Harry (Florida) , Jul 15, 2007; 01:16 p.m.
Here are a couple of images depicting the rangefinder focus accuracy of a recent
M8 body using two late 50mm lenses known to provide accurate focus on a variety
of M film bodies. The lenses are a 2.8 Elmar and a 1.4 Aspheric, both used wide
open. The target is a yardstick placed at an angle to the camera and focus was
on the 18" mark at about 1 meter distance, using a tripod and 1.25x magnifier.
I made the test because my images seemed to be sharpest a bit behind the actual
focus point at most distances.
My interpretation of the resulting images is that at 1 meter distance, the (or
rather, this) M8 focuses about 2" behind the rangefinder-indicated point of focus.
As a side note, it would appear that the depth of field of the Elmar wide open
is close to equal behind and in front of the focus plane whereas with the Asph
wide open the depth of field is mostly behind the focus plane.
I wonder if other users have similar test images to contribute? If you use
mainly wide angle lenses and small apertures you might not notice this effect.
Ellis Vener 
, Jul 15, 2007; 01:32 p.m.
unless they are testing on the exact same body as you are testing on other people's tests are meaningless. You should see about getting your camera's rangefinder recalibrated if you think it is off.
Harry (Florida) , Jul 15, 2007; 01:36 p.m.
Other tests would be meaningful in that they would show if few, some, many, most, or all M8's have the same problem.
dominic peticca , Jul 15, 2007; 01:51 p.m.
I always thought, as a general rule, that depth of field was roughly 1/3rd in front of, and 2/3rd's behind the plane of focus?
"My interpretation of the resulting images is that at 1 meter distance, the (or rather, this) M8 focuses about 2" behind the rangefinder-indicated point of focus."
This sounds like a problem. Hope you get that rangefinder adjusted!
Harry (Florida) , Jul 15, 2007; 01:55 p.m.
I know it is a problem and will return the camera. The point was to find out how common a problem it is.
Ronald Moravec , Jul 15, 2007; 02:15 p.m.
There have been many posts so it must be another bug to be sorted out.
I could take a wild guess the engineers forgot the the target point of focus on a film camera is somewhere between the rails and pressure plate because film is not held flat.
If they use the same RF calibration with a sensor which is dead flat, they need not compensate.
That and/or they compensate for field curvature of the lenses.
I will leave this to Leica as only they know what is going wrong.
Nobody complains about infinity focus.
Harry (Florida) , Jul 15, 2007; 03:03 p.m.
How would anybody know if the infinity focus is correct?
Harry (Florida) , Jul 15, 2007; 03:09 p.m.
My other image disappeared so here it is again, the result with the 50mm 1.4 Aspheric.
Tony Cobitz , Jul 15, 2007; 03:10 p.m.
Infinity adjustment is both crucial, and fairly easy to accomplish on the M8. Here's a thread which includes photos on how to adjust:
(link)
One final note, though. I strongly recommend that you choose a far away point of reference in order to adjust most accurately. In other words, use a star at night, rather than something which is (for example) 100 ft. away, as it will calibrate more accurately.
Regards,
Tony C.
Harry (Florida) , Jul 15, 2007; 03:51 p.m.
Hi Tony -
As I understand it, the "infinity adjustment" above has to do with setting a lens to the infinity mark and then adjusting the cam for coincidence in the finder of the two images seen of a target at/near infinity.
But my concern is the correct focus of the image presented at the film plane or sensor surface in the case of the M8 which of course is not affected by that adjustment. You can turn all the cams all you want and it has no effect on the actual image recorded.
