| Author | Message | ||
     Jim Brokaw Rating: N/A |
Hmmm - you posted twice... I'll only answer one. Generally you are OK if you set the focus correctly for infinity, comparing the focus with the lens set at infinity (or turned against the stop) and a ground glass (or you can use an old SLR focusing screen) at the film plane compared with the rangefinder alignment split image. You need to be sure the focusing screen or ground glass is sitting on the film rails, some cameras use a double set of rails to create a 'channel' for the film to run in, and if you bridge the higher set of rails you'll set your focus off. Note too that the focus distance scale on the lens is not necessarily correct either. The correct sequence to do this is 1) set the infinity focus of the lens looking at something far distant imaged on the ground glass (use a magnifier) 2) set the lens to the correct infinity stop - sometimes you need to loosen screws and turn the focusing ring *without* moving the optics until the focus ring bumps against the infinity stop; occasionally this will result in the scale markings not lining precisely up with the index 3) set the rangefinder split image in alignment (generally you set the vertical alignment first, then the horizontal alignment as setting one may throw the other off). Then check everything again and button it all up. You can also use an 'auto-collimator' to set the infinity at the film plane using a line scribed on a plate of glass and a light shining through from the back... I think there is a web page showing how this can be done using an SLR with a telephoto lens as the viewing device instead of a dedicated auto-collimator. I've done it both ways and if your're careful they yield equal results. |