Enlarging Meter-Timer

Dave Gooding

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Hi,
I’ve previously posted on here about other electronic photographic equipment we produce at DLG Electronics.
We have now started work on an enlarging meter-timer device and would appreciate any comments or suggestions while the design as at a concept stage.
It can be found here on our website:
http://www.dlgelectronics.com/enlarging_meter_timer.html
There is a pdf download available (4 pages) with an outline of our concept.
I’d be interested in any views on functions that should be provided or which are considered of little value, as well as general useability comments.
Also of course - would you buy it? Is there a market for this? The development costs for this will be significant, including regulatory compliance for all the major markets, so I’d like to have some confidence in selling a reasonable quantity before sinking too much capital into it.
Thanks,
Dave
 

larfe

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Hey Dave,

I would not be interested personally, here's why:

* The timer does not offer the F stop printing method which I find far more intuitive.
* Does not offer a program feature, to put in memory successive steps etc...
* Only offers a single channel. Come on this is 2018, give us 10 channels.
* This densitometer is a gimmick IMO. Imagine someone gives you an old pack of 25 sheets of discontinued paper, you really gonna do the calibrate thing?

just me...
 

mmerig

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Hello Dave,
I would start with the features of the RH Designs Analyzer Pro. I reluctantly bought one of these -- I actually needed it rather than wanted it-- but it has saved me tons of time and paper. Perhaps you can compete on price, matching its features and perhaps improving on it. One weakness of the RHD AP is the sensor unit. It is kind of thick and seems a bit fragile. Perhaps you can make a more durable sensor unit that works with the RHD AP that has a smaller sensor size and thinner body. But I doubt that would be worth the trouble.

It's hard to tell if your meter-timer works in f-stop increments, but as larfe mentions, that is important. The 1-second resolution is a bit course but workable. I use an enlarger with an incandescent lamp, and did some test at various voltages, using a variac, and found minimal changes in exposure adjustments. I think the three-point print intensity is barely enough to be usable. The 15-step tonal scale via LED's on the RHD AP is very helpful.The paper-grade knob should show the 00 grade, with half-grade lines in between the full ones. Calibration should include exposure (e.g., the minimal white tone) and contrast. The RHD AP has a comprehensive calibration procedure, and if multiple papers are calibrated, the user can set the exposure for one paper (and develop it and tweek it) and then shift to another paper without going through a test strip. This latter feature is a primary reason why I bought the RHD AP (I have a project requiring RC and FB prints for over 500 images). It works extremely well.
 

Mick Fagan

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Unless my current enlarging timer died, I wouldn't need another one.

Requirements for me are:- 1/10 second increments; something I use every time I enlarge with any exposure that is sub 20 seconds. This allows manual f/stop timing.

I wouldn't purchase it unless there was a foot switch possibility as an accessory. With a wall mounted enlarging timer, you are never going to lean over to a back wall if your enlarger is reasonably sized day in day out. My current foot switch has two switches, one turns the lamp on for focusing and so on, requires me to keep my foot held down. The other starts the timer itself. Works like a farming tractor foot brake for left and right braking.

A sort of budget timer does not need to have inbuilt f/stop timing in-built, but unless you have 1/10 of a second increments, you cannot do accurate exposures in the sub 10 second exposure arena.

I would suggest having the electrical inputs on the bottom, this helps to keep stuff out of the sockets, which over time can be an issue.

500W of lamp power with 230V supply, is about right for the majority of possible enlargers, so you are covered.

Your probe doesn't look as though it caters for light angle (fall-off) as you move further away from the centre of the base board. Jobo, among others, had a simple fix for that, as shown here.
https://www.google.com/search?q=lic...QsAQIQw&biw=1536&bih=709#imgrc=iqS7kwdQw2v0DM:
These work a treat and are very accurate in telling you what the fall-off is.

The compensation feature could be handy in some instances, but I'm not too sure if many people would really know how these work. They were a standard feature in industrial graphic arts exposure units, back when I was using them.

Your measurements seem a bit odd compared to what the concept drawing looks like. I would have thought 200mm height x 150mm width x 50mm depth is more like it. While I realise the USA market would probably be your largest market, that is about the only country in the world using those measurements, the rest of the world is metric.

Mick.
 

larfe

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I didn't want to chime in with this but since mmrig has done the reference, I too would suggest that you start from the features of the RH Designs timers (which itself is an improved Nocon timer I believe?).

