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Testing Film ISO & Development Time - Large Format Friday
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- Опубліковано 14 сер 2024
- The materials we use as photographers, especially in large format, vary from person to person. Getting repeatable results with so many variables to the process can be tricky. One way to help get a handle is testing your photographic films. Today I'm going to show you how to test B&W film in a large format camera to determine your personal film speed (ISO) and normal development time.
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Paul Wainwright's Articles: www.paulwainwri...
Stouffer Step Wedges: stouffer.net/Tr...
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#largeformat #filmphotography #darkroom
00:00 Intro
00:40 Why Test Film?
02:01 The Bond Method
03:00 Test Setup
05:08 Metering
07:05 Testing
09:31 Developing
11:12 Finding ISO
12:55 Min. Time, Max. Black
15:00 Finding Dev Time
16:38 Conclusions
you don't need to buy a step wedge. set your shutter to say 1/100s, expose the entire sheet once, insert the dark slide just enough to cover a thin strip of the negative, expose one more time, insert the dark slide a little more and expose 2 more times, insert the dark slide more, expose 4 times, etc.. basically you're doubling the total number of exposures every time you cover another strip, so 1,1,2,4,8,16,32,64... that'll give you 1/100s, 1/50s, 1/25s, 1/12.5s, 1/6.25s...
Good point
The step wedge purchased new from Stouffer costs in the range of $8 to $15. The hassling around with multiple exposures, the risk of making mistakes in the repetition, and the dubious assumption that your shutter is linear (accurate) puts this suggestion in question as a matter of cost, convenience, and accuracy.
Stouffer wedges are 30£ on E-Bay
This would be much much faster if you broke it into sections, not 1/100 the entire time. A hundred exposures is ridiculous to save like $1.50 on another sheet of film. Maybe if it was portra.
After decades of just going with box speed for ISO and using development charts from the producers, I felt the need to do this type of evaluation when I started using my own DIY developer. I followed the Adams procedure because I was passingly familiar with the zone system. I found a used densitometer fairly inexpensively. By setting up fixed standards, I am now able to fairly quickly dial in any film I wish to try, taking an afternoon, mostly consumed by processing time for development time tests. The overall improvement in my negatives was immediate and significant.
What a great re-cap of everything I've forgotten! I need to rewatch this a few times, maybe I won't have such flat negatives! Thanks Matt! Great job!!!
It is a mistake to test film speed with an exposure that causes reciprocity failure. When you get reciprocity failure, the contrast of the film increases. The exposure difference between highlights and shadows alters. Do your test with more light to ensure the exposure does not suffer from reciprocity failure.
I just found you today... and very happy I did...Such great pictures!!! Lot of tech info too....so I am going to have to go back and binge watch your other videos to see what good info I can absorb.
Dave thanks for the comment and welcome to the channel. Happy to have you and hit me up with any questions in the comments or the LFF email!
Mat, your post is interesting and informative. I would like to see further discussion about two items you mention.
1 is focusing a view camera at infinity. Please discuss how you achieve this.
2 The typical 4x5 film holder is designed to hold one sheet of film firmly in place so there is limited movement. Loading a 4x5 film holder with a sheet of film and the 4x5 step wedge into the slot for the film is an extremely tight fit. Please discuss how you manage to make both sheets fit in a single film holder.
Thanks
Gary
Doing the lord's work. Thanks, Mat!
Thanks Chase! This was a video that had sat on the topics list for a long time and glad I got the chance to make it happen.
Thanks Mat, I would like to try this in the future. It is so interesting to look back at old negatives to determine if I am hitting proper exposure. As I gain experience I hope to isolate and dial in my process. I am still too happy when I get (what I consider) a usable negative, but have to start getting fussier to produce more consistent results. When it gets too overwhelming I have to remember to step away from the edge and have fun again. While I understand what you are doing here, it is still a little beyond me to get there. Your videos are great and I will revisit this when I feel more able to get it completely. This is becoming such a great resource for how to become competent. Thanks for the efforts!
That's fantastic Matt, informative as always, thanks.
