68degrees
Well-known
I have a light meter that displays in EV. Is there a way to convert EV to an exposure time for printing in the darkroom?
nikon_sam
Shooter of Film...
Not too sure how it works but Gossen made an attachment for the Luna Pro for exposure times in the darkroom...
I have a Beseler Analite 300 (Enlarging Exposure Meter) but have never gotten around to figuring it out...making test strips works for me...
I have a Beseler Analite 300 (Enlarging Exposure Meter) but have never gotten around to figuring it out...making test strips works for me...
Godfrey
somewhat colored
IF the meter is sensitive enough:
- determine the correct exposure for a negative including an 18% gray card first. (trial and error, making prints)
- once you have that, with the enlarger at the exact same height and the lens opening at exactly that setting, use the meter to take a reading.
Whatever it says in EV is the right exposure for that test print. You can now read any 18% gray area on any negative, at any height, and if you get that EV number, you know what the right time is. If you get a lower or a higher number, do the math and calculate the difference in exposure time required to achieve the right density.
Did this years ago with a Minolta Autometer II. It was only barely sensitive enough.
G
- determine the correct exposure for a negative including an 18% gray card first. (trial and error, making prints)
- once you have that, with the enlarger at the exact same height and the lens opening at exactly that setting, use the meter to take a reading.
Whatever it says in EV is the right exposure for that test print. You can now read any 18% gray area on any negative, at any height, and if you get that EV number, you know what the right time is. If you get a lower or a higher number, do the math and calculate the difference in exposure time required to achieve the right density.
Did this years ago with a Minolta Autometer II. It was only barely sensitive enough.
G
68degrees
Well-known
Ok so do I take a picture of a gray card properly exposed and then use that negative to figure out what EV is correct?
Godfrey
somewhat colored
Always work with a properly exposed and processed test negative when you are calibrating a printing process.
G
Livesteamer
Well-known
Long ago in my college days when I shot lots of film for yearbook, newspaper and the development office, I used a Luna Pro as an enlarging meter with just a piece of cardboard taped on at a 45 degree angle in front of the cell. With a little practice it was effective. Maybe a lot of practice. There were a number of all nighters in the darkroom where I stumbled out in the morning with more than 75 prints for the year book. It was fun but I don't want to do that again. You have to know where to take the reading from on the negative and that is the key. Joe
Roger Hicks
Veteran
Ideally you need to read the lightest area in which you need texture and detail (darkest part of the neg) and the darkest area in which you need texture and detail (lightest part of the neg). This will give you both exposure and paper grade.
Generally, by the time you know enough to do this properly, you can judge the projected image by eye well enough to go straight to a test strip.
Cheers,
R.
Roger Hicks
Veteran
Yes, but what IS a 'properly exposed and processed test negative'? Of what subject? For what sort of enlarger head?Always work with a properly exposed and processed test negative when you are calibrating a printing process.
G
The only way to 'calibrate' any enlarging system is via a negative that you already know prints well, regardless of subject matter, or via a negative that is, in effect, a step wedge with a known range of densities (measured with a densitometer).
Cheers,
R.
Roger Hicks
Veteran
There is no such thing as " a picture of a gray card properly exposed". Stop and think: a carrier with no neg on it will look like 18% grey if you stop down a little. A picture of a general subject with a grey card in it may be of some use, but even that is disputable. If you want more information about 18% grey cards, and what they can and can't do, see http://www.rogerandfrances.com/subscription/ps 18 per cent.html
Cheers,
R.
sevo
Fokutorendaburando
It is possible, but pointless. There only have been maybe half a dozen meters (top end models from the seventies) with a range suitable for darkroom use, and a display applicable for that purpose.
Earlier on, the low range did not extend far enough, later on, literal f-stop/time digital displays unsuitable for a darkroom setting became standard on better handheld exposure meters, and the price for electronic devices (including dedicated darkroom timers with integrated meter) dropped to a point where photographers bought dedicated equipment for each purpose rather than owning one single device with expensive attachment probes and complicated manual table lookups.
