Pinhole photographers! How do you guess the exposure?

Máx Arnold · Jun 19, 2020

I'm interested on pinhole cameras and them being homemade.

As a photographer, I rely on my instinct to guess the exposure for a given substrate and camera, and I manage to get it right most of the time.
I've... realized that I'm good at guessing exposures.

But how do you? How do you, fellow photographers, guess get the exposure right every (or mostly every) time?
Given the entire ISO and f/ number paradise...

I'm up to your replies!!

Max.

DWThomas · Jun 19, 2020

Wel-l-l-ll, I'll confess I generally use a meter! Likely if I shot more pinhole work than I do, I could guess with some reliability, but I don't feel that's something I need to do. And even metering can involve some mysterious "intuitive compensation." In my mind, pinhole is a "loose" process. For starters, exposures tend to be quite long because of the tiny apertures. That brings up issues of reciprocity failure, which is film dependent and can be quite pronounced when the uncompensated exposures run into the minute range. As such, I like to start a with measured reading and then adjust and extrapolate from that.

There are phone apps specifically to deal with pinhole issues, supporting tiny apertures for one. I often just produce a pocket-sized table that lists exposure times as measured for f/22 with a correlated listing of times to use with the actual pinhole f-stop and reciprocity adjustment factored in. A Windows app -- Pinhole Designer -- can produce a small spreadsheet file to create that. The program has a lot of capability, but for things related to specific films, it hasn't been updated in ten or fifteen years, so some newer films offer no built in support. (And it does not support creating your own reciprocity tables.)

jay moussy · Jun 19, 2020

As a beginner, I had to look into it.

Most helpful (to me) was Joe VanCleave's comprehensive youtube video, from figuring out your pinhole camera focal ratio, to extrapolating exposure time off a traditional lightmeter reading, or app, or the sense for exposure you have.

Other option: the Ilford dial calculator. A little hard to find the PDF file, but it is out there: I was curious, so I just made a copy of the dial for myself, yesterday!

I am sure there are more sophisticated ways, But that's as far as I got. Next will be studying and accounting for RF... hmm.

rst · Jun 20, 2020

I also use a meter and a little cheat sheet where I have adjusted times for my cameras and films. Or I use an app on my mobile phone where I stored the reciprocity for the films I use. Guessing is OK, but I tend to say if I anyway have exposure times in the minute range, why not take that few seconds to take a meter reading. It might be a waste of a few seconds, but if I guess wrong it is a waste of a few minutes for the exposure, a waste of film and a waste of processing time. And in contrast to the OP I am just not that good on guessing the exposure time.

Daniela · Jun 20, 2020

Hey, otro Argentino por acá?
I have one pinhole camera I use regularly (it was a gift), and I learned by using it. I know there are methods to calculate the pinhole size and all of that, but I'm more interested in the surprise factor of using it; and in being able to do exposures intuitively. So, I learned by trying and failing. I now know how long to expose for in shady and in sunny conditions. I still get less than perfect exposures sometimes, but again, that's part of the fun.

Donald Qualls · Jun 20, 2020

Sunny 16 works fine, in general -- but when you're at f/150 or f/250 things change a bit.

For a start, different films with the same box speed react differently when exposures go beyond one second. Some (original Acros, Acros II) hardly need any reciprocity correction out to a minute or so; others (Fomapan, for instance) need much more than doubling for each stop beyond a one second exposure time. There are charts, formulae, apps -- but the bottom line is, you need to know the reciprocity characteristics for the film you're using. Manufacturers often publish this information, but sometimes what they publish is, um, optimistic. And occasionally it's just a flat-out lie. In the end, you need to make tests -- and it wouldn't be going too far to choose your film specifically for its reciprocity characteristics, if you're buying specifically for pinhole.

Worth noting: if you build your own cameras and aren't married to roll film, enlarging paper is actually faster at pinhole exposure levels than some 400 speed films -- because it's designed for multi-second exposures as its normal, and a couple minutes isn't far enough out of its normal range to require large corrections. Another option is ortho lith films; these are comparable in speed and emulsion characteristics to enlarging papers, but produce a transparent negative (easy to print/enlarge) -- and, like paper, you can handle them under safelight (red only, please). You can also control contrast without filters (and they don't change contrast when the light changes, though they do change speed some); it's done by altering the developer dilution (develop in a developer intended for prints, generally -- higher dilution => lower contrast).

