Using an Enlarger Meter?

[glbeas]

I have an old PM2L color analyzer, has an analog meter and does a fine job metering my black and white prints.

 

[RalphLambrecht]

Are you using an enlarger meter? It sits on the easel and tells you the brightness of a spot in your image.

While I'm waiting for the meter from Darkroom Automation to arrive, I hacked together a meter out of a photodiode taken from a 1990's plastic SLR connected to a decent voltmeter. I convert millivolts to EV numbers using a table I printed. Here are three levels of sophistication I can think of:

Level 1: Use the meter to get a tone correct. You must determine (once) from a test-strip that a certain EV (at a given exposure-time) yields the correct skin-tone (or some other tone, such as near-black or near-white). From then on, for any negative, turn the aperture ring until the meter gives you that EV, and then that metered spot will print at that tone. Simple.

Level 2: Measure nearly-black and nearly-white points in your image, average them, giving you the mid-tone EV. Turn the aperture until that mid-tone is at the correct EV, thus ensuring the overall exposure is correct.

Level 3: Use the nearly-black and nearly-white numbers measured above to select the grade. To avoid the calculations and looking up a number in a grade-table, an analyzer such as from RH Designs can do this work for you.

I'm at level 1 (getting one tone right). Even that takes experience, as shown by my stupid mistake from yesterday: I measured a bright spot on somebody's forehead and used that as the skin-tone, which made everything else too dark. Duh. But even at my basic level, I have eliminated most test strips.

If you have a meter, how are you using it?
Mark Overton

I'm using the Timer II exposure meter from RHDesigns and it is excellent when used similar to your Level1-approach but please avoid a fundamental mistake. darkroom meters are only good when used in your level1-method. They should not be used as a method to avoid test strips. test strips have invaluable information in them and done correctly and possibly in combination with a darkroom meter,they can not just save you time and paper but get you closer to a perfect print.

 

[DREW WILEY]

I routinely once used a high quality Gossen easel probe for Cibachrome printing because it saved me from wasting time and expensive paper. I don't bother with such a meter for either RA4 color neg prints or black and white prints because test strips do the job just fine. I do still use an expensive very precise easel densitometer or cc reader in relation to precise mask and separation negative exposures which would otherwise be rather dicey. These kinds of devices are quite rare. Ordinary light meters and lux meters aren't even remotely sensitive enough for that same kind of precise usage.

 

[MattKing]

It is probably important to note that I work either in a temporary darkroom, or (in non-Covid times) in other people's darkrooms.
So I do get a benefit from my EM-10 - it gets me back to a dependable and repeatable starting point.
I combine that with an eye that has enough experience behind it to "guess" reasonably reliably at where my tests need to start, and how close to each other my test strip steps can be.
If I were new to this, I would use the EM-10 more, but be careful not to let it take over.
More than anything, experience teaches you how important analysis is, and how important intuition is.
And that balancing varies between printers.
And printers gravitate to systems and environments that suit them.
Some of the best fast printers I ever worked around didn't even use timers, much less analyzers.

 

[John Wiegerink]

I have used both the EM10 and a Beseler P22. Both will get you very close. I'm 70+ and my eyes sometimes don't always tell me the truth like in my youth. A meter saves me time, but I still test strip before doing a full-size print. I'll use any automation that saves me money and a little time.
My darkroom is in limbo at the moment as my wife and I are moving up to our cottage permanently. When my new cottage darkroom gets setup I'm going to try a Jobo ComTime 6254 that a fellow gave me. It seems to be a pretty well thought out product and should work fine for my work. Has anyone out there used the Jobo 6254?
I do also have a Beseler PM2L from my Cibachrome days, but have not used it for B&W. I did just check the big auction and there seems to be many Beseler analyzers at much cheaper prices than I paid for mine new. JohnW

 

[Patrick Robert James]

I have an Ilford EM10 I use for quick small prints from time to time. Works great. It doesn't produce a perfect print, but one that is acceptable. I have a chart with the values matched to grades but i split print so it makes it pretty simple. Match the highlight value and that is 7ish seconds through the green filter, then meter the shadows. Take that number and consult the chart and I get the blue exposure. It isn't perfect of course because there is a bit of a sliding scale, but it is close enough to avoid test strips on things i don't want to spend time on.

