Bellows fabric

andrewch59
Posts: 69
Joined: 08 Sep 2013, 12:56

Re: Bellows fabric

Postby andrewch59 » 15 Nov 2017, 11:56

Ray, stand in a dark room, with window or door that receives light, point the rear of the lens toward the light coming through the window. Hold a piece of plain paper up to the front of the lens and when an image appears sharp on the paper, measure the distance between the paper and the waterhouse slot or iris (axis). Ensure that you have the focus on something outside in the distance(infinity)

andrewch59
Posts: 69
Joined: 08 Sep 2013, 12:56

Re: Bellows fabric

Postby andrewch59 » 15 Nov 2017, 12:04

I guess I should add that the aperture should be wide open, and you can turn the lens round the other way and recalculate to find the back focal length(which some would deem more important).
To find the F stop, measure the smallest aperture of the lens wide open, normally where the iris or waterhouse stop fitting is and divide by the focal length.

Ray Heath
Posts: 146
Joined: 15 Oct 2012, 13:21
Location: Lower Hunter Valley, NSW

Re: Bellows fabric

Postby Ray Heath » 15 Nov 2017, 14:59

Thanks Andrew, I actually knew all that but when you wrote calculate I thought maybe I'd missed something.

Why would back focal length be important?
Ray

Frank Meadow Sutcliffe's photographs are "a bridge that spans the widening gulf of time" (Michael Hiley 1979, 5).

andrewch59
Posts: 69
Joined: 08 Sep 2013, 12:56

Re: Bellows fabric

Postby andrewch59 » 15 Nov 2017, 18:02

I know some use it to calculate bellows factor, and realistically its the back end that determines the size of the image.

andrewch59
Posts: 69
Joined: 08 Sep 2013, 12:56

Re: Bellows fabric

Postby andrewch59 » 15 Nov 2017, 18:03

Ray, everyone puts their lenses on ebay these days.

Ray Heath
Posts: 146
Joined: 15 Oct 2012, 13:21
Location: Lower Hunter Valley, NSW

Re: Bellows fabric

Postby Ray Heath » 15 Nov 2017, 20:44

Thanks Andrew.
Ray

Frank Meadow Sutcliffe's photographs are "a bridge that spans the widening gulf of time" (Michael Hiley 1979, 5).


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