F stop timer options

[Certain Exposures]

Moderator's Note: This discussion of Darkroom Equipment options has been moved out of the thread respecting an exhibition and Photographer found here:

https://www.photrio.com/forum/threa...journey-to-my-exhibition.210931/#post-2857779

Wonder why he uploaded that more than a year after his exhibition.

It doesn't work that way. You can't just "scale up." Large prints are their own beasts. Things change as you go larger, especially with smaller negatives. Contrast drops. Tonal relationships change.

Time spent scripting, filming, and editing for YouTube is time lost to photograph or print! Video demands so much.

Have you ever tried using one of the already available f-stop timers? Derek is working on making an improved and modernized one. His documentation links to more detailed blog posts he wrote.

I do have one of his books.

Lucky!

 

[Patrick Robert James]

Have you ever tried using one of the already available f-stop timers? Derek is working on making an improved and modernized one. His documentation links to more detailed blog posts he wrote.

No I've never gotten into the F-Stop timing thing. I knew Nocon who invented it and produced the first F-Stop timer. I never saw the point to it. There really isn't that much need for so much precision in the darkroom I don't think. A tenth of a second either way won't matter at all. I prefer a more organic approach. I just print by instinct but I've been doing it a long time. I kind of go by volume of light, imagining the tones rising off the paper. Everyone is different though, so do whatever works.

 

[Pieter12]

Derek is working on making an improved and modernized one.

That looks amazingly identical to the RH Designs Stop Clock. Is this the same person?

 

[Certain Exposures]

That looks amazingly identical to the RH Designs Stop Clock. Is this the same person?

No, he's not. You may want to join his discord if you'd like to ask him some direct questions. I recall a few discussions about the differences. It has been a while, though.

 

[Pieter12]

No, he's not. You may want to join his discord if you'd like to ask him some direct questions. I recall a few discussions about the differences. It has been a while, though.

He must be using either some of the same suppliers or bought surplus from RH designs.

 

[Certain Exposures]

He must be using either some of the same suppliers or bought surplus from RH designs.

No need to speculate. Check out the update videos and open source info for details. The latest update:



He built a densitometer too:

 

[Sundowner]

No I've never gotten into the F-Stop timing thing. I knew Nocon who invented it and produced the first F-Stop timer. I never saw the point to it.

For me, it offers solutions to problems that linear counting either introduced, or simply couldn't resolve.

There really isn't that much need for so much precision in the darkroom I don't think. A tenth of a second either way won't matter at all

It's precise; no argument there. Moreover, I can absolutely see the difference in my prints before/after the adoption of f-stop timing, which is why I began using the method in the first place: my results are simply better with that method because the exposures are more predictable, sensible and accurate. As far as seeing that accuracy is concerned: I would say that a tenth-second gradation very much matters to me, especially depending on when it occurs. When I'm shooting test strips for highlights I can absolutely see a tenth; it's too coarse of an adjustment for the most delicate features, so I go down to the 1/24th increment on my timer and dial it in from there. Sometimes the step between one exposure and the next isn't incredibly visible, but at other times it's quite stark. Most of the time I find that I can round it to a 12th and be happy, but not always.

More importantly, there's the question of whether or not these kind of incremental differences can be seen in the finished print. My answer to that is "probably not in any conscious way, no...but they do have an impact." Over time, I've found that even a 24th can have a noticeable and visible difference when it impacts the relationships of the various tonal values in the print; that doesn't always happen, but it's also far from a rare occurrence.

Now, could someone else see that kind of difference in my work? Maybe, but I doubt it...but "someone else" isn't really who I'm printing for, in most cases.

I prefer a more organic approach. I just print by instinct but I've been doing it a long time. I kind of go by volume of light, imagining the tones rising off the paper. Everyone is different though, so do whatever works.

I hope that I can be that good, someday...but I don't think it'll happen: I don't have a good internal sense for what's correct and what isn't, so despite my frenetic habits I try to rely on math to help me do what I can't accomplish by instinct. But like you said: it's whatever works. As long as the prints are good and we're happy with what we're doing, that's really all that matters.

