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#12389619 - 11/10/17 Ask John Barsness Questions About "Testing Riflescopes"  
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RickBin Offline
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It's time again for me to thank John Barsness (our own Mule Deer) for his latest exclusive (and particularly timely) Campfire article "Testing Riflescopes", which can be found on the Home Page and by clicking the link.

Please use this thread to ask John questions about the article.

Thanks John, and Happy Birthday. smile


Rick Bin
24hourcampfire.com
CMG 300 BP

#12442470 - 12/04/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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Bob_B257 Offline
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Thank you John for the thoughts on this subject. Interesting to read on the change in testing over the years as the technology advanced and as the use refined the common practice with the optic.
Did not know that you and Craig had worked together. That must have been some spicy conversation in the break room back in the day.


I used to only shoot shotguns and rimfires, then I made the mistake of getting a subscription to handloader.......
#12442494 - 12/04/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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EdM Offline
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John,

Have you considered a consistent method for testing scope durability, ability to hold zero, etc., when "thumped", etc? Particularly given the posts on same of late.


Conduct is the best proof of character.
#12442648 - 12/04/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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Omid Offline
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Hello John,

I really enjoyed reading your article too. According to your observations, here is the state of the art:

a) Current scopes are very good in terms of being sealed and weatherproof.
b) The optical quality of most premium scopes is very good too.
c) Even the most well-known brands, seem to fail to retain their zero or follow a desired elevation adjustment.

I agree with the above assessment. I'd add the following observations: The main trend in the recent years has been making scopes with more zoom range. First we had the 3X zoom range (such as 3-9X), then it became 4X (3-12X) and now we are being offered 6X and even 8x zoom ratio in the latest Swarovski and Zeiss products. It is also becoming "normal" to produce hunting scopes with larger main tubes (34mm tube on Schmidt and Bender Polar and now the huge 36mm tube of Zeiss V8). The result is that we have heavy, ugly and ultra expensive scopes with features that we really don't need. A high-quality scope with magnification of 1.5-6X and objective of less than or equal to 42mm is good enough for nearly all kind of big-game hunting. A little more power (say 12X) is good for zeroing-in and target shooting but not really needed for hunting. Larger objectives (say 56mm) are good because they enhance optical resolution and also enlarge the exit pupil but the weight and bulk they add is a problem. (The weight of the scope is being added to the top of the rifle which is the worst location to add weight. It also adds to the stress that mounts must withstand)

Zero retention is a basic requirement but we hardly see it being advertised or discussed in marketing literature. Few manufacturers want to talk about it. A scope's robustness can only be verified until you buy it, mount it, zero it and use it. Even then, it could be that one particular sample of a scope works well and exact same scope model used by someone else fails.It is somewhat correct that this issue is caused by poor material and poor quality control (the economics of scope manufacturing you mentioned in your previous article). But let me point out the real cause:tilting the inner tube that holds the reticle and the erector lenses is a bad idea.

In virtually all hunting rifle scopes on the market today, an inner tube holds the reticle and erector lenses. This inner tube is attached to the main scope housing at the rear using a two-dimensional joint such that it's front end can tilt up and down (elevation) or left and right (windage). The front end of the inner tube is held by the elevation nob, the windage knob and a supporting spring. This assembly is fragile and has many mechanical weaknesses. For example: when the inner tube is tilted, only one single point from the elevation knob's stem can touch it. The point of contact is not a surface, not even a line, just a single point! (Pick up to two cylindrical objects such as two shotgun shells. Hold one in your hand horizontally then tilt it a bit upwards. Hold the other one vertically and try to touch the side of the first shell as if this is your elevation knob. Observe how the two shells touch.)

When we dial elevation and windage, the contact points that hold the inner tube shift around and this causes irregularities in the position of the reticle. The rear hing also needs to be very precise to keep the inner tube in exact same tilt under strong recoil forces. This method of holding an inner tube at a precise tilt using two knobs and a spring is simply not robust enough to handle the recoil of a high power rifle.

[Linked Image]


As long as a scope's mechanical design is as I explained above, then it is susceptible to failure. Machining the parts better, using brass parts, or better quality springs would not solve the fundamental weaknesses shown above. We need to address the root of the problem and solve the "zero retention" problem once and for all! Being a PhD researcher with some knowledge of optics and mechanics, I have devised some solutions for this problem myself. This thread is not the right venue to get into technical details but if I see you at Shot Show this year, I would be happy to discuss these new solutions with you. laugh

Thank you again for writing these articles which address real issues with modern rifle scopes. I hope articles like these start a dialogue and get manufactuerers' attention so that the problems of mechanical reliability are addressed at a fundamental level.

