- Original Message -
From: earthecho
Hello, Frazer Bryant here - New member from England.
Hello Frazer and welcome to the list.
The sheet Film size is 8 and a 1/2 inch X 6 and a 1/2 inch.
(I will be using paper negs.)
I have one of those, only mine is 6 1/2 X 8 1/2 !!!
Just kidding, Frazer. :-)
Q1 What Dia. pinholes should I use for a) wide angle, and super
wide angle images, and, what would be their corresponding fstops ?.
Q2 What would be the appropriate distances between negative and pinhole
for the above pinholes ?.
The above question should probably be formulated in reversed order, in other
words, you first want to know what focal lengths constitute super wide and
wide, then what diameters should be used for them and finally what f/stops
would they be.
Wide: 120mm to 180mm
Super Wide: anything under 120
In general, you could multiply a 35mm format focal length times 6 and that
would be the equivalent to 6.5X8.5 format, I.E., 50mm is normal for 35mm
formt, the equivalent for your half plate camera would be 50x6 = 300mm
The so called optimum diameters would be given by:
diameter in mm = 0.03679 x SQRT ( focal length in mm)
SQRT stands for square root.
F/stops could be found by dividing the focal length by the diameter of the
pinhole you are using.
The appropriate distance distance between pinhole and film plane is the same
as the focal length.
Download David Balihar's PinholeDesigner at
http://www.pinhole.cz/en/pinholedesigner/ , excellent tool to help you with
diameters, focal lengths, angles of view, f/stops, etc.
Read my articles:
http://members.rogers.com/penate/pinsize.htm
http://members.rogers.com/penate/diameter.htm
Peruse the resources page at Pinhole Visions
http://www.???/resources/ and the one at the World Wide
Pinhole Photography Day http://www.pinholeday.org/
Guillermo
