Flexmoney Posted October 1, 2002 Share Posted October 1, 2002 We had a stage at THE Ohio match with some long shots thru a mid-height port. You had to have a good squat to see throught the port (some went to a knee?). On the walk-thru, I noticed that the targets didn't "look normal". I am thinking the shooting position put the shooters head at a different angle than normal...this also would cause the shooter to look through the tops part of his/her glasses. I kow that one real good shooter had his hit impact low on the target. I wonder if there is a conncetion? Link to comment Share on other sites More sharing options...
shred Posted October 1, 2002 Share Posted October 1, 2002 I've noticed that some shooting glasses seem to change point-of-impact based on where you are looking through them. It could be an optical effect or it could be all in the brain. Link to comment Share on other sites More sharing options...
vluc Posted October 1, 2002 Share Posted October 1, 2002 aah...there was a previous post here, flex...matt trout asking about it...can't remember where it is...dealt with parallax and glasses...use your magic to find it! Link to comment Share on other sites More sharing options...
3quartertime Posted October 1, 2002 Share Posted October 1, 2002 I think I remember a post also that dealt with this. It was one of the ones TravisT deleted the answer to. Bummer!!! Link to comment Share on other sites More sharing options...
Alan550 Posted October 6, 2002 Share Posted October 6, 2002 There is parallax, or "image displacement" as we call it in the industry, once you're looking through anyplace except the "optical center" (OC) of the lens on Rx glasses. The stronger the Rx, the worse the displacement. I'm an Optician who specializes ( after a fashion) in shooting glasses, mainly for friends, and I have them bring the gun in question to the office. I mark the sighting point they're using on the lens and put the OC at that spot. The lenses aren't worth much for just "walking around in" if the Rx is high, but scores always improve. Made a pair recently with an intermediate focal length lens in the sighting eye and a distance Rx in the weak eye for defensive-type shooting. That way, with both eyes open, he could switch his focus between target & sights comfortably and see each clearly, as the brain shuts out the "fuzzy" eye. In lighter Rxs, there's not much problem, but the stronger the lens and the further you're shooting, the worse it gets.....as much as 8" at 50 yds. Alan Link to comment Share on other sites More sharing options...
InTheBlack Posted October 24, 2002 Share Posted October 24, 2002 I have to wear contacts when shooting the AR. Looking out the top, nasal corner of my glasses causes parallax that shifts the groups to 11 o-clock by about 6" at 100 yards. If you hold your glasses far enough away to be able to see over the top, and pass a pencil in front, you can see it "split" into two halves as it moves from the optical center to the edges. Excellent to have an optical guru on the list. I just got the postcard saying I'm due for my biannual eye exam and my glasses are getting scratched up. How do I explain to my eye doctor about what I want in the way of moving the optical center? When does the strength of the Rx start to mess up the walking around aspect? I'm nearsighted on the order of -2.00 left,-2.25 right Link to comment Share on other sites More sharing options...
Alan550 Posted October 25, 2002 Share Posted October 25, 2002 InTheBlack, Your Rx is right in the range of the problem I mentioned. Insofar as dealing with the Doctor, explain what you want along the line of where you want to look through the lens and the distance at which you need the clearest focus. These 2 things have to work together in concert with each other to minimize the parallax difficulty. Also, age is a factor in this as well. Until you start having near-point accomodation problems (having to hold things at arms-length to read) usually in the early 40s, you may not have problems with the power difference in an Rx of your level. You might try contacts for the handgun as well, along with a good pair of shooters, i.e. Oakley or some such. Otherwise, moving the OC into your line of sight will be the most important part of fabricating your new Rx for shooting, moreso than the power change. Hope this helps. Alan~^~ Link to comment Share on other sites More sharing options...
InTheBlack Posted October 25, 2002 Share Posted October 25, 2002 Yup, I have the near-point accomodation problem. We'll see if I'm ready for bifocals this year. Glasses are too powerful for reading but without them it gets to be a strain. I set my browser to display Ariel or Monaco 16 point type and when my eyes aren't tired I can read that at arms length on the laptop. I also have convergence problems, and I have less strain with glasses than with contacts. So I prefer the glasses for IDPA. I close the weak side eye to aim anyway since I see two images otherwise. Any exercises for convergence? There's some kind of beads on string, held from you nose thing??? Link to comment Share on other sites More sharing options...
