How to measure "clear glass"

[TitanRebel]

I've been "one of those guys"... always blowing my budget on the gun, and then having to compromise when purchasing the scope. I want to change that, and potentially buy a nice scope. I have a couple of the old SWFA SS 12x and 10x scopes, and most recently bought an Arken EPL-4 4-16x44. The Arken seems a tiny bit more clear. All seem pretty good to me when initially looking through them. However, since I've been shooting more, I've noticed that I need to periodically take a break. I have to rest my eyes. My assumption is a nice scope with "clear glass" and "forgiving eye-box" would allow me to shoot longer before eye fatigue? And, a "nice scope" would be a better shooting experience all around.

How can I quantify / compare "clear glass" and "forgiving eye-box" between scopes and manufacturers? Is there a measurement of glass clarity/resolution, or is this all anecdotal? Does the eye-relief measurement have anything to do with the eye box being "forgiving"? Are there other factors (objective lens size, tube size, etc..)?

If there is no quantifiable way for me to compare clarity/resolution, then I need suggestions... I'm looking for a medium magnification range (upper magnification of 16x to 25x), with the best clarity. So when I look through it I can definitely tell it's more clear than the scopes mentioned above, and gives me less eye fatigue. $2500 would probably be the limit.

Thanks for any input!

 

[Firewalker]

I'm far from any kind of expert in glass, let the optical engineers answer the scientific aspects of your question but I'll give you my experience and you can go from there.

I bought a Nightforce Bench Rest scope a while back. I went to a gigantic gun meet where all the reps slinging guns, glass and ammo went to and I got to compare scopes side by side and even shoot guns with the glass mounted.

I spent your upper limit and it's a lifetime scope!

But....

I still had eye fatigue after a few hours of BR shooting and went to my old work where I'd smithed on weekends.

My old boss told me that because I was left eye dominant and a right hand shooter, I needed to do 2 things:

Refine my reticle focus

Blind my dominant eye

With a solid blue sky in front of me, I cheeked the scope and made a dozen small changes until the SKY was my focal point and the reticle was sharp, pulling the gun away from me every change.

Then I did a dozen quick gun to battery checks, adjusted the eye relief a few times and adjusted my eyebox distance.

I then rotated my eyebox flip cover 90° so that it would blind my left eye. I used a circle of black, self adhesive velvet inside the cap to really knock out any reflection.

The final step was to put a higher cheekrest on the stock. Keeping your head straight and vertical helped me shoot all day.

Good luck

 

[TitanRebel]

Wow! Thanks for the response, maybe you will save me money!

As a matter of fact, I'm cross-dominant too (shoot right; left eye, same as you)... maybe you're on to something. My cross-dominance has proven tricky for my sporting clay scores ;-). And, recently I've been feeling like I've mounted my scope too low after working so hard to get it as close to the barrel as possible. I'll definitely start tweaking my gun setup/ergonomics and see how that plays a role. Maybe spending more money isn't the answer?

Otherwise, one vote for NightForce!

 

[rsfrid]

You could buy a pretty nice March scope for your budget. I have a High Master competition 45x45 scope and a Sightron competition scope and both are very nice scopes with ED glass elements (means Extra low Dispersion for less chromatic aberrations). Generally, scopes with ED glass elements or Flourite elements will be "clearer" or seem like they are clearer because there will be little or no color fringing.

 

[Firewalker]

Wow! Thanks for the response, maybe you will save me money!

As a matter of fact, I'm cross-dominant too (shoot right; left eye, same as you)... maybe you're on to something. My cross-dominance has proven tricky for my sporting clay scores ;-). And, recently I've been feeling like I've mounted my scope too low after working so hard to get it as close to the barrel as possible. I'll definitely start tweaking my gun setup/ergonomics and see how that plays a role. Maybe spending more money isn't the answer?

Otherwise, one vote for NightForce!

Nope, I'm not schlepping for Nightforce, I love mine but there are a LOT of clear glass out there.

I'd recommend going to a large gun shop if you can. Look through a few.

I have an old Japanese Nikkon scope that will pull light in until dark. I don't know how they did it but it's as bright in the scope as the world outside it!

It failed the box test years ago so it's relegated to a Marlin .22lr now.

 

[JEFFPPC]

For clear bright glass in a given price range I find Sightron hard to match.

