07-15-2013, 03:00 PM
Rambozo Wrote:LR,
I always adjust parallax by wiggling my head around behind the scope before shooting. I've been in the habit of setting it and forgetting it though. That is, unless I changing range.
Yesterday though, out of curiosity, I decided to do the jiggle test after powering the scope down. I noticed the parallax, and I noticed a relatively greater error across a greater portion of my target (smaller magnification, smaller target). When zoomed in at 32x the error seemed much finer relative to the target size. After adjusting parallax out at the greater magnification, it appears as if I have to adjust it again after moving to the lower magnification.
It's almost as if the error is behaving as if it's second focal plane, and that it isn't simply a one setting fits all across the magnification range. Well, that's all based on my observation from yesterday alone. Perhaps it's a peculiarity of the less than stellar optic I was using? It was an old Tasco, I think.
RB:
Yes, the jiggling of the head behind the optic is a test to see if you have a parallax problem. I didn't mention it because most of my shooting with an optic is from a sling or a front rest using a toe bag to fine tune sight picture. With either of these positions, the head jiggle test doesn't work well so I maintain the best hold possible and adjust the focus to get a clear sight picture. I always give the head moving test a try but it works much better when you can rest the rifle completely without touching it.
I don't have an answer for your situation because it is the opposite of what should and normally does happen.
About the only things I can imagine are the ocular lens adjustment is not right or maybe those older TASCOs aren't of the highest quality.
The bottom line is that you knowing it is a peculiarity of your optic is good enough.
LR1955