40mm scope versus 50mm...
 

Im getting ready to buy a new scope, it will be a Leupold. I want to hear some opinions on the objectives, 40 and 50. We own several 50mm, and a few 40s as well. Though it seems we always have more trouble getting the 50s dialed in. Is there really THAT much more advantage has far as light transmission is concerned? And while Im at it...any recommendations on which Leupold for a .300 RSAUM? Its been a while since I bought any Leupold and you know how times change as well as products (not always for the better) thanks.

RE: 40mm scope versus 50mm...
 

Your sight rings moght answer this for you. I had to go with 40mm because the 50's would hit the barrel with the scope rings that came with the gun. (Ruger . . . love it!)
I can't see any reason to go with the 50mm unless it is a high powered variable say up to 14 or more. The higher you go in power with any optics, the more light you loose so the larger objective will let in lore light. Look at the objective on most spotting scopes.
As far as which scope? I went to buy a Leupold (only scope I'd used for 30+ years) and came home with a Nikon Monarch on it. Much better light gathering, clearer view, easier object chase, and less money. Worth a look.

RE: 40mm scope versus 50mm...
 

Kbeaner...I called Leupold a few years back and asked the difference between 40 and 50 mm objectives...The 50 lets in about 3% more light if the lenses have the same coatings etc...

Now, what does this mean to us deer hunters?? I bought a VX-II 3x9x40 and my brother (the one always wanting bigger/better...) bought the
VX-III 3.5x10x50 for his .280...

Let me make a couple of points as I have hunted and killed deer with his setup...
1) The 50mm affects your cheek weld on the stock, not as bad as see through mounts, but enough that when I shoulder his gun I have to move my face to look through the scope...
2) I can tell no difference in how "late" you can see to shoot deer...In other words, in a quality scope a 40 mm is plenty bright to shoot even as much as 15-20 minutes after legal shooting time is over....This in itself makes a 50 mm a mute point to me...
3) As you get older your pupils will not dialate as well as when you are younger....Guess what, that little bit of extra light the 50 mm gives ain't going to help if your eyes can't use it....

The biggest improvement I have made to my two Leouplds on my deer rifles were to return to Leupold and have the Heavy Duplex reticle installed...The crosshairs are what fade in low light, more so than the deer.

One other point...The Leupolds I have are the older VX-IIs...The current VX-I has the same glass as I have...The new VX-II and VX-IIIs let in even more light than mine would, but mine is plenty bright...I'd go with the 40mm...

Hope this helps...

RE: 40mm scope versus 50mm...
 

What alot of people don't understand is a 50mm resolves more at far distances. In other words for varmit hunting, I highly suggest 50mm. At 500 yards, instead of a groundhog looking like a fuzzy blob, you can actually make it out. You might be able to actually id a deer antlers at 500 yards. A 50mm has 36% more area also, so lets in more than 3% light. I wonder if that 3% is linear or logrithmic.

RE: 40mm scope versus 50mm...
 

I have never seen the need for a 50mm scope,and I don't like to mount my scopes as high as is required with a 50mm objective lens.If I need a brighter scope,I buy a scope with better quality coatings and lenses.

RE: 40mm scope versus 50mm...
 

IMO their is a difference between light gathering, and light transmission. If the light is not transmitted to the eye, then it is of no value(actually a negative). Again IMO if you go to the 50mm objective, then go with the 30mm body to transmit this light to the eye.

The second and thirdfactor with light transmission is lens quality, and lens coating quality. Obviously the better the lenses and the better the coatings, then the more light transmission to the eye.

Bottom line, buy the best glass you can afford. A one inch tube-40 mm Swarovski will transmit more to the eye than a wiz bang 50 mm, with a 30 mm tube at 32 power.

Determine the power you need (most people buy too much). I would rather have a straight 6X Swarovski than a 3.5 X 10 Leupold. Tom.

RE: 40mm scope versus 50mm...
 

Check this out...

http://www.leupold.com/hunting-and-shooting/products/scopes/vx-l-riflescopes/vx-l-4-5-14x50mm/

Want a 50mm that sits low, you got it. It will sit as low as a 30mm, but it's gonna cost ya!

RE: 40mm scope versus 50mm...
 

I haven't found any advantage using a 50 mm for hunting during legal hours that a 40 or 42 mm couldn’t do...

RE: 40mm scope versus 50mm...
 

A humans eye will only dialate to aproximately 7mm in diameter in pitch black total darkness. At early and last light your eye will be dialated to about 4mm - 5mm if you are a young healthy human with no eye problems. Less as you get older and less the brighter it is.

Divide the objective lense diameter by the magnification to get the scopes exit pupil diameter. Example... a 3-9X40 scope will have an exit pupil of 13.3mm at 3 power- 4.4mm at 9 power.

If a scope has an exit pupil larger than what your eye is dialated then that light is wasted and not absorbed by your eye and will not appear any brighter than the same magnification with a smaller objective. Example... a scope set at9 power will appear equally bright regardless if your arehave a 40mm or 50mm objective lense.Because with the 40mm the exit pupil diameter is 4.4mm which is just about exactly what your eye will be dialated at last shooting light and with the 50mm lense the scopes exit pupil will be 5.5mm which will likely be larger than what your eye is dialated.

