How to use a light meter in the darkroom?

Jim Jones · Oct 1, 2016

I used the Gossen enlarging attachment long ago and the EM10 more recently. The EM10 was quicker, but not as versatile. Neither were as informative as test prints. Faster and almost as reliable was comparing the density of the shadows with the clear edge of the film and relying on experience to get a decent exposure the first time. Another method is to make a small print for evaluation and a larger finished print. With some enlargers it takes only seconds to change print size. Having two easels facilitates this.

RalphLambrecht · Oct 1, 2016

samhuwyler said:
Hello Everyone

I'm currently working on a Portrait series and have to get a lot of printing done. I do test strips and all but still, I use up a lot of paper before I'm happy with a print.
I remember hearing something about using a light meter in the darkroom to determine density of the film and use this information to calculate printing time. I searched the web but couldn't find any explanation how this actually works.
Does anyone know a good website or such to understand this procedure?

Thank you and
Cheers from Switzerland
sam

light meters are not sensitive enough for this;use a darkroom meter.

Bill Burk · Oct 1, 2016

samhuwyler said:
I remember hearing something about using a light meter in the darkroom to determine density of the film.

Absolutely can be done. But it's best to get density of film for the purpose of determining developing time... I don't use density much when "printing".

samhuwyler said:
... and use this information to calculate printing time.

I agree with DREW WILEY that you really need to use test strips. I also want to emphasize the practical value of using f/stop printing when you make your test strips...

Gene Nocon gives a good description. I like to work in third-stops which are good gradations when printing on paper approximately of grade 2 and 3.

RalphLambrecht · Oct 1, 2016

Bill Burk said:
Absolutely can be done. But it's best to get density of film for the purpose of determining developing time... I don't use density much when "printing".

I agree with DREW WILEY that you really need to use test strips. I also want to emphasize the practical value of using f/stop printing when you make your test strips...

Gene Nocon gives a good description. I like to work in third-stops which are good gradations when printing on paper approximately of grade 2 and 3.

f/stop printing is the way to go.I use it in 1/12stop increments.

ac12 · Oct 1, 2016

It wasn't until I read about f-stop printing that I understood the fault of the old method of making a test strip the way that I learned in high school.

A wedge of exposures each 2 second apart will not give a beginner what he 'thinks' it will give him.
Frame 1 at 2 sec is 1x, frame 2 at 4 sec is 2x of frame, frame 3 at 6 sec is 1.5x of frame 2, frame 4 at 8 sec is 1.3x of frame 3, frame 5 at 10 sec is 1.25x of frame 4.
The f-stop exposure increments gets smaller as you go up the wedge. The problem was the inconsistency between each frame. So the test strip was more accurate on the high end, were the increments were smaller, than the low end where the increments were larger. All rather frustrating to a beginner.

Years later, after I learned about f-stop printing, I tried to do an f-stop test strip at the junior college darkroom, the old fashioned way, by sliding a cardboard over the test strip. But it was difficult to get the delta increase for each frame correct, and I messed up more than a few times. So it was frustrating. A jig with the delta times written on it would have worked much better.
Much easier and better than the sliding cardboard is to use an old test strip easel, where you can open a door for just that one frame. Then expose each frame for the correct time; 2,4,8,16,32 sec, for 1 stop increments, or whatever increment you want. The advantage of the test strip easel, is that I could move the easel to put the frame under the specific important part of the image, which I cannot do with the traditional sliding cardboard method.

The other tool that I used at school, and still surprises the new kids today, was the old Kodak projection print scale.
http://farm6.staticflickr.com/5049/5357450760_1760650759_z.jpg
A piece of film with pie wedges of different density, in half stop increments.
One 60 second exposure and you are done. Develop the print and just read off the exposure time for the 60 second exposure, or 1/2 if you do a 30 sec exposure.
http://farm4.staticflickr.com/3190/2504582871_cb4ef0f747_z.jpg?zz=1
EASY and FAST to get "in the ball park," then you can fine tune the exposure.

RalphLambrecht · Oct 2, 2016

samhuwyler said:
Thank you, the Ilford EM-10 looks like a handy tool. But I can't convert the Information given by the instruction sheet to work with my light meter.

