To honour the best pinhole forum of this and last century, I thought I'm going to build me a f295 pinhole camera out of Afzelia wood.

I used the pinhole designer ( http://www.pinhole.cz/en/pinholedesigner/ ) to calculate everything.

It's going to be an all 295 camera:
* negative size = 295 x 295 mm,
* focal length = 295 mm,
* pinhole = 1,0 mm
* Angle of View = 73 degrees
This will give a f-stop of 1/295 !!

Before I start building, I would like to ask you specialists to check for me if these numbers are correct.

I never used a pinhole this big. Will it still be able to give (reasonly) sharp images??

Any other tip/recommendations are welcome!!

I'm using pieces of wood in size of 72 x 355 x 6 mm. They come from a leftover, opened package, used for the floor in my living room. I would hate to throw it away. It's the same wood I used before for my first pinhole camera (negative 100 x 100 mm). I'm glueing the pieces together into 3 panels for the back and the two sides. I'll make the top and bottom later to fit.
Since I'm going to use photographic paper as a negative, I'm going to make a silmple insert to slide the negative into. Maybe flat onto the back or maybe with a curved film plane. It will be a single shot camera.
The side panels are sticking out a bit in the front, forming a build-in lenshood. The inside will be painted black or I'll use black filt if I can find any overhere. The outside will be varnished. In a few years the wood will turn into a nice, warm red-brown color (due to sunslight).
Thanks,

Pinhole Designer suggests that the optimum pinhole diameter for a 295 mm camera is 0.8 mm, so I would think you should get some kind of image. Its going to be a bit of a monster!

Gee, it's a pity the site isn't f-279.org instead of f-295.org so you could print on 11x14 inch paper!  Optimum pinhole diameter has been argued for over a hundred years.  My choice for a focal length of 295mm would be .6mm, but this is based on optical performance, not number games.  I'm even less an accountant than photographer.  A pinhole diameter of 1mm would produce images that look fairly sharp at a distance of several feet.

Below you'll see a drawing of what the camera will be like. I'm using pieces of wood in size of 72 x 355 x 6 mm. They come from a leftover, opened package, used for the floor in my living room. I would hate to throw it away. It's the same wood I used before for my first pinhole camera (negative 100 x 100 mm). I'm glueing the pieces together into 3 panels for the back and the two sides. I'll make the top and bottom later to fit.
Since I'm going to use photographic paper as a negative, I'm going to make a silmple insert to slide the negative into. Maybe flat onto the back or maybe with a curved film plane. It will be a single shot camera.
The side panels are sticking out a bit in the front, forming a build-in lenshood. The inside will be painted black or I'll use black filt if I can find any overhere. The outside will be varnished. In a few years the wood will turn into a nice, warm red-brown color (due to sunslight).

to determine fstop:

f-stop = focal length / pinhole diameter

so, many different combinations will give a f295..........

tp

Quoted from tpersin

to determine fstop:   f-stop = focal length / pinhole diameter

Using this formula leads to the same conclusion: the pinhole diameter should be 1.00 mm to get a f-stop of 295 for this camera. But what is the optimal pinhole size? Well, I'm not going to (re)start a 100 year old discussion, but the Pinholedesigner 2.0 tells me it is 0,765 mm.

I made some calculations and a graphic to see where these two formulas will meet. It seems that, to get a f-stop of 295, a focal length of 173.3 mm is needed. This equals an optimal pinhole diameter of 0,587 mm.

Who wants to know all the details, can read the PDF-file on my website.
See: http://www.studiotegenlicht.nl/pinhole_eu/downloads/What_pinhole_size_do_I_need_to_get_f295.pdf

And in the meantime: remember these wise words of Ansel Adams (quoted from his book The Camera):
"... avoiding the common illusion that creative work depends on equipment alone ..."
Nuff said!!

Here is a picture of me drilling holes for 6 pinholes in the camera. The pinholes will be placed vertical. This way I have shift and tilt capability or just fun with multiple exposures from different angles.
The camera is almost finished. However, I'm going on holidays this Friday for 3 weeks. So I'll have to wait to finish and paint the camera!!! I would almost cancel my vacation, if it wasn't for my children being veeeery dissapointed...
(Picture made with a Agfa Click I, converted into a pinhole camera, exposure 30 seconds on Fuji NPC 160 rollfilm)

So where did the f295 come from for this site - or was it just pulled out of the sky cos it sounds good?