I wear prescription glasses and use an iris to sharpen the front post, but found Knobloch-type systems to be more stuff than I require. Sometimes less can be more.
Meritcorporation.com sells a very nice adjustable aperture that mounts on the lens of glasses.
For me, positioning the suction cup was a bit of a fiddle, so I bought a jeweler's loupe from Behrloupes.com for its nifty spring mount.
Then, I bought Harbor Freight's loupe [item #94364] which has a nearly useless mount, but it does have a laterally adjustable arm.
The Merit aperture was soldered to the Harbor Freight arm, then the arm with its bracket was mounted on the Behr loupe assembly. Knobs made from CCI SV cartridges added for grins. The result was a practical vision aid with two axis adjustment that can mount on the right or left side of the eyeglass frame with no alteration.
Last edited by zoned on Tue Jul 11, 2017 2:25 am, edited 7 times in total.
However, if you can't see the front sight clearly, you need a different lens, not an iris, and if you are going to use an iris, it's better on the eye-side of your correction lens.
However, if you can't see the front sight clearly, you need a different lens, not an iris, and if you are going to use an iris, it's better on the eye-side of your correction lens.
Agree with that 100%. An iris just makes everything more in focus rather than correcting just for the foresight - which is what you require.
Thanks. Other than removing the mount tab from the Merit and the spot of solder, it was just a parts swap.
> However, if you can't see the front sight clearly, you need
> a different lens, not an iris, and if you are going to use an
> iris, it's better on the eye-side of your correction lens.
The intent of the Merit aperture is to sharpen up the view of the sights which it does admirably. It works the same way as an adjustable aperture on a match rifle. Pistol shooters with older eyes don't benefit from a lens calibrated to focus on the front post because it wipes out the view downrange. As you suggest, a calibrated lens used with an aperture works--been there with the Knoblochs. If you already wear corrective glasses, though, this loupe widget does the job without the redundant headgear.
This post has me confused. Why do you want to see the target clearly? I have perfect 20/20 that I can see my 22 holes from 50 feet. I have a prescription that doesn't let me see the target clearly but my sight is very clear.
zoned wrote:Pistol shooters with older eyes don't benefit from a lens calibrated to focus on the front post because it wipes out the view downrange.
In most cases this is exactly the result you want. If you can't see the target sharply then it is easier to accept the area aim.
Yes, David, quite true. The view with the aperture when concentrating on the front post is crisp sights with a soft bull, an ideal picture. If your vision is bad enough to require bifocals, it will be a challenge [if at all possible] to find joy with just a lens. The result for me with a single lens was crisp sights and total blur down range. Optics is about compromise, there is no free lunch.
Gents, thank you for the critique. I understand it all, I've been shooting air, standard, and Free pistol since the mid 70's.
I have and use the style you have shown with the loupe. I have the older "original" ones know as Clearsight. I could not shoot open sights without such a critter. I have tried the iris, and it seemed to cause distraction to me being "behind" that iris. Just my opinion, you have to do what works for you.
zoned wrote:If your vision is bad enough to require bifocals, it will be a challenge [if at all possible] to find joy with just a lens. The result for me with a single lens was crisp sights and total blur down range.
I don't wear bifocals but I do wear progressives (Right -6.25, +2.25 near addition), and have done for many years. The different areas of the lens allow me to clearly see things at different distances.
As I only want to see the sights clearly I use a single focus lens for shooting, just as I have always done (-5.75 at the moment). The target is nice and blurred.
The iris increases your depth of field just like in photography. The more you stop down the apeture the greater the depth of field. This means that at some point the front sight will be clearly in focus as well as the bull at ten meters.
The apeture also limits the amount of light getting to the retina. In a slightly darker range stopping down your apeture may make it more difficult to see the front sight.
I used an iris for several years and in bright conditions it worked. However, I am much happier with a properly prescribed shooting lens. I still have an iris. It is on the eye side of my lens. Most of the time I leave it wide open. In this mode it helps keep me focused on shooting as it helps eliminate the distractions around me.
The iris works better the closer to the eye you can get it. Therefore on the eye side of glasses is best.
Try this experiment. Put a pin hole in a piece of opaque paper. Hold the paper with the hole a few inches from your eye then move it closer until you see well through the hole.
Having been a professional photographer I'm well aware of the effects produced by the iris.
Something to think about: when you make the iris smaller it will make the bull and sights sharper. Not necessarily a good thing. It will also change the apparent size of the bull, changing your vertical zero when using a sub six hold if you change the iris hole.It doesn't matter if using a center hold.
I took a seminar back in the late 80s with Don Nygord (after which I bought shooting glasses from him).
He stated that the purpose of the iris was to maintain a uniform "pupil", since the pupil of your eye changes with varying light levels.
Rover wrote:
Something to think about: when you make the iris smaller it will make the bull and sights sharper. Not necessarily a good thing. It will also change the apparent size of the bull, changing your vertical zero when using a sub six hold if you change the iris hole.It doesn't matter if using a center hold.
Does this mean that a change in the size of your pupil, due to a change in lighting, could cause a shift in your vertical POI?
As a myopic spectacle-wearer, it's an everyday experience tthat distant things are fuzzier in dim light, when not wearing specs. This includes target bulls! So if I shot without specs, I'd expect POI to change with large changes in light levels. Problem is, I can't see the sights either!
As stated above, the artificial iris removes the depth of focus variations due to your eye's pupil changing in size (because of light level changes, anxiety, etc.). Pupil size is not generally under voluntary control, but I have a trick which allows me to voluntarily constrict my pupil, producing an outstanding depth of focus. Sometimes this trick happens unbidden - most annoying! So, keep the effective iris diameter smaller than the likely smallest pupil diameter, then the iris is the dominant aperture and is fixed.
The iris also provides a way of ensuring your head position is constant.
I had to join this forum to say this is a great idea and will get the loop parts on order today. Thank you.
The stick on type work but I rather go without for all the fiddling around it takes to find the sweet spot, then all over again with a change of position.
A fixed aperture would be lighter weight and less cost. I borrowed the stick on type that came in two sizes. I no longer have those available to measure. Could someone advise, what is the optimum (or all around compromise daytime) hole size for either rifle or pistol. Or a range of pin hole sizes I could experiment with.