Ron Ankeny Posted October 25, 2002 Share Posted October 25, 2002 I am in my mid-forties, have prisms in my glasses to correct for double vision, am near sighted to the tune of 20/300, presbyopia (spelling?) is kicking my ass, and my new Varilux glasses are going to set me back $500.00. Last summer I swore my vision was holding me back so I went to an optical sight. I then took a class from Ron Avery and he told me that Master Class is attainable with aging vision by simply using a softer sight focus. He more or less told me to stop blaming my poor vision for my lack of performance. For what it is worth he is right. We need to see what we need to see to make the shot, and at IPSC ranges that's a whole lot less than many people think. My scores have gone up even with my vision in decline. I think vision is much more important in the precision shooting sports than it is in the practical shooting arena. Sure, good vision is a fantastic assest, but I think you would be real suprised just how well a person can shoot (in this game) without the eyes of an eagle. Link to comment Share on other sites More sharing options...
Flexmoney Posted October 25, 2002 Author Share Posted October 25, 2002 When I originally started this thread, it's wasn't really a eye-sight (or lack there off ) thread. My eyes are still 20/20 (or close to). My concern was with the looking thru a different part of the shooting glasses (non-scrips, in my case), and with a different head/body position. Ron, you make a good point about the softer sight focus...and not using vision as a crutch/excuse. Link to comment Share on other sites More sharing options...
InTheBlack Posted October 26, 2002 Share Posted October 26, 2002 Alan- I'd like your opinion in this thread http://www.brianenos.com/cgi-bin/ikonboard...14&start=30 in the IDPA Questions forum, topic Speed vs Quality. You have the expert knowledge to help us understand how long it takes to switch focus from infinity far to the front sight. I can get an "on paper" hit without perfect focus on the front sight, but of course taking the time to focus results in a better hit. Link to comment Share on other sites More sharing options...
Alan550 Posted November 4, 2002 Share Posted November 4, 2002 InTheBlack: To start this on a humorous note, I've always been reluctant to let someone call me an "expert"! If that word gets broken down like they taught us with "assume" (makes an ass out of U and ME) it becomes......an ex is a has-been, and a "spert" is a drip under pressure! Anyway, back to your question. The time to refocus will vary with age, and from person to person, much like reaction times to the buzzer do. Age is a major influencing factor here, since we lose the ability to accomodate for near vision as we get older. Hence the need for "reading glasses" past the age of 40 or so. A young healthy person with "normal" vision, i.e. no correction needed, will have a much faster focus change time than they will later in life. So there's not much in the way of an accurate timing measure to be applied here. I know this doesn't really tell you what you want to know, but, as in many other questions on here, there's no finite answer that will apply to everyone. Flex: For non-Rx glasses, there may be some peripheral distortion near the edges of the lenses. The easiest test for this is to hold the glasses in your hand, indoors, so that you get the reflection from a ceiling light on the front surface of a lense. Move them so that this reflection shifts around on the lense and check for changes in image size or being "wavy". Without optical equipment, this is the best test for distortion that I know of. Use it when purchasing non-Rx of any kind to see if they are optically correct, or junk. Alan~^~ Link to comment Share on other sites More sharing options...
Flexmoney Posted November 4, 2002 Author Share Posted November 4, 2002 Alan, Thanks for the heads up on the glasses. Link to comment Share on other sites More sharing options...
InTheBlack Posted November 5, 2002 Share Posted November 5, 2002 re check for distortion: You look at the bounce off the front surface, not through the back, right? Link to comment Share on other sites More sharing options...
Alan550 Posted November 23, 2002 Share Posted November 23, 2002 ITB: Sorry I was so long in answering. Check both front and back on non-Rx lenses. There should be no change in image size or shape either way. This does NOT hold true for Rx glasses. Alan~^~ Link to comment Share on other sites More sharing options...
vluc Posted November 23, 2002 Share Posted November 23, 2002 Here's teh thread I was referring to... http://www.brianenos.com/cgi-bin/ikonboard...00&start=10 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now