rbiemer
Unabashed Amateur
This fall/winter I am building myself a 6 x 9 (on 120 film) pinhole camera and would appreciate it if you folks would help me out a bit.
I want to make this one with multiple focal lengths and I think I'll be able to use my FSU turret finder if I have the correct equivalent focal lengths?
So, 6 x 9 is 2.5 times as large as 24 x 36 and if I'm correct, I should be able to use:
28mm for 70mm
35mm for (aprox)87mm
50mm for 125mm
85mm for (aprox) 212mm
135mm for (aprox) 337mm
Do these seem like reasonable approximations to you folks?
I will likely not use all five but will probably go for three: wide, "normal", and short tele or 70, 125, and 337.
Not sure if I'll be attempting to make a bellows for this or--more likely but I've not settled this in my head yet--something like a set of nested boxes.
I have some old cameras I'll use for some of the winding mechanism, cold shoe, and red window.
Thanks, all!
Rob
I want to make this one with multiple focal lengths and I think I'll be able to use my FSU turret finder if I have the correct equivalent focal lengths?
So, 6 x 9 is 2.5 times as large as 24 x 36 and if I'm correct, I should be able to use:
28mm for 70mm
35mm for (aprox)87mm
50mm for 125mm
85mm for (aprox) 212mm
135mm for (aprox) 337mm
Do these seem like reasonable approximations to you folks?
I will likely not use all five but will probably go for three: wide, "normal", and short tele or 70, 125, and 337.
Not sure if I'll be attempting to make a bellows for this or--more likely but I've not settled this in my head yet--something like a set of nested boxes.
I have some old cameras I'll use for some of the winding mechanism, cold shoe, and red window.
Thanks, all!
Rob
pvdhaar
Peter
The ratio is not exactly 2.5, that because the actual 6x9 frame is 55.6mmx85.6mm.
But it's close enough according to an angle of view calculator:
70mm on 6x9 is ca. 72.2 degrees; 28mm on 35mm is ca. 75.4 degrees
87mm on 6x9 is ca. 60.8 degrees; 35mm on 35mm is ca. 63.4 degrees
125mm on 6x9 is ca. 44.4 degrees; 50mm on 35mm is ca. 46.8 degrees
212mm on 6x9 is ca. 27.1 degrees; 85mm on 35mm is ca. 28.6 degrees
337mm on 6x9 is ca. 17.2 degrees; 135mm on 35mm is ca. 18.2 degrees
Hope this helps..
But it's close enough according to an angle of view calculator:
70mm on 6x9 is ca. 72.2 degrees; 28mm on 35mm is ca. 75.4 degrees
87mm on 6x9 is ca. 60.8 degrees; 35mm on 35mm is ca. 63.4 degrees
125mm on 6x9 is ca. 44.4 degrees; 50mm on 35mm is ca. 46.8 degrees
212mm on 6x9 is ca. 27.1 degrees; 85mm on 35mm is ca. 28.6 degrees
337mm on 6x9 is ca. 17.2 degrees; 135mm on 35mm is ca. 18.2 degrees
Hope this helps..
rbiemer
Unabashed Amateur
Very helpful, indeed. Thanks!
And you reminded me of the Pinhole Designer software so I have got that again (see here for it: http://www.pinhole.cz/en/pinholedesigner/ )
And since I'm building this camera, I can decide my own film gate size. Which will be as close to 56 x 90 as I can get.
Thanks!
Rob
And you reminded me of the Pinhole Designer software so I have got that again (see here for it: http://www.pinhole.cz/en/pinholedesigner/ )
And since I'm building this camera, I can decide my own film gate size. Which will be as close to 56 x 90 as I can get.
Thanks!
Rob