Large format pinhole camera

i have been shooting large format with lenses for years, and was

interested in making a large format lens-less (pinhole) camera.

right now i regularly shoot 4x5 and 5x7 and i wanted to go maybe

to 7x17 or 8x20 and shoot paper negatives. i have micro drilled

shims, and plans for making the "box" ...

has anyone every made a really BIG pinhole camera?

will i have any problems with image circle / coverage ?

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thanks in advance!

john

John:

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I built an 11x14 Pinhole several years ago as a bridge to larger

format cameras. My 11x14 pinhole has a focal length of about 5" and

uses a .016" pinhole. This arrangment covers 11x14 although you do get

the light falloff characteristic of pinhole shots.

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If I remember correctly, the relationship between focal length and

image circle is approxiately 1:3.5. Thus, a 1" focal length pinhole

camera will produce an image circle of 3.5". For the larger film

formats you will need a minimum FL starting at about 5-6 inches.

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...................................

Dave:

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Out of fascination, can you remember what the length of exposure was

under "sunny 16" conditions?

thanks dave -

if / when i build it i'll post my results :)

- john

Go to:http://home.online.no/~gjon/pinhole.htm. Jon has alot of useful

info. If you also plug in "homemade cameras" into your browser, you

will get so many sites!!!!

I built an 8x10 pinhole a while ago. It has a focal length of 8.25"

and an f/346 .

I purchased a laser-drilled pinhole from Lenox Laser - they drill

these in 1/5000th stainless and mount them on a 3/4" disk.

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The camera itself is a plywood box with an 8x10 spring/back from an

old Kodak. I have only used film so far, but you could use paper in

the holder as well.

I initially had recessed the disk (with pinhole) and made a 1.4" hole

in the wood, but the edges of the wood showed on the negs.(the disk

with pinhole is mounted on the inside surface of the box), so I had to

enlarge the hole to about 3/8" -

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I like it alot!

To combat light falloff you might consider building the camera with a

curved film plane. I made a 4x5 out of a coffee can that works

beautifully, and I recently completed a 5x7 version. See the 4x5 at

<a href=http://unblinkingeye.com/Articles/PinCam/pincam.html>

http://unblinkingeye.com/Articles/PinCam/pincam.html</a>.

This does not answer your question, but I thought I would chime in.

I am a LF in focus kinda guy. But, a while back I purchased a 4x5

and 8x10 Leonardo(used) and I must say they can be a kick in the

butt. I carry the 4x5 with me most of the time and I find playing

with the pin holes to be a great break. There is no dissatisfaction

in a soft focused finished print because it's "supposed to be that

way" so a lot less pressure.. And I have a lot of fun trying to play

around with motion. It's also a great way to introduce a kid to

photography at a very basic level. And you really can have cars and

people go by and not get in the photo. I purchased my 4x5 at almost

new price and the 8x10 for $15.00 with a holder. Check out Eric

Renners(sp?) Book

and site.

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Good Luck,

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Mac

A spin-off question:

Considering the rule of thumb for pinhole circle of coverage being about 3.5 x f.l., does using a longer f.l. than 'normal' for a format reduce the falloff?

Numerical example - 4x5 bellows camera, pull the lens board, put in a pinhole board with right size hole for 300 mm, and extend bellows to 300 (or whatever), and still use a 4x5 filmholder, does the edge falloff end up being way out beyond the diagonal of the 4x5 film, and thus have a 'telephoto' perspective with more even illumination than one would have with 4x5 film, 150-160 mm bellows position?

Thank you.

Murray

<p>Please note that in October 2015 my webpages on building large format cameras move to: jongrepstad.com</p>

<p>Jon Grepstad</p>