I've been thinking about buying the RHDesigns meter to move the process along. Only issue though is I haven't done any research into it so I don't know if I can keep printing the way i like to print or if I'd have to use contrast filters instead...

 

[dkonigs]

I've been thinking about buying the RHDesigns meter to move the process along. Only issue though is I haven't done any research into it so I don't know if I can keep printing the way i like to print or if I'd have to use contrast filters instead...

The RH meter assumes you're metering w/o filters and always printing with them. That being said, you could probably calibrate it to work for filter-less printing, and I don't think it would be too hard to do.

 

[albada]

I have an Ilford EM10 I use for quick small prints from time to time. Works great. It doesn't produce a perfect print, but one that is acceptable. I have a chart with the values matched to grades but i split print so it makes it pretty simple. Match the highlight value and that is 7ish seconds through the green filter, then meter the shadows. Take that number and consult the chart and I get the blue exposure. It isn't perfect of course because there is a bit of a sliding scale, but it is close enough to avoid test strips on things i don't want to spend time on.

Patrick, could you describe your process in more detail? Perhaps include your chart?

I use a LED lamp, which eliminates filters. It's easy to switch green and blue on/off, so your technique is appealing. My concern is that paper is more sensitive to blue than green, but a meter that matches the human eye will be more sensitive to green. Perhaps your chart accommodates this difference. Also, green has some effect on shadows, and blue has some effect on highlights. Do you have a way to compensate for these cross-effects? Or are they minor enough to be ignored?
Mark Overton

 

[Patrick Robert James]

Patrick, could you describe your process in more detail? Perhaps include your chart?

I use a LED lamp, which eliminates filters. It's easy to switch green and blue on/off, so your technique is appealing. My concern is that paper is more sensitive to blue than green, but a meter that matches the human eye will be more sensitive to green. Perhaps your chart accommodates this difference. Also, green has some effect on shadows, and blue has some effect on highlights. Do you have a way to compensate for these cross-effects? Or are they minor enough to be ignored?
Mark Overton

I set the EM10 to 95, put the sensor in a highlight with the green filter on the enlarger and dial the aperture until the meter goes green. Then I put the sensor in a shadow and turn the meter dial until it goes green with the green filter still on the enlarger. That number then determine the blue exposure. I never really made it precise, just a rough guess based on printing. The green exposure is usually 6-8 seconds depending on the blue exposure. The higher up the dial the blue is, the less the green is. For example, when the blue exposure reads at 70, that is 16s and two seconds less for green. when the blue exposure is at 30, that is full green and only 4s blue. Of course sometimes you need all blue and no green but then I just look at the neg. If it is super flat or super contrasty I just do the appropriate. Again, I just use it for simple quick small prints. I suppose if you wanted to calibrate it all it would be doable. Maybe one of these days I will. I think Lambrecht's Beyond Monochrome? has something about calibrating the meter.

 

[albada]

Interesting responses.
Some folks don't use a meter, as their experience and intuition serve them well.
Most people with a meter use it to get close enough for casual prints, and to get a jump-start on critical work.
Those with an RH Designs Analyzer Pro use it to eliminate most or all test strips.

I read the instructions for the RH Designs Analyzer Pro. It's impressive and well thought-out. You measure two or more tones, and then you can shift them as a group to be lighter/darker until they will print the tones you want. But the meter in this unit assumes you are using a tungsten/halogen or cold light lamp, so it has no calibration data for LED lamps, so I would have to calibrate it myself. Hmmm. This is something @dkonigs might consider adding to his Printalyzer: Make it easy to enter a calibration-offset (one EV number) for the light-source used for metering. That would be helpful for those with LED lamps.

The Analyzer Pro requires you to stop down the aperture when metering. But doing so makes it hard to see things in the image (and thus hard to meter them) because they are dim. A smarter meter need not have this requirement, because the meter can tell you both how much to stop down, and time. I am using a crude home-built meter consisting of a photodiode connected to a voltmeter, and even it lets me meter at open aperture. A subtraction tells me how much to stop down.

