Is there a wallet-friendly way to test for film speed and development time?

[timbo10ca]

I'm in a similar boat to you, so let me say that in my inexperienced hands, one cannot translate roll-film EI or dev times to sheet film- the processes and films are too different, I think. Also, I do not believe that one can use the same EI across different developers.

A question for Jason: I'd like to try your method of pulling the darkslide incrementally- How do you calculate the exposures so each one is 1/3 stop different than the previous. It sounds like doing a test-strip using f-stop printing, so I'm pretty sure there's a simple way to do this. Also, since the exposure is building up, rather than having one single exposure, would there be the same "accuracy" problem that people say exists in printing (i.e. 10 one second exposures is not equal to 1 ten second exposure)? Lastly, would there not be a light-leakage/scatter problem along the film where the darkslide edge is pulled? My main problem with film testing has been what looks like uneven lighting, and it seems this method would cause a similar effect.

Tim

 

[JBrunner]

I'm in a similar boat to you, so let me say that in my inexperienced hands, one cannot translate roll-film EI or dev times to sheet film- the processes and films are too different, I think. Also, I do not believe that one can use the same EI across different developers.

A question for Jason: I'd like to try your method of pulling the darkslide incrementally- How do you calculate the exposures so each one is 1/3 stop different than the previous. It sounds like doing a test-strip using f-stop printing, so I'm pretty sure there's a simple way to do this. Also, since the exposure is building up, rather than having one single exposure, would there be the same "accuracy" problem that people say exists in printing (i.e. 10 one second exposures is not equal to 1 ten second exposure)? Lastly, would there not be a light-leakage/scatter problem along the film where the darkslide edge is pulled? My main problem with film testing has been what looks like uneven lighting, and it seems this method would cause a similar effect.

Tim

I just move the aperture 1/3 stop. The EI difference would be calculated from the EI you choose as a baseline, for example 1/3 stop from 200 ISO would be about 160. The accuracy problem is negligible because a shutter opens or closes much faster than an enlarger lamp ramping up and down. There will be a small amount of scatter along the line where the darkslide is positioned, but you will have a good usable strip on the neg. The amount of light getting up under the slide wouldn't be enough to matter, as it likely isn't enough to even engage reciprocity if you don't lollygag around, so for all intent and purposes the area under the slide stays dark. It could be argued that there is some effect, depending on situation, but the variance wouldn't amount to anything that would bother most persons. It all depends on how anal you want to be about exactitudes. I can usually determine a speed/developing combination within three sheets, though certainly not with the accuracy of a full BZTS regimen. I generally extrapolate my full expansion and contraction from my baseline -1 0 +1 testing information, and adjust from field results after that. Some photographer like to test things to the last detail, some just wing it. Most are comfortable, like me, in the middle ground. It's simply individual choice, and in the end, the print is what counts. For some reason, many (not all) of the most technically exacting photographers I am familiar with make limp prints. A good photographer is one who can stand astride both the art and the craft, without half baking, or over baking either.

If you change emulsions, or developers, a new round is in order. Since my testing method is based on performance with particular papers, I test new papers with my saved negatives from particular film/developer regimens as well. Basically, if something changes, you need to examine the performance of the new thing. Before I figured this out I might say- such and such film or paper is crud, but the truth is it just wasn't behaving like a familiar friend. Many criticisms of papers, film and developers stem from such things.

 

[jd callow]

You can make incremental exposures on one sheet of film by pulling the dark slide out in increments.

This is the method I use. The first sheet covers 4-1/2 stop cincrements with the fastest speed being the box speed and the dev being manu recomended. I inspect the film and decide how close I can get to box speed by adjusting development. The second sheet is exposed at the choosen speed and developed at the new time. I inspect and adjust for the third and generally final sheet. Using the dark slide in this manner was told to me by an APUGGER in a similar thread where i asked for help testing some SXX.


D F Cardwell has thought/told me that semi-stand can be used to achieve box speed with at least one film (TXP). This will be something that I'll be employing in the future on other films, but don't know enough about to be advising anyone.

Sorry that this doesn't help you with +N or -N, but it will get you to the film speed/dev combo prettry quickly.

