Pinhole success

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mark dyson
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Pinhole success

Post by mark dyson » Mon May 04, 2009 4:15 pm

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.

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Re: Pinhole success

Post by TerryMooney » Mon May 04, 2009 5:59 pm

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

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Re: Pinhole success

Post by TerryMooney » Mon May 04, 2009 7:34 pm

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 ???

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pammie
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Re: Pinhole success

Post by pammie » Mon May 04, 2009 9:13 pm

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

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Re: Pinhole success

Post by sunsworth » Tue May 05, 2009 9:47 pm

I hav'nt yet seen any Depth of Field tables for pinhole cameras - have you ???
There's a reason for that <grin>

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Walter Brooks
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Re: Pinhole success

Post by Walter Brooks » Wed May 06, 2009 7:28 pm

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] :-O

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? :lol:

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

Walter
“The camera is an instrument that teaches people how to see without a camera.”
― Dorothea Lange

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Re: Pinhole success

Post by sunsworth » Wed May 06, 2009 11:25 pm

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.

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Re: Pinhole success

Post by TerryMooney » Wed May 06, 2009 11:35 pm

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

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John
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Re: Pinhole success

Post by John » Tue May 12, 2009 9:46 pm

If you guys are getting serious about your pinholes:

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

It ain't cheap!
Best regards

John

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pammie
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Re: Pinhole success

Post by pammie » Wed May 13, 2009 8:34 am

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

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Walter Brooks
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Re: Pinhole success

Post by Walter Brooks » Wed May 13, 2009 9:52 pm

Nope - but by the thickness of the spectacle lenses of the assistant, doubt if anything would have been in focus to them :lol:
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
“The camera is an instrument that teaches people how to see without a camera.”
― Dorothea Lange

mark dyson
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Re: Pinhole success

Post by mark dyson » Sat May 16, 2009 11:07 pm

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

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