Earlier on, the low range did not extend far enough, later on, literal f-stop/time digital displays unsuitable for a darkroom setting became standard on better handheld exposure meters, and the price for electronic devices (including dedicated darkroom timers with integrated meter) dropped to a point where photographers bought dedicated equipment for each purpose rather than owning one single device with expensive attachment probes and complicated manual table lookups.
Godfrey
somewhat colored
Geez Roger. This is not that complicated.
-Load camera with a known good shutter and lens.
-Frame a reference gray card that has been evenly lit.
-With an accurate meter, determine the correct exposure and set it on the camera.
-Process the film according to the manufacturer'specification.
-(optional) If you have access to a densitometer, check the gray card density against the manufacturer's gray card spec.
You now have a reference negative from which to develop a reference print with whatever enlarger setup you wish to calibrate. That is a separate exercise.
Type of subject, type of enlarger, etc is not relevant to the creation of a properly exposed reference negative. Of course, a more versatile reference negative could be made with gray solid as well as continuous and stepped white to black tone bars. That allows your reference prints and measurements to encompass both dynamic range and gradient bias. And then there are color reference negatives.
But why complicate every little thing with the full weight of formal lab process? Just make a good negative, make a good print from that with your enlarging setup, and use that as the calibration basis for your metering reference. Simple.
As sevo said, there are few meters sensitive enough to do this at all.
G
68degrees
Well-known
this is what I meant when i asked about taking a properly exposed picture of a gray card and using that as a reference.
Roger Hicks
Veteran
What are you calling 'an accurate meter' and 'a correct exposure'? What density are you looking for on your negative of a grey card? What are "the manufacturers' recommendations" Ilford used to give two dev times, for a G-bar of 0.56 and 0.70. They gave up because so few people understood why they'd give two recommendations, and therefore chose the mid-point between the two.
Shooting a grey card is a complete and utter waste of time. The ONLY test of a 'good negative' is that it prints well -- and what prints well will depend on subject matter, lighting, enlarger... You can piddle around with grey cards to your heart's content, but it will do less than nothing for learning to print, which is at least as much art as science.
So yes, is IS that complicated -- or that simple. The simple bit, as you say, is "Just make a good negative, make a good print from that with your enlarging setup, and use that as the calibration basis for your metering reference. Simple." Where do negs of grey cards come in to this?
If, on the other hand, you are going to try to be 'scientific' about it, then do it properly: don't play half-arsed games with grey cards.
Cheers,
R.
Godfrey
somewhat colored
Forget it, Roger. The OP seemed to understand what I meant. I have no interest in pursuing a picayune debate with you. You seem to want nothing more than to disagree with me, in this and other threads.
G
Roger Hicks
Veteran
Dear Godfrey,
I had more than half expected this from your response on the thread about college. I have no desire to pick any sort of personal quarrel with you: I wish merely to point out your errors and omissions when you make them. You can complain about the college debate if you like, but here we are discussing matters of simple photographic fact. I suggest that you either put me on ignore or attempt to refute my arguments.
Cheers,
R.
Sejanus.Aelianus
Veteran
Roger was raising some extremely pertinent points, in my opinion. In order to automate any process, it is necessary to establish the basic parameters. When you talk about "known good shutter" it is necessary to define "good". Do you mean accurate to 5%, 20%, 50%? All are perfectly valid, provided you make that clear. The same applies to exposure meter accuracy.
However, consider a shutter accurate to 20% and an exposure meter accurate to 10%. We need to know which direction each is out (20% + 10% = 30% but 20% - 10% = 10%) so that we can get an idea of what error we are dealing with. We also need to know the constancy of the errors.
In my opinion, rather than being "small" points, these are germane to 68's original question.
Livesteamer
Well-known
Roger explained things far better than I could. Back when I was doing a large quantity of prints for yearbook, the meter was worthwhile. I was not doing fine art, just a lot of decent, usable prints. Today, for what little I would print in the darkroom, I would much prefer a test strip. Joe
68degrees
Well-known
For volume I only see myself making 100 or so 8x10s a month.
Roger Hicks
Veteran
68degrees
Well-known
Is it enough to warrant researching meters or still just use test strips. Understand I am setting aside the "meters are for pussies" for the purpose of the exercise.