 

[dkonigs]

He must be using either some of the same suppliers or bought surplus from RH designs.

View attachment 389393

As this thread just came to my attention, I figured I should jump in and offer my own comments.
I'm not using the same suppliers at RH Designs. However, I am using the same buttons. They're made by Marquardt and from the 6425 series. I picked them because I really like how they feel. Its a similar touch to a computer keyboard, but with flatter key caps. I haven't really found anything else I like better that's an off-the-shelf part.

Though I will admit there's a lot of physical design similarity. That's because the design just makes sense from a hardware perspective, and is sufficiently simple to dial in, and because I used RH equipment before jumping into my own project. Of course the RH boxes were all designed in the mid 90's, and my hardware is contemporary, so the innards are completely different. The firmware on mine is also user-update-able, so I expect the actual user experience to evolve over time.

 

[Sundowner]

However, I am using the same buttons. They're made by Marquardt and from the 6425 series. I picked them because I really like how they feel. Its a similar touch to a computer keyboard, but with flatter key caps. I haven't really found anything else I like better that's an off-the-shelf part.

Those buttons really do feel great; can't argue that fact at all.

Of course the RH boxes were all designed in the mid 90's, and my hardware is contemporary, so the innards are completely different. The firmware on mine is also user-update-able, so I expect the actual user experience to evolve over time.

I may have to talk to you about one of these; my StopClock went missing in a big move and if it doesn't turn up, I'll have to replace it.

And while we're not on the subject, I have a question: is it even remotely possible to have two separate outputs on a timer like this? Specifically, to control two different light sources from the same unit, albeit on different channels?

 

[Xylo]

Am I missing something that learning to multiply and divide by 2 hasn't solved?

 

[Pieter12]

As this thread just came to my attention, I figured I should jump in and offer my own comments.
I'm not using the same suppliers at RH Designs. However, I am using the same buttons. They're made by Marquardt and from the 6425 series. I picked them because I really like how they feel. Its a similar touch to a computer keyboard, but with flatter key caps. I haven't really found anything else I like better that's an off-the-shelf part.

Though I will admit there's a lot of physical design similarity. That's because the design just makes sense from a hardware perspective, and is sufficiently simple to dial in, and because I used RH equipment before jumping into my own project. Of course the RH boxes were all designed in the mid 90's, and my hardware is contemporary, so the innards are completely different. The firmware on mine is also user-update-able, so I expect the actual user experience to evolve over time.

One of the large buttons on my RH designs Stopclock is intermittently unresponsive, frustrating to say the least. I am not sure if it is the button or the circuitry causing the problem, but since I am in the US it is difficult to have the unit checked. I have high hopes for the long-delayed Maya timer.

 

[Pieter12]

Am I missing something that learning to multiply and divide by 2 hasn't solved?

It gets more complicated when you work in fraction of a stop.

 

[Sundowner]

It gets more complicated when you work in fraction of a stop.

Or when you're as bad at math as I am. Button-pushing, though: that I can do.

 

[Xylo]

What I usually do is, lets say I have a 20 second initial exposure and I want to add 1½ stops.
20 seconds + 1 stop = 40 sec.
20 seconds + 2 stops = 80 sec.
so, for the ½ stop, I just aim in the middle: 60 seconds.
the real way to calculate is 20 secs x 21.5=56.5 seconds.

so just having a calculator can help. Or just having a table that lists the most common exposure times and the different f/stops variations can do the trick.

I should really make one of those on a spreadsheet.

 

[dkonigs]

Those buttons really do feel great; can't argue that fact at all.

Yeah, it took a little bit of work to figure out what they were, but I showed pictures to some friends who thought they looked familiar from a different product and we eventually nailed it down.

And while we're not on the subject, I have a question: is it even remotely possible to have two separate outputs on a timer like this? Specifically, to control two different light sources from the same unit, albeit on different channels?

Yes, its absolutely possible. Though like many things, there's a big difference between "Can the hardware do it?" and "What would the user interface/experience be for actually configuring and using the feature?"

