Must i get a centering device if i buy shooting glasses?
Moderators: pilkguns, m1963, David Levene, Spencer, Richard H
-
Guest
Must i get a centering device if i buy shooting glasses?
Is it necessary? Extra device means extra money. Current using Knobloch K1. I just bought it.
-
David Levene
- Posts: 5617
- Joined: Mon Mar 01, 2004 12:49 pm
- Location: Ruislip, UK
You shouldn't need to buy a centering device provided that you know people who can help you set up the lens position correctly, your frames are capable of holding a setting and you do not use differing extreme stances.
I have been using a set of basic Champions for over 20 years and have never needed a centering device. I have however always had access to a good shooting optician and coaches who knew how to set a lens up.
I have been using a set of basic Champions for over 20 years and have never needed a centering device. I have however always had access to a good shooting optician and coaches who knew how to set a lens up.
The centering device is necessary when using an adjustable iris. If your pupil is not exactly centered in the lens/iris, the aperature openings will begin to "fuzz out" as you stop it down. If you're planning on using your glasses as a platform for color filter and/or positive corrective filter lenses - +25. +50, etc., - then the centering device is merely for peace-of-mind.
-
Fortitudo Dei
- Posts: 256
- Joined: Tue Mar 02, 2004 8:30 pm
- Location: New Zealand
I ummed and aarrred over getting the centering device but finally bought one - and I'm glad I did. It's purpose (in case you are unfamiliar with it) is to adjust the lens so that your pupil is directly behind the dead centre of the lens - that being the most optically perfect part of it. As Knoblochs can be adjusted up/down, left/right, and angle (in/out) a centering device really helps to get the adjustment of the lens position perfect. You only need to use it occasionally, but when you need it - you need it. I didn't find my optician to be much help (those that know what ISSF shooting glasses are about are a rare breed) so the CD was very helpful.
-
Guest
-
Guest
-
Fortitudo Dei
- Posts: 256
- Joined: Tue Mar 02, 2004 8:30 pm
- Location: New Zealand
Don't fret too much about it. If you ask around, someone else may have centering device and you could use theirs. Otherwise, a coach (or if you are lucky) an optician may be able to do a pretty good job of it.
You don't say whether you are shooting rifle or pistol. Rifle shooters that use shooting glasses tend to have their lens adjusted along the left/right axis more like a normal spectacle lens - because they face the target in a much more "front-on" manner. Because pistol shooters stand sideways to the target, many people (myself included) find that if the shooting lens were positioned as if it were a normal pair of glasses, you would end up looking at the sights through the far-right edge of the lens (assuming you use your right eye for shooting) - which of course is not optically the best part of the lens. To compensate, the obvious thing to do is to slide the shooting lens over to the right so that when you are in your shooting position you look at the sights more through the middle of the lens. This is where a CD can become very useful to do the final fine adjustment.
An iris does not really work like a centering device as the hole you look through is very "thin" - if you adjust the position of the lens wildly (with the iris closed) - you can still see out of the hole. The hole in the centering device is positioned at the end of a little tunnel which you look down. This means that if the lens is only slightly out, because of the length of the tunnel you cannot see the hole (or the position of the hole of obviously "out") - which makes it easy to correct the position of the lens.
An aside - one thing about the Knobloch K1's is that the two little screws on the top-front of the glasses which hold the rail (on which the lens holder is suspended from) to the frame, tend to work loose very quickly in normal use. This will in turn make the lens wobble. Tighten these screws up and lock them with a blob of clear nail polish. This can easily be removed with nail polish remover or acetone should you need to later slide a new lens holder or a blinder onto the frames.
You don't say whether you are shooting rifle or pistol. Rifle shooters that use shooting glasses tend to have their lens adjusted along the left/right axis more like a normal spectacle lens - because they face the target in a much more "front-on" manner. Because pistol shooters stand sideways to the target, many people (myself included) find that if the shooting lens were positioned as if it were a normal pair of glasses, you would end up looking at the sights through the far-right edge of the lens (assuming you use your right eye for shooting) - which of course is not optically the best part of the lens. To compensate, the obvious thing to do is to slide the shooting lens over to the right so that when you are in your shooting position you look at the sights more through the middle of the lens. This is where a CD can become very useful to do the final fine adjustment.
An iris does not really work like a centering device as the hole you look through is very "thin" - if you adjust the position of the lens wildly (with the iris closed) - you can still see out of the hole. The hole in the centering device is positioned at the end of a little tunnel which you look down. This means that if the lens is only slightly out, because of the length of the tunnel you cannot see the hole (or the position of the hole of obviously "out") - which makes it easy to correct the position of the lens.
An aside - one thing about the Knobloch K1's is that the two little screws on the top-front of the glasses which hold the rail (on which the lens holder is suspended from) to the frame, tend to work loose very quickly in normal use. This will in turn make the lens wobble. Tighten these screws up and lock them with a blob of clear nail polish. This can easily be removed with nail polish remover or acetone should you need to later slide a new lens holder or a blinder onto the frames.
-
Guest