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 http://unblinkingeye.com/Articles/PinCam/pincam.html.

 

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

 

There's a great pinhole discussion forum at www.pinhole.com

 

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

 

Please note that in October 2015 my webpages on building large format cameras move to: jongrepstad.com
Jon Grepstad