New to using a 'PEEP & GLOBE' at 50 yards...

[OS OK]

Harry Tobin's Creations . . . arrived today... yahoo! Thank you Harry soooooooooooo-much.



Who would'a thunk? I had to get a small tackle box now to handle all the assorted iris's & globes for this one rifle...anything associated with the MKII is in this box.



I think I'll start with the largest OD and the same ID that I am using now...I have a suspicion that this globe here will give me all I need...a wide open iris for the best light gathering and clarity.



This is the one I had in the rifle for all of the previous tenex practice...



I have a couple days of rain starting this evening late but it should be clear by Saturday & I can get out and test this new globe.
Got my fingers crossed!

[tazman]

I am VERY interested in how this works out for you.

[303Guy]

You're having waaay too much fun, OS!

And I'm enjoying following your progress.

In the meantime I have to wait another ten days to get out to the range. I've ordered 1,500 rounds of ammo which I have to collect on Monday. The one particular one I wanted I can only get online at a ridiculous price and that is Geco Match which has shown some impressive results. Aguila Subsonic Solid has shown similar results but again, online only from the same place and same price. So I ordered some Eley subsonic hollow nose, Eley Standard and Geco Rifle, 500 rounds each. These cost me NZ$215. So that's what I've to look forward to.

Oh yes, I had a thought on the lensing effect of an aperture. It's to do with the brightest spot of a shadow being in the middle of that shadow. You see, this effect only happens if the object casting the shadow has a smooth surface. It's refraction. So I though, if one could give the aperture a spline type of thing, whatever one might call it, then maybe the refraction would be reduced without having to go to a bigger orifice. There is not much you can do with an iris which is where it is needed most but you can try it on the globes. Of course it might not have any effect at all. Anyway, it was just a thought.

[OS OK]

303Guy... I am not quite sure I'm tracking with your explanation but if I am...Harry Tobin & I talked about this & Harry came up with the idea of tapering the front side (the side facing the target) to reduce this 'lensing' effect of light coming through the hole in the globe.



Yesterday was my first day to test one of his creations however I did not do it justice...I had too many irons in the fire & like a kid with several new birthday presents I was trying to play with all of them at the same time....which one am I? 'Dumb...dumber or dumbest?'

I picked the CZ452 up early Sat. morning rushed home to do my early morning shooting with the MKII and one of Harry's new globes...as you might have guessed the weather was not permitting...looked like a full blown rainstorm was about to set in. I got involved with the CZ452 instead & started making adjustments to my front rest so I could shoot the CZ off that rest.
I made a wood block to fit the Caldwell & covered it in leather...fits that front stock of the CZ like a glove...



Now I can use the Caldwell rest with either rifle I choose...only takes about a minute to change the front stock support out...



A few hours later the skies had cleared and I dropped what I was doing and rushed out to the 50 yd. line only to 'muck-up' a day's shooting...as you can see here below...



I patched up last Tuesday's target with the white 2" stick on spots and used that target.
Something I should mention, not as an excuse (you guys kick me in the butt if you ever suspect me making excuses...."they're like belly buttons, everybody's got one!") but as a fact.
The spots I'm painting into the targets are done with a milk jug cap, about 1 1/4" diameter & that spot looks good with that small amount of white in the X-ring...but when I repair one of those targets with the 2" white stick on spots, it changes the look of the spot in the globe, makes it look like a doughnut...sorta weird looking & it's a bit of a distraction.
I won't be doing this anymore, I'll start cutting them up to cover the previous holes and see about ordering some 1" white stick on spots for the future.

I have been thinking of running a new thread for the CZ452. That rifle will be going through a remodeling of sorts before I put it on the 50 yd. line as a f-class shooter off the Caldwell rest. The Open style rest I don't intend to use until I can build a proper shooting bench,



preferably concrete & 'hopefully' extend my home range out to 100 yds. That means I'll be shooting from the east pasture off a raised platform or I have to relocate the backstop further west...decisions, decisions...I don't know.
I first need to do some range-finding and decide what exactly I will do about that. Anyway, I'm thinking of a new thread called...

