Wednesday, April 25, 2012

Old Eyes and iron sights -- Part #7

Rear sight diopters --Testing and selection

April 24 promised to have blue skies, light winds, 70 degrees and low Mosquito count.  So I headed off the North Star Rifle Club for part 2 of lens testing and a few more pictures. Today’s test was under clear blue skies vs. cloudy but good light on test 1.
As you will recall from part 1, I was checking various lenses for a rear sight on a Palma rifle with a .3 front lens. Photo #1 shows Old Glory set up in my deluxe sandbag rest …. This testing was done with the Neergaard lens kit by holding the various power lenses between thumb and forefinger, then moving the lens up and down between the rear of the sight and my eye.
Click to enlarge Picture
Since that first test my good friend and high power team mate Kevin Bangen has developed a new, revised and improved version of the holder shown in part 1.  See photo #3.   Photo #5 shows the actual lens that drops into a slot at the top of the holder.
Some sources have indicated that the Neegaard lens might work better with a longer sight radius. So today’s testing started with my # 2 Mid Range Prone rifle chambered in 240NMC.  It has a 5” bloop tube on a 29.5” bbl. with a 22MM front sight and a .3 lens.  So the only thing different between this test and the first was the 4 ½” longer sight radius. 
Starting with the +1.5 lens every lens down thru – 1.5 was inserted in the holder clamped on the rear iris.  All the lenses made the front sight just barely sharper. To the best of my ability I could see no difference in the clarity of the target between any of the lenses. It was certain that none of the lenses made the target look worse but if there was an improvement it was very small. I would insert each lens into the holder and take a quick look then pull it out of view and try & compare how the sight picture compared with and without the lens.  After doing this with 10 lenses I think for me at least, I can see just as well with no rear lens and the .3 front with a bloop tube. The Micro Sight was then inserted and all lenses checked as described above.  The Micro Sight did not help with any lens and in fact was probably just slightly worse. I tried the Gehman rear sight with the 1.5 magnification and it too was worse than no lens at all in the rear.  And finally I removed the .3 front lens and looked thru the Gehman 1.5.  The target looked sharp and the front sight was sharp.  But the target looked about like a 200 yard center. It would have been VERY difficult for me to call any shots with the pin head looking target inside the great big aperture. I believe the old adage about there being no free lunch applies here.
Today’s next test was the same as described above but with Palma rifle # 2 on a Stolle action.  This rifle wears a 30MM Right Sight with a .37 rose tint lens from our favorite Snake Oil Salesman, Bob Jones. The results with this front sight were similar to the results with the bloop tube rifle.  In fact if anything I think the sight picture was just slightly better with no rear lens at all.
The instructions with the test lenses indicated it might be better to remove the rear sight and look through the big hole as there will be greater sensitivity to focus changes by looking thru the largest aperture available.  So I tried this and everything was a complete blur until I got to the + 1.50 and + 1.75 lens. I doubt I would have hit the target had the sight picture been that poor with the rear sight in.
At this point about the only thing I want to try is the above with a .5 front in my # 1 MRP rifle. I hope to have that report next week.
So many rifles, so many lenses, so much testing, so little time.
Capt. Bob Peasley 
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