RH Designs Stopclock Pro - opinions now in 2025

Alex Benjamin · Apr 2, 2025

sperera said:
thanks for that Alex, makes perfect sense.....I think I would do a traditional test strip first though........get in the ball park and then fine tune with the f stops

My advice would be to start right away with f-stop test strips. The beauty of f-stop printing is that the test strip will not only give you a base exposure for your print, but will also indicate, or at least give strong hints, as to what might be needed, or possible, in terms of dodging and/or burning. You might note quite early, for example, that some shadows would look good with 3/4 stop dodging, while the sky, or certain areas of it, could use 2 1/3 stop burning. If you're only fine-tuning with the f-stops, you're losing a lot, if not most, of what f-stop printing brings to the table.

Pieter12 · Apr 2, 2025

Alex Benjamin said:
As you do in any other system: trial and error, intuition, and experience.

When turned on, the machine automatically sets 16 seconds as base exposure. You can change that to whatever you want, using the "Up' or "Down" button before you hold on the "Test strip" button.

I generally set mine to 8 seconds, my lens to f/8, and do a 2 to 2.5 stop test strip at 1/4 stops. This often take me where I need to be on many negs that are developed in the same way (many are HP5+ developed in Thornton Two Bath). If the negative is very dense, or very thin, I'll change my base exposure accordingly. If I really don't have a clue, I might start at 4 seconds and go up to 3.5 stops for the test strip.

If my 1/4 stop strip only brings me "close but not quite," I'll do a 1/6 strip around the general time I've pinpointed.

The beauty of the method is revealed in the test strip itself. Because every strip is even, you immediately get a clear view as to where you have to be, and what's possible.

Not only that, but it makes it easy to interpolate to determine a starting exposure.

Chan Tran · Apr 2, 2025

I would always do the test strip with the f stop as it's the most useful feature of the f stop timer.

Nicholas Lindan · Apr 2, 2025

Alex Benjamin said:
If you're only fine-tuning with the f-stops, you're losing a lot, if not most, of what f-stop printing brings to the table.

Exactly.

A test strip isn't adequate to let you see dodge & burn possibilities. For that a test print of the whole image is needed. I often make use of a banded 5x7" print.

See pg 9 of http://www.darkroomautomation.com/support/mfs-manual-110.pdf

Pieter12 · Apr 2, 2025

Nicholas Lindan said:
Exactly.

A test strip isn't adequate to let you see dodge & burn possibilities. For that a test print of the whole image is needed. I often make use of a banded 5x7" print.

See pg 9 of http://www.darkroomautomation.com/support/mfs-manual-110.pdf

I usually make a full 8x10 test strip, both for 8x10 and 11x14 prints. That's as large as I usually print, though I have a hankering to do some 16x20s. Since I will have made at least an 8x10 from those negatives already, I will have my printing notes that I can easily use for the larger size by adding the appropriate number of stops to the original exposure. Dodging and burning should remain the same as a factor of the new exposure.

logan2z · Apr 2, 2025

Pieter12 said:
I usually make a full 8x10 test strip, both for 8x10 and 11x14 prints.

I do something similar, but with a bit of a variation. I usually start by making a few test prints of a smaller, but 'important', bit of the image that (ideally) contains some deep shadows and bright highlights. Once I have something that looks good from an exposure/contrast point of view, I'll make a full-size print (I also stick to 8x10 and 11x14 prints) from which I make further exposure/contrast adjustments and decide on a dodging and burning plan.

RalphLambrecht · Apr 3, 2025

Alex Benjamin said:
My advice would be to start right away with f-stop test strips. The beauty of f-stop printing is that the test strip will not only give you a base exposure for your print, but will also indicate, or at least give strong hints, as to what might be needed, or possible, in terms of dodging and/or burning. You might note quite early, for example, that some shadows would look good with 3/4 stop dodging, while the sky, or certain areas of it, could use 2 1/3 stop burning. If you're only fine-tuning with the f-stops, you're losing a lot, if not most, of what f-stop printing brings to the table.

exactly!

sperera · Apr 3, 2025

.....but that's the thing I don't get at the moment.....the starting point......'guessing' a starting point of......ah yes this negative looks thus so I'm gonna start at xx secs.....well, it isn't obvious for me at the moment.....I've come back to printing after a long hiatus just scanning negs so don't have the 'feel' for a neg at the moment.....

