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.