Rangefinder patch askew

[Ariston]

What causes the image in a rangefinder patch to be crooked? When I look through my view finder at a vertical line, the line in the patch is slightly askew...

 

[Dan Daniel]

Mirror is tilted, backwards or forwards, from a true optical path. Or the whole assembly is not aligned with the main viewfinder window.

Actual camera model is helpful. Many different designs of rangefinders, especially when you get to medium format cameras.

 

[Ariston]

Mirror is tilted, backwards or forwards, from a true optical path. Or the whole assembly is not aligned with the main viewfinder window.

Actual camera model is helpful. Many different designs of rangefinders, especially when you get to medium format cameras.

Thanks, Dan. It is actually doing it on a Mamiya 6 Type K and a GW690. Both function fine as long as I line up at the center of the patch, but I was just wondering what causes it since it is present in two of my cameras.

 

[Dan Daniel]

For the Kodak Medalist, the rangefinder imagce is formed by two different prism systems. When you have one half of the image not in vertical alignent with the other half, you need to tilt the prims forward or backward to change the orientation of one image. If the whole system is off in comparison to the viewfinder image, you rotate the main imaging prism of the rangefinder.

If I am having the same optical issue on two different cameras, I start wondering if maybe it is an operator issue, not a camera issue? Sometimes rangefinder patches need to be vieiwed from one angle for proper imaging and if ou go off angle a bit things get sort of goofy. Maybe try moving your eye location in reference to the viewfinder and see if this changes anything? Or rotate the camera slightly? I have a mild astagmitism and can get funny effects as I rotate because the correction of the eyeglass lens is rotating slightly. And oftnetimes the viewing distances and such of the viewfidner and rangefinder image are slightly off so a variation like an eyeglass barrel rotation can affect each system differently and make a minor optical design flaw stand out? Just an idea.

 

[Ariston]

Thanks - I will try varying how I hold the camera. I don't have the issue on my 35mm, crown graphic, or standalone rangefinders. Maybe it's just how I hold the larger medium format cameras...

 

[Ces1um]

Thanks - I will try varying how I hold the camera. I don't have the issue on my 35mm, crown graphic, or standalone rangefinders. Maybe it's just how I hold the larger medium format cameras...

I had brought a camera in for repair twice before the clerk noticed I was lining things up wrong with my eye.