At what range(s)(yrds) does a TA 31 become clear??

I look at it inside my house and things are a bit blurry, I attribute this to to close a range. However, I looked at one (TA31) at a gunshow prior to my purchase and it seemed like CRYSTAL clear optics. But I don't know what range I was looking at and it was the first time ever looking thru an ACOG.

It's not a problem and it could just be me, but it just seems like the optics are not as sharp as I was expecting or remembering for my $800. But then again, I could be at the wrong range.

I am nearsighted and don't usually wear glasses (I do when I shoot) but at close range, like in the house 10-15 yrds, the ACOG is MUCH clearer without my glasses.