Pinhole success

[mark dyson]

I have just developed my first film from my homemade camera and it has worked. The pictures are out of focus but i should be able to solve this problem. I thought i would post this to let Walter know the pressure is on. With this type of camera is the sharpness due to the pinhole diameter as i am working at f88 with a diameter of 0.67mm. I am using fp4 and was getting shutter speeds from 1/2 to 8th of a second. How far have you got Walter.

[TerryMooney]

Mark - The optimum diameter of a pinhole to give the sharpest image is calculated from the following formula devised by a Lord Rayleigh many years ago but still appropriate today.

d = Diameter of Pinhole
f = Focal length (50mm)
L = Wavelength of Yellow/Green light (0.00055mm)

d = 1.9 x Square Root(f x L)

d = 1.9 x Square Root(50 x 0.00055)

d = 1.9 x 0.16583124

d = 0.315mm (This gives f159)

This info can be found on the website - www.pinhole.cz/en/pinholecameras/whatis.html

It contains all the info required to make a camera and also take the photographs.

TerryMooney

[TerryMooney]

Mark - By the way with a pinhole of 0.67mm the optimum Focal length for best sharpness is 226mm.

I hav'nt yet seen any Depth of Field tables for pinhole cameras - have you ???

TerryMooney

[pammie]

Hey guys,

On july 6th 2009 I have scheduled in an informal competition for prints up to A4 size, unmounted, mainly for beginners. But I had already seen someone suggesting using pinhole cameras or disposable cameras, and thought I would combine the 2, so please enter some pinhole images!

I have also booked Steve Gosling to visit us on March 18th 2010 with his talk entitled "Lensless Landscapes".

Pinhole images is something I am interested in having a dabble at, so let us know how you get on.

Pammie

[sunsworth]

I hav'nt yet seen any Depth of Field tables for pinhole cameras - have you ???

There's a reason for that <grin>

[Walter Brooks]

Mark, I'm in there with you - bagged a 36 exposure at varying apertures and exposure times using extension tubes [thanks Andy] of three vistas! Waiting for it to come back from Tesco then I can fine tune the exposure times/ aperture [kept a log as I went along!] using the exposure guide off the Web. May even be lucky to hit on a reasonable exposure combination first time, if not got something to work for the next roll of film.

Terry, will look at Rayleigh's formula if I am completely off the wall with what I get back.

Len it's 50/ 50 unless I let you see the prints before you judge them annonymously [if you want to be a winner]

Pammie thank goodness it's July - gives us a bit longer - especially Mark who will no doubt want to spend time in the darkroom to produce his out of focus winner?

Steve - if you do come across a depth of field guide, I am sure Mark will find it useful ...

Walter

[sunsworth]

Steve - if you do come across a depth of field guide, I am sure Mark will find it useful

I thought the thing with pinhole cameras was that everything is in focus.

[TerryMooney]

Steve - No the thing with pinhole cameras is that nothing is in sharp focus !!!!!

TeeryMooney

[John]

If you guys are getting serious about your pinholes:

http://cgi.ebay.co.uk/Brass-Shim-12-Pie ... 7C294%3A50

It ain't cheap!

[pammie]

Walter - when you got your film back from tesco did it have "out of focus" stickers on it?

[Walter Brooks]

Nope - but by the thickness of the spectacle lenses of the assistant, doubt if anything would have been in focus to them
Some "clear" images with an optimum exposure determined ... so out for some serious photography with my modified body cap this weekend - even going to try a bit of fill in flash!
Mark, you seem a little shy on this thread - getting worried yet? Share a tip with you vibrant colours work best out of focus ... at least it helps to indicate that there was something there to catch the eye in the first place

Walter

[mark dyson]

A good poker player never reveals his hand untill he takes the pot. You will just have to wait.