"New to shooting 'F-Class-Open' at 50 yds." . . . or something like that? I have much research to do before attempting to talk about & do such things.

[uscra112]

Light is refracted as it passes through the aperture, and if you study it you will find interference fringes. I suspect that is the "lint look" you are perceiving. And yes, the target spot will appear to move if your line of sight is not dead-nuts on the center of the aperture. The smaller the aperture, the worse it gets.

Best way to see this clearly is to shine a laser through a fine slit, say .050 wide, letting the beam fall on a piece of white paper. The fringes will be very distinct, because the laser light is monochromatic. Sunlight is a wide range of wavelengths, and each gets refracted through a slightly different angle, so you just see fuzz. This is one of the classical proofs that light is composed of waves.

http://labman.phys.utk.edu/phys222co...iffraction.htm

Other experiments prove that light is particles. If that makes your head hurt, take comfort. It does the same to every physicist who tries to resolve the paradox. Engineers ignore it, and use whichever model works best for the task at hand.

[OS OK]

Light is refracted as it passes through the aperture, and if you study it you will find interference fringes. I suspect that is the "lint look" you are perceiving. And yes, the target spot will appear to move if your line of sight is not dead-nuts on the center of the aperture. The smaller the aperture, the worse it gets.

Best way to see this clearly is to shine a laser through a fine slit, say .050 wide, letting the beam fall on a piece of white paper. The fringes will be very distinct, because the laser light is monochromatic. Sunlight is a wide range of wavelengths, and each gets refracted through a slightly different angle, so you just see fuzz. This is one of the classical proofs that light is composed of waves.

http://labman.phys.utk.edu/phys222co...iffraction.htm

Other experiments prove that light is particles. If that makes your head hurt, take comfort. It does the same to every physicist who tries to resolve the paradox. Engineers ignore it, and use whichever model works best for the task at hand.

Thank you very much uscra112... this is exactly the sort of information that gets my motor running!

[uscra112]

But I used the wrong word. It is diffracted, not refracted. Refraction takes place when light passes from one medium to another, as in a lens.

[303Guy]

OS, I wanted suggest that very thing. My aperture has exactly that but the effect is still there. I'm wondering what effect a more tube shape aperture would have. Or perhaps a double aperture. What I was talking about are star shaped orifices' to alter the diffraction patterns. I was playing around with a V rear sight and found the diffraction pattern to suite my eyes the best for a fine hold with an inverted V front sight for open sights.

uscra, you have given me an idea to play around with. I was thinking of multiple orifices' and shaped orifices'. Shining a laser through them would give some indication of the effects, although as you say, that would be wavelength specific.

[tazman]

OS,

uscra, you have given me an idea to play around with. I was thinking of multiple orifices' and shaped orifices'. Shining a laser through them would give some indication of the effects although, as you say that would be wavelength specific.

Try using a focusing flash light(small maglite, etc). The light is white and should be close to normal sunlight. You can try one of these through a peep and see what it does without much extra effort. You should be able to see the effects on a piece of paper on the other side of the peep.

If you have an iris that is adjustable, you could test the effects at various sizes very easily that way.

Concerning the tube type peep sights and globes, Many top level shooters use those. I have never looked through one so can't comment further.

[Harry Tobin]

Well boys I’m all over this, I have been thinking about this for weeks. I was thinking if I added veins it may help redirect the light waves. So I talked to OK today and ran it passed him and he liked the idea. My theory if you don’t try something you’ll never know if it works or not. So I came up with this it has 7 veins but that could be changed to any number I want, so we’ll see if I’m on the right track with this. They still retain the .110 center hole even with the star. So we shall see

[tazman]

Please inform us as to how it works out.
Lots of different configurations you can play with.

There is a scene in a Charles Bronson movie named Death Hunt where a character, played by Lee Marvin, is wearing a set of sunglasses that only had narrow slits in a star pattern. These were used to prevent sun-blindness from the snow.

[uscra112]

An ancient idea originated by the Inuit peoples.

