Poor eyesight is a big problem for shooters, particularly for rifle shooters who peer through scopes. Wearers of bifocals or trifocals especially know the challenge of coming up easily and quickly into their scopes to target an animal that might be visible for only brief moments.

Jay Eller, 67, knows the problem firsthand. Like a lot of hunters and competitive shooters who are getting older, his eyesight has changed over the years.

Result: When he shouldered a rifle, he often had to move his head up or down, or closer to the scope, or farther from it, to get his eyes seeing through the correct part of his eyeglasses as he attempted to look through the scope and keep both the crosshairs and target in focus.

The challenge grew more acute about six years ago when he started to shoot rifles competitively.

"I figured there had to be an answer,'' said Eller, a former Twin Cities resident who now lives in Wisconsin.

Consulting an expert in the eyeglass lens business, Eller came up with a product he calls ScopeAid, which he markets through his company, Clemit (www.clemit.com).

A spokesperson for the company contacted me earlier this fall to inquire whether I would like to test a ScopeAid. They asked the right person: I wear blended trifocals, and have long suffered from the same scope-adjustment problems that plagued Eller.

I began by sending my eyeglass prescription to Clemit via e-mail. I also measured my preference for "eye relief,'' or the distance that I'm comfortable keeping my eye from my scope (about 3 inches in my case).

A few days later, a small package arrived with my ScopeAid. (ScopeAids come in clear, amber, yellow, "flame,'' and "mirage'' tints for use in different conditions at varying times of the day. I tried a clear lens.)

"We don't match your prescription exactly,'' Eller said. "Instead we make a complementary prescription specifically for individual shooters. Another person, for example, with different eyesight wouldn't see through your ScopeAid with the same clarity you do.''

All of this sounded too good to be true. Since the day I started wearing glasses at about age 45, l've been on uncertain footing every time I look through a scope.

Critical to the process, I've found, is that my glasses are pushed up all the way onto the bridge of my nose. Otherwise it seems I look through the scope with the portion of my glasses that is intended to help me with up-close vision, such as working at a computer.

Mounting the ScopeAid was easy; I just pushed its rubber casing around the rear of my scope. Then I went to the gun range.

Two results: I was able to come up into the scope quickly and see my target clearly, and was able also to readily see the windage markers on my scope's crosshairs.

Upshot: It worked for me.

In the time since, I've probably put 50 rounds through my .270 using the ScopeAid. But I haven't pulled the trigger yet with a deer in the crosshairs.

With luck that will happen this weekend in Wisconsin.

Note: Prices of ScopeAids range from $129 to $169. Nonprescription ScopeAids can also be ordered in various tints to enhance low-light conditions.