Why does sighting thru aperture rear and red dot remove starburst?

[Tallbald]

An odd question perhaps, but I've found that if I look through my MBUS flip-up rear aperture on my AR pistol, into and through my co-witnessed red dot, the projected red dot becomes more concentric and lacks the starburst "rays" of the dot viewed without the aperture rear up. Flip down the MBUS rear aperture and the dot I see again has rays that make a fine aiming point more difficult. I'm 60 and don't regularly wear glasses 24/7. But I do need them for reading.
Am I seeing something different from everyone else?
Thanks. Don

 

[Scooter22]

Looking through a aperture site causes your eye to focus sharper.

 

[Tallbald]

Oh. That's pretty cut and dried. Thanks. Don.

 

[wally]

Looking through a aperture site causes your eye to focus sharper.

Yup, and its exactly why many 2700 bullseye shooters where optics and red dots aren't allowed use those weird looking eye occluding "pinhole" contraptions.
There is no free lunch, as while the image will sharper and have more "depth of field" it'll also be dimmer and have less resolution (which can still be significantly better than old out of focus eyeballs) Since these matches are generally held is very good lighting conditions the dimmer image is a welcome trade-off.

I suspect the "more concentric" part of it is because the BUIS forces a more centered eye position in order to see the dot.

 

[Walkalong]

I have found my 1X reading glasses fixes "bleedout" of the dot from astigmatism. It can't fix cheap dots.

 

[berettaprofessor]

Yep, mostly astigmatism. I discovered in middle school as my vision deteriorated that if I closed my fist to leave only a small pinhole to peer through, I could see distant objects again. It ain't the nearsightedness, it's the astigmatism.

 

[roval]

it corrercts for errors of refraction. it acts as a pinhole only allowing the light that goes through the center of your cornea and blocking the others that normally should be refracted to the same spot that in a person with EOR would be focused elsewhere

 

[kidneyboy]

Yup, and its exactly why many 2700 bullseye shooters where optics and red dots aren't allowed use those weird looking eye occluding "pinhole" contraptions.
.

Where does this 'optics and red dot not allowed' happen?
Based on my limited experience shooting bullseye if optics and red dots weren't allowed there wouldn't be to many participants.

 

[kidneyboy]

On topic - I had some trouble with red dots till I got a new prescription for my glasses. The astigmatism went away. I use red dots for bullseye shooting and have found that using the lowest brightness setting that works for conditions helps with sharpness of the dot. YMMV

 

[Tallbald]

Hmm. Learning lot and I thank all. Would this clarify the image I see with a regular scope having cross hairs? Can't get to the range to try it yet. I also believe I'll "look into" (grin) a pair of large lens 1x reading glasses to try. All I have now are 1.5X. Don

 

[roval]

a scope should have diopter settings to make your crosshairs look sharp . just look against a blank background such as a whitewall and adjust the diopter setting.