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Posted: Thu Aug 28, 2008 12:15 am
by mikio
Bill Poole wrote:younger folks can see distance (perhaps with correction) AND bring their focus in close enough to see the front sight or read a book or even closer, as we get older our ability to bring the focus in close degrades, our arms get too short, we need reading glasses to bring the focus in closer. I believe this is cuz the eye muscles get weaker as the lens gets stiffer.
the front sight is just a bit further away than a book so for about a year in your early 40's you can still read but can no longer shoot, then you can't shoot anymore.
Reading glasses are typically +1.00, +1.25, +1.75, +2.50 whatever works for the reader, but rarely can one find +0.50 reading glasses.
for shooting, at least for the first few years, that +0.50 seems to work, then maybe the +0.75 maybe more
in either case the positive diopter correction brings the relaxed-eye focus closer, so the sight or book is in focus with less muscle stress, and distance, (target) is a little blurry
The above is for someone with normal distance vision, or vision corrected with contact lenses to normal distance.
if one wears glasses, quite often there is a spherical correction, usually but not always a - number and an astigmatism correction.
one would have one's eye doctor determine the correct distance correction, then with a stick or something find a decent 20" correction.
for someone in his 40's with modest to no astigmatism and a little nearsightedness it will be about +0.50 different than the distance prescription, that is, about half a diopter LESS NEGATIVE, bringing the focus in closer
get a Knobloch or Olympic style shooting glass, wear it over your normal distance condition (nothing, contacts, street glasses) and put in the +0.50 or +0.75 lens, later your optomitrist should be able to cut a round lense to your prescription offset by what you need.
This is intended as a description of process, not a recommendation for a specific prescription.
bring a stick with a front sight on it you can hold out and focus on with the eye chart off in the distance when you goto your appointment. You may have to train your eye doctor. They tend to be kinda knowledgable, ocassonaly you find one that likes guns but doesn't know how to shoot, my eye doctor said "I'm a shooter too, here..." and handed me a bright yellow toy pistol... WITH NO FRONT SIGHT!!!!" she got some training.
Oh, the dual focus contacts are not usable for shooting.
Poole
thanks Bill i'll be taking this post to my doctor next week!!!
Posted: Sun Nov 02, 2008 12:06 am
by Rudolf the Red
I am a new NRA Pistol Coach in Northern California but too far north! I moved from Sacramento to Tehama County just south of Redding. Dang. I would love to help!
Posted: Sun Nov 02, 2008 1:50 am
by deadeyedick
Most optomoterists will sell you the uncut lenses in either 65mm. or 70mm. diameter, anywhere from $15 up...depending how profit concious the particular person is. You can then get them cut to fit your particular shooting glass frame. As you will only be using one eye, you could also go to a $2.00 shop and buy a pair of cheapo reading glasses that has the correct diopter lens for your eyes and distance, and for a couple of bucks you will still have a spare lens. They are usually in .5 diopter increments, but some places have them in .25 diopter as well. I have tried all methods, and the most succesful for me was to measure the distance from my front sight to my eye,...cut a piece of dowell that length, walk into a $2.00 shop and try lenses starting at 1.00 diopter upwards until the front sight was perfectly clear...then buy! simple,effective and LOW cost. Remember that optomoterists only have access to the same range of lenses, and this choice always proved clearer than when performed professionally [ not to mention cheaper ]....its definately not rocket science, and when you find a lens that provides a clear sight picture...Bingo !
Posted: Sun Nov 02, 2008 2:45 pm
by GaryN
You CANNOT just focus on the front sight.
As Warren mentioned in his article, and I verified with my eye doc by experimenting with different test lenses. I brought my AP into the office and we used a hallway in her office that let me stand 10m from the end. If you get a prescription perfectly for the front sight, you may not be able to see the target...not good. So you have to compromise the front sight prescription with being able to see the target. As it turned out, the offset that Warren recommended in his article was exactly the compromise my eye doc and I came up with in our testing.
Posted: Sun Nov 02, 2008 7:26 pm
by deadeyedick
GaryN...that statement is totally incorrect. Just to update you, you're NOT supposed to look at the target...you are supposed to look at the FRONT sight ONLY. Unless you wish to re-write pistol coaching and training manuasl, I would alter my perception of technique.....worse than that, less experienced shooters may think it to be true, and develop bad habits, hindering their development. Where in the world did you get the idea that looking at the target was acceptable. Its regarded by accredited coaches worldwide [ and I have been one of them ] as a fatal mistake in technique.
Posted: Sun Nov 02, 2008 8:00 pm
by higginsdj
I guess it depends on what Gary means by 'not able to see the target'. The basic premise is that the target should be out of focus but would a prescription that allows the eye to focus easier/better on the Front sight put the target so out of focus that it could not be discerned?
Posted: Sun Nov 02, 2008 8:15 pm
by deadeyedick
Hello David, ..if the correct lens is used to provide focus on the front sight, then it goes without saying that the eye will not be able to accomodate focus on the target as well, so the target will automatically take on an out of focus appearance. This state of de focus on the target at 10 metres will vary from one individual to another, with factors such as age, eye health and the particular strength of lens used by that person to achieve correct focus on the front sight. But never be led astray by being told that focus should be anywhere but on the front sight, or with pistols having a longer sight radius such as free pistols, maybe slightly rear of the front sight, which is a compromise to not allow the rear sight notch to blur too much.
sorry for the delay in response ...
