Home Forums Hunting & Shooting Ask The Gunwriters Why has everyone gone ape over larger, i.e. 50mm, objective lens on scopes?

Since most of my hunting these days is from a fixed stand, I am beginning to like the 50mm lens'. I even have a swarovski 8x56 and there is nothing not to like about it!!! It is clear and bright but it only makes a real difference for about 20-30 minutes per day, the first and last 15 minutes. If I were hunting on foot, I would probably limit myself to a 40mm but my 3.5x10x50 leupy is not too cumbersome. It just seems to me that the scope needs to fit the use and rifle. I just dont see a big scope on a small stalking rifle but they do have merrit on larger platforms. We kept kill stats in a lease I was in a few years ago and most of our bucks were killed between 9-11 am so the big scopes would not help much then. I would put the money, if I had to choose, in a very good binocular.

i use mine to hunt pigs at night under a full moon you you'd be surprized how well you can see with the 50mm

257: Those are really good points. Most of my best bucks have been killed mid-day and under circumstances where the ultimate in brightness has not been necessary.OTOH I have hunted some places where it would be a very good idea to have some more brightness, resolution,etc; most notably for me, central Canada.Coastal Alaska is also very dark and dismal sometimes.

But I don't own any 50mm scopes because I don't want anything that bulky for most of the hunting I do;for much of that,the emphasis is more on light weight,portability,and most of these needs are served by something of smaller size and not a great deal of magnification.

As a matter of fact, I am noticing that I am seeing more big bucks(mule deer in particular,where I hunt them) by going to their "bedrooms" in heavy cover, than by waiting for them to stick their noses out.Unless they are rut-addled, I am noticing they don't emerge from cover until after dark.

From the S&B websight.

"It is impossible for any scope to "gather" light. It can only transmit existing light. And, regardless of advertising claims you may have heard, there is no riflescope made that can transmit 100% of available light.

As light enters the objective end of the scope, before it reaches your eye it passes through several lenses. Each lens absorbs a small quantity of light. Residual reflection from the individual lenses will also prevent a certain amount of light from passing through the scope. In addition, undesired reflections within the metal tube can hinder the quality of the viewed image and the transmission of light.

Each lens has two surfaces. Thus, the total number of lenses within a scope (a variable-power scope can have between seven and ten) is multiplied by two, then multiplied by 0.25% to determine the amount of light lost in the transmission. Simple multiplication is not accurate, however, as each succeeding lens progressively reduces the total amount of transmitted light. It is a favorite technique of some scope manufacturers to claim light transmission values of nearly 100%. Of course, they're measuring the first objective lens only, conveniently forgetting about the other eight or nine!

Any higher transmission levels are physically impossible to achieve with current technology, and claims to the contrary are to be discounted. What does light transmission mean in practical terms? An average scope may transmit 85% or so, and inferior scopes substantially less. The human eye can distinguish transmission differences of 3% or more. Consequently, there is a very real difference in what you can see through a superior scope versus run-of-the-mill optics.

The very best rifle scopes human beings can create will transmit to your eye�under perfect conditions�a maximum of 94.5% to 95% of available light. There are but a handful of scope companies remaining that produce optics approaching these levels, Schmidt & Bender being one of them.

Under hunting conditions, when you might be trying to distinguish a target at absolute last light, these differences can be critical. It can determine whether you bag your game or whether you have long since called it a day"

I prefer transmit.But thats just me.
dave

Transmit and gather are two different things.

Transmit refers to how well (efficiency) the scope passes through the available light through the lenses. The more efficient lens coatings well lose a smaller percentage of light (photons) from the objective lens to the eyepiece lens.

The S&B site is wrong about light gathering.

from the Meade Instruments Corporation web site:

"Meade�s new, larger 80mm diameter ETX delivers more light-gathering for increased image brightness and greater detail. Moon craters by the hundreds, cloud belts on Jupiter, and Saturn�s rings are just the beginning of what can be seen with this telescope."
http://www.meade.com/etx/


Light-gathering power
Light-gathering power is proportional to the area of the telescope objective. A lens or mirror with a large area gathers a large amount of light. Because the area of a circular lens or mirror of diameter D is pi(D/2)�, we can compare the areas of two telescopes, and therefore their relative light-gathering powers, by comparing the square of their diameters. That is, the ratio of the light-gathering power (LGP) of the two telescopes A and B is equal to the ratio of their diameters squared:

LGPA / LGPB = (DA/DB)�

Example A: Suppose we compare a 4cm telescope with a 24cm telescope. How much more light will the large telescope gather?

Solution:

LGP24 / LGP4 = (24/4)� = 6� = 36 times more light

Example B: Our eye acts like a telescope with a diameter of about 0.8cm, the diameter of the pupil. How much more light can we gather if we use a 24cm telescope?

Solution:

LGP24 / LGPeye = (24/0.8)� = (30)� = 900 times more light.

http://users.zoominternet.net/~matto/M.C.A.S/lightgathering_power.htm

-Bob F.

5 a: to summon up <gathered his courage> b: to gain by gradual increase <gather speed> c: to prepare (as oneself) by mustering strength d: to gain or regain control of <gathered his wits>

Trouble I have with it is the gain/increase part.
dave

"gather" also means "collect" which also means "accumulate". And the objective of a telescope does indeed gather/collect/accumulate light (photons).

The larger the diameter of a telescope's objective, the fainter the objects it allows an astronomer to see because the larger objective accumulates more light (photons), in the same or a given time interval, than a smaller objective.

-Bob F.

Correct Dave, which is why I stated that sport optics are "passive" instruments. A larger lense has more light casting on it, but it does not actively gather light.