If the scopes exit pupil is smaller than what your eye is dialated then your eye/ brain will interperate this as less bright. Example a scope set at 12 power will be brighter with a 50mm objective lense than it would be with a 40mm objective lense. Because with a 50mm lense the scopes exit pupil will be 4.2mm and with a 40mm lense it would only be 3.3mm.

So figure out how much magnification you are going to purchase and select your ebjective diameter accordingly.


Just a note.... There is no such thing as light gathering. A scope doesn't hop off the rifle and go out and gather up light as if it were picking berries. A scope only TRANSMITS light.

RE: 40mm scope versus 50mm...
 

Well, photons move. The larger the objective is to pick up the photons, the more bright an object will appear. Same as with satillite dishes, same physics apply. But I understand what your saying. If you are viewing say a licence plate at 500 yards, and it appears very bright contrasted to without. It would be brighter if you walked up to it to the point its at the same magnification. Photons flying thru lenses concentrating polarized light at your lenses loses some brightness, clarity, etc. As some recent independent tests have concluded, scopes claiming 95% is pure bull. Its more like 92% as John Barsness recently reported. I believe that.

RE: 40mm scope versus 50mm...
 

It's a common myth that scopes with 30mm tubes transmit more light. It's simply not true, however. I was convinced of this too a few years back but was set straight by the late Dick Thomas (a legimitate optics expert) of Premier Reticles.It's verified on several scope manufacturer's websites if you do a little looking. For example, this is from Leupold's website:

Advantages of a 30mm Maintube
Does a 30mm maintube give you more light? The principal advantages of the 30mm tube are added strength and increased adjustment range for windage and elevation. For example, the M8-12X (1" maintube) has a total elevation adjustment of 51 minutes. The Mark-4 M1-10X (30mm maintube) has 90 minutes. The percentage of light passing through a scope is a function of lens coating and optical design, and has nothing to do with tube diameter.


I'm partial to 1" tubes myself, but have owned 30mm scopes in the past.

Edited to add: I guess this site has a filter that blocks certain words. Mr. Thomas's first name was the same as a particular male appendage, so I suppose that's why it doesn't appear.

RE: 40mm scope versus 50mm...
 

I also found out from Leupold a while back that on the Leupold Euro series with 30 mm tube that the internal parts are the same as the 1” tube, so no real benefits there either...

RE: 40mm scope versus 50mm...
 

Better not tell that to our Optics engineers. They will have to go back and rewrite all physics books dealing with transmission of light.

What a 30mm body can give you, is more margin of error in gathering of the light. In other words, what your saying is correct, if the objective lense is perfect, but due to flaws in the objective lense grinding, a 30mm tube can correct for these flaws with giving a huger surface area to collect light from the objective.

RE: 40mm scope versus 50mm...
 

Sure but a scope does not go out and gather up these moving photons. It simply transmits a certain percentage of the ones that are traveling in the direction of the scope... per lens surface.

Provided your eye is dialated wide enough to accept all available light being transmitted. If your eye is dialated to 5mm and the exit pupil of the scope is 6mm then all light outside of that 5mm circle is wasted and won't make the view any brighter than it would with a smaller objective lens. All other things being equal. Becasue even though that larger lens is transmitting more light it is transmitting it outside your eyes ability to absorbe that light.


Each lens surface (front and back) will reflect a cetain percentage of light away from your eyeas it passthrough the lens. The more lenses a scope has the more light is being reflected back away from your eye and the less brightthe object will appear.


A 30mm tubed scope will transmit more light provided that scope has 30mm glass inside it.

RE: 40mm scope versus 50mm...
 

Holy crap! Where are my hip waders, the bs is getting deep in here.

I can tell no difference between a 40 mm and 50mm objective at normal distances during legal shooting hours.

Like was said before if you're varmint hunting I fully recommend a 50 mm obj. Not for "light gathering" rather for better resolution at distance.

I like low power and low mounts for quick target acquistion on a big game rifle. My favorite is a Leupold 2.5-8 x 36mm set in low mounts. AT 2.5 x I can shoot with both eyes open.

RE: 40mm scope versus 50mm...
 

Kbeaner:

I think it depends a lot on exactly what you want to use your rifle for? Also exaclty where you will be hunting?

If you are int he south, with our long seasons, and often very thick forests and high humidity levels, and light pick up is your #1 concern, then yes a larger objective will help (exactly how much...well there are lots of numbers being thrown around, but even 3% is more, might be just enough more). Quality of the glass and the coatings are the most important thing. The coatings on the VX-IIIs are the standard minimum for what i put on my rifles. Expensive, sure...but its the most important part of the set up save the bullet itself.

If you are out west, and will be hunting by day, then light pick up is no big issue. If you are hunting big game, then I'd say go with a 40 AT MOST. I'd rather have a 36.

One other thing to consider, fixed power scopes will, for the most part, transmit a little bit more light, just because there are fewer pieces of glass. So if you were REALLY wanting the brightest thing out there....Schmidt and Bender makes a fixed 8x56mm thats one of the brightest in the world.