 

[Smok3y]

I've been "one of those guys"... always blowing my budget on the gun, and then having to compromise when purchasing the scope. I want to change that, and potentially buy a nice scope. I have a couple of the old SWFA SS 12x and 10x scopes, and most recently bought an Arken EPL-4 4-16x44. The Arken seems a tiny bit more clear. All seem pretty good to me when initially looking through them. However, since I've been shooting more, I've noticed that I need to periodically take a break. I have to rest my eyes. My assumption is a nice scope with "clear glass" and "forgiving eye-box" would allow me to shoot longer before eye fatigue? And, a "nice scope" would be a better shooting experience all around.

How can I quantify / compare "clear glass" and "forgiving eye-box" between scopes and manufacturers? Is there a measurement of glass clarity/resolution, or is this all anecdotal? Does the eye-relief measurement have anything to do with the eye box being "forgiving"? Are there other factors (objective lens size, tube size, etc..)?

If there is no quantifiable way for me to compare clarity/resolution, then I need suggestions... I'm looking for a medium magnification range (upper magnification of 16x to 25x), with the best clarity. So when I look through it I can definitely tell it's more clear than the scopes mentioned above, and gives me less eye fatigue. $2500 would probably be the limit.

Thanks for any input!

There isn’t a specification you will find. And you can’t go solely on what others think to find the perfect scope. You are going to have to try them out with your eyes. Only you can decide if the $600 is worth it or if the $2500 scope is worth it. I have owned $2500 scopes I wouldn’t buy again and have owned some I loved. The next guy didn’t care for my favorite. Scopes have come along way the last 15 years, so paying up becomes less important to most people.

Most scopes are going to be “clear”. It is the other stuff that matters to your eyes. Cool/warm, resolution, contrast, etc.

The biggest issue with eye fatigue is not having your diopter properly focused (this is the reticle focus).

Eyebox has a lot of factors including the magnification you are shooting at. The higher the mag, the bigger the objective you want. It gets way more unforgiving the higher in mag you go because the exit pupil gets smaller and smaller. That is why it is harder to find that perfect spot behind the scope when you are at 40x instead of 5x.

 

[Tumblinginflight]

Firewalker made some excellent points. I will add some observations (ha!) about scopes and eye fatigue that may help as well.

Eye relief is not really a metric that corresponds to “eye box”, but one that is easier to quantify in scope specs. In general, larger diameter scope bodies and objective lenses will provide a more forgiving eye box. The quick check is objective lens diameter in mm divided by magnification equals exit pupil. The bigger that number, the easier to get a useable image behind the scope. Finding one that is easy to get behind not only helps the eye, but all the muscles helping hold your eyeball in position, including little ones in the neck and shoulder regions.

Next consider erector ratio. Basically max mag divided by min magnification. Generally the smaller the number, the better the image quality.

Maximum magnification is another interesting point. Typically scopes are like coil springs in the sense that they behave predictably in the middle of their working (magnification) range, and compromise a bit at the low and high extremes. Getting a scope with slightly higher magnification but only using say 90% zoom can help avoid darkening and keep it in the sweet spot.

Reticle. Of course adjusting, readjusting, and micro-adjusting the diopter to focus that reticle is important, but the reticle itself still has to show up. What I mean is that too fine a line thickness, too thick line thickness, too busy a reticle, or one that just isn’t etched as crisply (my Arken exhibits this) will lead to greater eye fatigue. IMO this is hard to gauge without seeing the scope in person, much like…

The glass! Glass composition, grinding technology and coatings have seen a meteoric rise in quality, but some combinations just play better with certain eyes than others. Some love Japanese glass because it’s bright, others feel it’s washed out. Some love the color saturation of Euro glass, others find it muddy or dark. This may be the most personal and individual component in the system.

I’ll try to wrap up this novel with parallax/focus. Influenced by erector ratio, objective diameter, scope length overall, and I’m sure other factors, some scopes have very forgiving focus adjustment while some are extremely picky. Having an image slightly out of focus can force the eye to work overtime as well.

$2500 opens up a world of options, and should provide ample opportunity to find something that works better. The Arken delivers a lot for its price point, but even stepping up to the $1000-1200 should get you into a much higher class of optic. Good luck.