RalphLambrecht · Apr 3, 2025

sperera said:
.....but that's the thing I don't get at the moment.....the starting point......'guessing' a starting point of......ah yes this negative looks thus so I'm gonna start at xx secs.....well, it isn't obvious for me at the moment.....I've come back to printing after a long hiatus just scanning negs so don't have the 'feel' for a neg at the moment.....

I usually start with a 7-step test strip in 1/3 stop increments with a base exposure of 16s. That gives exposures from 8s -32s in 1/3 stop increments. To guess the right starting exposure within a 1/6 stop is easy from that. My test-strip printer fits those on a single piece of 5x7 paper. Someone here on Photrio was nice enough to design 3D print files for my test strip printer and I may make those available to the public if I get permission and a copy myself.

sperera · Apr 3, 2025

RalphLambrecht said:
I usually start with a 7-step test strip in 1/3 stop increments with a base exposure of 16s. That gives exposures from 8s -32s in 1/3 stop increments. To guess the right starting exposure within a 1/6 stop is easy from that. My test-strip printer fits those on a single piece of 5x7 paper. Someone here on Photrio was nice enough to design 3D print files for my test strip printer and I may make those available to the public if I get permission and a copy myself.

Thanks Ralph that sound great.
Thanks to EVERYONE for their help

Pieter12 · Apr 3, 2025

Starting exposure times depend on many factors. The enlarger lamp intensity, the head height (magnification), lens aperture. Even if you are split- or single-grade printing. With my set-up, I start with a 4 second exposure for a grade 00 with 1/2 stop intervals for split-grade, making 4 to 6 intervals on an 8x10 sheet. What I see on that test will lead me to judge the staring time for the 5 filter test.

Nicholas Lindan · Apr 3, 2025

You can find an appropriate starting time by making a very wide ranging test strip, as suggested above. Over time you develop a feel for about what the exposure will be.

The alternative is to use an enlarging meter. One of RH's offerings has a metering probe. Darkroom Automation sells a stand-alone enlarging meter with 1/100 of a stop of resolution.

But if all you want is to get to a very rough guess then any meter will suffice. You will have to 'calibrate' the meter as it will have a generic dial reading 1-10 or a dial with markings for grade and time, these markings are best ignored. If you have an old Gossen meter then you can get an enlarging metering accessory for it.

A drawback of some early meters is they used a 'logarithmic' radio volume control potentiometer. These potentiometers aren't very logarithmic. If you remember old radio volume controls that suddenly go from too quiet to too loud - that's the sort of user experience you will be in for. Expect the control to be noisy, like an old radio, and to wear out as the resistive element is made from deposited carbon film that gets flaky with age.

As a result early enlarging meters gained a deservedly bad reputation that lives on to this day. If they had worked back then everyone would be using them now - the idea of enlarging without a meter would be quaint, like taking pictures without a light meter. (Though, to tell the truth a 'Black Cat' exposure guide works about as well as a meter - exposure for negative films is very non-critical as long as the exposure is on the generous side).

MattKing · Apr 3, 2025

Pieter12 said:
Starting exposure times depend on many factors. The enlarger lamp intensity, the head height (magnification), lens aperture. Even if you are split- or single-grade printing. With my set-up, I start with a 4 second exposure for a grade 00 with 1/2 stop intervals for split-grade, making 4 to 6 intervals on an 8x10 sheet. What I see on that test will lead me to judge the staring time for the 5 filter test.

This is one of those situations where some sort of enlarging meter can help.
Not to make better prints, but to get there a tad quicker and with less paper used.
I use a simple Ilford EM10 meter sometimes. That permits me to take an easel level reading from an appropriate mid-tone area in a negative, adjust the lens aperture appropriately to get the reading to a useful standard, and then use those settings as the starting exposure time for the test strips.
I mostly do that to start a printing session, because once in the midst of things I can usually can work from what I was doing with the last print, and my "eye".

MattKing · Apr 3, 2025

Looks like Nicholas and I posted at the same time - "great minds....?

Nicholas Lindan · Apr 3, 2025

MattKing said:
"great minds....?"

Tend to be in same gutter at the same time...

sperera · Apr 4, 2025

I like the idea of the Ilford EM10 metre.....found one on Ebay for £25. No brainer. Thanks for the continuous advice and messages.

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