That thing looks awesome! Awesome and expensive.
I might consider buying something like that in the future, but since I'm currently a student my budget for awesome photo-gear is limited.
That's why I'm looking for a way to use my light meter. I figured, since it can read the light in incident and reflected both shown in EV, there gotta be a way to use it for printing. But maybe I'm wrong...

Thank you and Cheers
Sam

D you're not wrong but you're making it too tough on yourself. Just getting an Ilford OM10 will make it easy and solve your problem. You can probably getne for about $10.

M Carter · Oct 3, 2016

My starting point - I make sure to develop enough blank, unexposed leader for this, or shoot the first frame with the lens cap on. So I have at least a frame or half frame's worth of unexposed (clear) film. For 6x7, the bit before the first frame or after the last will do.

Set contrast for 2.5 or 3, put your neg in the enlarger and find crop and focus. Then remove the neg and put a blank piece of the same film, from the same dev time in the carrier. Do a test strip. Look for the first section that's full black and not gray. There's the maximum black that film can produce (film base + fog). Stick your neg back in the carrier and print for that time. That will give you the optimal time for maximum blacks. If you're developing and exposing properly, it should be very close (you don't want to use printing times that don't supply max blacks, right?). If your highlights are too dark, you've got an exposure or development problem. To me, this means you're getting the max dynamic range the paper can produce, without pushing things with dodging or burning - aim to dodge/burn for composition, not to make a problem neg workable.

samhuwyler · Oct 5, 2016

Thanks everyone for your help.

Definitely gonna try out the f/stop printing and Carters method to find the full blacks.
Always looking for new ways to optimize my printing process.

Cheers from Switzerland
sam

Ronald Moravec · Oct 7, 2016

a test strip need only be 1" wide. Pass it thru a white and black area. No need to use a full sheet.

You can also use a contact sheet. Print it at 8.5 x and find the fudge factor for an 8x10. 5x7 is one stop less. 11x14 is one stop more.

The best way is learn to expose properly, use the same film/developer & paper. print exposure will always be the same

Mainecoonmaniac · Oct 7, 2016

Here's a wild idea. How about using a high sensitivity digital camera as a meter? Make a print that's decently exposed first, then turn on the enlarger with the neg still inside the enlarger. Point the camera on the projected image, on the baseboard. Set the camera on manual then tweak the ASA dial on the camera until the image the camera's screen has an image that has a full range of tones from black to white.

Try a different neg to test. After composing and focusing the projected image, tweak the enlarger lens aperture until the image on the camera screen looks the same as the first image. Expose and process. I might try it myself. That way, I'll use my digital camera more

DREW WILEY · Oct 7, 2016

Not as straightforward as it might seem. You'd have to have a special program for cosine and falloff correction, and when you were all done you'd
still not have the basic language needed, ideally actual density, which can then be converted to time or whatever. But I guess it's something to do
if you own a digital camera. If you happen to own enough of em, they're handy in a mesh bag hanging from a hook, to add extra weight to a tripod with a real camera atop.

Mainecoonmaniac · Oct 7, 2016

DREW WILEY said:
Not as straightforward as it might seem. You'd have to have a special program for cosine and falloff correction, and when you were all done you'd
still not have the basic language needed, ideally actual density, which can then be converted to time or whatever. But I guess it's something to do
if you own a digital camera. If you happen to own enough of em, they're handy in a mesh bag hanging from a hook, to add extra weight to a tripod with a real camera atop.

I'm thinking that the camera is viewing the projected image on the easel. I remember years ago when I worked in a photo lab that had a Kodak PVAC. I wonder if a camera set to the right ASA can be used to judge reflected density off an enlarger easel. The PVAC had the old video tube technology.

Bill Burk · Oct 10, 2016

DREW WILEY said:
...
if you own a digital camera. If you happen to own enough of em, they're handy in a mesh bag hanging from a hook, to add extra weight to a tripod with a real camera atop.

Good one.

samhuwyler · Oct 10, 2016

Sounds interesting, but unfortunately I sold my DSLR to buy more real cameras.

...no regrets.

