Weird, but at least its still something you can buy.looks like it might be one of these https://www.mutuallc.com/MINI-J-3-pin-signal-connector-pd45173085.html
Its a shame that neither of their chosen cables are friendly to just having an actual mount-able connector on the timer side.
They are very ver focused on that connection being water tight for some reason. Maybe its something they hut in a regulatory review, or just being ultra focused on it bein in super confined spaces with trays of liquid.? It is weird though. Its not super high current or voltage there and they could have had a connector straight into the LED head.
Still, in these circumstances I just assume they had a reason.
Hello,
I had a chance to briefly see the Heiland Splitgrade system in action and I would really like it for some applications. But the price of the solution and the light source is out of my reach right now.
But I wonder how difficult it would be to put something like that together? I'm assuming it wouldn't be that fancy and comfortable.
It doesn't even have to be a fully automatic system. Let's say I have a basic electronic and programming skills and some of the following equipment:
Darkroom Automation Meter /RH Designs ZoneMaster/ another meter for measuring light levels.
Reflection densitometer for measuring density on paper.
Light source with suitable blue and green LEDs (maybe red for easel work) with PWM dimming.
Microcontroller (ESP32, Arduino MEGA) for light control and exposure management.
So i have the ability to measure/calibrate the paper and control exposure to blue and green light.
How to find out the parameters for splitgrade? Does anyone have an idea?
Thank you very much.
Forget about official "grades" as they are just fairly arbitrary ranges of ISO-R. To "calibrate" your grades, all you need is a Stouffer step tablet and some paper. You can define the grades as a combination of blue and green exposure within your specific implementation of a light source.
W.r.t. the light source, for b&w multigrade you can use whatever arrangement of blue and green LEDs you like. These can be strips, stars, individual (smd) LEDs on a PCB, COB etc. Whatever you choose, you'll have to make a light path that results in even exposure of the negative. Duffusion-based systems are easy to make; just experiment a bit with LED arrangement and e.g. milky plexiglass.
As to the controller, use any old Arduino etc of your choice with and LCD hooked up to it and buttons, rotary encoders and keypads as you see fit. Making a simple timer with two PWM outputs isn't very complicated.
This is a pretty straightforward project that many have undertaken; it's definitely feasible, just get cracking and have fun!
Not quite; you generally need to mix in a tiny bit of blue with the green to get a decent grade 0 or grade 00. With just pure green you often end up in some kind of below-zero twilight zone, and on some papers that can be very non-linear. On other papers, you can end up with no possibility to get a decent black on that grade. So add a little bit of blue; you could use a Stouffer print to hit something like grade 00 or so, or whatever you find useful as a grade at the lower extreme of the scale.The extreme values are clear, only green or blue LEDS on
That's what I did before I realized I could just as well forget about grades altogether. Yes, do a bunch of Stouffer prints and then plot the results. Using the plot, you can determine which mix you need for which grade. This is fairly simple/straightforward; things get a little tricky if you want your settings to behave like the Ilford Multigrade filters and produce the same exposure time across various grades, but that's also possible.Do a larger number of tests with the Stouffer tablet and then choose from the measured ISO R?
This is interesting... Lately I've been doing some bench-tinkering with an Ilford 500 system to figure out its interface on an electronics level, and one of my to-do items there is mapping out its exact blue/green control signals for each combination of settings.Not quite; you generally need to mix in a tiny bit of blue with the green to get a decent grade 0 or grade 00. With just pure green you often end up in some kind of below-zero twilight zone, and on some papers that can be very non-linear. On other papers, you can end up with no possibility to get a decent black on that grade. So add a little bit of blue; you could use a Stouffer print to hit something like grade 00 or so, or whatever you find useful as a grade at the lower extreme of the scale.
Not quite; you generally need to mix in a tiny bit of blue with the green to get a decent grade 0 or grade 00. With just pure green you often end up in some kind of below-zero twilight zone, and on some papers that can be very non-linear. On other papers, you can end up with no possibility to get a decent black on that grade. So add a little bit of blue; you could use a Stouffer print to hit something like grade 00 or so, or whatever you find useful as a grade at the lower extreme of the scale.
That's what I did before I realized I could just as well forget about grades altogether. Yes, do a bunch of Stouffer prints and then plot the results. Using the plot, you can determine which mix you need for which grade. This is fairly simple/straightforward; things get a little tricky if you want your settings to behave like the Ilford Multigrade filters and produce the same exposure time across various grades, but that's also possible.