[303Guy]

Well boys I’m all over this, I have been thinking about this for weeks. I was thinking if I added veins it may help redirect the light waves. So I talked to OK today and ran it passed him and he liked the idea. My theory if you don’t try something you’ll never know if it works or not. So I came up with this it has 7 veins but that could be changed to any number I want, so we’ll see if I’m on the right track with this. They still retain the .110 center hole even with the star. So we shall see

That's exactly what I had in mind!

[OS OK]

Experimented today with Harry's Creations... Got out early, had the sun to my back...hardly a cloud in the sky and 55ºƒ, so - no excuses for my mediocre performance today hahaaa!



Written under each target is the dimensions of the globe, OD x ID.
Also I was opening the iris wider than I usually do after we talked about the diffraction of light and I went to that site uscra112 gave a link to. Seeing it expressed like waves in water made it much clearer as to what is actually happening to cause that lint look.
I do enjoy using a tight iris around the globe, seems easier to see concentricity of the rings but if that causes more diffraction then I need to learn to deal with a different sight picture...that's the bottom line on that, can't always have things my way!
You'd think at 70 yrs. old...I would have learned that by now!

I took the scope off the CZ today, that stack of 11mm rail to weaver ring adapter and rings were just way too tall to adjust to...



I measured what it would take to increase the height of the comb and needed 1.5" to get up to the correct height for the scope. I measured the objective and tube to determine the minimum height ring I need to get that scope down close to the barrel, got some rings on order. After resolving that, I'll work on the cheek riser and at that point I should be ready to start another thread about the CZ and shooting from the Caldwell rest.
Lot's of work to be done with her...first thing is to find where the harmonic tuner needs to be reset since prolly everyone that looked her over in the gun shop gave that tuner a twist.

[OS OK]

Mulling on your work...studying the groups...

Yesterday I patched up Sunday's target, made a plan to work on my sight picture & open that iris as much as possible to avoid diffraction in the peep...



As you can see, it didn't work...or did it?
Most of these shots felt good & I expected to look into the range scope and see that round where I mentally called the shot.
It wasn't there!
Later in the shop after measuring the spots, I put the target up where I could rock back in my chair, sip on a cold brew & mentally take that set of groups apart...try to understand what it is that I do that makes those groups what they are.
Back-engineer my shooting and come up with a theory of what I am doing wrong...then I have a new exercise to add to the next days practice.

One of the things I have done consistently for probably 10 sessions or so is to leave my right hand up resting on the 'lock bolt & adjustment turret screw'. (remember, I'm a leftie & you have to reverse what I am saying to relate as a right handed shooter) Having that elevation adjustment there made me think I didn't need to pull that hand back under the stock to squeeze the rear bag for that adjustment.



What can be wrong with this? Seems like a comfy way to shoot.
Observation of the groups has been generally a wide disbursement in windage and that indicated either 'canting' or 'wind deflection' ... the wind is always calm to about 3mph so I've made it part of my setup to check canting. Still this disbursement exist and that really puzzled me.............until yesterday.
I sat there watching Y-Tube videos in my head of a friend, (Eli @ Day at the Range . com) adjusting a similar rest and realized that Eli was locking that elevation lock bolt each time he made an adjustment.

"Oh my gosh!" Does that matter that much? I got up, loosened the lock bolt and tried to wiggle the rest sideways, to my surprise...it wiggles substantially, prolly 3/16" side to side. Now at about this point in time, I was feeling pretty stupid for making this kind of mistake.
Today, I'll repeat yesterday's practice but today lock that bolt down after adjusting elevation and see whether I am right or not. I think I should bring that hand back to the rear bag also...I'll find out today.

"Fingers Crossed!" I desperately need to see groups with at least...some the rounds touching one another.

