paint can pinhole camera, what size pinhole?

[timeUnit]

Hi!

I'm a total noob to pinhole photography and I aim to start my attempt with a simple paint can pinhole camera.

The paint can is approx 8 in (20 cm) diameter and about 7.5 in (19 cm) tall (deep?). I will try to shoot 12 x 7 in (30 x 17 cm) paper negs with it.

As the "focal length" is set and will be about 8 in / 20 cm, will a .6 or .7 mm pinhole be alright? I tried the Mr. Pinhole thing on the net, and that gave me apertures in the 280-330 region. I have no idea if that will look good or bad...

Advice?

 

[Erik Hartmann]

Take a look here:

Dead Link Removed

OK it is not a paint can, it is a the can !!!!

But I got some god pictures using enlagment paper from Ilford....

Niels-Erik

 

[rwyoung]

For on-line calculators, http://www.mrpinhole.com/holesize.php works pretty well. Keep in mind, the formula assumes your "lens" plane and film plane are parallel. In this case, they really aren't, the film curves around the back of the can. You can use the diameter of the can but keep in mind, that means the edges of the film are closer to the hole than the center of the film.

But for all intents and purposes, you can get some pretty spiffy images with a 0.6mm hole and start your exposure estimates with f-335.

Lets assume you use photo paper as your negative. Depending on both the exact brand of paper, VC vs. Graded and the quality of the light (bright sun, shade, overcast, indoors) etc you will find the paper speed is anywhere between ISO 2 and ISO 10 (YMMWV). Lets compromise and call it ISO 8, outdoors with full sun and bright shade.

Sunny-16 rule says you would need 1/8 sec exposure if your f-stop was f-16. But you have f-335, the correction factor for time would be:

(335 * 335) / (16 * 16) = 438. 1/8 sec * 438 = 54.75 second. Lets just call it 55 seconds. So as a first try in bright sun/open shade I'd try 55 seconds exposure.

Yes, there is reciprocity failure with paper negatives, yes shade with more blue light messes with the speed. Yes, you will need to try several times to get your baseline exposure figured out.

Enjoy your camera!

 

[Jim Jones]

Mr. Pinhole is popular, but http://www.pinhole.cz/en/pinholedesigner/ is more sophisticated. Using it with a user constant of 1.5 (chosen after considerable testing) gives a diameter of about .45mm for paper negatives and .5mm for panchromatic film. The curvature of the paper in a paint can camera has less effect on optimum pinhole diameter than one might first think. Even though the edges of the negative are closer to the pinhole, the pinhole diameter is reduced because of the oblique angle through it.

Some of us quibble at length over the optimum pinhole diameter. This has been debated for over a hundred years. Ultimately, the optimum pinhole diameter is the one that gives the best results for each individual photographer, not the one that best satisfies arcane formulas.

 

[timeUnit]

I'll just do the hole as best I can, and I'll see what size I happen to make...

 

[walter23]

How do you actually drill the pinhole? A pin? Are there better tools?

 

[timeUnit]

Ok, so now I'm half way through. I've cut a 3 x 3 cm square hole in the paint can, made a pinhole with a beer can and a pin. I'll paint the inside of the can tomorrow when I find some paint. Matte black spray paint is not sold in gas stations anymore in Goteborg. Nuts. I can get lots of different porno mags, sandwiches, CDs and barbecues, though.

Walter,
this is how I made the pinhole. Though I used aluminum from beer can instead of brass. http://www.pinholeday.org/support/faq.php

 

[timeUnit]

Now I'll make the shutter and a "holder" for the paper negs.

 

[timeUnit]

I made a holder for the negs out of heavy black paper, and out of the scraps from that I made a shutter, model "sliding door". The shutter looks really nice, I must say!

Today I'll buy some spray paint (cross my fingers I find some) and paint the inside, tomorrow I'll mount the shutter in the can. On friday I might bring the thing to work and shoot one picture!

If anyone's interested in how the shutter works, feel free to ask.

(I'm writing this so anyone else attempting to build a paint can camera, could find this thread for hints.)

 

[rwyoung]

Wow, you seem to be going to a lot of trouble for a paint-can camera.