 

[rwyoung]

Fomapan 100 5x4 and 10x8 are on different bases (thickness), presumably the emulsion is the same but I don't know if affects anything else?

Ah ha! Didn't realize that one.

But like Jason mentioned, you can just pull the dark slide part way out and get multiple tests on a single sheet. I did this for some 8x10 testing and put 4 per sheet. Worked well since I was doing Zone System testing and shot a "blank" wall about 10 feet away but with infinity focus to kill any detail. Just wanted the tone.

 

[timbo10ca]

I just move the aperture 1/3 stop. The EI difference would be calculated from the EI you choose as a baseline, for example 1/3 stop from 200 ISO would be about 160. The accuracy problem is negligible because a shutter opens or closes much faster than an enlarger lamp ramping up and down. There will be a small amount of scatter along the line where the darkslide is positioned, but you will have a good usable strip on the neg. The amount of light getting up under the slide wouldn't be enough to matter, as it likely isn't enough to even engage reciprocity if you don't lollygag around, so for all intent and purposes the area under the slide stays dark. It could be argued that there is some effect, depending on situation, but the variance wouldn't amount to anything that would bother most persons. It all depends on how anal you want to be about exactitudes. I can usually determine a speed/developing combination within three sheets, though certainly not with the accuracy of a full BZTS regimen. I generally extrapolate my full expansion and contraction from my baseline -1 0 +1 testing information, and adjust from field results after that. Some photographer like to test things to the last detail, some just wing it. Most are comfortable, like me, in the middle ground. It's simply individual choice, and in the end, the print is what counts. For some reason, many (not all) of the most technically exacting photographers I am familiar with make limp prints. A good photographer is one who can stand astride both the art and the craft, without half baking, or over baking either.

I'm almost embarrassed to post this as it will probably make me seem quite thick, but I must be making this more complicated than it is (which is usually my problem). I want to set the stage here:
1)The way I see it is that when using a set repeating time exposure, it won't matter if the exposures are being made as the slide is pulled out or pushed in, i.e pull slide all the way out give 2sec exposure, cover 1/4 of the film give 2 sec, cove another 1/4, give 2 sec, cover another 1/4 give 2 sec will give a sheet of film with exposures of 2, 4, 6, and 8 seconds. This would be the same if the film is uncovered as the exposures are made. I make this obvious point, because when f/stop printing, the test strip must be covered, and not uncovered as exposures are made. This leads to point 2, where my confusion lies:
2)Say there is a base exposure of 1/60 at f11 to give zone 3 for ISO 100.
If multiple sheets were used and exposed individually, the ISO 80 would be 1/60 at f8 2/3 , ISO 64 is 1/60 at f8 1/3 and ISO 50 would be 1/60 at f8. I cannot see how a repeatable building exposure would give 4 successive regions using the single sheet method differing by 1/3 stop, or how one would calculate that exposure to lay on top of that 1st one of 1/60 at f11. I'm sure the answer is obvious, but I just can't get my brain around it. Even in the example of point 1, region 2 will be one stop more exposed than region 1, region 3 is 1/2 stop more than 2, and region 4 is 1/4 stop more than 3..... It seems to me that one would have to be adjusting the amount of exposure quite precisely as the film is covered, like in f/stop printing. Now I've run out of brain powe...

Tim

 

[cowanw]

I did it the hard way. I figured my longest exposure and worked backward in increments cutting the time as I went until I got to my fastest speed.Then worked it out so the slowest speed needed 64 accuations of the fastest speed (for example) Next full stop down was 32 units and in between was 42 and 53. and so on.
Then start
pull a little bit with 1 accuation pull a bit more 2 accuations pull a bit more and 4 and so on 8,16 and 32 would give 1 stop differences. figure differently if you want finer differences.
This kept the f stop constant but I was worried I would wear the shutter out.

In any case you still have to eyeball the shades of grey and when my measurements were complete my portraits still needed grade 4 paper.
oh well; Back to empirical experience.
Regards
Bill

 

[sanking]

I would add this to Sandy's comments on the BTZS testing: once you undertand the basic principles of BTZS and how to meter, you can "borrow" someone else's data (exposure and development times) and use it very effectively without ever doing your own testing.