Great video, made me kinda want to run through and re-calibrate since it's been years since I did my initial testing. I standardized around FP4+ in Rodinal and HP5+ in HC-110 when I started shooting 4x5. Still love both of those combos. I did my testing using a more involved method with my Spotmeter F + an inverted 50mm lens substituting for a densitometer, and a lot of math that seemed a little questionable. Whenever I had questions or wanted clarification on something that Ansel Adams wrote in The Negative, I went online to communities like Photrio (previously APUG), and generally got a lot of contradictory advice and opinions stated as facts.
This seems like a really good method that is light on wasted film and gives a pretty useful bottom-line view of how things look when they're printed.
Thanks for the comment Andrew and I know that feeling about asking for help online. There's a wealth of knowledge on forums, but there's a lot to sift through to find it.
Fantastic Mat! This video is exactly what I've been looking for!
Glad it was helpful!
The video reminds me on my early work using the minimum exposure time to reach maximum black for printing negatives. Once the maximum black of a particular roll film is determined (FB+Fog), the time can be used for printing every shot on the film, provided the camera exposure is correct for each shot with normal contrast.
Raymond you hit the nail on the head! That's a great procedure to learn and practice at least once if one plans on printing from B&W negatives. Once that foundation is laid out, arriving at printable negatives from any film becomes easier and the photographer has more options available. Cheers!
Great video, Mat! I've used a densitometer for so many years I'm not sure I could learn a new way. ;) The most elusive variable when using a densitometer to measure a stained negative is simulating a response to blue light. I use a Kodak Wratten Dark Blue gel that has served me well. That said, one of my favorites is Fomapan 100 developed in Pyrocat-HD. Beautiful tonality and very reasonable price point for 8x10.
Thanks for the comment Alan! Getting readings of of Pyro negatives can be tricky, that's why I ended up with the X-Rite 361T. That being said, I feel like I need to be retrained I go to use the thing.
Excellent presentation very informative and extremely useful. Thank you!
Glad it was helpful!
Just a note. You focus on infinity as that eliminates the need to use the bellows extension exposure compensation you would need for accurate exposure in close focus.
This is such a good video on a topic that many of us hate but you keep it interesting. Thanks agin - done
Until I found Alex and Paul's system, I wasn't a big fan of testing. Plus that Stouffer wedge has some good applications in alt process printing too!
@@MatMarrash I’m going to running this test now. Question, should you really be running this test on each lens? Since shufflers and lenses render different
where did you get the black grid thing in the Bottom on your sink? The mat that lets water drain when items are sitting on it? thanks and sorry for the random question. I need one of those. b
Very interesting demonstration. I am a non professional 35mm photographer because I never print above 8 X 10, often only 7 X 5 and large or med format film would be wasted. However I am intrigued by your method. I do have a stoufer step wedge (single Strip) and I am trying to figure out a method that is as simple as yours. Thank you for the explanation.
I have a Kodak Projection Print calculator. I don't have as many steps, but do you think this could be used instead of the Stouffer Step wedge? Thinking about resources I have available.
This is a great question and something I didn't think of! The slices of that scale should be equivalent to two steps of a 21 step tablet. Great idea!
Hey Mat, great content! How would the process of testing film ISO and Development Time change if one were to use a TP4X5-31 aka, 31 Step Projection Scale instead of the TPX4x5-21? 31 step reads in 1/3rd stop increments as opposed to 1/2. Where would that place the zones on the projection scale? My Pentax digital spotmeter and Sekonic L758-DR read out in 1/3rd of a stop increments so wouldn't it be better to match my meters and go with the 31 step projection scale tailored to my individual setup rather than go with with 21 step projection scale? I plan on using this technique to determine FILM ISO + Development times for Tri-X 320 and TMAX 400 in D76 1:1 dilution at 20 degrees celsius since these are my go to film stocks for both 4x5 and 8x10 B&W work. Thanking you in advance for your time! Cheers
This was great Matt. I came across Paul's website several years ago and agree that it is a simpler way of doing things. I haven't seen anyone else talk about this method so I'm glad you are brining it up here.
