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Defraction, lenses and irises
Posted: Sat Nov 16, 2024 9:16 am
by Bret P
Hi all,
Another question, about the basics.
My sight picture has changed and back to sub six, literally a thin space just below the black. However while focusing on my foresight, when it is near the target I do get alot of defraction, the foresight looks curved/concave as opposed to perfectly flat when dry firing to a white wall.
While the sight picture is correct, I think it is very fuzzy, grey and also bent out of shape.
Interesting when I turn off the target lights and the sight picture is dark, I've shot my PB at 540, with one card having 6 x 10's, nice tight grouping. With full lights on, more like I've used an elephant gun.
I've booked in to see Gary in Newbury (for UK specific info), apparently he is very good and maybe some of this will be sorted out with lenses? 0.5 most likely on my distance prescription etc. But concerned about if I'm missing something more basic? If I hold lower then, yes sight picture is clearer as less defraction, but then becomes a more random aim.
Also, what would an iris do, or is this a waste of money? Some use them, many don't.
Would like to hear your thoughts.
Regards
Bret
Re: Defraction, lenses and irises
Posted: Sat Nov 16, 2024 10:07 am
by Gwhite
Everyone's eyes are different. Also, your eyes this year aren't going to be what they were a few years ago.
A thin line of white is hardly "sub-six", and may be part of your problem. Check out:
viewtopic.php?p=335266#p335266
I'm not an ophthalmologist but I've been tinkering with my shooting glasses for decades. Definitely talk to your local expert, but depending on your vintage, you may be seeing the effects of cataracts. I'm 72, and have the beginnings of a cataract in my aiming eye, but I don't recall seeing what you describe, but I shoot a true sub-six, well away from the black.
Re: Defraction, lenses and irises
Posted: Sat Nov 16, 2024 10:37 am
by thirdwheel
This is a classic example of what I explain when I'm coaching, the reason you are getting a fuzzy front sight when you aim under the black and the target light is on is because your eyes are getting drawn to the target, and you are not then focusing on the front sight. Turning the light off stops that "draw" so much. You will also find the black gets smaller when the lights are on as the "white" floods the optic nerve making inroads on the black area, this is why you need to adjust your sights in different light conditions. The extreme at one time in the UK were the "Welsh" electronic targets they were so bright they burnt an imaged into your retina. Don't try and "lollypop" the black on top of the front sight leaving a little white gap. Do as Gwhite suggests and go much lower and believe in your aim area hold zone - it works it really does but most books lead you into doing what you are doing. If you come up close under the black you are going to get drawn into considering that black blob over your sights just at the point when it will do the most damage, this will hold you back so much so take the advice and go for area aim. Best thing to do is not to shoot at a target for a month but instead shoot at a blank target, perfecting your aim, release and follow through, with a shooing lens the card area will be so fuzzy you will not end up using the holes to help you aim. I'm not going to comment on the amount of add needed for your shooting lens as everyone is different but make sure there is a lot of light in the room at the opticians when you go for that lens.
Re: Defraction, lenses and irises
Posted: Sat Nov 16, 2024 2:45 pm
by Bret P
Thank you both,
Thirdwheel, yeap this is exactly what's occurring. Will test going lower but then I think my shots will be more random. Will see how it goes.
Just done 2 weeks of blank wall firing and my aiming does appear to have gotten better, especially in the dark lol.
I was at the Welsh championships a few weeks ago, yeap very bright and shooted the worse I'd done for a while. Had a play with centre hold and doing other stuff but now calmed down. I did the lollipop hold so I know what I'm aiming at, but I assume the price is alot of defraction. I'll do what you say and go lower and realign sights and then back to blank wall firing, trigger action and follow through.
Thank you
Take care
Bret
Re: Defraction, lenses and irises
Posted: Sat Nov 16, 2024 5:41 pm
by thirdwheel
Classic - don't do something new at a comp stick with what you have built up with your shot process in training. Work at the low area hold and making your stance produce a Natural point of aim - move about until it is the best you can do, you will slowly "get it" and don't ever look at the black fuzzy blob and don't worry about movement just sight alignment. Ingrain your shot process and stick to it and let that take control. Just aim, aim, aim squeeze, squeeze, pop, aim, aim, aim. As you train more your hold will become calmer and slower, don't curl fingers or use the thumb. And also do a month of live fire at blank cards - this different to dry fire as other stuff is going on - recoil, tension, noise, blah, blah. Oh and don't close up the rear sight too much keep it wide at the moment for all sorts of reasons.
Re: Defraction, lenses and irises
Posted: Sat Nov 16, 2024 8:07 pm
by Bardolph
Hey Bret,
I was also at Wales and had similar struggles on the megalink targets. My spread was a lot wider and it was hard to hit the middle. Talking with my sport optician now. Another shooter showed me some of the lens filters they had, yellow, magenta and others - did not get to test properly but I’m looking for a place to try (before another big event).
I have a lens from a sport optician with a shallow depth of field that focuses on the front sight without my eye doing any work - they make a great difference in general and you can get clip-on filters for different environments
Re: Defraction, lenses and irises
Posted: Sun Nov 17, 2024 5:33 am
by thirdwheel
For brightness use a Grey filter all of the others are used to make the "white" and the black contrast better and normally used outdoors in daylight, everyone sees differently, but those megalink targets use LED's to light them up so will be at a frequency of about 6000K which is the frequency of daylight. Unless you can borrow some to try on them it is going to be an expensive experiment but I do know people use grey filters when using them. You can get different densities of grey too so it is opening up a whole new can of worms going down the filter route.
Re: Defraction, lenses and irises
Posted: Sun Nov 17, 2024 8:49 am
by Gwhite
I use a mild grey "neutral density" filter when shooting on overly bright electronic targets. I also use an iris, which can be used to cut down the light a bit as well. I have no idea what density the filter is, but it's the lowest one I got for shooting outdoors.
They make variable density filters for photography work, but I've never seen them for shooting glasses. I suspect they are rotating polarized filters.
Re: Defraction, lenses and irises
Posted: Mon Nov 18, 2024 4:17 am
by Bret P
Thank you for everyone's advice.
Will be interesting to see if I need lenses and if it makes a difference.
I thought coloured lenses weren't allowed under ISSF rules? But currently only shooting 10 meter indoor pistol, unless rapid fire event gets changed to an airpistol event (unlikely) lol.
Blank target training and sight alignment and trigger training now.
Next comp will probably be the Scottish Championships or in Holland but need to shoot above 540 really.
Take care all
Best
Bret