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

Number one. That's because it has no lenses to rob light. Assuming that by "brightest," you mean the one that transmits the most light.

The larger scope has a larger exit pupil which allows the eye to resolve the image better.
It may also be better focused..... Just had to put that in there. Grin. E

dj,

No, no. no. I deliberately asked the question the way I did because I wasn't looking for your answer. The answer to your set of assumptions and your question is obvious.
I want MY question answered, not yours. If you want to ask your question, please do so.

Are you thinking of the theoretical maximum resolution of the optical system as limited by the size of the aperture in the front?

Read my assumptions. My eye pupil opens to 4mm for both scopes. My 4mm pupil fits inside of both scopes exit pupils equally well, only one has more (extra) exit pupil surrounding the pupil of my right eye. Why would the larger objective scope be better than the other, as far as the photons striking the retina of my eye?

DMB, No need to be rude. I answered your question with my first sentence.

There might be a theoretical difference in that the 3-9 might have more lenses and be slightly dimmer due to more lenses but that difference is likely below the detection threshold of the human eye. Also the scope with the larger exit pupil will be more forgiving of eye position. You'll see the full image in the entire 11mm shaft vs the 4mm shaft of the smaller objective with 7mm of tolerance..............................DJ

It's not a theoretical question at all. Guys on different forums are claiming that a larger objective scope allows you to see better than a smaller objetive scope. I'm trying to get to the bottom of the whole thing, with some clarity. If, on a given day, your eye pupil only opens up to 4mm, as an example, why does all the "extra" scope exit pupil of a large objective scope make for better viewing, than a smaller objective scope? (Given that the smaller obj scope has an exit pupil as large as 4mm, in my example)
That's exactly whay I worded my question as I did.

Wrong. You threw your stuff in the equation to muddy up the question I asked, and I didn't miss that.

I didn't mean your question was 'theoretical' in the pejorative way some use that word.

The fineness of the details a given optical system can resolve has a theoretical limit determined by the size of the aperture. Here is an explanation given to me when a resolution question came up a while back:



I was asking if you were considering that effect.

If you want me to take a stab at this I will have to say that the scope with the larger objective perhaps just has a better optical design. I know that you stated that you felt both were equal in quality (glass and coatings) but that doesn't mean that the design of the optical system is the same, especially given that we are talking about a fixed power vs. a variable. Just because a variable has more len's doesn't mean that it can't or won't resolve an image better. Some of the more expensive scope these days have more len's in them to sharpen image quality, be it brightness, resolution or contrast.

I have three Ziess V series scopes,a 2.5-10x42,a 2.5-10x50,and a 3-12x56.

It is reasonable to assume that the optical quality of all three is practically the same,the only difference when all are set at a given magnification( 8x for example) is the exit pupil which is a function of the objective diameter.

In very dim light,it is possible to see more detail in the 56mm variable,followed by the 50mm,and the 42mm shows the least detail.

I typically use the 56mm scope from stands over agricultural fields,the 50mm is for hunting food plots,and the the 42mm has mostly been used stalk hunting.

I use even smaller and lighter scopes when I am going to have to carry a rifle a lot,mostly small Leupold variables.

Big scopes excel at some things and stink at others,but when it comes to serious low light performance, there is really no contest,a big exit pupil with plenty of magnification and really good optics wins easily.

I'm not going to read the relms of posts on this thread but I'm betting their are some goodies!

EVERYONE is not into big objective scopes or big scopes in general..My largest scope is a 2x7 Leupold and its on my varmint rifle, and a 4x12 is a nice varmint scope..

For big game I want no objective larger than 20 mm and I don't want it to protrude much beyond the front ring..My all time favorite hunting scopes are the 1.5x5, 1x4, and the old 3X Leupolds..They stay sighted in with rough use and they can be depended on to hold a zero almost as well as iron sights but not quite. Big scopes are continually going off zero with hard use and we see this every year in out hunting camps. I have done a lot of tests along these lines and they have convienced me that I am correct on this subject.

Don, I suspect clarity difference you seeing has something to do with your first assumption.
Also I suspect that your pupil size may have changed when you changed scopes.

Does a magnifing glass "gather" light? It certainly focuses it enough to start a fire.

A couple of you guys would make Bill Clinton proud trying to Parse an easily understood and commonly used term........................DJ

that depends on how commonly the word common is commonly used.........

I don't know about others, but I'd be splitting some pretty fine hairs to be able to distinguish these three examples of the two words' definitions, "focus" and "gather":







(from dictionary.com)

But while I don't especially like the term, in part I suppose because it does get used in a deceptive manner sometimes, it isn't really inaccurate either when used appropriately.

That said, I don't especially care much for high light "focusing" or "gathering" scopes as much as I appreciate scopes which are compact and fit more closely to the rifle. IOW, I don't do 50mm stuff - but have no problem with those who choose to.

I guess one question I have is, "Would it be more or less confusing to say that one scope focuses light better, while another focuses the image better?" (Better definition)

Originally Posted By: Dew
It is my understanding that the 50 PASSES more light through the scope than a 40 does. No scope can "gather" light.

Wow! I've been off the site and I come back and find 14 pages. I think I will stick with my "PASSES" or transmits rather than "gather". I suspect the word gather has been used more lately to describe a change in the meaning that we we think. I offer the word Gay. It used to mean happy etc. Now we know that the meaning has been "changed" to replace homsexual or queer.
The photo of the tubes of two sizes show no gathering of light. just a "catching" of it as would a straignt tube only allow what is direct line with the opening. An example would be a rain guage which MUST be straight without a belled end. If it is belled it will pick up or gather more water than the tube will measure properly. I cannot see how you can "bend light" to go into the tube of a telescope if it is out of the alignment of the tube. It really is a slow day for this thread to have had this much time spent on it. Sorry about my spelling. I am using a laptop for the first time and my big fingers hit the wrong keys and on top of that I can't figure out how to use a spell check on this thing. Not to worry though, I have a new tower sitting in the box and the puter guy is coming tomorrow to fix me up. One last request.... The reply from Meade was nothing but square little boxes. Can someone tell me what it had to say? If you copy it and post to a thread I still just get the little boxes and that is all.
Dew

You answered your own question didn't you. Most scopes aren't Straight at the objective end are they? It's rather queer that you didn't notice that. .........................DJ

DMB, first of all, during daylight, your eye's pupils won't be dialated to 4mm. That only occurs during twilight and the very brightest nights. During daylight, the eye's pupils are usually dialated to not more than 2mm's.
Second, the extra exit pupil size of the larger scope will allow the eye to "roam around" inside that larger exit pupil and that will allow the eye to see more detail. All of this is explained in Barsness's great book, "Optics for the Hunter."
I might add that as a practical matter, alot of other things come into play in this ability to see detail as well. So true comparisions with rifle scopes may be very difficult to find.
What Barsness points out in his book is that if you take two identical binoculars, differing only in magnification,, and compare them, the one with the lower magnification will resolve an image just a hair or so better than the one with more magnification. I presume that this applies to rifle scopes as well. E