1) Empty paint can from hardware store, $0.99 and already a flat gray inside, no painting. YMMV on cost and interior finish of can.
2) Cut dime sized hole in side of can, centered top to bottom and opposite of the seam. Dremel and spiral cutting bit. You could use a nail and tin-snips. Now you can use the seam of the can to help you aim the pinhole even when it is covered up by your shutter.
3) Make pin hole in brash shim stock, but a soda or beer can works fine. The shim stock was a small sheet, maybe 3x5" and another buck.
4) Beading needle stuck in a pencil eraser. 1" x 1" square of the shim stock. Spin, buff with 600 grit paper, flip, spin, buff, repeat until drilled through. There are size equivalent charts on the web for beading needle to hole diameter. But I happen to own a direct measuring microscope (work related equipment) so I just measure it directly.
5) Sharpie marker to color one side of the shim stock. Gorilla tape to tape pinhole inside of can.
6) Make shutter from refrigerator magnet. Realtors seem overly fond of passing out cheap, flexible magnets with the advertising on them. I just printed a cartoon monkey on a large label and used it to cover up their advertising.

As for film holders, two little bitty blobs of "blu-tak". The sticky stuff you use to put up posters in the dorm room. For a quart paint can I cut a sheet of 8x10 down to two 4x10s. Paper wraps nearly all the way around on the inside and friction seems to hold it just fine. For the gallon can I cut down 8x10 to about 7.25 x 10. Theis is where the blu-tak helps because my particual gallon can has two ears that stick into the can for the handle. They cause problems getting the paper centered so I just have an itty-bitty piece of the blu-tak on two opposite corners to hole the paper to the back of the can.

Paint can lids are light tight (if not bent). Also, you can put a pinhole in the lid too. Just keep an extra magnet over that one. Film/paper goes on the bottom of the can or still around the circumfrence.

By the way, Jim is right about the software he mentioned. But for the life of me I couldn't find the link to post so I just used Mr. Pinhole instead. But pinhole designer has more power.

 

[timeUnit]

Sure, I'm going through a little "trouble" to make the camera... But it's a lot of fun!

The only paint can I found was glossy yellow inside, so I "needed" to paint it black, which I did last night. Took maybe ten minutes.

The pinhole was made in the fashion you mention. Looks pretty good under a 8x loupe.

The shutter was easy to make, and looks pretty cool. If I had any magnets lying around I might have used them, but I don't.

One thing that needs to be understood is that Sweden is quite different from the US. While we have hardware stores in the city, they are less and less oriented towards selling hardware, and more into selling domestic appliances etc. Not seldom am I forced to take the car out of town to a hardware store for professionals, a store that of course closes at 5 pm, so I have no chance of making it after I get off work...

There is a big trend in Sweden towards buying everything pre-made. Getting parts to build things is increasingly difficult. Even the huge hardware stores in the suburbs have less and less material, and more and more pre-made. To me it's quite frustrating.

But back on topic. Paint can camera is almost ready. Tonight I'll mount the lens. ;-) That is, tape the pinhole to the inside of the can. Done!

 

[rwyoung]

Disappointing to hear about the hardware store dilemma in your country. Too bad. Lots of neat stuff to be had at old mom-and-pop style hardware stores!

Congratulations on your camera work though. Exciting stuff.

Two other accessories you might want to consider are a small platform you can screw onto your tripod. Then you strap the camera down to the platform. The second is a bean-bag style weight for steadying the camera.

I first tried attaching an appropriately sized nut to my metal cans and while that worked for a can set on its flat bottom, twisting the tripod for a horizontal shot let the can flop a bit as the metal bottom "bent".

Instead, I cut out a small platform from 1/4" MDF board. Covered with black felt so it was a little less slippery. And used a "t-nut" driven in from the back side to mount to the tripod. Now I can use some large rubber bands to hold my cameras to the platform either upright or on their side.

As for making a bean-bag, I just poured a pound or so of bird seed into a zip lock plastic bag. Then used a second bag for extra "strength". Cheap and works but down side is the plastic is a little slippery. Should really use fabric for the outer bag.