I hate doing testing but if you want to be consistent in your results I think it is a necessary evil. For me it's Pyrocat HD and FP4 & HP5. Though I have to admit that I like to play with other films and developers but I haven't done any testing yet for other films/developers.
I've been told that the film base for LF is that same so if you are shooting 4x5 moving up to larger sizes your personal ISO and developing times won't change. True?
I think this little step wedge is about to see a lot more use in the coming months with that UV source up and running! As for the base, I don't believe it changes in thickness until you get up to ULF roll films for Cirkut cameras (thinner base there).
Assume this is a good approach for expired film if you have enough to test. Thanks Mat.
Possibly even more beneficial for expired since there will likely be more base fog the older it is!
Very well done presentation on calibrating a film type's ISO for an individual's developing and printing practices. I don't have a darkroom, instead I scan negatives and print using a decent Canon inject printer. How could this calibration procedure be modified for use with scanned negatives? Your LFF videos are extremely helpful, thanks!
Thanks for the comment Francisco and great question. If you plan on reading your test negatives via scanning, it's important to scan your film in such a way that no adjustments are introduced via your scanning software. From there, you would need to bring in the scan to Photoshop (or equivalent) and use the eyedropper tool to identify calibrated patches and compare them to the base fog of the film. Looking around, there weren't too many resources out there on this, I may need to make a video!
Are two 1second exposures equivalent to one 2 second exposure? Recently I read in a photography book that they weren't.
When I used to try and follow the zone system, I used my Minolta Autometer IV with a flat disc as a sort of densitometer. I'd set it to read in EV and then take every 0.3 change of EV when reading the light projected through the film as 0.1 change in density. Nowadays, I just can't be bothered. Interesting method BTW.
That's just it, keep it accurate enough to reproduce, but not so laborious that it's a chore. Thanks for the comment!
Hello Mat, Thank you for this video. I would try myself but I cannot put Film + wedge inside my Fidelity holders....any advice?
Hey Laurent it's a bit of a tough fit with thicker base films like Kodak and Ilford, but should still fit. Are you by chance using older film holders with curved metal rails on the edges?
@@MatMarrash yes have old lisco holders too with metal rail. But it's very tight too. Do you suggest to bend a little the rails?
@@laurentgauthier2029 a small bend should do the trick!
Thanks.
Thanks.
This is great but, I shoot 35mm. The large format investment wouldn’t be practical. Anyone have suggestions on another way I could test film?
Dear Matt, thank you for videos. I would like to ask you, if can you show us, how you decide times of n+1 and n-1 developing? Thank you. Jan
Hey Jan, to determine N+ and N- times, you'll perform the same step wedge test at your personal ISO with a couple of fresh sheets of film. Then, develop one sheet for ~25% less time and another for ~ 25% more time. What you're looking for in a Zone shift is a change in two steps on the Stouffer wedge. N+1 will push two steps higher, and N-1 will pull two steps lower.
Have your ever experimented with stand developing film in HC-110 or Rodinal?
Thank you for showing this method 👍 How about the paper gradiation? If we use multigrade paper for contact prints does the results not shift depending on the set gradiation filter and output wrong results?
Fantastic work! Just wondering, why the "STO" characters are still exposed since it's located under the round sticker?
The sticker may not be fully opaque for the exposure or there was some halation from the nearby steps on the wedge.
I wish I'd have seen this earlier. I invested in a densitometer. I do have a question. 2 parts... Where can we get the step wedge tool, and how can this info to transfer over to scanning 4x5 negs with an V850? I don't have access to a darkroom, so I am using a scanner, and photoshop. Thoughts?
Thanks
Monty
Hey Monty! While it's been quite some time since I've used a scanner in this way, here's an old forum thread on getting started: www.photrio.com/forum/threads/scanner-as-densitometer-linearity-issue.149893/
Hey Matt, I was unclear in my question I think. I don’t have a darkroom available, and I scan into my Mac. Does the info on a negative transfer the same as with printing, or is it two different animals?