In fact the additions I've listed are what I think is missing from the RH Designs StopClock Pro namely:

* "Limited" to 9 (or is it 10) steps in program mode. Give us 30 for gawd's sake.
* In program mode, each step is limited to (can't remember the exact number) something like 30X12th of a stop. Very annoying if the initial exposure is very short and if an area of the print requires a long burn.
* "Limited" to 2 channels. Come on this is 2018, give us 10 or 20 channels.
* Figure out a proper dodging mode. The RH timer does not have one.
* The longest expose time is officially listed at 230 seconds, but realistically is more like 180 seconds.
* Has too many bugs.
 
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mmerig

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The Stop Clock Pro is different than the Analyzer Pro -- see the RH designs website for the differences. The Analyzer Pro is closer to what Dave is trying to make.
 

larfe

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I believe the Analyser Pro is what used to be sold as the StopClock Lite + the current ZonemMaster II in 1 package. Therefore the StopClock Pro + ZoneMaster is a much more "powerful" (or flexible) setup...
 
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Dave Gooding

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Thanks all! There’s a lot of useful input in these comments. It’ll take me a day or two to go through and give each point raised a detailed consideration and response, and I’m sure I’ll have some further queries on some items.

Meanwhile, I note that my initial view is that there is no fundamental reason why any and all of the suggestions made above could not be incorporated in the design. Indeed, the power of even a modest microcontroller could easily handle far more than suggested here. In practice the limitation is more likely to be front panel space for the controls and/or useability of an excessively complex device, and the non-recurring costs of the software development which of course would have to be recovered over what is likely to be relatively modest production quantities.

It is our intent not to produce something competing head-on with an existing product (the market is not large enough for that) but instead to take advantage of modern electronics to produce a more flexible, versatile and powerful product to support today’s darkroom user. This is your opportunity to shape that product!

I’m compiling all of the above suggestions into a single table listing each point raised individually, and will assess each one and come back with further questions.

I will be updating the concept paper over the coming weeks as these points are addressed.

At some point after initial development and testing we’ll be producing a couple of mature prototypes with “beta” firmware and hardware and I’ll be asking for a volunteer to try one out, before investing in production set-up and tooling.

Thanks again

Dave.
 

pentaxuser

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I do not run a business and have never run a business so there are my two minuses in terms of pontificating but it seems to me that in the relatively small market for such devices and the relatively "mature" age grouping of those likely to want to such a device, the standard to be aimed for has to be the equivalent or near equivalent of the RH Designs Analyser Pro but at a sufficiently lower price to make those who are interested in the likes of the RH Designs Analyser want to opt for your equipment.

I fear that we have two markets. The beginner who may be "In love" with the idea of darkroom work but who either lacks the money or at that stage the commitment to buy a bells and whistles analyser and the mature user who wants and now feels he deserves just such a piece of equipment, has the money but is only likely to opt for your piece if it is cheaper or offers extra but very useful adjuncts.

pentaxuser
 

larfe

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Dave,

I forgot one quite important point:

* Do make firmware upgrades possible by the end user without having to go through the expense of having to buy a new chip, which is the case for the RH StopClock.

Since I live in the UK I could potentially offer to test your timer, it would have to be when the cooler days are back with us though as my darkroom in the current heatwave is unbearable and have no access to another one.
 

mmerig

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larfe said:
I believe the Analyser Pro is what used to be sold as the StopClock Lite + the current ZonemMaster II in 1 package. Therefore the StopClock Pro + ZoneMaster is a much more "powerful" (or flexible) setup...
Click to expand...

The Stop Clock, including the LE (Lite), is a timer only. That is why I mentioned that the Analyzer Pro, which is a meter and timer in one box, is similar to what Dave is doing. But I agree that the Zonemaster and Stopclock combo is more flexible etc. than the Analyzer Pro.
 
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Dave Gooding

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Larfe,
The ability to allow firmware upgrades is by far the most challenging suggestion so far! It’s not straightforward at all and I suspect that’s why RH don’t offer this. We have been looking into the ability to do this as a bit of low-level R&D work and will do it if possible.

By the way if your darkroom is too hot we do sell a temperature-compensating developing timer haha! It’s no coincidence that most of the sales of these have been to hot countries!

Thanks for the offer to test a prototype anyway. It’ll be a few months yet so hopefully it will be cooler by then.

Dave
 

larfe

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Fair enough, I know next to nothing about such thing. Although it does surprise me since most electronic gadgets these days can be plugged into the USB port of a computer and do the upgrade this way.

Dave Gooding said:
By the way if your darkroom is too hot we do sell a temperature-compensating developing timer haha! It’s no coincidence that most of the sales of these have been to hot countries!
Click to expand...

