Film tests

[Stephen Samuels]

I'm launching into 10x8 and, for reasons of cost as well as sanity, want to make the whole process a lot more consistent than my previous work. Consequently I need to run a series film speed/developer/paper tests which could burn through half a box of film at no small cost.

My question is: can I run these tests on medium format film - so for example would results from HP5+ medium format be the same as HP5+ 10x8?

It may be a naive question but wanted to be sure the films were exactly the same and therefore cost controllable when doing the tests.

Many thanks

 

[L Gebhardt]

I have found small differences between some sheet films and the roll films in the past. This could very well be just development differences since I use a different type of tank and agitation for roll film from sheet. Can you pickup a small box of 4x5 to run your tests on?

 

[PhotoJim]

Agreed, 4x5 would be a safer choice.

 

[Christopher Walrath]

Different processing procedures between roll and sheet film. If you can't test on sheet film, don't bother testing at all. Consider cutting your8x10 sheets into 4x5 to give you four times the bang for your film buck for purposes of testing.

 

[fotch]

How about cutting down to 4x5? Then you are assured to get the exactly the same film. Better yet, get a 4x5 back for the 8x10, they you also get the exact lens/shutter combo and eliminate many variables.

 

[dpurdy]

I wouldn't go overboard on your testing just yet. Everything is different in LF and I see you are thinking of going alternative process as well. You can assume the speed of HP5 is 200 if you want a lot of shadow detail or 400 if you like more contrast. Pick a good standard developer like ID11 or Xtol or HC110. Shoot a sheet of film on a white wall exposed as you are used to calculating. If you are going to process in trays you can cut the sheet of film in halves or quarters in the dark and process a portion at a time to get the processing time established. At that point you should just load up some film and shoot a few sheets and see how it all feels to you. Depending on what you like to shoot and how you like to print it, 8x10 is a beast that takes a long time to master due to aesthetic differences and reciprocity failures and bellows factors and printing options. I would suggest spending one sheet to get close to the processing time and then jumping in with both feet. Everything you need to learn is interrelated and largely subjective.
Dennis

 

[Stephen Samuels]

Thanks everyone - cutting the film seems an obvious idea but unless I invest in a 5x4 back and darkslides then I'm not sure i'm much further forward.

As you rightly guessed Dennis the aim is alternative processes so I want the full 10x8 - I'd be buying the extra kit just for the testing. Will take a couple of pot shots as you suggest and if I still end up with muddy prints then I'll bite the bullet and test. Thanks again.

 

[fotch]

I wonder if you could cut the film into 4x5, then just tape it in the middle of an 8x10 holder? Just a thought, never mind.

 

[Konical]

Good Afternoon, Stephen,

How about running exposure step tests using the dark slide? It would be easy to put at least five or six stepped exposures on film as large as 8 x 10. One sheet should tell you a lot. A second or third sheet to zero in on processing time should provide enough information to be very close to what you need.

Konical

 

[dpurdy]

"

Thanks everyone - cutting the film seems an obvious idea but unless I invest in a 5x4 back and darkslides then I'm not sure i'm much further forward."

I am not sure if you are processing in trays but what I meant was to shoot 1 full sheet at a white wall (out of focus set at infinite). Then in the dark cut the sheet into halves or quarters and processing just one portion at a time to find the right processing time.
Dennis

 

[Stephen Samuels]

Doh!! Didn't think of cutting after exposure! And the step exposure too. These forums really help those with a slow mind. Many thanks to all for your help.

 

[Maris]

I test film, usually in the 8x10 format, by making a series of exposures from Zone 1 to Zone X by moving the dark-slide stepwise across the film for each exposure. My target is usually a white sheet evenly lit in sunlight.

In the darkroom I cut the film into four equal strips with each one bearing the ten step exposure sequence. Then all four strips go into the developer at once and get routine tray agitation. At regular intervals, say 2 minutes, 4, 8, and 16 minutes, I take a film strip out of the developer tray and put it in the stop bath. After 16 minutes I take all the film strips through the usual fix, wash, dry routine.

The end result is 10 exposures for each of four different developments. The data, plotted out in the usual D versus log Exposure format, give me four curves and everything I need to know about EI, and N-, N, and N+ development either directly or by simple interpolation.

Total cost: a sheet of film, some chemicals, and a couple of hours.

 

[Mahler_one]

I suggest calling Dr. Ross at RHDesigns in the UK. He might be able to do the film tests for you, or direct you to his associate who may do such tests. At any rate, it is entirely possible that you will actually save funds by having Dr. Ross take you through the process...no need for you to cut film yourself, and guaranteed to yield results that are usable the first time out. Please let us know how you make out, and the very best of luck to you!

 

[Mahler_one]

I test film, usually in the 8x10 format, by making a series of exposures from Zone 1 to Zone X by moving the dark-slide stepwise across the film for each exposure. My target is usually a white sheet evenly lit in sunlight.