Posted: Wed Jan 21, 2009 2:16 pm
by mikio
Rudolf the Red wrote:I am a new NRA Pistol Coach in Northern California but too far north! I moved from Sacramento to Tehama County just south of Redding. Dang. I would love to help!
thanks for the offer RTR, and apologies for the delay in response, i got lucky and found a coach, and a pistol a couple of weeks ago, from TT of all places!
i'm confused a bit ...
Posted: Wed Jan 21, 2009 4:35 pm
by Guest
deadeyedick wrote:...you are supposed to look at the FRONT sight ONLY.
if i ONLY look at the front sight, how do i line it up with the rear sight?
my coach says that my ONLY focus (attention) should be on the sights, and that the target should ALWAYS be out of focus, even in competition.
i was baffled to say the least, but then again what do i know, i'm new.
he proved his point by teaching me proper holding techniques first, then instructed me NEVER to shoot or dry fire on a live target, not until my arm was strong enough, but really what he was doing was nipping a bad habit before it became a habit, and that was to NEVER rely on a target.
also, he verbally discussed the three holding patterns of shooting, again which baffled me, but i knew understanding that would come in time.
jump a few months later, and sure enough that time came, we went to test out my new LP1C on a live target, which i didn't want to do at first because the target was distracting, as it should be, so he said focus on a sub 6 pattern and shoot, so i did, and wouldn't you know it ... success!!!
all my shots were TIGHT in a group, nowhere near the BE, but my coach didn't care, he says changing the ballistics of a shot is easy, what's not so easy is breaking bad habits, so maybe it's best everyone speak with an official ISSF coach before misinterpreting the basics, just my novice 2ยข.
if an occluder helps ...
Posted: Wed Jan 21, 2009 4:40 pm
by Guest
higginsdj wrote:I guess it depends on what Gary means by 'not able to see the target'. The basic premise is that the target should be out of focus but would a prescription that allows the eye to focus easier/better on the Front sight put the target so out of focus that it could not be discerned?
if an occluder helps, would Rx glasses still be necessary? i don't seem to have a problem focusing on my sights, nor keeping a tight group. any thoughts?
Posted: Wed Jan 21, 2009 5:44 pm
by Rover
RE: Shooting AP in your house.
As in the military, "Don't ask, don't tell."
No one will know or care about your perverted pastimes. Of course this advice precludes shooting a .45 through your walls.
Posted: Wed Jan 21, 2009 6:49 pm
by Spencer
deadeyedick wrote:...This state of de focus on the target at 10 metres will vary from one individual to another, with factors such as age, eye health and the particular strength of lens used by that person to achieve correct focus on the front sight...
Surely the out-of-focus of the target would be more a matter of the lighting levels (and the f-stop equivalent of the iris) - the optics laws remain the same irrespective of age, eye health, etc.
Many older shooters complain that when focussing on the front sight, they cannot see the target as clearly as they could when younger. They never could, but they were able to rapidly (and probably without knowing it) change focal length such that they thought they could focus at both distances.
Spencer
Posted: Tue Feb 03, 2009 3:29 pm
by somewhereinla
Sad to hear that the Prado monthly matches are no longer, it was a very friendly crowd, and I remember a few people drove from quite far away for the matches... Some of us have tried to figure out alternatives to Prado, but nothing never really happened. Without a club and a strong commitment it's really difficult, not to say that everybody lives all over the place which is always a problem in Los Angeles and the nearby counties...
As far as training, I train in my living room on 5m targets. It's a good and easy way to stay in shape. The only problem is that when I do a 10m match, the depth of field is different and get some getting used to...
Posted: Wed Feb 04, 2009 1:10 pm
by Steve Swartz
Maybe this is a repetition of what someone else already tried to say . . .
" . . . I train in my living room on 5m targets. It's a good and easy way to stay in shape. The only problem is that when I do a 10m match, the depth of field is different and get some getting used to . . . "
If you are properly focusing on the front sight (physically and mentally), how does the distance to the target come into play?
If the target was *on* your front sight, o.k., but the target should be in the background and out of focus at 5m anyhow?
Steve
Posted: Wed Feb 04, 2009 5:35 pm
by Spencer
Steve Swartz wrote:Maybe this is a repetition of what someone else already tried to say . . .
" . . . I train in my living room on 5m targets. It's a good and easy way to stay in shape. The only problem is that when I do a 10m match, the depth of field is different and get some getting used to . . . "
If you are properly focusing on the front sight (physically and mentally), how does the distance to the target come into play?
If the target was *on* your front sight, o.k., but the target should be in the background and out of focus at 5m anyhow?
Steve
If a shooter wants the same depth of field perception (5m/10m), a lower light level for 5m training would open the iris and give a reduced depth of field to give the effect.
My optics calculation skills are restricted to reading the rings on the camera lens - perhaps one of the experts could do the calculations and pass on the answer?
Spencer