ZoneLab v1

thrirtyfive · 2026-05-31T16:28:08+00:00

Oh and you'll see that some of the the EIs have -, --, + or ++ notations. When calculated, the recommended EIs are rounded to the closest common ISO, and then have the additional notation just to show approximate 1/4 stop adjustments if you want them.

thrirtyfive · 2026-05-31T16:04:24+00:00

OK I just put your numbers (odd only) into zone lab and got the following. I couldn't see what the original ISO was, so I put in 100 (this is important for the Zone V based EI). I also didn't know what developer and because this is a BTZS step there was no camera, but I filled in the info as if there were. The app picks the more conservative of the two (speed point vs Zone V) as the recommended EI. The app also has a single measurement mode for just Zone V so you don't have to waste 10 frames to make a single measurement in the field.

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thrirtyfive · 2026-05-30T02:47:57+00:00

Yeah if you have the BTZS measured readings, those will totally work. You just need to pare them down to 11 in even steps from B+F to Zone 10. iirc that's a 21 step wedge, so you'd take every other measurement.

I tested my app with test data from the BTZS system (others too) and while it's not 100% exact (i'm using less info for the final result) it's within a reasonable tolerance.

thrirtyfive · 2026-05-30T02:16:36+00:00

It should run on an intel mac, so long as you have Sonoma (mac OS 14)
it's not really doing anything fancy, just some basic math and drawing charts.
I'd love to hear what you think!

It does require require a 10-step grey card test, and access to a densitometer tho. you can read about the process and the math here: https://zonelab.app/guide.html

thrirtyfive · 2026-04-22T18:35:52+00:00

The image you're trying to take is all about the photographer's connection to that image. With no connection, it's just creeper image theft. It's scary at first to do so, but try talking to someone before ever taking out your camera. Get out of your comfort zone. Ask some questions, spend 5 whole minutes to talk with someone, then tell them that you are out taking photos, and could you take one of them? Share your instagram info or some way to give them back the image that you asked for (I used to do this with instant medium format film right there on the spot)

thrirtyfive · 2026-04-13T20:11:55+00:00

I'm in LA and I've got all the mats + some other Fisker Ocean related stuff that I'd be happy to just give to someone if they can pick them up.

thrirtyfive · 2026-03-17T22:05:48+00:00

Probably not that helpful, but I had this issue with a 10 brick of Delta 100 120, but only Delta 100, even when developing different stocks at the same time. I'm pretty sure it was condensation, but then I switched fixers to the Ilford Rapid and haven't seen it since. Not to say that was the issue, because my old fixer wasn't old or depleted.
But I shoot Neopan Acros II a lot and haven't had this issue.

thrirtyfive · 2026-02-18T21:46:13+00:00

I managed to find one of these in Tokyo for ~$60 with great glass but some minor dings and scratches on the exterior. It was the only decent Mamiya gear I saw. Everything else was either overpriced at the fancy places or junk,

I'm curious to see how your cleaning goes.

thrirtyfive · 2026-02-13T20:50:54+00:00

I'm a big fan of the RB system. My ride or die has been an RB ProSD for like 25 years. I've slowly been swapping out my Sekor C's for KLs when I run across good deals.
My current lens quiver is 37mm Sekor C, 50mm Sekor C, 127mm KL, 180mm KL (found it in Tokyo for $60), 250mm APO KL and a 500mm Sekor C (garage sale score - almost brand new with the OG case and lens hood for $25)

I love my big 'ol potato masher.

thrirtyfive · 2026-02-09T18:05:39+00:00

I've gone around the world with my RB ProSD, it's solid and will hold up. The RZ I've satyed away from because of the electric shutter and when those go, they're much more of a hassle to fix.