Mark Overton

 

[logan2z]

The Analyzer Pro requires you to stop down the aperture when metering. But doing so makes it hard to see things in the image (and thus hard to meter them) because they are dim.

I've never found that to be a big problem. I simply open up the aperture to find my metering location then stop the lens back down before metering.

 

[Craig75]

Interesting responses.
Some folks don't use a meter, as their experience and intuition serve them well.
Most people with a meter use it to get close enough for casual prints, and to get a jump-start on critical work.
Those with an RH Designs Analyzer Pro use it to eliminate most or all test strips.

I read the instructions for the RH Designs Analyzer Pro. It's impressive and well thought-out. You measure two or more tones, and then you can shift them as a group to be lighter/darker until they will print the tones you want. But the meter in this unit assumes you are using a tungsten/halogen or cold light lamp, so it has no calibration data for LED lamps, so I would have to calibrate it myself. Hmmm. This is something @dkonigs might consider adding to his Printalyzer: Make it easy to enter a calibration-offset (one EV number) for the light-source used for metering. That would be helpful for those with LED lamps.

The Analyzer Pro requires you to stop down the aperture when metering. But doing so makes it hard to see things in the image (and thus hard to meter them) because they are dim. A smarter meter need not have this requirement, because the meter can tell you both how much to stop down, and time. I am using a crude home-built meter consisting of a photodiode connected to a voltmeter, and even it lets me meter at open aperture. A subtraction tells me how much to stop down.

Mark Overton

It doesnt matter what light source you are using you have to calibrate it for the paper. From memory it is set up for ilford multigrade iv (with a condenser enlarger?) but it still recommends calibrating it.

 

[dkonigs]

The Analyzer Pro requires you to stop down the aperture when metering. But doing so makes it hard to see things in the image (and thus hard to meter them) because they are dim.

The manual assumes you're going to do it this way, but you could easily calibrate it otherwise. Remember that its process assumes you're taking measurements with no filters, then printing with a chosen contrast filter. (and those filters already have a similar effect on light intensity as "stopping down")

The calibration is basically just a set of numbers that tell the meter what light reading (as you meter the image) is equivalent to a particular density on the paper (as exposed with the contrast filter). There's nothing stopping you from having these points be at different lens apertures. All that would happen, is that your calibration offsets (from their stock profile) would be a lot larger than if you didn't do that.

Of course the biggest downside of doing this is simply that you'd forget to stop down the lens after metering.

 

[dkonigs]

It doesnt matter what light source you are using you have to calibrate it for the paper. From memory it is set up for ilford multigrade iv (with a condenser enlarger?) but it still recommends calibrating it.

Yes, calibration is still recommended. I've done it several times with mine. (They also provide a list of contributed starting points for other papers.)

One challenge here is that the metering of the device basically depends on a reference point that (probably) has to be determined experimentally, and there's no guarantee that their experimental conditions match yours. I did a bit of a deep dive on this a while ago, so here's a short explanation...

B&W printing papers, in their published datasheets, specify their sensitivity with two numbers: ISO(P) and ISO(R).
ISO(P), the paper speed, is specified as the exposure necessary to achieve a density of D=0.60.
ISO(R), the contrast range, is specified as the exposure range between what's needed for a density of D=0.40 and D=0.90.
There is absolutely nothing in those paper datasheets that tells you the relationship between the ISO(P) and ISO(R) values, which means that you unfortunately cannot determine absolute exposure for either endpoint of the contrast range just from the paper's published data.

The way the RH Analyser calibration works, is by having you experimentally determine the exposure necessary for a density of D=0.40, as well as the ISO(R) value (which you can determine with a step wedge, or just copy off the paper datasheet).

 

[albada]

B&W printing papers, in their published datasheets, specify their sensitivity with two numbers: ISO(P) and ISO(R).
ISO(P), the paper speed, is specified as the exposure necessary to achieve a density of D=0.60.
ISO(R), the contrast range, is specified as the exposure range between what's needed for a density of D=0.40 and D=0.90.