Alan9940 · Jun 20, 2020

Meter here, too. I meter the exposure at f/22, use a chart for the conversion to my pinhole's f-number, consider reciprocity, then shoot. Pinhole exposures are generally long enough that a few seconds (preferably more) won't make a big difference.

Nick Dvoracek · Jun 20, 2020

For a long time this was adequate. Now I use Pinhole Assist on my iPhone.

Andrew O'Neill · Jun 20, 2020

I never guess. I always use a light metre.

Sirius Glass · Jun 20, 2020

I use a light meter, occasionally Sunny 16 and then calculate for the f/stop and ISO.

ic-racer · Jun 20, 2020

I used pinhole on my 8x10 for the last eclipse. I calculated the exposure based on the estimated pinhole size and focal length and empiric data from prior exposures of the sun.

Daniela · Jun 21, 2020

ic-racer said:
I used pinhole on my 8x10 for the last eclipse. I calculated the exposure based on the estimated pinhole size and focal length and empiric data from prior exposures of the sun.

So interesting! Can you share the image?

narsuitus · Jun 23, 2020

First, I use the pinhole size and the pinhole-to-image plane distance to calculate the f/stop of the pinhole.

Second, I use the Sunny-16 to give me an idea of the correct exposure.

Third, I use a light meter to give me an accurate light reading.

Fourth, I use a pinhole exposure calculator to give me options for the correct exposure.

Fifth, I use a cheat sheet that gives me reciprocity adjustments I need to make to the correct exposure to adjust for the film and long shutter speed that I am using.

Pinhole exposure calculator by Narsuitus, on Flickr

bsdunek · Jun 23, 2020

Mr. Pinhole has lots and lots of information. I use this page - printed out and in my bag. Always works for me.
http://mrpinhole.com/exposure.php

Máx Arnold · Jun 25, 2020

Oh, this is so great! I'm very happy to see your replies!
I use the Mr. Pinhole calculator for designing my cameras because it gives important info like angle of view and optimal pinhole size/ focal length.
I also love Joe Van Cleave's videos! So important while studying on the subject...

I see some of you meter (Joe does every time), some guess, some really take it seriously, like narsuitus.
Everyone, while we get the exposure right, is correct.
Donald Qualls basically explains part of my success at guessing exposures, though I have to say to me that I've underexposed a wholesome lot of anthotypes and I still hideously overexpose my cyanotype prints sometimes.
I don't use film on my pinhole cameras because exposure times of less than 2 seconds are difficult to manage with a cardboard shutter. I'm in the same quest of Joe about finding a working homemade shutter for sub-second exposures. I guess imitating Packard shutters are a way to go, but I could be wrong! I'm not good at crafts, if anything my cameras work, but you don't see how ugly they are, haha

Wrapping up, this is so great, and I really thank you for answering. Let's keep going!

Donald Qualls · Jun 26, 2020

Falling guillotine shutters are good in the 1/10 to 1/2 seconds range, but they can be a little finicky in the field. I think it should be possible a roller blind shutter with repeatable exposures, driven by a free-falling weight, to get into the 1/2 to 2 second range. Again, likely to be a PITA to calibrate and make reliable, but seems possible.

Personally, I don't have a problem with lens cap type shuttering in the 1s range, and if I'm likely to shoot a lot at faster speeds, I'll probably buy a junky folding camera that has slow speeds and pull the shutter off that. I've got a dial-set Compur with a pinhole lens in it, that covers every exposure I could possibly want...

Roseha · Jul 2, 2020

I have only been using pinhole cameras a few years but for almost all that time I have used a free Android App called Pinhole Calculator by Mickael Adam. It's really reliable. Once you have the focal length and aperture for each camera you can save it under My Pinhole Collection. I find it easiest to take an EV reading with a separate meter (phone or handheld) and then calculate with the ISO to get the required speed. It's done a great job for me.