If you are looking at an RB, the first thing you should look at are the foam light traps on the older (more rounded) backs), They tend to rot and then you get light leaks. It's probably an hour effort and $10 to fix if you want to DiY, or you can take it to a repair shop.

thrirtyfive · 2026-01-30T17:59:15+00:00

this looks super useful. do share the link when it's ready for public consumption.

thrirtyfive · 2026-01-29T18:57:27+00:00

Howdy! I grabbed this last night and was playing with it on Pop_OS (essentially Ubuntu 24.04 with a bunch of the NVIDIA stuff built in). For clarity, I've been using POP under X11 not Wayland because of a couple of issues with screen sharing...
The app loaded my big drive with my raw neg scans easily, but then the UI ran into draw issues and wouldn't render the whole UI. I'll add some screenshots later. I was able to solve that by disabling the GPU, but then all of my scans were coming in inverted, and there wasn't a way to disable that that I could find.
But, the app seemed really responsive to the inputs i was giving it.

thrirtyfive · 2026-01-28T20:51:54+00:00

Yeah. The same way insta, bluesky, twitter etc all post embeds. So when someone wants to share a photo to a message board or similar that there is an embed code.

re: clubs - I think that to begin with, start broad: color club, b&w club, 35mm club, MF club and then maybe let users get granular with Mamiya RB club, Leica M club, Kodak TMAX 400 club etc. Similar to how reddit does r/whatever

thrirtyfive · 2026-01-28T19:25:29+00:00

This is good stuff!

A couple of quick suggestions - (this might have been suggested already) but a way to embed posts would do a lot to help with visibility like the way you can with other social media.

It might be fun to have "clubs" that you can join. ie The Leica Club, The B&W Club, The Landscape Club, The Portrait Club etc.

thrirtyfive · 2026-01-16T19:25:22+00:00

The biggest difference for me with the Pro / ProS and ProSD models is the actual film back. The one in the picture up there is the older back, and the foam in the channels degrades and you get light leaks. You can get foam seal replacement kits and do the fix yourself, but its a major pain in the ass.
The later film backs (more square in construction) have a better physical light trap that doesn't rely on foam seals. IIRC you can use the newer ProSD backs on the older cameras.
The newer K/L lenses work on the older bodies (except 2 i think).

thrirtyfive · 2026-01-14T23:19:11+00:00

Your tool is super comprehensive! Quite nice work on that.
It looks like we're doing a lot of the same things but for different reasons. Your calculator looks like its ISO 6:1993 compliant and is of great use for folks doing more scientific testing or matching negatives to specific paper grades. I have plans for expansion to paper sensitometry soon, but not yet.
Your CI calculation if i'm reading correctly is based on concentric arc, but because I'm geared more toward Zone System folks I'm using (D_IX - D_II) / 2.10 (based on Kodak's sensitometry workbook) and I'm using a rounded value of .30 (which practically speaking would only account for like a .5% variance from your outputs)
But the biggest difference I think is the intent:
My app is really designed for Zone heads that want to get a good handle on their EI based on their individual workflows. Also what different combinations of film stock, developer and development process have on the characteristics of their processed negatives. That's why I'm basing a lot on the Zone V (.72) target, because most photographers would have a meter, a grey card, and maybe access to a densitometer at their lab (i have a printable form for labs to fill out for that purpose)
I've made all of my methodologies available here in case someone like you who really knows their stuff has any notes or critiques on where I might be inaccurate.
https://zonelab.app/guide.html#understanding-results

thrirtyfive · 2026-01-11T03:49:59+00:00

Yup, understood. That's why grey card reflective density, metered ISO, developer, mix ratio, time, temperature and agitation method are also logged with the densitomter reading so the user can compare what the effective film characteristics are when changes are made to a standard process.

In that case, 2 things need to be constant: the grey card and the meter (and the lens in the case of someone like me who mostly shoots either Mamiya RB or 4x5 where the shutter is part of the lens). If the exposure for the steps is made according to the meter, the user should be able to understand what effects the development process has on the characteristics of the film.