[Harry Tobin]

In an attempt to help my buddy (OK) I have been making him different inserts for his front sight, in hopes that one will fit his old eyes. Now being 3000 miles apart we can’t just get together and try things out in one or two days. So we talk and I try to come up with ideas that will help him out. Now with all that being said I had no way to see what he was seeing till it dawned on me, I wonder if I could design a peep and globe in CAD and then 3D print it! Not being an expert in CAD but know enough to get simple things made. So I did all that and printed it up, holy cow it worked. The threaded part that screws in the front globe worked fist time around, so I made a mock-up stock and (OK) gave me all the dimensions from front sight to rear sight and all the inserts fit my set-up also. So now I can see what he is seeing, some of my ideas work and sometimes not. So this will be a big help when trying to help my buddy. Here’s some pictures of it.

[OS OK]

Hahaaa Harry! When I was a kid we had sticks like that for guns....but if someone would'a said I'm going to print me up a peep sight for my stick gun, I would'a thought you were nutz!
I mean....how the heck are you going to 'memeograph' a rifle sight?

What I was trying to explain to Harry is this:
-The little black spot with the white looking center represents the 4" spot at 50 yards.
-The actual 4" spot on this paper represents the globe in the front sight apparatus.
-The black square represents the rear peep, the iris...

When I am behind the peep, the proper allignment looks similar to this...I have the iris as wide open as possible to stop the diffracrtion but it is still there to some extent at 12 where you see the yellow highlighter mark.



After making my cheek weld I should be seeing the picture above but if my eye is not centered properly, I might see something like this where my eye is off towards the 2 position. That sliver of black, the arc from about 4 to 11 is the inside of the front globe holder, the inside of that tube.
This is my first alignment in the shot setup to get me looking straight down the barrel.



If the iris is too wide open or if my eye is too close to the peep the iris appears very large and I see the entire inner surface of the front globe holder tube assembly. That view is very clear but I can't make proper alignment of my eye to the rifle & sights if I see this...the yellow at 12 representing the diffraction in the iris dissappears and the sight picture is clear & crisp...



If I bear down on the cheek weld I can make that yellow diffraction area shrink considerably but there is a fine line between that and getting my eye too far towards the 6 position and I will see a very slight sliver of the upper inner side of the globe tube. It is hardly noticeable in some ambient light conditions but I know instantly when I have done this as the shot registers around the 6:00 area of the target. One might even call this a 'flier' but it is not...it was me.



So...this was what Harry and I were talking about yesterday afternoon on the video-phone thingie we use to show each other things.
Here's yesterday's work where the emphasis in practice was on:
-proper eye alignment in the sight system using as wide-open of an iris setting as possible (attempting to defeat the diffraction)
-a constant & repeating cheek weld
-making myself stop and start all over if I push the 'breath window' of time in which I send the round...

I did get a few to group together a little closer in the bottom 3 spots, that encourages me to do better in the next practice session.



I'm tellin'Ya boys..."it doesn't take but a very slight, almost imperceptible sight miss-alignment to make those rounds get out of group!"

[uscra112]

For a .22 at 50 yards, not much beats the old Weaver J series scopes. 3/4" tube nestles right down close the the barrel axis. J2.5 is pretty good, a J4 is even better. You don't need that great big objective lens for shooting in good light. You'll find them for sale on evilBay. I don't think I've ever paid more than $75 for one.


'

[Harry Tobin]

If the iris is too wide open or if my eye is too close to the peep the iris appears very large and I see the entire inner surface of the front globe holder tube assembly. That view is very clear but I can't make proper alignment of my eye to the rifle & sights if I see this...the yellow at 12 representing the diffraction in the iris dissappears and the sight picture is clear & crisp



This is what I was trying to explain to you the other day, if you have a colored sticker on the front of the globe screw it would give you a crisp picture. You said it was clear and and the diffraction disappears, so with a sticker on it would look something like this. you would see a very distinctive ring to center. Hey give it a try, can't hurt.

[uscra112]

Another bit of optics lore: The very small iris reduces the amount of light your eye receives, which it compensates for by opening its' own iris, (the pupil). Exposing more of the cornea, (you eye's objective lens) also exposes more irregularities in the curve of the cornea, reducing the sharpness of the image. More light, smaller opening in your pupil, gives you a sharper image on the retina. Probably not a big factor here, but worth knowing about. I've often wondered if this isn't the main reason for keeping both eyes open when sighting.