How do you know your RF is adjusted correctly?

T

Tom Diaz

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Is there a simple test you can do yourself? In other words, if you see a series of pictures that are just a little soft and suspect maybe your rangefinder is not adjusted quite right, is there a simple way to verify it all, or do you just have to send the camera and the lens in question to a technician and rely on that person?
 
A quick check is to put your camera on a tripod in front of a target (a book, a monitor) put the camera at 3 feet, or 1 meter (whatever your lens says) from the target, measure from the film plane. Focus and see if the lens marking lines up with your measurement. Do the same for infinity using the moon.

This is a simple check, it won't tell you if your lens is out of order or shifting focus. If the focus ring of your camera is not where it should be, the camera can pass this test and not focus right or can focus correctly with the rangefinder and still fail this test.
 
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I used this: http://focustestchart.com/focus21.pdf

I tried doing above but wasn't too sure about the accuracy of the focus markings on my fixed-lens Yashicas (the markings are few and far between and where do you set them -- in the centre of the text? How does that work at focus min/max then?). My Yashicas have little red marks on the top plate that indicate the film plane though which is useful.
 
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Hi Tom,
One option if you don't have a ground glass of the right size is to cut out a clear piece of plastic that fits on the film rails. Tape one side with scotch tape. Place the taped side against the film rail. Leave the back off, mount the camera on a tripod, and then use a loupe to compare the focus in the finder with what's on the 'ground glass'.
 
Lens at infinity, moon as target, as Ranchu says. For the near range I rely on actual photos of a test target at closest focus. I photograph a ruler end on, at a shallow angle. at full open aperture. Focus being off could be the R/F or it could be the particular lens.
 
Since the OP posted this thread in the Nikon forum, I assume the camera is a Nikon rangefinder. If so, the only adjustment is the infinity adjustment. If the focus patch is correctly aligned at infinity the camera should focus properly. If it doesn't, either there's a problem with the lens or with the register (distance between the mount and the film plane) of the camera.

WRT the register, there are shims in between the focus helicoid and the camera body that have to be of the correct thickness so the correct register is achieved. If the camera has been disassembled and then reassembled incorrectly at some point, the correct shims may not have been installed. If the camera is front focusing, the shims are too thick.
 
I will try the above tests as well; I dont know how specific they are to Nikon RF, or to RF focussing in general. The issue I have is my RD1s has correct horizontal alignment, but the vertical alignment is off just enough to create a little blur and second-guess my focussing. And I havent found enough consistently in-focus or OOF shots to blame either the RD1s or a lens, or both. Any suggestions?
 
With the Nikon, Canon, Leica, and most Rangefinders, you adjust the vertical alignment before setting the horizontal alignment. If the vertical alignment is off, it will affect focus throughout the range.

With the Nikon and my other RF's, I pick a spot (usually a tree top), at 500ft or so to adjust for infinity.
 
jonmanjiro said:
Since the OP posted this thread in the Nikon forum, I assume the camera is a Nikon rangefinder. If so, the only adjustment is the infinity adjustment. If the focus patch is correctly aligned at infinity the camera should focus properly. If it doesn't, either there's a problem with the lens or with the register (distance between the mount and the film plane) of the camera.

WRT the register, there are shims in between the focus helicoid and the camera body that have to be of the correct thickness so the correct register is achieved. If the camera has been disassembled and then reassembled incorrectly at some point, the correct shims may not have been installed. If the camera is front focusing, the shims are too thick.
Click to expand...

Right. The camera is a Nikon S. Thanks to everyone for the explanations.
 
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