The other approach I have taken with roll film is to expose at the manufacturer's rating (more or less) and develop for the recommended time. This works too!

-Paul

The Winplotter program comes with dozens and dozens of film files, including virtually every film on the market, with exposure and development data for many different developers. If you develop using the same method recommended by Davis, i.e. in tubes in a water bath with moderate rolling action, your results should be very close to the data on the files. To take advantage of this data and use it for exposure and development all you need to learn is how to understand it, which you could do with a couple of nights readings of Beyond the Zone System.

There is much less variation in effective film speed than most people believe. A few developers, including Xtol and a few others that contain phenidone, are capable of increasing real film speed by about 1/4 to 1/3 of a stop. Most others give true film speed, assuming you develop for the density and contrast specified by the manufacture.

Type of development and length of develoment also play a role in determing EFS. Minimal type (stand, semi-stand) etc. can boos EFS by about 1/3 to 1/2 stop compared to continuous agitation. And negatives developed for long periods of time for processes that require negatives of high contrast (pt./pd. for exampe) will have higher EFS than those developed for printing on most silver gelatin papers.

Sandy King

 

[rwyoung]

Lets say to get Zone III assuming box speed you needed f32 at 1/10. We are going to test for box speed, -1/2 and -1 stops on a single sheet.

1) Expose whole sheet at f32 1/10
2) Close down to f64 but leave shutter at 1/10
3) Insert darkslide 1/3 and expose
4) Insert darkslide 2/3 and expose

So, working from the light-trap end of the holder you have 1/3 exposed at f32 & 1/10, the next got f32 & 1/10 plus f64 1/10 and the third bit got f32 1/10 plus f64 1/10 plus f64 & 1/10

That should be 1, -1/2 and -1 for the film speed.

You can make finer gradations by closing down the iris more after the first initial exposure. Want to go by 1/4 stops? Close down 2 stops after the first exposure.

Please somebody check me on this. It made sense when I wrote it out to make my tests and the test results seem to be working OK so either I got lucky or I got it right...

 

[Anscojohn]

Justin,
Take pictures: one camera, one lens, one film, one developer, one year.

John, Mount Vernon, Virginia USA

 

[JBrunner]

I'm almost embarrassed to post this as it will probably make me seem quite thick, but I must be making this more complicated than it is (which is usually my problem). I want to set the stage here:

Tim

No, not thick at all Tim. My advice on opening the aperture 1/3 was thinking based on full sheet exposures. Too early and not enough coffee. For multiple EI on the same sheet pulling the darkslide use time and shutter both, as outlined in rwyoung's post. For my little brain it is much easier to follow the logarithmic pattern in half or quarter stop increments than thirds, where the math gets messy. Bigger brains have an easier time than I.

 

[smieglitz]

Buy a stepwedge.

Well, I think I'm opening a big can of worms here but...

The push-the-darkslide approach will work if you use the right interval, but I think it is a pain compared to other methods. First calculate a zone 1 (-4 stop) exposure from your meter reading. Assume the meter reads 1/60s @f/8 @ manufacturer's ISO. That would be zone V if the speed is correct. From that example, zone I would be 1/250s @f/16. Pull the darkslide until only about 1/2 inch of the film is covered. Then expose for Zone I (1/250s @ f/16). That's 1 exposure unit. Push the darkslide in 1/2 inch and expose again for 1 exposure unit at 1/250s f/16. That makes a 1-exposure unit stripe plus a 2-exposure unit stripe. Push the slide some more and add 2 more 1-exposure unit exposures (e.g., 2 at 1/250s f/16 or 1 at 1/125s @ f/16). Now you have 1, 2, and 4-exposure unit stripes. Push and add a 4-exposure unit exposure (e.g. 1/60s @ f/16). Push and add an 8-exposure unit exposure. You will now have stripes that represent zone O, I, II, III, IV & V with cumulative exposures of 0, 1, 2, 4, 8, & 16 exposure units, respectively.

Do the same thing on another sheet but use the zone V exposure as the starting point instead of zone I. Produce exposures of 16 (zone V), 32 (zone VI), 64 (zone VII), 128 (zone VIII), 256 (zone IX) and 512 (zone X) exposure units on the stripes and you'll have all the zones on two sheets of film. Assuming you guess and get the film speed and development close, you can make some judgement about tweaking things and then repeat the test for different developments and/or EIs.