RE: 40mm scope versus 50mm...
 

Fortunately, no physics books will have to be rewritten as a result of whatI wrote, which was essentially correct.I suppose a 30mm tubehas the potential to offer a slight (emphasis on slight since 30mm is not significantlylarger than 1") improvement in resolution, but only if larger internals lenses are utilized. Maybe that's what you're talking about, but I'm not sure. The fact is, however, thatLeupold and many other scope manufacturers use the same size internal lensesin their 1" and 30mm scopes.So in this case the only advantage to the larger tube is more adjustment range and a little bit more rigidity.

RE: 40mm scope versus 50mm...
 

It's a common myth that scopes with 30mm tubes transmit more light. It's simply not true, however. I was convinced of this too a few years back but was set straight by the late Dick Thomas (a legimitate optics expert) of Premier Reticles.It's verified on several scope manufacturer's websites if you do a little looking. For example, this is from Leupold's website:


I respectfully disagree. I do believe a 30mm tube on a high quality scope with high quality glass is better than 1 inch tube. But I believe the difference is splitting hairs.

IMO, and as I believe I stated earlier, it is the quality of the glass and coatings that makes the scope. If all things are equal(lenses and coating), then IMO a 30mm tube with 56mm objective will allow me to see game better in the fading light. And isn't that what we are all really getting at?????

When I hunt in low light situations, and fading light is the best time for a large buck, I hunt with my 7600 Carbine that has an 8X56 Zeiss on top of it. I have a couple of Zeiss scopes, A couple of Swarovski scopes, and a pot full of Leupold's. They are all god scopes, but if you want the best in low light-then believe me that Zeiss 8X56 is tough to beat. I have nothing but experience to prove this with, but again IMO the fixed power scopes seem to do a better job in low light. I can not prove that, but it has been my experience. Tom.

RE: 40mm scope versus 50mm...
 

I'll call Amen! T* Coatings on Zeiss Diavaris are right up there on the top. I suspect we would have to get BigCountry to analyze the lot to tell us which one really is brighter, but a lot of it has to do with each shooters indiviual eye sight. Schmidt and Bender and T* Zeiss' get my nod for the top two....which is #1...depends on who you ask...but you can't lose either way!

RE: 40mm scope versus 50mm...
 

Ok, your right, I was making assumptions that someone would use 30mm lenses. But leupold is the only one I know that does this. I could be wrong.

RE: 40mm scope versus 50mm...
 

Not sure if your pulling my leg or not. But I only can test in spectrums barely visable to dogs. All my equipment is set up for 800nm or above. I am not sure of how valid my tests are. I just play around with my hunting gear after work. I do have a Back reflection test set at 1200nm that is pretty cool. I get like -20db back reflection on a pine ridge 2X I got and get like -45dB on a ziess conquest. I am not sure what spectrums apply in twilight. These guys who work in this field have the equipement to change coatings nad test at the exact lamda at twilight and morning. I just play. I am not even remotely in thier applications. Mine is all freespace data transmission and such. I just take an interest in this stuff.

RE: 40mm scope versus 50mm...
 

wow, some great info here. Thanks everyone. I had pretty much decided on a 40mm, but wanted to see the argument for the two, and the info here settled mythoughts and debatesI have had with our hunting buddy.I have 50mm on my .260 and my Encore 50cal of all things...simply b/c one was free and the other was a gift from my father, who was went with the 50mm due to a couple people giving the "it gathers more light" argument. I have been eye-balling the Leupold VX-III in 3.5-10 X 40, and I think that is what im going with....and going to see if the guy will cut me a deal on 2 leupolds so I can replace the 3-9X50 Tasco that sits atop my .260. :D

RE: 40mm scope versus 50mm...
 

Checking the leupold website the VXIII 3.5x10x40 is listed as having exactly the same field of view as the VXIII 3.5x10x50.In fact this seems to be the case with all of the leupold variables that I bothered to check.

RE: 40mm scope versus 50mm...
 

That's correct, a larger objective lens has nothing to do with the field of view.

Field of view is determined by howeach piece of glassis ground and contoured which effects how the light is bent when it enters the scope.

RE: 40mm scope versus 50mm...
 

I ain't gunna try to get technical so just go with 40mm. Otherwise,you have to go with high rings and you lose natural fit so it ain't worth it.

RE: 40mm scope versus 50mm...
 

Wow!!! the physics here I can admit are far beyond me. My 2 cents would be buy what feels most comfortable to you. See if you can shoulderyou gun orthe same gun at a gun dealer with both a 50 and a 40mm scope. I think it's most important what is right for you.It alsodepends on what you are scoping for. If it is for deer within 300 yards I don't think it will make much difference ifthe scopes are the same model from the same manufacturer. Over the years I've seen some guys buy the biggest and the best butwith out the time in the bush their harvests have been no better than the guy who spent 100's if not 1000'sless. I prefer the Nikon scopes but I'm no expert, just another hunter that has become comfortable with the equipment that I use.