Sincerely,
-Omid

Last edited by Omid; 12/04/17.
#12443890 - 12/05/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: Bob_B257]  
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Bob,

Craig and I never worked in the same office. His was at Petersen Publishing headquarters, then in Los Angeles, and mine was in my house in Montana. But we did have some interesting phone conversations!


John

"Gunwriters, as you know, aren't as informed as their readers are and if it wasn't for the readers, there would be no need for writers..."--Shrapnel, May 2015
Alpha

#12443910 - 12/05/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: EdM]  
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Ed,

Haven't developed a thumping routine, partly because (as I pointed out on at least one of the threads on the subject) it's difficult to separate the effects of thumping on the scope and mounts. Back in the 1990's the quasi-government German testing agency DEVA performed thumping tests on various scopes with a rubber mallet, which I reported in my first hunting-optics book OPTICS FOR THE HUNTER. But even they never attempted to separate whether the mallet affected the scope or the mounts.

However, over the decades I have observed that scopes more resistant to recoil also tend to be more resistant to accidental thumping--unless they're actually bent. Have seen that a few times, but even then most could still be used reliably after re-zeroing.


John

"Gunwriters, as you know, aren't as informed as their readers are and if it wasn't for the readers, there would be no need for writers..."--Shrapnel, May 2015
#12445198 - 12/05/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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kandpand Online content
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John,

Thanks for the article. I am a rifle loony and have been buying and selling rifles and scopes for the past several years. Always want to try the next thing. For now I have have found that a rifle that fits me and balances well for me in more important than the caliber or cartridge that the rifle is chambered for.With scopes, I tend to like fixed power scopes with duplex reticle and not over a 40-42 mm objective. I have taken a few range trips recently with several Leupold M8 friction adjustment scopes which were not exactly easy to sight in. What scopes would you recommend that have accurate adjustments for sighting in and then leaving them alone? I am not oppose to going with a variable scope if needed.

Thanks


http://relaxedfamily.blogspot.com/

"Mother To Son"
by Langston Hughes
#12446329 - 12/06/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: kandpand]  
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kandpand,

While fixed-power scopes aren't as common as they used to be, some are still being made--and I suspect more will show up in the future, not so much because of ruggedness but because more hunters are becoming aware of the advantages of a constant reticle size, especially with multi-point reticles.

It's too bad Burris doesn't offer their 6x40 anymore. It had click adjustments that were certainly consistent enough for a set-and-forget scope. However, the Burris 3-9x Fullfield II has equally good click adjustments, and is a great all-around set-and-forget scope, in my experience very reliable and tough.

Two fixed-power scopes that work pretty well are the 4x38 and 6x38 Weaver K's. Some people don't like the relatively short tube and eye relief of slightly over 3 inches in the 6x, because the combination can make the scope difficult to mount on some rifles. However, a rail-type base allows more mounting options, and I haven't found as much difficulty in mounting the 6x38 on long-action rifles as some other people have. (In my experience it works fine on short actions.)

The 4x38 has almost 3-1/2" of eye relief, so is more flexible in mounting. The only reticle available in both scopes is Weaver's version of a Duplex--a trademarked Leupold name--the Dual-X. Right now I have four of 'em, three 6x38's and one 4x38, and the adjustments are pretty good in all four. Dunno how much recoil they can take on a consistent basis, but they've worked fine on my rifles up to .30-06.

Another fixed-power option is the 6x42 SWFA, though it isn't available with a plex-type reticle. It's considerably bigger and heavier than the Weavers and is designed as a dialing scope, but doesn't cost much more than the Weavers. However, the adjustments are dead-nuts, it holds zero, eye relief is 3-1/2", and the long tube makes mounting easy.


John

"Gunwriters, as you know, aren't as informed as their readers are and if it wasn't for the readers, there would be no need for writers..."--Shrapnel, May 2015
#12464932 - 12/13/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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jpr9954 Offline
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I have a question about testing for light transmission through a scope. How do you test for it?

One thought I had was to have a consistent light source and use a photo light meter. You would measure the difference between the light at the front of the scope and the light as seen through the lens itself. Does seem like a valid, objective way to test for light transmission if you didn't have lab-grade testing equipment?

#12465011 - 12/13/17 Re: Ask John Barsness Questions About "Testing Riflescopes" [Re: RickBin]  
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Mule Deer Online content
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That doesn't work, because a typical light meter's sensor isn't large enough to measure all the light passing through a scope.

I described how test for light transmission (or "brightness") at the end of the article. It isn't as precise as using an integrating sphere, but correlates pretty well with the results from one.


John

"Gunwriters, as you know, aren't as informed as their readers are and if it wasn't for the readers, there would be no need for writers..."--Shrapnel, May 2015
Bravo


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