DREW WILEY · Oct 10, 2016

You could put one of those integrating "white balance" caps over the DLSR. But the gist of the problem with any number of such schemes is that you're creating a lot of neutral density in the light path, and I'm skeptical if enough low-range sensitivity would be left over for realistic use, if it was ever there to begin with. And that would be just the beginning of potential problems. Somebody will probably have some fun trying this approach, but it won't be me!

Mainecoonmaniac · Oct 10, 2016

DREW WILEY said:
You could put one of those integrating "white balance" caps over the DLSR. But the gist of the problem with any number of such schemes is that you're creating a lot of neutral density in the light path, and I'm skeptical if enough low-range sensitivity would be left over for realistic use, if it was ever there to begin with. And that would be just the beginning of potential problems. Somebody will probably have some fun trying this approach, but it won't be me!

Ah. I see that you're tempted

Since I'm full of curiosity. I have another idea. If anybody uses an Iphone and don't want to spend any money on a meter, just get a FREE Iphone light meter app. I use Light Meter. It has an ASA range of .8 through 102400. I'm sure if someone is willing to experiment, Some sure someone can find a reflected reading off the easel or an incident reading by putting a diffuser on the lens. For me, I'm always playing with ideas.

DREW WILEY · Oct 10, 2016

First of all, I'm pretty skeptical just how accurate or linear a phone meter would be, especially at the color temperatures typical of enlargement, versus just the software interpolation and BS marketing extrapolation that comes with consumer electronics. Second, my actual easel densitometer is sensitive about twenty EV lower than most pro light meters - yeah, twenty, and linear the whole way. Of course, the big observatories make their pay grade measuring light vastly dimmer than even that. Maybe I could discover a new planet or two if I put my darkroom meter behind a telescope - or maybe it would just be reacting to a mosquito flying around in the scope barrel. Hard to say whether aliens suffer from alien mosquitoes or not.
Either way, I don't like being around the sound of either mosquitoes or some obnoxious cell phone buzzing beneath a sofa pillow.

Bill Burk · Oct 10, 2016

But hey... if we're talking about cranking out a stack of 4x6's here just to get the negatives on paper...

This is a job for a device.

I don't think you need to deal with the intricacies. I think tethering an old digital SLR and aiming it at the easel... would get you there.

Get one negative to print right.

Aim SLR at easel shot and shoot, adjusting f/stop and shutter speed until the preview looks good enough.

Extra points if the SLR has an "invert" function.

Then get another negative in the carrier and open/close the enlarging lens f/stop until the preview screen looks good.

Sorry. You're on your own for contrast.

Mainecoonmaniac · Oct 11, 2016

Bill Burk said:
But hey... if we're talking about cranking out a stack of 4x6's here just to get the negatives on paper...

This is a job for a device.

I don't think you need to deal with the intricacies. I think tethering an old digital SLR and aiming it at the easel... would get you there.

Get one negative to print right.

Aim SLR at easel shot and shoot, adjusting f/stop and shutter speed until the preview looks good enough.

Extra points if the SLR has an "invert" function.

Then get another negative in the carrier and open/close the enlarging lens f/stop until the preview screen looks good.

Sorry. You're on your own for contrast.

I do contact sheet on a light table and a digital camera. I invert the image and adjust the contract in Photoshop. My long range plans is to put info in the metatags about the subject, date and possible geolocation. Most important, where the neg filed. I hate the drudgery of making contact sheets.

Andrew O'Neill · Oct 11, 2016

I think test strips are important. I wouldn't stop making them as I find them quite informative, not just for finding exposure, but for tonal differences under different exposures. I used to own a EM10 for determining exposure when making a larger or smaller version of the same negative.... but it would only get me in the ball park. I would end up tweaking the exposure anyways... so it's better to just to test strips, in my opinion.

DREW WILEY · Oct 11, 2016

Much ado about nothing. View cameras came with an invert function a hundred years before digital options. Taking pictures of pictures, well, that's
been around a long time too. And Metatag has been making washing machines and dryers for decades, though they seem to be a bit sloppy with
Dektol in them. I'm not quite sure what a DLSR is, but highly suspect that the last two letters stand for "Soon Recycling".

How to use a light meter in the darkroom?

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