Help me determine if my scope's behavior is normal

[Corn-Picker]

I have a Bushnell Elite 6500 2.5-16x that was a demo unit. I'm trying to determine if the behavior it exhibits is normal for a rifle scope. I'm a little ignorant of what to expect with such a scope, so I thought I'd ask the experts here for some help.

The scope does not have an adjustable objective, the parallax is handled by the side focus. Here is what I've noticed using the scope:

1. At max magnification (16x), the scope will not focus a 100 yard target or anything closer. It seems that ~150 yards is the minimum distance that's focused at 16x.

2. At max magnification, the parallax seems to be at about 80 yards (tough to tell exactly because it's a blurry image) when the parallax adjustment is set to max (infinity). Stated another way, the reticle never appears in the same plane as the 100-300 yard targets at high magnifications, there's no crossover point. The reticle plane will crossover with the target plane at lower magnifications (e.g. I can eliminate parallax at 100-300 yards at 10x zoom). This brings me to my next point.

3. The parallax error changes as magnification changes. This may be an immutable law of optics, I'm not sure.

4. I'm wondering if these problems could be due to the extremely high "erector ratio" of the scope, the ratio of the max power to the lowest power? None of my other scopes seem to have these issues, but they have a lot lower erector ratio.

 

[243winxb]

Has the eye piece been adiusted by following the instructions? http://bushnell.com/global/customer-service/product-manuals

 

[Walkalong]

At max magnification, the parallax seems to be at about 80 yards

I don't understand this.

I can eliminate parallax

Explain how you are doing this.

Has the eye piece been adiusted by following the instructions?

Because it is the first step.

 

[entropy]

3. The parallax error changes as magnification changes. This may be an immutable law of optics, I'm not sure.


No, you are using the parallax adjustment as a focus, which it is not. The focus is the ring at the back of the eyepiece.

 

[243winxb]

Set the side focus (parallax) to 100 yards while looking at a 100 yard target. Adjust the eye piece as clear as possible. 20/20 vision is needed, so wear corrective glasses, if you must. Now adjust the side focus to get the clearest view. When you shoot at 300, adjust the side focus to 300 yards and fine tune as before. If this doesnt work, contact Bushnell. Should work like your other scopes, even if the parallax is on the front lens? I dont have side focus, so could be wrong?

Bushnell- Please note the distance markings on the dial are intended as reference points only. Exact side focus adjustments may be
needed after making adjustments to the eyepiece in order to achieve a high resolution, parallax free image.

 

[entropy]

243winxb is right about setting it at 100 yards. Then set the rear focus at 100 yards.You then only need to adjust parallax by setting the side focus at the yardage you are shooting at. You should never readjust the rear focus ring after that, unless you are another shooter. Then the rear focus needs to be readjusted for each shooter.

 

[Corn-Picker]

I think the rear focus ring may have been the issue. I checked out some trees in the backyard today, and I could get a 100 yard target in focus at max magnification by adjusting the quick focus eyepiece. I never even thought of this because the Bushnell literature suggests you adjust the rear focus ring by looking at a clear blue sky until the reticle is in focus (which I did). Everything I've read online and in Bushnell literature suggested that the rear ring should only focus the reticle and nothing else, so I never touched it after I adjusted it.

The point of zero parallax still changes if I adjust the power. For instance, let's assume I have the side focus adjusted for zero parallax at fifty yards at maximum magnification. Now, if I do not touch the side focus, and decrease the power from 16x to 10x, the target is no longer parallax free at fifty yards, it seems like the point of zero parallax has moved out to about a hundred yards. That's what I was thinking may be an "immutable law of optics" as I mentioned in Point 3 of my original post.

Thanks again for the help, now I know that the rear focus ring is for more than the reticle...

 

[243winxb]

When i said

Adjust the eye piece as clear as possible.

The cross hairs (reticle) should become sharp, not fuzzy looking. Some cross hairs will get thicker as you increase scope power. Overall, when the parallax is set correctly, moving you head around should not make the cross hairs move.

 

[Walkalong]

Which is why I asked how you are checking parallax.

 

[Corn-Picker]

Which is why I asked how you are checking parallax.

I put the rifle in a rest, look through the scope, and move my head around without touching the rifle. When I can't perceive the reticle moving relative to my target I consider it to be parallax free.

 

[Walkalong]

I only asked because some folks ask scope questions, but are doing that part wrong. Thanks.

 

[Berg]

Yeah I'm confused by the people saying he should use the eye piece to get the target in focus. Every manual I've read says to do what the OP described and use it to focus the reticle only (while looking at the sky or other blank back ground).

 

[Corn-Picker]

Yeah I'm confused by the people saying he should use the eye piece to get the target in focus. Every manual I've read says to do what the OP described and use it to focus the reticle only (while looking at the sky or other blank back ground).

That is indeed what the manuals say, but I'm going to stick with the new method since that one allowed me to get parallax free and in-focus images at max magnification The reticle is still sharp, but honestly the reticle looks OK over a wide range of rear ring focus settings. I have better than 20/20 vision so that shouldn't play a part.

Following 243winxb's advice, the plane of the focus now seems to move in sync with the point of zero parallax, which is how it should work in an optimal world. Before, when the rear eyepiece was maladjusted, it was impossible to obtain a parallax free image (or a focused image) at 100 yards at max magnification. The parallax setting ran out of adjustment before the reticle plane would crossover with the target plane.

 

[Haxby]

Corn-Picker,
I've seen the same thing on a couple scopes fairly recently. I'm convinced there's something different about the new fast-focus eyepieces.