Speed and development test. HP5, FP4, Caffenol-C

[elerion]

Hello everyone.

I'm doing some development and EI tests on Ilford FP4+ and HP5+ films, using a densitometer, developing with Caffenol C-H, but I got some results, that I don't know how to interpretate.

I shoot at a grey card, with uniform, difuse light, with a shutter speed tested camera. I shoot zone 0, I, II, III, V, VII and VIII, for a certain EI. I develop right away after exposure.

After a few tests, to nail down the EI, my last test densities were:

HP5+. EI 250
Caffenol C-H. 10' @ 21ºC
Base + fog: 0,48
Zone - Density
I - 0,08
II - 0,13
III - 0,17
V - 0,57
VII - 1,09
VIII- 1,37

FP4+. EI 125
Caffenol C-H. 10' @ 21ºC
Base + fog: 0,44
Zone - Density
I - 0,10
II - 0,19
III - 0,22
V - 0,61
VII - 1,23
VIII- 1,56

- Zone I, seems correct. I read that a value between 0.09 and 0.11 confirms the EI.
- The weird thing is that zone VIII exhibits quite a high density. FP4 but also HP5, seem pushed (overdeveloped). I'd like to get a 1.25 zone VIII, but also a higher zone V (around 0.7). Thus, decreasing developing time will not work (I tried already to play with development time), because it also decreases a litte bit zone V, which I want to increase.
- Dark zones ( I to III ) are very thin, also zone V is weak, but then, in a few zones up to VIII, the density scales up so fast.

I thought on setting a lower EI, so I get denser darker zones, but then HP5+ will have an EI which is 200 or lower, when its box speed is 400.

I'm looking for some ideas on how to proceed from this point. Anyone?

Thanks!

 

[markbarendt]

Here's a link to an article that may help you think about this. (there was a url link here which no longer exists)

Two thoughts I have are: that you may want to try using a step wedge rather than adjusting exposure at the camera; and that you should experiment with the type of subject matter and situations you are looking to shoot in normally and take it all the way to the print.

 

[Gerald C Koch]

Here's a link to an article that may help you think about this. (there was a url link here which no longer exists)

Two thoughts I have are: that you may want to try using a step wedge rather than adjusting exposure at the camera; and that you should experiment with the type of subject matter and situations you are looking to shoot in normally and take it all the way to the print.

+1

The is enough inconsistency in even the best mechanical shutters even those that are electronically controlled to effect your tests. So using a step wedge is good advice.

 

[Alan9940]

I've never used any of the Caffenol derivatives...is that a staining developer? If so, and you don't have a densitometer that can correctly read a stained negative you have to 'kludge' it a bit. I just finished a round of testing with Pyrocat-HD, using a densitometer, and here's what I did: 1) place dark blue gel filter (#47 I think) over light source and zero out, place Zone 0 negative over blue filter and zero out, now read whatever negative you need to. The blue filter simulates the enlarging paper's response to blue light. Also, don't know if a Caffenol negative's stain (assuming it has a stain) adds printable density, but Pcat stain does; my Zone VIII density reads at 1.20. A normal Zone VIII density for a negative developed in a non-staining developer would be around 1.35.

Hope this helps a little.

 

[elerion]

Thank you everyone.
I read the article thorougly.
I didn't think about the step wedge. I don't own one yet.

I did the same test using Rodinal, and got much better curves. It might be something related to Caffenol response.

Also, it stains a little bit. I didn't thought on that either.

place Zone 0 negative over blue filter and zero out, now read whatever negative you need to.

With the filter always placed? I'm not sure to understand it right.

Thanks again. I'll keep investigating.

 

[Alan9940]

With the filter always placed? I'm not sure to understand it right.

Yes. Basically what you're doing is creating a blue light beam to simulate the enlarging paper's response to blue light. It's probably most accurate for graded papers, but I use VC paper and haven't noticed any significant deviation.

 

[elerion]

I ordered a step wedge. Nice also to not shoot so many frames (one for each zone).
I'm still not sure how to use the step wedge for testing.
How do you match steps in densities to zones?
Using shutter speed/aperture, it's just shooting at a grey card, at lightmeter exposure.
But placing the step wedge over a light source,... how do you know?

 

[removed account4]

elerion
i don't use the same recipe of caffenol c as you
but i can tell you from my 10+ years of using it
that you might lose speed using caffenol.
to get the sort of film i want to print, i always
end up overexposing and developing for a little more time
when using a coffee based developer.
i'd be interested in seeing how your recipe stacks up against the
other developers you have picked !
good luck !
john

 

[ic-racer]

I ordered a step wedge. Nice also to not shoot so many frames (one for each zone).
I'm still not sure how to use the step wedge for testing.
How do you match steps in densities to zones?
Using shutter speed/aperture, it's just shooting at a grey card, at lightmeter exposure.
But placing the step wedge over a light source,... how do you know?

If testing FILM and not a camera, place the step wedge close to the film. A 21 step wedge usually contains half-stop increments. So two steps per "Zone."

 

[elerion]

I think I'm missing something.
You mean not using a camera at all?
How to expose the film then?

 

[macheck]

Put the wedge on the film and expose like contact print

 

[elerion]

I finally got a step wedge. They are hard to find in Europe.
I understand about making a contact print on the film, but I wonder how to relate that to exposure.
I mean, using the camera you know what step of the wedge will render zone I, V, or whatever,... because you can just open 5 stops over the base light meter reading, and get ten zones with a 21 steps wedge. Step 11 will be zone V, and from that you get the rest.
But, putting the wedge directly over the film and giving it a short light pulse will give me a curve, sure, but, how do I know what exposure on the camera it relates to? How can I find the effective film speed (or right developing time)?

 

[macheck]

The wedges, as it was previously said, have standard increments – if you have a stepped one you have an exposure parameters spectrum to choose from but first you have to get a reference point.

Yes you are right somehow you have to relate wedge exposure parameters with your camera metering parameters. It depends on how much hair splitting you are interested in.

The most simple, for me, would be to point your camera (with no lens and speed properly set) towards the light source the one arranged for wedge exposure in its place, to read the exposure time, expose a frame and then to expose the wedge with the same time as camera indicated. No lens might be assumed as ultra fast lens (f0.7) – standing for first transparent step, next full wedge increment might represent f1 and so on. I don’t know if the test frame is mandatory but it might be useful for comparatory exposure time check. One has to keep in mind that film speeds are calculated for certain minimal film response not medium one (as far as I remember).

Afterwards you have to verify the above mentioned method against your zones and make some corrections I thing mostly due to this “ultra fast lens” assumption.

BTW try pure vitC and NaOH developer it gives no stain.

 

[elerion]

Thanks for the explanation. It's quite clear now
Problem, my enlarger timer (Viponel) is not that precise. I can measure a few seconds with nice results, but not fraction of seconds, even a single second will not be an exact measurement. For longer exposures, reciprocity failure will enter into the equation.

Large format seems a lot easier, as the wedge can be placed directly over the film in the holder, just shoot at a white surface, and use the camera shutter, which is very similar to the method you guys are recommending.

As an alternative, I shoot yesterday at the wedge over a LED light panel. My shutter is very accurate (I tested it). Not sure about the apertures (seem ok). The problem: I have no macro lens, so I used extension tubes to focus closer (else, steps are so small I cannot measure densities). The tubes reduced light by 1.65 stops (50mm lens with 32 mm extension (32+50)/50), but I forgot to compensate for it, so I ruined the test

 

[elerion]

How should I place the step wedge? with the glossy side in contact with film, or matt side?
My densitometer measures slightly less density if placed with matt side on the light source side.