In the OLC Gui mod, which this one is based on iirc, there used to be a scratch mark on the most inner scale around 14.5 degrees (AOB) to help with the lower power zoom correction. As the sine of 14.5 degrees is approximately 0.25, or equivalent to a fourth of whatever mark is above the 90 degree position on top. Don't know if H.sie ever considered implementing this, or even knew about this trick.
Anyway, if you need to get a range from a mast reading at low power zoom (1/4th of high power zoom) you simply drag the observed mastheight to the 14.5 degree mark (instead of above 90). Then you read the range oposing the known mastheight.
Going to get AOB from that is basically the same, except for a correction in the end.
So you still drag the middle wheel from the target's known mastheight to the target length.
In the high power zoom, the AOB would be across the observed target width (2 smallest scales). But that is too small in the low power zoom view. The false AOB is probably somewhere at the bottom. So you need to perform a x4 correction on the wheel, by dragging the middle wheel from 14.5 degree over to 90. THEN you locate the observed width from the low power view on the middle wheel, and read the AOB across it.
As you don't seem to have that scratch mark at 14.5, you can also use the angle between the 10 and 40 marks, and between 50 and 200 (or whatever pair is a x4) on the outer mastheight/length scale for reference. This should have the same effect of doing x4 multiplications.
Unless the target is so close that it is larger than the periscope view, I see no reason to ever do a low power zoom measurement.
|