Yuck. What a pain. The holes in darkslide method is easier and quicker.

Here's a much better way from John Schaeffer in his Ansel Adams Basic Guide to Photography book 2:

Schaeffer's method uses an inexpensive Stouffer's 21-step transmission density tablet (#T2115) taped over a piece of 4x5 film loaded into a regular holder. The step tablet increases by ~0.15 density units/step from a value of approximately 0.05 for step 1 through ~3.00 for step 21.

The target is a blank wall evenly illuminated, the light reflected from it measured, and the film given a single Zone X (+5 stops) exposure. The step tablet reduces the exposure on the film under the various steps about 0.15 density units/step. (That is equivalent to 1/2-stop per step). The film thus records all exposures simultaneously from around Zone X to Zone O. The film gets a Zone X exposure from the area not covered by the stepwedge. As the density increases on the wedge, the amount of light to the film underneath is reduced until it gets no exposure (Zone O). This method eliminates the effects of multiple, intermittent exposures. It's all there, all at once.

Start by exposing and developing a sheet using your best guess as to the EI of the film (usually 1/2 the manufacturer's recommended ISO for me) and the recommended development time. After seeing the results from that sheet, expose another 3 sheets (or 5 depending on how accurate you wish to get) of film similarly but making an adjustment for the EI of each, and then develop them for different amounts. I usually can get a pretty good handle on the +/- and N developments in 4 sheets.

The adjusted EI sheet (#2) gets what I believe will be normal development after looking at the first sheet, how it contact prints, and any characteristic curve I may construct (to get the contrast index).

The #3 sheet is exposed to zone X using a reduced EI (IOW overexposed -1/3 stop from #2), and that sheet is developed less than #2. (I use HC-110 and vary the dilution rather than time).

The #4 sheet is exposed to zone X using a increased EI (IOW underexposed +1/3 stop from #2), and that sheet is developed more than #2.

(If I use 6 sheets, I give the other two -2/3 stop in EI coupled with an even greater development and +2/3 stop coupled with even lesser development.)

I then determine the contrast index (or one could use Ilford's G-bar measure) from the film curves and create a contrast index vs. development graph.

Use the Stouffer tablet to also determine the paper's proper proof time and exposure scale. Once the proper proof time is known, proofing the sheets of film gives a visual record of the density shifts with exposure and development. From that, and the fact that each step is about 0.15 density units different than its neighbor, one can determine all the zone system effects visually. This eliminates the need to use a densitometer. (Though a densitometer makes the whole thing a lot easier the first time around.)

Hopefully, this makes some sense. It has been a lot harder to explain than actually do. Schaeffer's book leads you through it very clearly.

The following pic shows the stepwedge being used to determine the paper exposure scale and proper proof exposure. On the left is a T2115 wedge taped to an unexposed but developed sheet of film. The exposure on paper to the extreme right was deliberately overexposed. The dark tones are blocked until about step 6 (which you probably can't discern on the scan). To get the proper exposure, the first step should be black and step#2 near black (and around zone I). So, the second sheet needed to be exposed to shift the black step down 5 steps to step #1. Since each step is 1/2-stop, the exposure needed to be reduced 2 1/2 stops. The first sheet was exposed for 60s @f/8 with a #2 filter. To move the black tone to step 1, the second sheet was exposed for 10.5 seconds @f/8 with the #2 filter. I found the time by multiplying the original exposure by 17.5%. (x.70 moves it 1 step = 1/2 stop, x.50 moves it 2 steps = 1 stop, x.35 moves it 3 steps = 1 1/2 stops, x .25 moves it 4 steps = 2 stops, and .175 moves it 5 steps = 2 1/2 stops.)

On the second print, an actual gray card is slightly darker than step 7. That tells me the density needed to produce middle gray on that paper with that filter is about .90 density units above fbf if I print for maximum black at the shortest exposure. (Step 7 would have a density of ~ .95 density units.)

