Film density variations

[fred aspen]

Hello All,

 

Doing some scans on Scan Dual IV in manual exposure mode on a roll of Neopan

400/ISO 400/5 min. HC-110-B/10 sec each minute-3 twisting, rotating

inversions/68 degrees and noticed some obvious, gradually increasing from frame

1 to 6, density changes from the first exposure (at the center of the SS tank

reel) to the sixth exposure. (Leica RE/Summ 50mm/F6.3 @ 1/500 manual exposure,

entire roll.) Exposures seemed to exhibit very little frame to frame differences

from frame 6 onward.

 

I would expect a slightly thinner neg from those right at the center of the reel

because of reduced agitation/flow but not (est.) 2/3 to 1 stop difference. Do

not have access to a densitometer to confirm but the scanner in manual exposure

mode can see very small differences in density.

 

Possibly could be because of the short development time for the HC-110? I may

try dilution H next go around. I have been using Xtol undiluted and haven't seen

obvious differences with that developer.

 

Possible differences in developer activity between 110 and Xol?

 

Curious what might be causing this anomaly. Not a problem as I can easily

correct the exposure but want to try and eliminate the variables.

 

I welcome all comments and suggestions.

 

Thanks!

[lex_jenkins]

While a short development time can lead to inconsistencies, I'm not sure whether it would manifest itself in such a specific way. I would expect to see inconsistencies throughout the entire roll. OTOH, I've never experienced that problem either!

 

When I was a journalist I used Dil B for HC-110 with Tri-X because it saved time. If uneven development occurred I guess it wasn't bad enough to cause problems with newspaper reproduction.

 

Nowadays I prefer development times around 10 minutes or so, at least with tank development of roll films. It makes pour/drain times less of a factor. So I use Dil H, usually around 10 minutes, give or take, for Tri-X, depending on temperature. Works fine.

 

BTW, you might consider altering your agitation technique to see whether that eliminates the inconsistency. If I'm reading your question correctly, it sounds like you're manually twisting/rotating a stainless tank/reel set. If so, that may not be the best technique for that kind of tank/reel. Inversion agitation is usually better for stainless tanks/reels. However with the plastic tank/reel sets, I usually go with the twisting/rotating technique which includes some vertical motion because a doodad at the bottom of the tank cams the reels up and down along with the twisting motion. Other folks prefer inversion agitation with both types of tanks/reels.

[fred aspen]

After pondering the problem somewhat and if uniform density is the goal, one could certainly make a case for some or possibly all of the following for this film/developer combination:

 

A) Only shoot 24 ex. rolls and develop on plastic reels which load from the outside not putting film at the extreme center;

 

B) Follow the Kodak method of agitation of 5 sec/30 instead the more commonly used 10 sec/60, especially with dev times of 5 min. or less;

 

C) Use the Hoy method of agitation:

 

(A 35mm technique which has, for me, provided the best results with the traditional spiral tank, was suggested by Bill Hoy of Bedford County, VA.

 

* Use a tank at least twice the size needed for the number of reels you plan to develop.

 

* Fill the extra space with empty reels, placing the film at the bottom of the tank.

 

* Pour in just enough developer to cover the film, then simply invert the tank at the specified interval, draining the developer completely from the film.

 

* After five seconds, reinvert the tank, reimmersing the film.);

 

D) Not use 'blocky center core' Kindermann SS reels with 36 ex. rolls which restricts agitation/flow at the extreme center of the reel. (Kindermann has been my personal preference but uses a phenolic center which has some mass as opposed to open centers found on Honeywell Nikor reels.)

 

E) As Lex suggested, use developers with longer developing times for the film/developer combination.

 

Note: I am using the inversion/twist/rotate method of agitation that was suggested in George Todd's book, Making Twenty Photographs.

 

Just some added thoughts,

 

Ron

[fred aspen]

One other thought/question:

 

Kodak (and others) suggest that dev times less than 5 min. lead to uneven development.

 

I understood this to mean mottled development within the frame rather than frame to frame variations. I am now thinking it means both.

 

Comments, anyone?

[pete_andrews10]

The most obvious cause would be that the lighting conditions changed subtley during exposures 1 to 6.

 

However, if it turns out that the density changes really were due to a development variation, then I'd suspect your agitation method Ron. Forget about any twisty-turny business, and just do one straightforward smart inversion of the tank every 30 seconds. Always making sure that you don't overfill the tank, of course.