Are these speeds specified for a particular wavelength? It seems to me that speeds and certainly exposure ranges will differ based on green-blue ratio.

 

[albada]

My meter from Darkroom Automation arrived today! But I found it difficult to find the spot I wanted to meter in the image because the white strip around the sensor is too narrow, so it shows too little of the image. So I taped a larger piece of paper around the sensor:

This paper makes the meter much easier to use. Now I can see plenty of context, making it much easier to locate the spot to meter.

Another criticism is that the sensor is 0.9 inches above the easel, causing EV numbers to be about 0.15 too high at my usual working-distance for making 4x5 prints from 35mm negatives with an 80 mm lens. Darkroom Automation suggests raising the enlarger 0.9 inches, then measuring, then lowering. But that is a hassle and it causes critical focus to be lost. Instead, I'll mentally subtract 0.15 when metering.

Another criticism is its poor sensitivity. Consider a spot that would print at near-white (Zone VIII) for an 8-second exposure at grade 2 on Ilford RC paper. Such a common spot is too dark on the easel for this meter. You would need to open the aperture some or remove the grade 2 filter in order to meter that spot. BTW, opening the aperture for metering is a poor option due to significant mechanical inaccuracy in apertures. But that's a topic for another posting.

A quirk I noticed (not really a flaw) is that if my fingers are above the display, even if I'm holding the sides of the meter, light from the display reflects off my fingers into the sensor, creating wrong measurements. I must remember to hold it below the display.

Despite these criticisms, I like the meter. It displays EV numbers to two decimal digits, which is more than sufficient accuracy for precise work. It updates the display once per second, which is quick enough that I can examine several interesting spots in the image. It even handles PWM (pulsed light) correctly, so you can measure light from an LED-lamp. Now I can stop using my Flintstones meter (that's what I call my photodiode+voltmeter arrangement).
Mark Overton

 

[dkonigs]

Are these speeds specified for a particular wavelength? It seems to me that speeds and certainly exposure ranges will differ based on green-blue ratio.

These speeds in the datasheet are typically based on a tungsten lamp, or a tungsten lamp as filtered by the specified contrast filters. If you are using dichroic filtration that matches the grades of the manufacturer filters, you'll likely get the same contrast range but not necessarily the same exposure.

Or as specified in ISO 6846, "The spectral power distribution of the illuminant shall be that of a black body radiator operated at a temperature of 2856K modified by the ISO standard camera lens [...]"

For LED lights of a different wavelength/spectrum, you'll probably have to build your own characteristic curves/numbers for the paper. However, armed with a densitometer and a step wedge (and some of my ramblings above), you should be able to get numbers that at least tell you the same info on the same scale.

 

[distributed]

ISO(R), the contrast range, is specified as the exposure range between what's needed for a density of D=0.40 and D=0.90.

I think the values are D=0.04 for the lower and 90% of DMax for higher bound.

Do you have a reliable and free source of these standards? For e.g. 120 backing paper I found a free Indian standard that is essentially a copy of the corresponding ISO standard. For the paper ISO standards I have unfortunately not had success using this route.

 

[dkonigs]

I think the values are D=0.04 for the lower and 90% of DMax for higher bound.

Do you have a reliable and free source of these standards? For e.g. 120 backing paper I found a free Indian standard that is essentially a copy of the corresponding ISO standard. For the paper ISO standards I have unfortunately not had success using this route.

You're right. Assume I meant D=0.04 every time above where I wrote 0.40. Sorry, that's an easy typo to make. (and now I wish I could fix the posts to prevent future confusion, but its too late to edit them.)

As far as sources for the standards, I found myself so tired of having to trust forum hearsay (from people who also haven't read it) that I actually went ahead and just paid ISO for the darn document. While I'll admit that paying for these things feels like a waste of money, its also really nice when you can actually look at the authoritative document yourself.

