Home Forums Hunting & Shooting Ask The Gunwriters Ask John Barsness Questions About "RIFLESCOPE BRIGHTNESS"

Hi Folks:

I want to thank John Barsness (Mule Deer) for providing the Campfire with another exclusive article, entitled RIFLESCOPE BRIGHTNESS, to be found on the Home Page.

Please enjoy, and then please use this space to ask John questions about RIFLESCOPE BRIGHTNESS.

I hope you enjoy the article as much as I am.

Good hunting!

Excellent article, JB. I always take away something new from your writings on optics. Thank you.

You're welcome! And thanks.

Yep JB, good, succinct, and info packed.

Im gonna get my bud, who loves Hubble Scopes to read it!

I'd be interested in hearing his reaction!

Hi John

A good article. Your analogy of the cardboard tube prompts me to ask myself why eyepiece boots haven't become more popular on rifle scopes. Probably worth a try, especially for shooting in moonlight.

Have you tried them?

Excellent, excellent article, John!

dan,

Yes, I have--and they do brighten the view. Which is partly why many night-vision scopes have them.

A good article but I can't help but notice that every curent euro scope intended for hunting in the moonlight features a 30mm tube,as well as an illuminated etched reticle.

I have few scopes that match the above description and they do work well for shooting wild hogs on clear nights.

And none of my one inch tubes,including the euros work quite as well in this job.

My thoughts are that the euro manufacturers use their best lenses and coatings on the 30mm scopes which they know will be used for low light hunting.

Well thought out and put together piece that hammers urban myths and "snake oil" optical physics permeating the internet.

Thanks, John.

DF

Excellent article John......as usual.......

-Ted

Excellent article!

ruraldoc, I think you may have some of the answer. I also think that some of the 30mm tubes allow the makers to put whatever is holding the glass in place further away from the center of the glass, giving a bit wider space for light, glass and coatings to do their thing.

JMHO.

I'm not sure some of the 30mm erector systems are actually larger than 1" erector systems, just more room for adjustments/more elevation for LR shooting.

Comments on that are welcomed.

DF

ruraldoc,

You're absolutely right, many if not most scope manufacturers tend to use their best glass in 30mm tubes. But that doesn't have anything to do with the possible brightness of 30mm scope tubes. Instead it has to do with European tradition--and that's exactly why so many shooters swallowed the advertising claim that 30mm scopes "allowed" more light to pass through a scope.

Not all the scope manufacturers who make 30mm-tube scope use the best glass, because their customers (who aren't European) are more concerned with elevation adjustment range.

Yes, some Euro-manufacturers now make illuminated reticles for their 30mm scopes, but that doesn't mean illuminated reticles don't dim the view slightly. Instead it means they're making for scopes for the American market, where illuminated reticles aren't outlawed in many states, as they are in some European countries.

And just because illuminated reticles dim the overall view slightly (an optical fact first pointed out to me by a European company, for the reasons I stated) doesn't mean they don't help aiming. Being able to put the bullet where we want to is due to several factors, and seeing every hair on a deer, or every point on its antlers, isn't necessary to aiming. Instead we just have to be able to see the outline of the deer AND the aiming point. If we can see every hair on the deer but the aiming point is vague, then scope "brightness" is useless.

Thanks for the detailed reply,very good information. I know that the limiting factors are the exit pupil and the size of the lenses in the erector tube which are plenty big if they can handle the diameter of the light passing through them.

The question that I have is this, do the larger lenses of some 30mm scopes allow for a larger sweet spot? I know that the optical properties of lenses tend to be better toward the center and poorer toward the edges.

Perhaps it is poor analogy but tennis rackets work fine whether they are regular sized or oversized. But many players pick an oversized racket because it has a larger sweet spot and keeps a ball further from the edge.

There is a little bit of that effect in scope lenses, but it usually affects definition more than brightness.

For years Swarovski used larger interior lenses in all their 30mm scopes and claimed extra brightness, but they also used better glass in those scopes. One major side-effect, however, was a relatively narrow adjustment range. This year they finally came out with "tactical" 30mm scopes that essentially use lenses for 1" tubes, allowing for the extra adjustment so many shooters want these days, and they're just as bright as their larger-lenses 30mm scopes. They also cost around $3000.

Can you recommend any particular ones for a Z3 Swaro 3x10x44?

Most excellent article, J.B. Very well done and to the layman's level.

Thanks!

Don't know of any specifically for Swarovskis. In fact haven't looked for any for a while. There used to be an ad in many of the shooting magazines for them, but I haven't seen one in a while.

This is a very informative article, in typical JB style......easy to read, very well put together, therefore very easy to digest and understand, with no apparent bias. I enjoyed it very much.

Thanks for the article, John.

fwiw:
in addition to longer ER allowing stray light betwixt eye & lens, have noted that sitting in a tree/elevated stand with a clear sky overhead as opposed to a blind with just the barrel protruding and the scope's objective lens inside, definitely impacts the low light "performance."

Also, a matted blue barrel reflect less light back up to the objective lens than a SS barrel.

Found this comparing a S&B Summit with 4" of ER & a Leupold to a short 3.15" ER Euro. The Euro gave a considerably "richer" low light view due to the shorter ER and additionally it was sitting over a blued barrel. Switching the S&B & Lupes off to a matte blued rifle and wearing a cap over the ocular lens brought low light performance right up to par...:)