Yes I saw it and thought it was a good thing! But I already have the RH one so unless yours come with a tiny AC unit attached to I'll have to pass for now =)
 
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Dave Gooding

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All,
I've been through all the comments and collated them together in the attached table, together with responses and in some cases, further questions. I'd appreciate any further input on these.
We will amend our concept design accordingly before proceeding with the detailed design work.
Thanks all for your input!
Dave
 

Attachments

  • Concept Comments.pdf
    418.5 KB · Views: 221

Mick Fagan

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Very interesting, I'll get back to you with a picture of my dual footswitch.

Yes, cosine is what I was referring to, I explained it in a manner for all to understand.

I manually do f/stop timing in 1/8 stop increments, but as refining sometimes very small increments, I halve to 1/16 stop increments; simple as anything to do. Been doing this for around 30 years now and have a chart on the wall that needs to be re-written as the ink is fading.

If I was to purchase a new timer, I really would think heavily in favour of one that offered f/stop timing.

The majority of enlargers I have used run around 250W lamps, some I have seen run a bit more others often less, down to 150W or 125W. Big enlargers will run 1000W, but in reality they are rather rare. As a matter of interest, Australia was 240V AC but is now 230V AC, have been since 2000. USA is I believe, 115V and 230V to align themselves with the rest of the world which is slowly turning to 230V, up from 220V.

Mick.
 
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Dave Gooding

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Thanks Mick. Operating in f/stops seems to be the way most people work, and is more intuitive to use anyway, so we will make f/stop operation the primary default mode of operation with direct time input as a selectable option. Your preferred 1/8 and 1/16 stop increment differs from the 1/6 and 1/12 stop that RH use. No reason not to allow either increment in the design though.

Regarding supply voltages we can make this universal (100VAC to 250VAC, 50-60 Hz) using a switch mode supply, which EU regulations require anyway now to meet energy efficiency requirements. The supply will be internal to the unit (not a “wall wart” as they call them in the US).

You may be interested to know that a large proportion of our sales for our existing products are to Australia - it seems that analogue photography and large format in particular is popular there. I think we will soon be looking for an Australian distributor!
 

MattKing

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Bill Burk

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Hi Dave,
You asked for clarification about channels.

When users calibrate their paper, they create a set of exposure/density pairs that define the characteristic curve of that paper... with that developer, development time, contrast filter. That calibration is stored in a channel. You may need half a dozen channels to store the calibration definition of one paper at its different grades.

This leads me to think. Essentially you are designing a "transmission densitometer" and perhaps you can consider designing a reflected light probe, so people can have a "reflection densitometer" as well, so they can completely calibrate without having to own a separate densitometer.
 

Bill Burk

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p.s. I don't see why there should be any limit to the number of channels. Made sense when designing a unit with limited memory but data like this doesn't consume much space at all and there's no reason to limit your system to 256 bytes like the old days.
 
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Dave Gooding

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Thanks. I think I got a bit confused as I was looking at both the RH Analyser Pro and the RH StopClock Pro and so I’ve done a bit more investigating. The RH analyser offers several (programmable) paper settings. The StopClock Pro offers programmable steps for incremental burns up to 9 steps in each of two channels. In response to your other comment we can certainly provide a lot more memory than the RH units even with a fairly basic micro controller - more programme steps (including dodging as well as burning), more programmes and so on. Moving up to more sophisticated devices, or off-chip memory, the number of programme steps, channels and paper characteristics could be essentially unlimited. The difficulty then becomes useability and clarity of what has actually been stored where, so I’m considering a small LCD screen for display of the programme steps, channels, paper types or whatever depending on the selected operating mode.

The reflection densitometer is a possibility I’ve been thinking of already. My general idea was you print a calibration test strip using a blank negative, develop it, poke it into a slot on the machine and it figures out the calibration all by itself. Is this the kind of thing you are proposing?

Of course all this adds to the cost of the unit, both non-recurring development costs as well as unit cost, but I kind of figured that there was little point ( given the small production volumes involved) in trying to trim pennies off the cost anyway - better to go for a high-end design rather than a low budget device with this kind of thing.

Thanks,
Dave
 

Bill Burk

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Hi Dave,
Auto-scan reflected light densitometers exist, and they can be frustrating. For example, the rubber drive rollers that feed the test strip into the reader can harden over time and lead to skewed feeding, which makes the readings fail. Don't ask me how I know haaaaa.

Instead, keep it a simple. Make a probe about the size and action of a wooden clothespin. The jaw opens and has a small target circle at the bottom that helps show the area you are reading while the top includes light source and sensor. When you press it down, take a reading and display density/store reading.

The user would print a step wedge, and read them in step by step.
 
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