Home Forums Hunting & Shooting Hunting Optics Low Light and Objective size?

My main hunting rifle, Winchester EW .300 WSM, wears a Leupold VX-3 3.5-10x40 CDS. Last year during deer season in Alabama, I had several bucks come into a field at not quite last light but at a time when the field was dark because the sun was behind the treeline, which put more shadow on the field.

I got to thinking I needed a better low light scope and started researching and everything points to high end German 56mm objective scopes as the best in low light. Now it is not worth that much to me for the extra minutes of low light capability.

But my question would be has anyone noticed if a more reasonably priced scope for example a VX-2 with a 50mm objective would be better than the VX-3 with a 40mm objective in low light? Or do the better coatings in a higher tier scope, of any brand really I just happen to like Leupold, trump the objective size?

I'm asking because I saw a Weaver K 8x56 for sale and with a reasonable price was wondering if a scope in that class and price range would do better with the larger objective than a VX-3 or Zeiss Conquest type scope with the 40mm objective in low light situations.

Bob.

Heres the crash course: there is no such thing as "light gathering", there is only light transmission.
Divide objective size in mm by power=exit pupil...basically the amount of light that is transmitted.

Your pupil, if you are over 40 yrs. old can only dilate to 5mm....an exit pupil considered optimum for you would be 7mm as it allows for some wiggle room and margin of error. A 40mm obj. scope on 6 power will give you an exit pupil of just under 7mm Great!

Quick thinking shows you at 4X you will have an exit pupil of 10mm...more than you can actually use.


Power is then a determining factor in light transmission....those little straight tube 20mm dangerous game scopes at 4x transmit a 5mm exit pupil...all you can physically use.

If you need more power, you need a bigger objective...

Marketing hints: 50mm objectives on one inch tubes are pretty much a marketing gimmick, they work better on 30mm tubes....56mm obj beg for a 30mm tube, and usually have it.


Im sure others will be along shortly to poo poo what I've said, after all, this is the optics forum!

What's your basis for this?

I've come to the conclusion that if a VX-3 or Conquest level scope with a 40mm front end and 6x magnification doesn't handle it, it's too dark and/or too far away for my taste.

Sometimes a good light is what is really needed!

But my conscience just won't let me.

I have shot deer at last light with that VX-3 and scopes of lesser quality. Just wondering if I'm leaving anything on the table in low light dept is all.

Bob.

My S&B 3-12X42 Klassic is one of the best at dark but it still has some flare after about 7 1/2 power because my eyes can't handle the extra x's. Even though it is the best in my opinion, there is no use in getting a 50mm scope if it's not coupled w/excellent glass...just throwing money away. powdr

This is the optics forum. You can say anything you want, with minimum actual knowledge, and zero actual usage.


But basically I based it on who I saw buying them, and what they were buying.....3x9s predominantly...cranked up to 9x it gave you a whole 4mm exit pupil, really 'gathering' light there! Same thing your old 3x9x40 would give them at 8X.
But John Q. Public lined up to buy them, and the craze eventually died down....

However there is no place better to sell the " Bigger is Better" concept than in America!

As for the 30mm tubes,looking at exit pupils on them it was easily apparent they transmitted more light, though I never bought or used one personally. ( Since the garden variety 3x9x40 will allow you to shoot anything during legal hours...)

Now, Im gonna go ice down some bourbon, and attempt to wash my sins away!

If you saw any additional brightness from a 30mm tube scope over a 1" one, given the same magnification and objective (40,50, or 56) it's almost a certainty it wasn't from the 30mm tube per se.

Nope, it was at the higher magnifications. As I said, old eyes can only dilate to 5mm, so on the lower powers if it is transmitting a 15mm exit pupil or a 7mm exit pupil, in practical use, it will make no difference whatsoever, you are only using 5mm of it. You can see it at arms length, but you don't mount your scope at arms length.

Wait a minute...I don't think I worded that right to give you a proper answer...given the question...


Im off my game!

