 5 minutes. Select the development time that gives you the most pleasing rendition and that is easy to print or scan.
This should give you a reasonable place to start and you will not be disappointed like you might be when you transfer your carefully calculated sensitometry test into the world of reality.
All of this can be accomplished with ten exposures. You can always tweak you ISO and development later based on your experience with scenes you normally shoot.