 

[Smok3y]

Reticle. Of course adjusting, readjusting, and micro-adjusting the diopter to focus that reticle is important, but the reticle itself still has to show up. What I mean is that too fine a line thickness, too thick line thickness, too busy a reticle, or one that just isn’t etched as crisply (my Arken exhibits this) will lead to greater eye fatigue. IMO this is hard to gauge without seeing the scope in person, much like…

A lot well said.

Good call. Can’t believe I forgot to mention this as it is usually my first point. People don’t pay enough attention to this. I can’t stand a thin reticle, which is one reason I like FFP scopes more.

 

[steve123]

I'm with Smok3y.

I've had expensive scopes that didn't work with my eyes well but other expensive ones do.
Same with any price level.

One example was a friends NF ATACR 7-35×56 that I didn't find any better visually than my Athlon Cronus G2 4.5-29×56.

I've got other examples but the worst was a USO 3.2-17 with really poor IQ.

One suggestion would be to buy used scopes and resell at little to no loss then try other choices.

I suppose my two top choices in order are;
Used ZCO 4-20 but it has 25y minimum parallax.
Or used March 4.5-28.

A used full sized S&B 3-20.

 

[JimD]

My method of diopter adjustment is different. I adjust it to the point that shifting my head a little does not change my point of aim. I like to doit while looking at a 30 yard challenge target at maximum magnification. Adjusted this way the reticle will be in focus.

I have a couple Athlons and an Arken. I am more impressed by the Athlons. Your price range would buy a top of the line or at least near top Athlon (not what I have) like the coronas and I'm sure it would be a great scope.

 

[Joedirt199]

You could print off optic quality testing sheets that have different colored and shaped lines that you can set up at distance and look at through different scopes. See for yourself which ones can resolve the smallest and see the colors the truest.

 

[Firewalker]

My method of diopter adjustment is different. I adjust it to the point that shifting my head a little does not change my point of aim...

I test them that way after mounting and adjusting them to see if I adjusted the diopter correctly.

 

[Smok3y]

One suggestion would be to buy used scopes a

This is what I do and would suggest.

 

[TitanRebel]

Thanks all for the reply's... there is some very valuable information here!

I was afraid the answer to "which scopes have clear glass" was going to be, individual preference and vision. That's too bad because it's not really possible to buy a bunch of scopes, shoot/hunt with them, then determine a winner. But, I get it, many examples in life like this. I've got an old pair of binos (Leupold 6x?)... I don't remember why or where I bought them, but I've never looked through another pair of binos that I like more! They give me a perfect image, and I think I could look through them all day. Hmmm, I wonder if that means I would like Leupold sopes??

There is some really great / helpful information about the importance of exit pupil, objective lens size, zoom ratio, reticle thickness. Since this scope will be on a hunting rifle, weight is also a consideration and will be a tradeoff.

Today I've looked at a few retail stores, and honestly looking through scopes in the store is almost worthless. Looking at specs online is interesting, because I like data... but overwhelming.

Please keep any suggestions coming! But, maybe I shouldn't spend my whole budget on a scope if I'm not certain it will be many times better than what i have already.

 

[ChefSparrowRagazzi]

I shot ARA benchrest for a while. I used a vudoo rifle with an IOR Valdada Recon 4-28x50 with a 40mm main tube. Expensive.
The glass quality is top notch. The difference between that scope........and the Leupold 6.5-20x40 EFR ...........virtually nothing. In fact the Leupold color rendition is probably slightly better. In my Opinion , for the money, The Leupold scope is very Very hard to beat, if It can be beat. The crispness of the image , the color and contrast, and sharpness is absolutely stunning at any magnification. It can be yours for 800.00.
No it does not have the fancy reticle that everybody wants and rarely uses ( IOR reticle is glorious) but I know how to use this scope. Once that happens, it would be very hard for me to step away from Leupold. It is also , of course, much much lighter than the 2 and a half pound IOR. The exterior finish of the Leupold is also nicer than the IOR. Here it is on my beautiful Daystate Regal XL

 

[boscoebrea]

Leupold, Nikon upper Hawke, Sightron: Look for Japanese glass first. If it is not European, look for Chinese upper glass made for USA companies.
Bushnell Elite, my best tip is this: If you like a certain scope,do some research on it. I also want a scope with AO so I can shoot at shorter distances.
Upper-class glass has a better coating on the lens, which requires more steps, which is another reason they costs more.