Topic: my first pinhole experience

[kentish cob]

After an all too brief meeting with F/Ws resident pinhole expert Diane last month during her UK visit, I felt compelled to join the ranks of "pinholers" in time for this years world pinhole day...
Sadly, in this part of the world, the weather was pretty poor, and I didn't make good on my promise. I did, however, take the plunge a few days later.
Here then, is my pinhole journey...

It must have been around five years ago that I decided to build a pinhole camera.
I'd come across this website:
http://www.teamdroid.com/diy-high-capacity-panoramic-pinhole-camera/
Which sparked my interest, so using the plans on the site as a guide, but making a few minor adjustments, I set about cutting, shaping, sanding, gluing, drilling and painting.

Using 6mm MDF for the outer shell, and 6mm "mighty-core" foam board for the internals, it's quite a sturdy little box. A simple winding mechanism to pull the 120 film in front of a piece of thin brass shim, hand-drilled with a 0.25mm drill held in a pin chuck.
With a 0.25mm hole, and a distance from pinhole to film of 40mm, the f/stop according to Mr Pinhole's calculator is f160.
A steel washer is glued onto the front of the brass shim in a recess on the front of the box, and a "memo board" type magnet fits snuggly into the recess as a shutter.

Upon completion, the little black box became a desk ornament until just two weeks ago. 

[kentish cob]

I was very pleasantly surprised by the results.
There were a few errors, a couple of accidental double exposures where I forgot to wind on, but I think I got the frame spacings fairly well worked out, and reckon I should get around 22 to 24 shots per roll.
The biggest problem seems to be the calculated exposure times.
Using a chart I copied from Andrew Sanderson's "Night Photography" book, I exposed according to metered readings (metered at f8 and adjusted accordingly) and took a second, longer exposure to account for reciprocity failure.
The standard exposures all came out acceptable, but the "reciprocity" exposures all grossly overexposed to the point of total white-out... Not at all sure why that should be, but as this was the first time, and effectively a test shoot, I'm happy to stick to metered exposures in future.

So, here's some results... film was Ilford Delta 100 developed in D-76, and only minor clean-up in P/S.

[kentish cob]

a few more...

[kentish cob]

and finally, those accidental doubles...

[Francois]

Pretty nice for a first build.
That high capacity part really intrigues me. It must feel a bit like a half-frame camera.

As for reciprocity, it changes with every film, so a single do everything chart is a definite no-no.
I use custom charts I make with the pinhole.cz pinhole designer. I usually leave the reciprocity factors out of the equation and simply eyeball it. If I get the data from the film maker, I'll use that. But as a rule of thumb, I just double when I reach 30 seconds. If it's not needed, it's just one more stop so no biggie there.

[Indofunk]

I like those a lot!! And I like the aspect ratio, what is it?

[cs1]

Great results. And the box looks pretty, too.

[Sandeha Lynch]

Very nice, and a great-looking format, too.

[EarlJam]

Low reciprocity was one of the best aspects of Fuji Acros. I'm holding on to my last two rolls of 120 for pinhole use. Charles Binn appears to have posted a useful reciprocity chart on FW back in 2012:

http://www.filmwasters.com/forum/index.php?topic=5298.0

[kentish cob]

Thanks for the encouraging comments, all.
I'll definitely be giving the little black box a few more outings.

As far as Andrew Sanderson's reciprocity correction chart is concerned; I understand, Francois that the increased exposure will differ dependent on the film, but AS is an Ilford master printer, so I figured his knowledge and experience would be a good place to start... Especially since it was published in his night photography book...
In any case, as I said, this was essentially a test roll, and it's given me a sound baseline to work from... and there's plenty more versions of reciprocity charts out there to try (I just copied on from APUG that looks more promising).
As mentioned by EarlJam, during the course of my "googling" on the subject, I've learned that Fuji Acros apparently suffers no reciprocity failure with exposures up to 2 minutes..! That seems ideal... Shame they're binning it... maybe I'll stock up!

I like those a lot!! And I like the aspect ratio, what is it?

Basic info I neglected to include above, Satish... Apologies.
Using the width of 120 film, negative size is 54mmx24mm, so aspect ration is just a whisker away from 2:1

[Francois]

Sanderson probably failed to specify that he probably adapts his development for long exposures.
I know that for high contrast scenes I almost always overexpose and underdevelop the film. Since reciprocity is mostly a slow shutter speed problem (though reciprocity applies to super high speed exposures done using air gap flash), it applies mostly to night photography which is inherently a high contrast situation.

[kentish cob]

The standard exposures all came out acceptable, but the "reciprocity" exposures all grossly overexposed to the point of total white-out... Not at all sure why that should be, but as this was the first time, and effectively a test shoot, I'm happy to stick to metered exposures in future.

I've just realised my schoolboy error in this assessment... the failed frames all resulted in clear negs, which is gross underexposure, meaning it's the metered exposures which are incorrect, not those adjusted for reciprocity... with humble apologies for misleading, and even humbler apologies for any hint of suggestion that reciprocity is bunkum... Andrew Sanderson (and his published reciprocity chart) is hereby restored to the pantheon...

Future outings with the little black box will, I hope, be more successful on account of my grasping the bleedin' obvious.     

[Francois]

One of the fun things with pinhole cameras is that precise exposure is not exactly required. When you expose for 1/250th, it's not 1/125th or 1/500th. But the difference between 15 seconds and 20 seconds is in all respect not that great. As always, it's better to overexpose a bit than to underexpose by a lot.