White occurs at step 12 with a little tone at the threshold step 11. Step 11 has a density of 1.55 so I know the paper goes white slightly above that value (and considering fbf in the equation as well). So now I have max black, near black, middle gray, threshold gray and paper white figured out in terms of the negative density need to produce those tones. I also can get the Exposure Scale of the paper/filter. That would be equivalent to step 3 (90% black with density around .35) subtracted from step 11 (threshold gray at 1.55) giving an ES of 1.20 for this combo.

Of course I don't do any of this now since I took up wetplate collodion a couple years ago. I just look at the light and guess.

Joe

 

[Ray Heath]

you people are making it unnecessarily complicated, the manufacturer has done lots of testing, the rated ISO/dev procedure will be pretty close for their conditions, you just need to tweak for your conditions

who really thinks worrying about a third of a stop makes any discernible improvemnet in image quality when using negative materials?

if you do, post a few images and prove it

Ray

 

[JBrunner]

you people are making it unnecessarily complicated, the manufacturer has done lots of testing, the rated ISO/dev procedure will be pretty close for their conditions, you just need to tweak for your conditions

who really thinks worrying about a third of a stop makes any discernible improvemnet in image quality when using negative materials?

if you do, post a few images and prove it

Ray

It's a personal choice, but yes, a third of a stop makes a noticable difference in how a negative will print if I am expanding or contracting the development. Unfortunatly, off hand, I don't have anything to post.

 

[Ray Heath]

It's a personal choice, but yes, a third of a stop makes a noticable difference in how a negative will print if I am expanding or contracting the development. Unfortunatly, off hand, I don't have anything to post.

same old excuse Jason

come on people this an imaging thing that we do, why are so many reluctant to USE images

Ray

 

[JBrunner]

same old excuse Jason

come on people this an imaging thing that we do, why are so many reluctant to USE images

Ray

Not an excuse Ray, you should know me better than that. I just don't happen to immediately have scans of identical negatives on hand that demonstrate expanded or contracted results at different speeds for a common emulsion.

 

[FM2N]

I found this to work well. Simple and cheap.
http://www.viewcamera.com/pdf/2006/VC_Getting Started.pdf

 

[jd callow]

On a similar topic to the OP and the current course of the thread...

In my experience I have never found the box speed and dev. recommendations supplied by the manufacturer as being the best or even close to the best combination. Some films are good at box speed and often the supplied dev times are great, but never does the twain meet in my world. This makes testing a useful thing.

 

[Nick Zentena]

A person just needs to consider how agfa would give times for much higher contrast then other makers.

 

[jd callow]

I have started a new thread "(there was a url link here which no longer exists)" using Rays request to See the fruits of the Film Testing labours as the seed.


I figured those who are interested in discussing film testing can continue on here and those who wish to see the results can go there.

 

[Ray Heath]

thnx John

 

[timbo10ca]

Sure, I've got a half a bottle of wine in me and a couple gin and tonics, but Joe, I was laughing 2/3 of the way through your post (in a good way though ) and guffawing at the end . I have the book of which you speak (just finished reading it a couple weeks ago, as a matter of fact), and if you got all that from the 2 paragraphs Schaffer wrote, you're a much brighter guy than I!. I must commend you on your firm grasp on the subject matter.

Personally I find Bruce Barlow's test kit the easiest by far to understand and use succesfully for film testing. What I lack (which you don't) is how to quantify for expanded and contracted development (I'll figure this out soon enough, I'm sure). I chimed in only because the thought of somehow adapting his technique to only a couple pieces of film intrigued me, as I shoot 5x7 and nobody in my city carries film in this format, and it is therefore a bit of a commodity for me.

Ray, I respect your opinion and have heard similar sentiments many times in the past, but as someone learning their tools, the "fly by the seat of your pants" approach teaches nothing useful, and everything remains guesswork until the massive accumualtion of negatives eventually teaches by trial and error. My tenet is that in order to use my tools to their full potential, they must be fully understood. I see it similar to learning to play an instrument by ear or by reading music. Two different ways to the same end. Just call me left brained, I guess.

Time to flip Dark Side Of the Moon to side B----- g'night all.