I have been down this path.

1. in the dark a day scope without NV capability can see nothing, why I carry a pistol with a laser on it when walking out of the stand.
2. 50 mm objective with a poor coatings will not match 24 mm objective and excellent glass and coatings when the light is waning....so the VX6 24 will see as good as the VX2 50 (probably)
3. a Thick reticle is best for lower light shooting, some IR are OK as well depending on how much you want to spend.
5. a red dot sight in low light is a trick, to keep the thing turned down as the light fades.
6. Shooting pigs at night with a good green or red light, it don't matter what scope you use as long as you have a good light and shoot reasonable distances.

Exactly. Tube size is irrelevant. Me, I'll take a scope with a 40-42mm objective lens and high quality coatings over some Walmart special sporting a 50+ mm scope anyday of the week.

fishybobtrout,

I didn't read through this thread so it may have already been stated. I have a few scopes. I have purchased four Swarovski z5 5-25X52 and a couple Bushnell 4200 4-16X40 and others. None of the others will stay with these two for low light. I have not been able to see the z5 as any better than the 4200 in low light until I turn the magnification ring above 16X in the z5.

I have compared lots of scopes side by side on my deer antlers 131 yards away in the woods. The idea of exit pupil is a good internet conversation topic, but in the real world it does not pan out.

If you can afford a Nightforce, there is no comparison between them and everything else I have looked through in a side by side comparison. That goes for low light or good day light. But I have never looked through a S&B; except a 1-6X at the range. For me it was next to useless. I like a scope to be a 4-16X at least.

Lense quality is far more important than objective size. Some better high end scopes transmit 95%+ of the light that comes through to the eye. Most decent mid-level scopes are in the 90-95% range. I'd say most Leupolds are in the mid-level. Some budget scopes are in the mid 80's.

The size of the objective, along with the magnification determine the diameter of the beam of light that comes through, not the brightness. Assuming equal quality glass a 50mm objective set on 10X, a 40mm objective set on 8X and a 20mm objective set on 4X all let exactly the same diameter beam of light through. Which is brighter will be determined by the lense quality

Long story short, if comparing equal quality scopes in 40 vs 50mm you'll never notice any difference below about 7X or above 9X. The 50mm lense offers a slight advantage only at around 8X or 9X. If you need a scope with more than 10X magnification then bigger objectives start making sense.

I will amend my earlier posts by saying I simply can't be objective about objectives....

A full moon is the best thing for shooting at last legal light!

Not necessarily. In your example, the "brighter" scope will be the one that has the higher magnification setting with the given (static) exit pupil diameter. Also, even though you might have equal exit pupil sizes and one scope achieves this using say 4x with a 28mm objective lense and another scope has say 8x with a 56mm obj lense the 56mm will be brighter even with all else equal because the 56mm has ALOT more light energy falling on it's obj lense to transmit. Only pointing this out because the old standards such as twilight factor and relative brightness don't take into account other factors besides magnification and objective lense size. I do completely agree with you with regards to lense and coating qualities.

just performed a sivetky goulet sliding boxcar analysis of your post and find it to be factoidal and relevance to the 9th power.

All this talk about "bright" riflescopes, exit pupil, glass and coatings and no one has even mentioned " the world's brightest rifle "( ) . Well according to Bushnell, these are "the world's brightest riflescopes " and I own a few of these too Rich. I own the traditional (BG) hunting sizes such as the 2.5-10 x 40 along with this new 3-9 x 40 Firefly as opposed to the varmint hunting sizes you speak of that top out at 25-30X.

Yup !

In a test of "tactical scopes", in Sweden. They had a good array of scopes, 4-16x50 Hensholdt, 5-25x56 S&B, 6-24x72 Hensholdt and a few others.

The 6-24x72 could keep on shooting at targets hundred of yards away, after the light was gone, and long after the others could not see a thing. I belive they stopped after 45 min, just becuase it was getting to cold for the other shooters to just lay there.

Objectice size matters.. it pulls in more light