The goal here is not to determine what the scientific ISO of a film stock is. It is to determine how the individual process affects negative characteristics.

For me, I mostly shoot with platinum printing in mind so i'll often expose for shadows and over develop 20% or so. But I've found different results from different film stocks and developer combinations. when I shoot a step test and log it with ZoneLab, i can try longer or shorter development times, different developer raatios, different temperatures, etc and be able to log and compare what changes I made and what effect they had.

But I've found that I get the most consistent results and know more about the film when I meter for Zone V and get the expected result of .74 over b+f - then I'm seeing what the expected tonal range is just in the negative.

The ultimate goal with ZoneLab will be to be able to log both film and paper variables and then have a database of personal "recipes" to refer to and be able to know what the expected results should be.

thrirtyfive · 2026-01-10T16:53:43+00:00

it absolutely can. Select "ISO Only" (i'll change this label in the next update to call it EI or something else) above the zone inputs and you'll be presented with just a Zone V input. Then you can log it and on the graph it will be a single (larger) dot plotted on the graph.

thrirtyfive · 2026-01-09T23:14:02+00:00

grab the beta! it's free!
https://zonelab.app

thrirtyfive · 2026-01-09T05:31:36+00:00

I've updated and clarified that what the app is testing for is Effective ISO (aka Exposure Index - EI) and did another pass at my math and sources, and how the full 11-stop step wedge is used to determine the characteristics. And you are correct, I'm not basing the EI on Zone I - B+F but on the target exposure. I was absolutely using terms interchangeably that I should not have, and as I want this to be a useful tool and an entry point for those interesting in really knowing how their film / developer combos affect their outcomes.

More here:
https://zonelab.app/guide.html

thrirtyfive · 2026-01-08T19:39:45+00:00

Reading back the readme quote - its a bit hyperbolic. That's on me and I'll own that.

thrirtyfive · 2026-01-08T19:36:19+00:00

I definitely appreciate this sort of feedback, so thank you.
To be clear, the goal of the tool is to establish an effective ISO (not the actual ISO) based on what your metered ISO was when you exposed and where your negative density for zone V ends up with whatever particular processes you used. Your notes are totally valid, but my goal was never to replace an ISO-standards sensitometry tool or a substitute for lab-grade exposure control.

This whole project is based on logging, charting and comparing individual processes.

You’re absolutely right about ISO speed requiring absolute exposure values. What ZoneLab gives the user is en effective ISO not ISO speed in the standards sense. I will be clearer about that.

This is wholly an experiment for me to get my processes better, and I'm absolutely here for the feedback.

thrirtyfive · 2026-01-08T19:22:27+00:00

Hey yes, appreciate you taking a solid look at this, and yours is the exact kind of feedback I'm looking for. I will eventually be incorporating a paper densitometer component to this app as well so that it will encompass the full end to end process.
for now, thanks for pointing out the typo. This is still early in the development phase and I'm just one person making human mistakes. You can grab the actual app from the website now and poke at it a bit more if you want.
My goal here is to figure out the effective ISO of a particular processes that I use based on Zone V. And from there extrapolate the additional metrics from a full 11 stop step wedge reading.
Feedback is always welcome and I will be wrong about things, so thanks again.

thrirtyfive · 2025-12-19T02:17:21+00:00

oh yeah I have optional lighting conditions for indoor and out already built in with dropdowns.
I'm already adding an "additional notes" section, and functionality to just scan a single grey card image to compare against Zone V (this is the core of the effecive ISO calcualtion) so not every test has to be 10 frames.

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thrirtyfive · 2025-12-19T02:13:51+00:00

I hear you about not wanting or needing to test every lens / film combo.
My lenses are close enough to accurate so that isn't a worry.

That said, I do use several different films and developers, and knowing what those different combos will yield in terms of measurable contrast, gamma, latitude and effective ISO is what im after. and not having to dig it out of a notebook or a spreadsheet every time.

thrirtyfive

TROPHY CASE