Tim

 

[Chuck_P]

you people are making it unnecessarily complicated, the manufacturer has done lots of testing, the rated ISO/dev procedure will be pretty close for their conditions, you just need to tweak for your conditions

who really thinks worrying about a third of a stop makes any discernible improvemnet in image quality when using negative materials?

if you do, post a few images and prove it

Ray

I did not continue reading the posts so someone may have already addressed this.

I don't have a way to scan right now but if I did, I would scan my family of curves for T-Max 100 to show you. The proof is in the curve and a 1/3 stop difference matters, especially with T-Max. My testing method was from Schaefer's book using the step wedge. N-1 and N+1 did not reveal a significant decrease or increase of film speed.

You would see that, with my process, the N-2 curve crosses the 0.1 density line at Zone I 1/3. To determine the speed accurately, I want the curve to cross the 0.1 density line at Zone I (icidentally, in my tests, it does that at the box speed of 100, so my EI for Tmax 100 is 100).

Back to the point, N-2 development indicates a 1/3 drop in film speed. Why? Because the rather significant reduction in development time has also reduced the fog level of the film base, and this lowers the density accumulated at Zone I (an effective loss in film speed). The curve tells me that when I plan N-2 development, I must consider the need to increase the exposure by 1/3 stop to keep "true" the tested EI of 100. This will help to keep the middle values supported but it could push the high value a bit high, but this is not as much of a problem as the loss of film speed in the lower zones.

Similarly, with N+2 development, which is a significant increase in development time, there is a corresponding increase in the fog level of the film base by 1/3 stop, so too much buildup of density at Zone I (an effective increase in film speed). The curve tells me that when I plan N+2 development, I should decrease my exposure by 1/3 stop so that the Zone I speed point remains true.

The big advantage to all this, you may ask? My anticipated negative densities are 100% predictable with each and every exposure. The densitometer bares this out and so the small amount of testing was well worth the huge increase in knowledge base.

I would suggest to the OP to save some money and search on ebay for a densitometer as the whole process is much easier and enlightening. He can get the whole testing completed in about 6 or 7 sheets---one for the speed test and the remainder for the development time tests.

 

[Ray Heath]

sorry C
the proof is not in curves, or steps tablet souffle things, the proof is in the image and the message conveyed

Ray

 

[smieglitz]

...What I lack (which you don't) is how to quantify for expanded and contracted development (I'll figure this out soon enough, I'm sure). ...

Tim,

If I understand your dilemma correctly, the solution is to look at the density numbers and/or the stepwedge. Whatever density produces what you wish to be zone VIII normally would be found at the zone VII exposure if you were expanding the film development. For example, if zone VIII and N development gave a density of 1.3, N+1 would give that density at the zone VII exposure on the other roll and the slope of the curve would have to increase to do so. Contraction goes the other direction and the N zone VIII density of 1.3 would show up at the zone IX exposure value with the curve slope decreasing to achieve that. (You could identify these shifts visually by comparing stepwedge prints but a densitometer simplies it.)

Now, I'll add a caveat and say it depends who you read and what your intent is. The system is not rigid and set in stone. You can adapt it for different purposes. For example, if you shoot mainly portraits you might want to consider zone VI as the target density for N. V exposure pushed to VI density could be considered N+1 by some folks and VII exposure pulled to VIs normal density value could be considered N-1. Some folks use 10 (O-IX) or 11 (O-X) zones for the normal scale. I think Ansel actually changed this at one time. It doesn't really matter except in communicating your results with others. But, it does affect how one visualizes things and whether one person's +1 expansion is the same as another person's. In my latter example, N+1 from V to VI would cause the upper zones to shift higher so that maybe VII goes to near IX and that is different than the effect when considering VII to VIII as N+1.

Whatever works.

Joe

 

[Chuck_P]

sorry C
the proof is not in curves, or steps tablet souffle things, the proof is in the image and the message conveyed

Ray

Yes, the proof is in the image, no argument there. Based on what you have been saying, I would be willing to bet you that my road to the final image is not near as bumpy as yours . So the OP has made a valid inquiry and some answers have been provided that he can accept or decline. It's that simple. Some folks believe in taking their understanding of their processes and materials to a higher level and we should support that, not imply he doesn't need to.