 

[Patrick Robert James]

My meter from Darkroom Automation arrived today! But I found it difficult to find the spot I wanted to meter in the image because the white strip around the sensor is too narrow, so it shows too little of the image. So I taped a larger piece of paper around the sensor:

This paper makes the meter much easier to use. Now I can see plenty of context, making it much easier to locate the spot to meter.

Another criticism is that the sensor is 0.9 inches above the easel, causing EV numbers to be about 0.15 too high at my usual working-distance for making 4x5 prints from 35mm negatives with an 80 mm lens. Darkroom Automation suggests raising the enlarger 0.9 inches, then measuring, then lowering. But that is a hassle and it causes critical focus to be lost. Instead, I'll mentally subtract 0.15 when metering.

Another criticism is its poor sensitivity. Consider a spot that would print at near-white (Zone VIII) for an 8-second exposure at grade 2 on Ilford RC paper. Such a common spot is too dark on the easel for this meter. You would need to open the aperture some or remove the grade 2 filter in order to meter that spot. BTW, opening the aperture for metering is a poor option due to significant mechanical inaccuracy in apertures. But that's a topic for another posting.

A quirk I noticed (not really a flaw) is that if my fingers are above the display, even if I'm holding the sides of the meter, light from the display reflects off my fingers into the sensor, creating wrong measurements. I must remember to hold it below the display.

Despite these criticisms, I like the meter. It displays EV numbers to two decimal digits, which is more than sufficient accuracy for precise work. It updates the display once per second, which is quick enough that I can examine several interesting spots in the image. It even handles PWM (pulsed light) correctly, so you can measure light from an LED-lamp. Now I can stop using my Flintstones meter (that's what I call my photodiode+voltmeter arrangement).
Mark Overton

Mark, I'll be curious to know how this meter works out over time. I was thinking about getting one myself.

 

[albada]

I've been using the new Darkroom Automation meter much lately to help create the following table. This table allows somebody with a LED lamp to change contrast without changing exposure. For example, if you metered on a skin-tone and set exposure based on that, then you can change contrast (grade) without affecting that skin-tone. The same goes for metering on a shadow or mid-tone. The Green and Blue columns in the table are stops of dimming (i.e., log2 attenuations), so 0=full power, 1=half power, etc.

Desired	Shadow	Shadow	Mid-gray	Mid-gray	Skin-tone	Skin-tone
Grade	Green	Blue	Green	Blue	Green	Blue
00	0	off	0	off	0	off
0	.1	4.3	.3	4.5	.2	4.4
1	.6	3.7	.8	3.9	.4	3.5
2	1.4	3.6	1.1	3.3	.7	2.9
3	2.3	3.4	1.9	3	1.2	2.3
4	3.3	3.3	2.7	2.7	1.9	1.9
5	off	3.1	off	2.6	off	1.7

You select the row for the contrast you want, and select green/blue columns for the type of tone you metered on (shadow/mid/skin). The table-entry at that row and column tells you the dimming-values for the LEDs. That's a lot of capability, and all you need is a simple meter. I'm enjoying this.
Mark Overton

 

[ic-racer]

t the sensor is 0.9 inches above the easel, causing EV numbers to be about 0.15 too high n

In that case I take the easel out when I meter. My probe (different meter than that one) is same height as my easel. I also have the white patch on mine (came that way) and the image would be focused on the white patch without the easel.

 

[eli griggs]

I use the Besler PM II, or regular exposure meters, such as the Luna Pros, Minolta III, and, I should try the Master IV, MV.

I have/do no bother with spotmeters.

The PM II, is a very good tool, in my experience, and being 'old' is a good bargain, in my esteem, and my #2 unit is still in my darkroom.

 

[albada]

In that case I take the easel out when I meter. My probe (different meter than that one) is same height as my easel. I also have the white patch on mine (came that way) and the image would be focused on the white patch without the easel.

That's a good idea! The DA meter is 23mm tall, and my (home-made) easel is 18mm. The leftover 5mm at my usual working-height will cause a 0.03-stop shift, which is insignificant. Thanks again for suggesting this!
Mark Overton

 

[MattKing]

Isn't the height correction a constant? Can't you just factor it in with each reading?