If you aren't confused by this discussion, you should be, so lets interrupt the thing for a few facts.
1. All my variable scopes are made by USO and all are first focal plane reticle design. All of those have the parallax adjustment in the objective housing and diopter adjustment in the eyepiece.
2. The diopter adjustment in the eyepiece will adjust to your eyesight to make the reticle appear clean and sharp.
3. The function of the parallax adjustment is in effect to focus the target and to assure the alignment of the target with the focal plane of the reticle for varying distances.
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> Parallax can be defined appropriately to riflescopes as: The
apparent movement of objects within the field of view in relation to the reticle.
This adjustment of the objective part of the optical system would ensure that the target can be brought in the exact focal plane of the reticle at any distance.<HR></BLOCKQUOTE>
Now as to the reticle:
First focal plane scope reticles grow in proportion to the magnification. This means that the reticle will subtend the same amount on the target regardless of power. A very useful feature on a ranging reticle scope.
Second focal plane reticles appear the same size regardless of power. They change the amount of subtension as the power is changed. This means that they often must be calibrated to subtend a certain amount at a specified power. Often 10x or some other value.
Like my old math teacher used to say, I can't help it, thats the way it is!
[ 11-23-2003: Message edited by: DMCI ]