Donald Qualls · Jul 3, 2020

Roseha said:
I have only been using pinhole cameras a few years but for almost all that time I have used a free Android App called Pinhole Calculator by Mickael Adam. It's really reliable. Once you have the focal length and aperture for each camera you can save it under My Pinhole Collection. I find it easiest to take an EV reading with a separate meter (phone or handheld) and then calculate with the ISO to get the required speed. It's done a great job for me.

I have that app, but as far as I can see, it doesn't compensate for reciprocity departure (specific to the film stock you're using). That means I have to take its exposure (which I can arrive at myself, quickly and easily, from the meter reading) and plug the result into a reciprocity calculator...

jay moussy · Jul 3, 2020

Reciprocity calculator... where to find a convenient one, something to use in the field - app or pre-printed paper cheat sheet, or..?

MattKing · Jul 3, 2020

Pre-printed paper cheat sheet works great if you always use the same film(s).
You can even get them laminated.
Quickness isn't one thing that you need worry about once pinholes get into the reciprocity failure range.

Donald Qualls · Jul 3, 2020

jay moussy said:
Reciprocity calculator... where to find a convenient one, something to use in the field - app or pre-printed paper cheat sheet, or..?

I use an Android app called Reciprocity. It's got a terrible interface -- you can only enter values by scrolling them up and down on a list, can't jump ahead a bunch, can't type in a value -- but it has a good film list to select from, and uses the Grant-Haist exponential method to calculate (which I once, when my brain was a little younger, used to do in my head). The core of the Grant-Haist method is the tested truth that any film, once it departs from reciprocity, requires something more than doubling the time for each stop of additional metered time.

Some films depart at slower times than others (Fomapan 100 departs at one second, Acros II at one minute, for instance), and some films depart by a larger factor than others (Fomapan, if I recall correctly, needs 2.8x for each doubling of metered time past 1 second; Acros needs only 2.1x for each doubling past a minute). The Reciprocity app does this calculation automatically. You could install AndrOpenOffice and use the spreadsheet to do the same, if you find you hate the interface badly enough...

DWThomas · Jul 3, 2020

Donald Qualls said:
an Android app called Reciprocity

There is a similar app, Reciprocity+ for the fruit company's phones too. I have it, but tend to fall back to my little spreadsheet concocted table.

rst · Jul 4, 2020

In the past I just had a little cheat sheet with me. Worked great. Nowadays I use an app called Pinhole Master which works as a light meter, reciprocity calculator, timer and exposure time logger. One app to rule them all ...

Donald Qualls · Jul 4, 2020

rst said:
In the past I just had a little cheat sheet with me. Worked great. Nowadays I use an app called Pinhole Master which works as a light meter, reciprocity calculator, timer and exposure time logger. One app to rule them all ...

I don't find that in the Android Play Store -- is it fruit-specific? Or side-loaded?

EDIT: yep, iOS only. And so is the only other competitor, Pinhole Assist.

What's up, Android developers? Our phones can do anything an Apple device can! Why should I have to use three apps plus the built-in timer (feature of the system clock) and still not get the features iPhone users get?

rst · Jul 4, 2020

Donald Qualls said:
I don't find that in the Android Play Store -- is it fruit-specific? Or side-loaded?

EDIT: yep, iOS only. And so is the only other competitor, Pinhole Assist.

What's up, Android developers? Our phones can do anything an Apple device can! Why should I have to use three apps plus the built-in timer (feature of the system clock) and still not get the features iPhone users get?

Given that there are more Android users out there I wonder why the developers of these Apps do not go for the larger user base.

Pinhole photographers! How do you guess the exposure?

Máx Arnold

DWThomas

jay moussy

rst

Daniela

Donald Qualls

Alan9940

Nick Dvoracek

Andrew O'Neill

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Sirius Glass

ic-racer

Daniela

narsuitus

bsdunek

Máx Arnold

Donald Qualls

Roseha

Donald Qualls

jay moussy

MattKing

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Donald Qualls

DWThomas

rst

Donald Qualls

rst

Pinhole photographers! How do you guess the exposure?

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