View Full Version : will this film testing work?

26-Oct-2003, 09:13
For 2 years I've had a 4x5 camera and have been using roll film backs because my current enlarger can't handle bigger than 6x9. I finaly decided to make the jump... Bought some new toyo film holders, (the smelly ones.), some new Tri-x 320, and a Uniroller and drum. I'm buying a 4x5 enlarger.

I've exposed and processed 8 sheets so far and love it!!!!

Now I think it's time to do some film testing, and here's the question...

Can I mark the dark slide in say 1/2 inch spaces, expose a half inch at one film speed/ zone 1, pull the slide out another half inch, expose that half inch at the next film speed/ zone 1 and so on and so forth ect? And leave the last half inch unexposed for base + fog. What would the film speed sequense be? It would be nice to only use one sheet of film for a film test.

Andrew O'Neill
26-Oct-2003, 09:25
Why don't you make a "zone board" as outlined in Gordon Hutchings' book about PMK? I use a dark gray wall in my darkroom with a 500W daylight bulb in the ceiling pointing down at it. Of course the bulb is in a big socket reflector. On the wall I have pieces of paper with zone numbers written on it. My light metre helps me seperate each zone marking by a zone. I have markings from zone 0 to X. I use a dimmer switch to fine tune the light. I've been using this method for a few years. I can get all the important zones on one sheet. By exposing 4 or 5 sheets and developing them at various times will give me all the info about particular film.

Kevin Crisp
26-Oct-2003, 09:52
d.s. Think about what you're suggesting. That first strip you expose at Zone I will be exposed again when you pull it out a little further, again, when you pull it out a little further, a third time when you do the third stripe, etc. Maybe I like to keep things simple, but I think it is worth it to do the test the plain old simple way, using one sheet and following simple instructions as in the Zone VI Workshop. You're out maybe 5 or 6 sheets of film to determine Zone I and do it right, then you go take pictures. If that is too much expense, cut sheets in half and tape them to the middle of the folder. If you want to save a few sheets on the development time test, expose one sheet edge to edge Zone VIII, cut it into quarters, pull the pieces out one by one from the developer at the time you are testing for. (Usually 30 seconds apart). The increased density makes it obvious which was which. Good luck with those smelly holders.

26-Oct-2003, 09:56
I figured out the failure in my logic. But I can do it with 3 sheets of film. Divide each sheet into fourths. Expose the first three quarters at asa 600, the last quarter gets no exposure for b+f. for this sheet the asa's will be 600,300,150. The next sheet is the same with asa's 500,250,125,b+f.

next is asa's 400,200,100,b+f

Andrew, your method sounds good, but I don't have the light, dimmer ect. It sounds like a worthwhile project though.

David A. Goldfarb
26-Oct-2003, 12:21
If you plan to do a lot of testing of various films, one approach I've seen is to take a darkslide and drill several large holes in it and cover each hole with an opaque patch. Then for each test exposure you remove the darkslide and remove one patch and replace the slide for the exposure. For the next exposure you cover the first hole and expose the second, etc. Through all of this the holder stays in the camera, and only the darkslide comes in and out, and presumably one uses a longer lens for the test to insure even illumination across the frame.

Steve Baggett
26-Oct-2003, 16:35
I use a modifed form of David's method. I bought a couple of cheap Riteway holders off e**y and "sacrificed" 2 of the darkslides by a single square (about 1" on the side) in each of them, one in the upper left quadrant on one and in the upper right quadrant of the other. I use these to make 4 test exposures on each sheet, by exposing using each darkslide twice, flipped over. You don't have cover/uncover any holes this way, but just don't forget to put the "real" (un-holy) darkslide back in the holder before removing it from the camera, unless you want a zone 200 exposure in one square. When you cut the "holes", use a sharp exacto-like knife and remove any "burrs" so that the slides go in and out easily. Don't make the holes too big or too near the edges, to maintain the structural strength of the slides. Make a notch or other variation in one hole and use that one first in the test and you tell the order of the exposure squares later (even though the exposure density varition is usually sufficient for this.)

Joe Smigiel
26-Oct-2003, 20:07

You might want to take a look at this recent thread from the "rec.photo.equipment.large-format" newsgroup. Of course, the thread degenerated into name-calling as do many "discussions" on usenet, but there were some good ideas discussed near the beginning of the thread.


I'm not sure if the url above will work (there should be no breaks or spaces in the url) but if not, googling the newsgroup for "Film Testing" should turn it up.


Mike Troxell
26-Oct-2003, 20:57
My method for film testing with 4x5 is simply to meter for Zone I at the suggested film speed, pull the darkslide halfway out and make a exposure. Then repeat for each film speed setting you are using. When you develop the film you just make a proper proof of each 4x5 and compare the exposed part to the unexposed half of the film. The first 4x5 that shows any diference between the exposed and unexposed halfs is your correct film speed. I don't have a densitometer so its alot easier for me than trying to compare the exposed sheets of film to the unexposed one and determine which one is different.

James Phillips
27-Oct-2003, 07:19

Exactly like Steve Bagget, I have sacrificed an older holder. Same thing that Steve does, I do. Works wonderfully! (I use round holes from a drill press drilling)

I get four exposures per film and the good thing is that those fours exposures are developed EXACTLY identical. This helps if you wish to set one exposure at Zone I and the others at say Zone III, Zone V and Zone VIII. A great way to verify the gradual increase or decrease in contrast versus development when testing.

I tried the other methods I read in books but I prefer to have a variety of information on the same sheet. I usually shoot two sheets at one time, develop the first, see the results, make adjustments if necessary and then develop the second sheet. Easy and quick.

Kind Regards,

Doremus Scudder
29-Oct-2003, 06:46
I routinely do film speed tests by making up to 5 "stripes" corresponding to different film speeds on one sheet of film. I also make Zone Rulers in a similar manner, getting up to 12 Zones on two sheets of film. The technique involves additive exposures and is a bit complicated, but if you are interested, drop me an e-mail and I will send you off the instructions in the form of an html document.