In the darkroom I cut the film into four equal strips with each one bearing the ten step exposure sequence. Then all four strips go into the developer at once and get routine tray agitation. At regular intervals, say 2 minutes, 4, 8, and 16 minutes, I take a film strip out of the developer tray and put it in the stop bath. After 16 minutes I take all the film strips through the usual fix, wash, dry routine.

The end result is 10 exposures for each of four different developments. The data, plotted out in the usual D versus log Exposure format, give me four curves and everything I need to know about EI, and N-, N, and N+ development either directly or by simple interpolation.

Total cost: a sheet of film, some chemicals, and a couple of hours.

Sound like a very, very clever idea...well done....however, how do you cut the film into 4 equal strips in the dark?:confused: Do you use your paper cutter?

 

[PhotoJim]

They don't need to be perfectly equal. Approximately equal would be fine.

 

[Mahler_one]

Agreed of course....was simply curious as to the way one cuts equal "anything" in the dark...still, a really clever way to test film.

 

[MattKing]

Sound like a very, very clever idea...well done....however, how do you cut the film into 4 equal strips in the dark?:confused: Do you use your paper cutter?

I use my paper cutter and my paper safe.

1st set the cutter to cut the sheet in half. Then do so, and put the two halves into the paper safe. Then adjust the cutter to cut each half in two. Then do so.

Matt

 

[mikebarger]

You could tape some corrugated paper to the paper cutter board to give you a guide to use in the dark.

Mike

 

[ic-racer]

If your paper cutter has a 'back stop' as an accessory that will help cut in the dark. Remember when cutting 8x10 sheets of film, prior to exposure, to mark the corner on each

I have three 4x5 sheets in my papersafe right now. "Ok lets see, put the film in the sensitometer emulsion side down....hmmmm this side, no this side, no... Ok get another full 8x10 sheet"

 

[Maris]

Sound like a very, very clever idea...well done....however, how do you cut the film into 4 equal strips in the dark?:confused: Do you use your paper cutter?

IDEAL Precision Safety Guillotine with the spacer bar set before I take it into the darkroom. The key word is safety. Cutting anything using a razor sharp edge in pitch blackness is frightening prospect without well rehearsed precautions.

 

[squinonescolon]

Get a Stouffer T2115 step tablet http://www.stouffer.net/Productlist.htm they are $6.55 US. Load the film and tape the tablet directly onto the film, point the camera at a white wall, expose for zone 10 and develop. You'll have all the info you need. That together with exposing only a small piece of film at a time and you can do at least 5 tests with 1 piece of film.

 

[Stephen Samuels]

Thanks for all the advice everyone - I'll get in the darkroom and see how many fingers I end up left with!!

But seriously, some excellent ideas - really appreciate the support.

 

[Stephen Samuels]

Ok, so here's what I did: I'm using an old Schneider convertible and am not confident of the shutter performance (will get it refurbed and calibrated at some point) but as I intend using studio flash, do not see this as too much of a problem. However, have checked that the flash is synching OK so light is getting to the film.

So I set up a white board at a reasonable distance to fill the ground glass and a softbox flash alongside the camera axis. I set the flash and metered multiple flashes so that five flashes gave me f22 at 100asa (the box rating of Foma 100). I reasoned that by lifting the darkslide as Maris suggested in 25mm steps, by the time I was half way up the film with one flash each step, I would be at five flashes, ie the equivalent of Zone V. When I'd exposed the whole film it would have received one flash at Zone 1 and ten flashes at Zone 10 and all the steps in between.

I then cut the film into four strips and developed in HC110 dilution H (1:63 of US concentrate) at 20degC taking strips out at 4, 8, 12 and 16 minutes. For agitation, I shuffled the strips for the first 90 seconds and then a couple of times on every second minute. And the results pretty much confirmed my view of Foma 100 (or maybe my technique!) - virtually no contrast at all.

Densitometer readings are as follows:

Zone 10 Zone 1
4mins 0.01 0.4
8mins 0.13 0.66
12mins 0.16 0.83
16mins 0.27 1.01

If I use dilution B (1:31) then I can achieve zone 10 of 1.81 but the rest of the strip is uniformly, and unusably, dark.

My conclusion is that this film is capable of achieving a reasonable Dmax but seems incapable of a meaningful contrast range. This confirms my untested trial photographs which were universally muddy and flat.

So my questions are:

1) Is my method correct or have I made some elementary mistake somewhere?
2) Is Foma 100 and HC110 just the wrong combination and can never be made to work?
3) Am I alone in reaching this conclusion?

As always, many thanks for your collective wisdom.

 

[ic-racer]

If 5 flashes gave zone V, then you need about 0.3 flashes total for zone I and 160 total flashes for zone X, if you are going to do it that way.

 

[Mats_A]

I have nothing important to add but I am very interested in your results. I have also shot Foma 100 and noticed that it is very low contrast. But I attributed that to my 90 year old uncoated lens.
In this case I think ic-racer is correct. There is a one stop difference between every zone. That is half or double light. If 5 flashes is zone V then zone IV is 2.5 flashes and zone VI is 10 flashes.

r

Mats