 

Inversion agitation uses the pocket of air trapped in the tank to create turbulence as it bubbles past the film. Twisting and turning the tank does very little to mix fresh and used developer together, which is what agitation is fundamentally all about.

 

Try this: fill a glass bottle brimful with water, and drip one drop of ink into the bottle. Next cover the top with clingfilm, making sure that you don't leave any air at all trapped under the film. Now tip the bottle upside down. Does the ink mix efficiently with the water? Thought not! And what happens if you twist the bottle around? The water stays still while the bottle rotates around it, pretty much.

 

Try the same thing, but this time leave some air in the top of the bottle. See how much quicker the ink mixes when the bottle is tipped upside down? That's what should be happening in your developing tank.

[fred aspen]

Pete,

 

Was an overcast day and light meter said the intensity was quite stable. However, I think you might have it with the air pocket. Unthinking, I was filling to the neck of the tank leaving no air trapped in the upper part of the tank.

 

Your mixing analogies are right on the money. It makes perfect sense what happened.

 

And I was just reading about Jobo tanks and the cautions about not underfilling nor overfilling.... Duh!

 

Thanks!

[pico_digoliardi]

<i>I would expect a slightly thinner neg from those right at the center of the reel because of reduced agitation/flow but not (est.) 2/3 to 1 stop difference. </i><p>

You should expect no difference if you are agitating properly.

[big toys are better]

The biggest problem with short development times is uneven wetting of the film by the developer. This is made worse by tanks which require upwards of 10 or more seconds to get the developer loaded, and then a few more seconds to agitate and shake off the bubbles. I lost some of my early work to my failures in proper agitation which left much evidence of such flaws.

 

I'm a big advocate of diluted developers and longer development times. IF you are using high speed films like the Neopan 400, then well diluted Rodinal is not a good solution for you, but well diluted HC-110 or D-76 is. You can also presoak your film in plain water prior to adding developer as this will slow the absorption of developer into the emulsion, also adding a safety factor that is critical for short development times. Using an oversized tank and adding any kind of spacer between reels is also a good idea. With an oversized tank you can even add your water bath first and then add a slug of semi-diluted developer to the top of the tank and quickly mix it for your first agitation step.

[ronald_moravec1]

Drop the loaded reel into the tank prefilled with developer ( in the dark). Pour out thru the cap. Best if you load and store the reel in the dark in an extra tank. Put the cover to the left of the tank, start the timer in the darkened room with 5 sec extra, count off 5 sec and drop the film in, cap, comence initial agitation.

 

Invert 5/7 times in five sec. Repeat each 30 sec. Rotate the tank 90 deg each time you finish 5/7 inversions.

 

I have done times as short as 3.5 min with no ill effects.

 

Initial agitation is for 30 sec- 6/8 in that 30 sec time period.

 

The single reel in a double reel tank also works. Twisting without inversion will not provide sufficient agitation. You can also get center to edge variation. Don`t fill the tank to the top. 8 oz will cover the reel. You want the developer to move into the empty space at the top.

 

Guaranteed no problems if you follow this exactly.

[fred aspen]

Thanks, all, for the helpful responses. Ran another roll today with a plastic tank that has an air space to get more flow and breakup.

 

Worked so well that I think I will have to back down on the number of inversions as the sky was a tad hot. There was a significant change in the results with all the mods so have to tweak the workflow a bit.

 

Again, thanks to all!

 

Ron

[pics]

As long you are agitating properly I would advoid adjusting your agitation routine and instead adjust the devlopment time and/or your personal EI for this film. Agitation is usually best left as a constant variable and monkeying arond with it can often lead to unpredictable results that leave you grasping for straws. FWIW, the general guidline for "standard" agitation is either 5 sec every 30 seconds or 10 seconds at every minute mark. Kodak recommends one and Ilford the other but both give about the same result. If your highlights are on the "hot" side you may try cutting back slightly on the dev time. Of course this may leave the shadows a little thin so more exposure may be necessary and you may find the need to rate the film at an EI that is lower than box speed for this film/dev combo.

[fred aspen]

Thanks for all the good advice. Checked my Weston dial against my Process thermometer and found it was reading about 1.5 deg. low which would account for the hot negs now that I have gone to a tank with an air bell. Apparently a full stainless tank with poor agitation/flow was offsetting the thermometer error.

 

Always somethin'....