Well, exactly..... that means it is gathering more light!

I think you guys are just getting hung up on the word "gather".

-Bob F.

Well, is there really no gain? Think of this: A 50mm objective lens transmits a certain amount of light proportional to it's area. The light that exits the ocular lens is focused to a much smaller area called "exit pupil." So, if the scope transmits 50% of available light overall, but focuses the light on an area that is 10% the size of the objective lens, is not the light intensified?

No, I really don't have a clue. I'm just curious. In reading the previous posts, my mind went to the parabolic dish antenna, which does indeed have "gain" based on it's size (diameter) and the wavelength of the energy being measured.

-

A scope with a larger exit pupil (50mm scope) will provide the shooter with a larger beam of light than a scope with a smaller exit pupil (40mm scope) if both scopes are set at the same power. If both scopes are identical in quality, say two Leupold VXIII's, the intensity of the beam or light concentration, will be the same in the two beams. The larger objective scope will provide a larger beam or exit pupil of light. The intensity or concentration is determined by the quality of the glass, it's coatings and stray light management.

I have 50mm, 40mm and 36mm Leupolds on 3 remington rifles. The 50mm on my .280 mountain rifle is probably the brightest but not by much and not enough to make it worthwhile. It is ugly, awkward and makes the rifle look funny. When I get around to it I will sell it and by another 2.5 x 8 x36mm.

Yes, I believe that the use of the word gather is incorrect.

Again from the Schmidt & Bender web site, "The Truth About Light"



http://www.schmidtbender.com/facts_light.shtml

I'll take Schmidt & Bender's definition over Meads anyday

.....Think of light as "PHOTONS", which indeed is exactly what light is composed of, "particles" called photons. Now think of each of these photons as twigs, or small pieces of kindling wood. The larger objective diameter receives MORE of the 'twigs' which are then, by way of the lens configuration they are passed through, "gathered" together into a bundle (a smaller diameter shaft of concentrated photons). Binocs, telescopes, rifle scopes ALL gather light together into concentrated shafts of light images, the larger the objective lens, the greater the gathering power of that optical instrument....The gathering of light is of course improved by having a larger objective lens which thus receives proportionately greater numbers of photons of light, the curvature of the lens surfaces then bends the path of the photons travel, "Gathering" the received light into a precisely focused shaft of light.It is this same principal of optical performance that allows a magnifying glass to "gather" light into a precisely focused shaft of concentrated light, thus giving it the capacity to start a fire! All optical lens gather light, larger lens gather more light.

....Some folks get hung up on the semantics being used, but the term "gather" was settled on long ago as most descriptive of this optical process. S&B may not like the terms use, but they then need to find a better more accurate word to describe the process of receiving X quantity of light and 'bundling' the photons (?) into shafts of light images.If they disagree with the most descriptive term found by the optical industry through the many decades of it's existence, they need to come up with BETTER terminology. They haven't done that, rather they just seem to disagree with semantics that have served well for a long time!

Transmit is exactly what happens and that is the term that S&B uses. Taking the available ambient light and as you call it bundling it together is not gathering, one gathers nuts, not light.

Have you maybe wondered that a German company might not be the best at English word use? ........................DJ

The [bleep] we argue about cracks me up sometimes. Minus a cErtain postEr I can laugh and Enjoy it.

I checked with Meade Optical this morning about the term gather or transmit and they said..............


&#24314;&#35774;&#20013;


&#24744;&#24819;&#35201;&#26597;&#30475;&#30340;&#31449;&#28857;&#24403;&#21069;&#27809;&#26377;&#40664;&#35748;&#39029;&#12290;&#21487;&#33021;&#27491;&#22312;&#23545;&#23427;&#36827;&#34892;&#21319;&#32423;&#21644;&#37197;&#32622;&#25805;&#20316;&#12290;

&#35831;&#31245;&#21518;&#20877;&#35775;&#38382;&#27492;&#31449;&#28857;&#12290;&#22914;&#26524;&#24744;&#20173;&#28982;&#36935;&#21040;&#38382;&#39064;&#65292;&#35831;&#19982;&#32593;&#31449;&#30340;&#31649;&#29702;&#21592;&#32852;&#31995;&#12290;


--------------------------------------------------------------------------------

&#22914;&#26524;&#24744;&#26159;&#32593;&#31449;&#30340;&#31649;&#29702;&#21592;&#65292;&#24182;&#19988;&#35748;&#20026;&#24744;&#26159;&#30001;&#20110;&#38169;&#35823;&#25165;&#25910;&#21040;&#27492;&#28040;&#24687;&#65292;&#35831;&#21442;&#38405; IIS &#24110;&#21161;&#20013;&#30340;"&#21551;&#29992;&#21644;&#31105;&#29992;&#21160;&#24577;&#20869;&#23481;"&#12290;

&#35201;&#35775;&#38382; IIS &#24110;&#21161;
&#21333;&#20987;&#24320;&#22987;&#65292;&#28982;&#21518;&#21333;&#20987;&#36816;&#34892;&#12290;
&#22312;&#25171;&#24320;&#25991;&#26412;&#26694;&#20013;&#65292;&#38190;&#20837; inetmgr&#12290;&#23558;&#20986;&#29616; IIS &#31649;&#29702;&#22120;&#12290;
&#20174;&#24110;&#21161;&#33756;&#21333;&#65292;&#21333;&#20987;&#24110;&#21161;&#20027;&#39064;&#12290;
&#21333;&#20987;Internet &#20449;&#24687;&#26381;&#21153;&#12290;

I wish they hadn't misspelled a word in the second sentence.

-Bob F.

Maybe some run in their Taiwan division can better explain all this stuff..................grin