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Exploding groupings
Posted: Wed Aug 20, 2008 9:37 pm
by Nick_Burman
Hi all, I would like to know if using an aperture larger than one's usual value has an adverse effect on one's groupings? I use a 3.8, I'm very confortable with it, but everytime I put anything larger (as an experiment, just to see) my groupings seem to collapse... I'm asking because I've decided to give triangular apertures another try (b****y asthigmatism! - and I DO wear corrective lenses!!!) and I'm using a 3.8 triangular aperture. My groupings have moved more towards the centre of the bull and I'm hitting more 10s per grouping but the groupings themselves seem to have opened up - I guess I need tighter apertures, 3.7 or 3.6. Comments?
Cheers NB
Posted: Thu Aug 21, 2008 5:33 am
by Rutty
Nick,
You don't say what type of foresight element you are using, plastic, metal, variable etc... If you have not tried a different type it may be worthwhile doing so. I have heard all the arguments in favour of triangular apertures and their advantages if you are astigmatic, but I remain to be convinced. It is still possible to experience distortion of any symmetrical shape although the triangular pattern may reduce it.
FWIW, after years of using a variable foresight I went back to perspex for some time, but have now moved on to Centra High End glass elements that I find make a significant difference to my sight picture.
Rutty
Posted: Thu Aug 21, 2008 6:36 am
by peepsight
Nick
I tried triangular AHG elements for a while and noticed that my groups tightened up. What i did notice was, if you are using for example a 3.8 circular element, come down one or two sizes for the triangular elements.
3.7 or 3.6
AHG told me that the theory behind triangular elements was any astigmatism you have will not bend a straight line as found on the 3 sided triangle, but a round element can go oval or distort. This is a general explanation and each shooter may experience different optical problems.
Get your optomotrist to check your eyes and wear correction lenses for shooting.
Posted: Thu Aug 21, 2008 11:42 am
by Nick_Burman
Thanks guys for the help. I've just paid a visit to the optometrist and although he didn't quite catch the situation (shooting-savvy optometrists are a rare breed here...), he gave the same explanation as Anschütz gave to peepsight - people with astigmatism have some difficulties perceiving circles, so he suggested using triangular apertures.
What I want to know is if it is normal to see one's groupings open up if one uses an insert which is larger than one's usual size, regardless of type or shape. I've been using standard clear plastic apertures for the past 6 monsths or so.
Cheers NB