@@montycraig5659 Hey Monty the info can transfer over, but it's not apples to apples. The link I provided was a discussion of how to scan the step wedge and negatives for basic sensitometry. Also you can buy the wedges direct from Stouffer or Bostick & Sullivan in the US: www.bostick-sullivan.com/cart/690.html
I personally don't test much of anything. But HC-110 has bit me in the rear end more than once, especially with Arista.EDU/Fomapan 400.
As for note taking, I saw about a year or two ago a video from David Hancock where he uses strips of masking tape on his holders to take notes. As a bonus, if there is something written on the tape you know the film has been exposed. ua-cam.com/video/7SErZwuDmik/v-deo.html
I have enlarger as your, but with dichronic module and 4-blade masking film stage :)
Nice!
What is the part number for the step wedge. Stouffer makes a lot of step wedges
Hey Michael this one is a 4x5" wedge printed out to 21 steps, so the part is #TP4x5-21.
US $57.50 is their current price.
@@MatMarrash they also have a "Calibrated" one... Which Stouffer wedge do you recommend?
I noticed that you have your holder notched. Care to do a 'How To" ?
Check out the previous video in the series, here I talk a bit more about notching: ua-cam.com/video/vkm0rwF_WQs/v-deo.html
Could you do a similar test using a Kodak Color Separation scale?
Hmm, I'm not too sure since the only color separation scale I recall from Kodak was one that was on a printed sheet/cardstock. If you had one printing on transparency that was calibrated you'd be good to go.
That was great thanks, will have to try this sometime. Question, is step 4 to 18 equivalent to 7 stops? If so, does that mean your paper has a range of 7 zones? That's quite a bit less than the 9-10 zones we read about for paper.
Hey Mark thanks for the question! I was a bit surprised about this as well until I read through both Paul Wainwright and Alex Bond's accounts on it and they noted the standard range not taking up the whole step wedge. Given how much dodging and burning I end up doing with silver prints vs. alt process, I wouldn't be surprised if the range of usable values was less.
@@MatMarrash I have limited experience in the darkroom doing art printing, I mostly did scientific stuff with micrography when I was in school. I would think paper would be fairly variable in terms of actual range depending on lots of variables. And with light reflection measurements, depending on the sensitivity of the measuring device, I could easily imagine "pure black" and "pure white" being defined differently for the same paper in different hands.
@@MatMarrash I've read that with ISO and normal development per manafacturers reccomendation, actual printable range on grade 2 paper is about 7⅓ stops, whereas zone system followers aim for 10 stops on grade 2, which is about ⅔ stops more light to the negative and developing it close to n-1. That would give you a little more room to breathe for errors or manipulation.
That being said, 10 stops compressed into the 7 on the paper makes for a pretty flat print. There's a reason ISO standards exists, so your exposure and print come out with lifelike contrast and get you the most speed out of any film.
I'm a little back and forth between if I should aim for 10 stops or iso standard. Perhaps it will vary on needs, that and most of my inherited paper is fixed grade 3, so 10 stops may be better if I've got a fixed higher contrast paper.
I was surpised to see how little stain was on the Selta 100 from the Pyrocat unless the video didnt pick it up
Got washed out a little bit in the video, but the stain looks about the same as what I'm used to with TMAX 100.
Does something like this exist for 35mm or medium format?
There are smaller calibration wedges available for use with roll films. Procedure doesn't change much and testing is a bit more economical. Cheers!
Cool, thanks! @@MatMarrash
I'll have to try this with paper negatives...
Something I didn't mention in the video but Alex points out in his blog post, the Stouffer wedge is as thick as a sheet of film, so space may be tight if you try it with paper. Let me know how it goes!
Matt, obviously you're very knowledgeable and dedicated to photography. However, I think you're too caught up in the technical minutia. Pre zone system, pre light/exposure meters great photographic masters Like Robert Cappa, Henri Cartier Bresson and their contemporaries produced master class photographs, why because they concentrated on the "Art" of photography and weren't distracted by technical minutia.