Split image focusing question

Post by **18fps** » Mon Apr 07, 2003 5:59 am

Hello-
I have a Canon camera and I have adjusted the eyepiece per the instructions and feel confident that the diopter is focused accurately. However, when I focus the lens while looking OUTSIDE of the split image grid (prism?) and get the subject looking sharp, the split image will show that I am focused slightly to close. The more distant the subject the more pronounced the disparity is. If I then focus according to the split image area, the periphery will appear to go out of focus momentarily until my eye readjusts/compensates. I have shot a test but I won't have the film back for a few weeks and I want to keep shooting, preferably IN FOCUS. Has anyone experienced this?? Which is accurate? Thanks for any info you might have.

Jerseyfilm8 · Post by **Jerseyfilm8** » Mon Apr 07, 2003 6:36 am

I have found this to be a problem sometimes, I set the eyepice up in this way, put the camera on a tripod, and set it at 5ft on the focuss ring, draw a straight line on e white piece of paper with a black marker, and put this on a wall,(using tape or pin.) now set the tripod with camera exactly 5ft from this paper, make sure you measure from the focal plane mark on your camera, usually a circle with a line running through it, now with the camera at full telephoto, adjust the eyepiece, until your split image is correct.

Post by **18fps** » Tue Apr 08, 2003 5:13 am

Thanks Jerseyfilm. I tried your technique and it seemed to work- my eye AND the split image agree on what is in correct focus now. Thanks again.

Post by **Lucas Lightfeat** » Tue Apr 08, 2003 6:55 pm

If that worked, fine. But the best way to set the diopter (eyepiece) is to focus the split image on a line over 100 metres away at full zoom and infinity focus. Also, look away continually, or else your own eye will compensate and focus, whereas you want the diopter to do that work for best results.

This way, you "should" be able to easily and confidently focus right through.

Hope this is of some help,
Lucas

Post by **18fps** » Wed Apr 09, 2003 9:35 pm

Lucas- I went to try your technique but there was no discrepancy in focus since following the "measuring to film plane" method. The REAL problem is with the owner's manual. It suggests that you focus the grid itself. The problem with that is that the diopter adjustments can be very coarse while the split image grid stays sharp. This serves to get close, but no critical focus can be achieved. Of course, I really won't know for sure if any of my adjustments have worked until I get some film back, so maybe I'll be employing your method after all. Thanks for the info.