My unit has 3 outputs on the back for controlling light sources. Two are your typical relay-switched outlets, and are currently hard-coded to be used for the "enlarger" and "safelights." The third output is a DMX512-compatible control port, and is designed to be useful for basically anything that can be controlled via that protocol. This is great because lots of compatible off-the-shelf hardware already exists. The intended use is multi-channel LED heads and also safelights. Of course the UI and control scheme for this is still something that I'm figuring out, but initially it'll likely be based on how the Heiland and/or Intrepid LED heads do their control interface. (But either way, its still going to have a lot of configurability by necessity.)

So what's your multi-output use case?

One of the large buttons on my RH designs Stopclock is intermittently unresponsive, frustrating to say the least. I am not sure if it is the button or the circuitry causing the problem, but since I am in the US it is difficult to have the unit checked. I have high hopes for the long-delayed Maya timer.

My RH Analyser Pro had button debouncing issues when I got it. There's one button where you'd press it once, and the device would go unresponsive while it kept registering button presses. I think it stopped doing that after I resoldered it a few times. I suspect RH is doing debouncing in the firmware, and their routine isn't perfect. Most likely it worked fine on the initial test units, but the real world has a lot more hardware variability.

Am I missing something that learning to multiply and divide by 2 hasn't solved?

Yeah, when its fractions of a stop you're multiplying by powers of 2. So adding 1/2 stop to a 10 second exposure is "10 * 2^0.5" which comes out to 14.1s, and subtracting a 1/2 stop is "10 * 2^-0.5" which comes out to 7.1s. Not hard to do with a calculator, but not so easy to do in your head. (And a calculator isn't so easy to see in a darkroom.)

And then if you want to do dodging/burning in stop units, it just piles on.

 

[Sundowner]

What I usually do is, lets say I have a 20 second initial exposure and I want to add 1½ stops.
20 seconds + 1 stop = 40 sec.
20 seconds + 2 stops = 80 sec.
so, for the ½ stop, I just aim in the middle: 60 seconds.
the real way to calculate is 20 secs x 21.5=56.5 seconds.

so just having a calculator can help. Or just having a table that lists the most common exposure times and the different f/stops variations can do the trick.

I should really make one of those on a spreadsheet.

But what about when I need to add 7/12ths of a stop and then do a burn operation for 5/12ths later on?

Yes, its absolutely possible. Though like many things, there's a big difference between "Can the hardware do it?" and "What would the user interface/experience be for actually configuring and using the feature?"

My unit has 3 outputs on the back for controlling light sources. Two are your typical relay-switched outlets, and are currently hard-coded to be used for the "enlarger" and "safelights." The third output is a DMX512-compatible control port, and is designed to be useful for basically anything that can be controlled via that protocol. This is great because lots of compatible off-the-shelf hardware already exists. The intended use is multi-channel LED heads and also safelights. Of course the UI and control scheme for this is still something that I'm figuring out, but initially it'll likely be based on how the Heiland and/or Intrepid LED heads do their control interface. (But either way, its still going to have a lot of configurability by necessity.)

So what's your multi-output use case?

Exactly what you just mentioned: a two-channel LED head. When I'm split printing I want to be able to start on my soft/#00 exposure and only illuminate the array for soft contrast, and when I go to the hard/#5 contrast I want to only illuminate that array. For working prints that just get shot at a 2.5 to determine composition or viability, it would be nice to be able to turn on both at once, but that's icing on the cake.

Yeah, when its fractions of a stop you're multiplying by powers of 2. So adding 1/2 stop to a 10 second exposure is "10 * 2^0.5" which comes out to 14.1s, and subtracting a 1/2 stop is "10 * 2^-0.5" which comes out to 7.1s. Not hard to do with a calculator, but not so easy to do in your head. (And a calculator isn't so easy to see in a darkroom.)

And then if you want to do dodging/burning in stop units, it just piles on.

I honestly just don't like doing math in the darkroom; I'm bad at it on a good day and I don't like interrupting my "what feels right, here?" process to try and figure out how to do whatever I've just selected. I prefer being able to say "Let's just add a few more 12ths" and just do that, without breaking stride.

