I have a cobra bow sight that is driving me nuts. It seems to change the point of impact about 3" to the right @20 yds when the light is low. My sense is its an optical illusion caused by the additional light that comes through when there is significantly more light out. Is it me or the bow sight? I've contemplated purchasing a Spot Hog or other sight that contains a vertical wire. It seem that the additional light coming through the fibre optics would not change the point of impact if you were relying on the wire. Thanks in advance.

This is more than likely caused by insufficeint light through your peep sight in low light. How big is the hole in your peep and what kind of peep are you shooting.

yep, sounds like a lack of light through the peep, causing your non dominant eye to take over aiming. Of course, if you close your non dominant eye, through my theory out the window.

Actually, I have a bad habit of closing my other eye. Any other suggestions?

For one reason or another, your centering your pin or pin guard differently in your peep. Just always remind yourself to center your pin and guard in your peep the same way every time.

Varying degrees of light will diffract over a round peep. A Square one will throw it off in all 4 directions depending on light levels. A crosshair has been the answer for me. I don't cae about the crosshair and I wish the round didn't diffract as it's easer to line them up on my round pin gaurd for an extra aiming reference but these Nitehawk sites give 4 right angles and the central squared sight picture is free from diffraction in any lighting situation. It's the thrid from the right onthe top. Only pic I could find.

They come in varying sizes as well.

I broke down and spent the money on the spot hog. As long as I focus on the vertical wire, the problem is taken care of. Expensive fix but at least the arrow are hitting where they are aimed irrespective of amount of light. I'm using the same peep sight. I hope the sight is durable.