Ideally, I would like to achieve a speedmatch, but from what I understand, it is only possible for one tone, for example highlights.
Not really; I'd just start by doing some strips with mixes of various ratios e.g. 10/90, 20/80 etc. and then plot the ISO-R you determine on the basis of a step tablet in Excel. Then make a chart from that and see how it behaves; take it from there.Do you have any tips on a clear procedure to achieve this?
Not quite; you generally need to mix in a tiny bit of blue with the green to get a decent grade 0 or grade 00.
I did my own custom LED head that allows me to change filter grades with a knob. 16x16 arrray of neopixel LEDs behind a diffuser panel, and a custom controller build around a Pico RP2040 and coded with CircuitPython. Works awesome. Ironically one of the reasons I built it was because I wanted to try split grade printing, and it was a huge pain to do so by swapping out physical Ilford MG filters in my condenser head. My experiments with split grade printing were brief and I no longer use the technique anymore, but I sure do love the LED head still.
I did my own custom LED head that allows me to change filter grades with a knob. 16x16 arrray of neopixel LEDs behind a diffuser panel, and a custom controller build around a Pico RP2040 and coded with CircuitPython. Works awesome. Ironically one of the reasons I built it was because I wanted to try split grade printing, and it was a huge pain to do so by swapping out physical Ilford MG filters in my condenser head. My experiments with split grade printing were brief and I no longer use the technique anymore, but I sure do love the LED head still.
Psss... For anyone wanting to take the easy route, the Intrepid LED enlarger head is basically this design (array of RGBW Neopixel-style LEDs behind a diffuser).
A couple of centuries ago...also, there are several iterations/versions of "the" Heiland LED head. It's not even clear they use the same wavelengths for blue.Ilford tested the Heiland LED light
The question is also on which papers, specifically. Some papers don't do a true grade 5 to begin with. E.g. look at the Fomaspeed Variant III datasheet and its grade "5", which is more like a 4+:where "ordinary" blue around 465nm is used, people have no problem achieving the same hard gradation as with filters.
A couple of centuries ago...also, there are several iterations/versions of "the" Heiland LED head. It's not even clear they use the same wavelengths for blue.
The question is also on which papers, specifically. Some papers don't do a true grade 5 to begin with. E.g. look at the Fomaspeed Variant III datasheet and its grade "5", which is more like a 4+:
Then there's the fickle issue of real-world curves not necessarily being the same as the neat plots in datasheets:
Above is a test I did on Fomaspeed paper with various wavelengths. Note how the toe of the (single!) 480nm wavelength exposure isn't anything like that of the 450nm exposure.
Also, in my interpretation/measurement, the highest grade was ISO-R 60, which is in my understanding grade 4.
Please do not misinterpret the plot above as a plot of various grades on this paper!!
So what's a "true grade 5" to begin with? It depends on definitions, as well as measurement methodology (which part of the curve do you use to determine ISO-R), as well as the paper you use, and perhaps a number of other things.
Now what, you might ask?
I'd consider the following:
If you want to enjoy the easy programming and spacing of RGB-LEDs like the WS2812 (and the conceptually similar ones used by Intrepid), then don't worry about it at all, because none of these products AFAIK has a shorter-wavelength blue anyway.
If you are OK with using your own selection of blue, green and red in distinct LEDs, and you want to play safe, go with 450nm blue. It'll work great.
If you want to get to the bottom of things, and are OK with potentially getting lost in a mass of definitions, curve shapes, differences in interpretations etc., then order a couple of flavors of blue and do your own testing with the papers you intend to use a lot.
Note that the first thing I said in this thread was "Forget about the official grades". Perhaps you're now beginning to understand why.
The report is from March 2017, when Heiland introduced a version of the LED source and controller on YouTube that looks the same as the one still offered. But maybe there was some fundamental change, I don't know.
By the way, Heiland has changed ownership and name, so I'm curious where they'll be heading.
https://heiland-vision.de/
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If you are OK with using your own selection of blue, green and red in distinct LEDs, and you want to play safe, go with 450nm blue. It'll work great.
Psss... For anyone wanting to take the easy route, the Intrepid LED enlarger head is basically this design (array of RGBW Neopixel-style LEDs behind a diffuser).
In another thread I read that the Intrepid uses only 2 wires though.
It will be. If you look at the video at 22:12 he has the light source open and there's three leads visible, red, black & blue. Those will be easily traced to +V, GND and data, and using a continuity tester you can easily verify which is which on the connector. But...you already knew this, having built your own systems!Hopefully it should be straight forward to identify when I get one and open it myself.
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