 

[MattKing]

It is a little bit like part of the Zone System - the important (pre)visualization part.
I've gotten pretty good at recognizing what the results from a 1/3 of a stop difference in exposure looks like.
And when things are ticking along well, being able to differentiate what difference a 1/4 or even 1/6 of a stop difference of exposure looks like.
If you try to learn to appreciate those differences in something different than fractions of a stop - say percentages - it is harder to do - at least with respect to the smaller differences.
Photographic paper responds logarithmically, so it works well to measure things logarithmically, and an f/stop approach does that.

 

[Chuck_P]

Have you looked at the Darkroom Automation F-Stop Timer?

 

[Bill Burk]

Am I missing something that learning to multiply and divide by 2 hasn't solved?

You’re missing the fun of making test strips in increments having each step be a difference that you can easily discern, without seriously overshooting “too light” or “too dark”.

All the better you are able to make a decision about how much to dodge and burn.

 

[Chuck_P]

All the better you are able to make a decision about how much to dodge and burn.

Exactly, a half stop here, a third of a stop there.......you can almost see it before you do it.

 

[koraks]

You’re missing the fun of making test strips in increments having each step be a difference that you can easily discern, without seriously overshooting “too light” or “too dark”.

Not to be flippant, but that's easy to achieve with a regular seconds-based timer. I do it all the time. Yes, it takes a little experience knowing what kind of times you'll have to aim for, but that comes within the course of a few printing sessions.

Exactly what you just mentioned: a two-channel LED head. When I'm split printing I want to be able to start on my soft/#00 exposure and only illuminate the array for soft contrast, and when I go to the hard/#5 contrast I want to only illuminate that array.

You could achieve that by having a multi-colored light source that's DMX controllable. Does it exist? IDK, never looked for it. You could of course build an interface box between any array of light sources on one end and a DMX interface on the other. Maybe something like that is already available off the shelf.

 

[Xylo]

You could achieve that by having a multi-colored light source that's DMX controllable.

That's probably easy to hack together on big enlargers like Omega D's and Besseler 45 by using some stage lights. But it would make exposures blindingly short.

You’re missing the fun of making test strips in increments having each step be a difference that you can easily discern, without seriously overshooting “too light” or “too dark”.

What I usually do is make a single test strip, develop the print and then make a plan for the final image. When you get used to thinking in terms of f/stops, it gets to be not that bad. The hardest thing is learning to convert from linear density to exponential exposure in your head. That's where the f/stops come into play.

 

[dkonigs]

You could achieve that by having a multi-colored light source that's DMX controllable. Does it exist? IDK, never looked for it. You could of course build an interface box between any array of light sources on one end and a DMX interface on the other. Maybe something like that is already available off the shelf.

That's probably easy to hack together on big enlargers like Omega D's and Besseler 45 by using some stage lights. But it would make exposures blindingly short.

No need to hack things with stage lights.

Its already a fair assumption that any sort of LED enlarger is somewhat of a DIY project. To run it, you can simply buy an off-the-shelf LED controller box that speaks DMX. Plenty are out there, and its basically plug-and-play. Alternatively, you can slap a DMX "shield" on top of an Arduino, use libraries that already exist, and write a small amount of code.

 

[albada]

And while we're not on the subject, I have a question: is it even remotely possible to have two separate outputs on a timer like this? Specifically, to control two different light sources from the same unit, albeit on different channels?

Here's a simple method that will work with any timer:
Connect a DPDT switch between the green and blue LEDs and the timer.
Here's how to expose:

Flip the switch to green.
On the timer, set green-time and expose.
Flip the switch to blue.
On the timer, set blue-time and expose.

Mark

 

[Sundowner]

Here's a simple method that will work with any timer:
Connect a DPDT switch between the green and blue LEDs and the timer.

That was going to be my fallback; I just wanted to eliminate that extra box/connection if possible. If not possible, no big deal; it would just make life easier to have it all completely synchronized so that I can't forget to throw that second switch.