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See lots people lean to lower power scopes. My question is 2-7 power scopes seem to be 32 mm and 3-9 runs 40 mm. How much light gathering difference is there? Will it give you an extra 5 min I'm the morning?
Scope confusion
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My experience is between the two scopes you mentioned and if everything else is equal, such as manufacture and lens quality, then the noticeable difference to you will probable be zero. Weight and size will be the main difference between the two. Two scopes of the same size from two different manufactures can have different light gathering capabilities due to the quality of the lens coating.
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Light-Gathering Power
The ability of a telescope to collect a lot more light than the human eye, its light-gathering power, is probably its most important feature. The telescope acts as a ``light bucket'', collecting all of the photons that come down on it from a far away object. Just as a bigger bucket catches more rain water, a bigger objective collects more light in a given time interval. This makes faint images brighter. This is why the pupils of your eyes enlarge at night so that more light reaches the retinas.
The ability of a telescope to collect a lot more light than the human eye, its light-gathering power, is probably its most important feature. The telescope acts as a ``light bucket'', collecting all of the photons that come down on it from a far away object. Just as a bigger bucket catches more rain water, a bigger objective collects more light in a given time interval. This makes faint images brighter. This is why the pupils of your eyes enlarge at night so that more light reaches the retinas.
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The ability for any scope of any power range to allow enough light to filter through so as to make it a capable scope at the fringes of daylight are found mainly in three factors. 1.) and most important is the quality of the glass used in making the scope. 2.) is the quality and number of coatings all surfaces receive helping the scope capture certain wavelengths from ambient light 3.) is the scopes objective size versus the magnification available or used.
A scope's ability to pass light is affected by the both the power (used) and objective size. During critical times a scope set on 9X and having a 40mm objective will pass no more light than a scope set at 6X and having a 32mm Objective lens, all else equal. Actually, in this case, the 32mm scope would pass just slightly more light through. Figuring how well a scope will be able to pass how much light at what power is a simple task of dividing the objective size by the magnification. In these two cases, the 40mm objective divided by 9X would equal 5 (we'll call that the light transmission factor), which is very close to the maximum any human eye can use. In the other case the 32mm Objective divided by the magnification of 6X equals approximately 5.3 which is just slightly higher, allowing slightly more light to pass.
People having perfect vision (is there such a thing?) would be able to utilize up to a transmission factor of about 6.0, and any additional light gathered and passed would simply not be usable. One can use a quality low power scope of say 1-4x20 and still have the same light available to their eye as a larger scope. The only thing they will not/do not have is higher magnification. If one does not intend to utilize their scope as binoculars nor shoot at long range in low light, a high power, large sized objective scope is not needed. If one plans on shooting at longer ranges in low light conditions, then a scope with higher magnification needs a larger objective, but still only up to about a transmission factor of about 6.
Again, the more important factors in getting a scope useful for low light situations lies rather with glass quality and coatings rather than simply adding a larger objective. Hope that helps some.
A scope's ability to pass light is affected by the both the power (used) and objective size. During critical times a scope set on 9X and having a 40mm objective will pass no more light than a scope set at 6X and having a 32mm Objective lens, all else equal. Actually, in this case, the 32mm scope would pass just slightly more light through. Figuring how well a scope will be able to pass how much light at what power is a simple task of dividing the objective size by the magnification. In these two cases, the 40mm objective divided by 9X would equal 5 (we'll call that the light transmission factor), which is very close to the maximum any human eye can use. In the other case the 32mm Objective divided by the magnification of 6X equals approximately 5.3 which is just slightly higher, allowing slightly more light to pass.
People having perfect vision (is there such a thing?) would be able to utilize up to a transmission factor of about 6.0, and any additional light gathered and passed would simply not be usable. One can use a quality low power scope of say 1-4x20 and still have the same light available to their eye as a larger scope. The only thing they will not/do not have is higher magnification. If one does not intend to utilize their scope as binoculars nor shoot at long range in low light, a high power, large sized objective scope is not needed. If one plans on shooting at longer ranges in low light conditions, then a scope with higher magnification needs a larger objective, but still only up to about a transmission factor of about 6.
Again, the more important factors in getting a scope useful for low light situations lies rather with glass quality and coatings rather than simply adding a larger objective. Hope that helps some.
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Scopes do not gather light, it is actually light transmission through the optics. It is the quality of the glass and the anti reflective coatings more than the size of the objective lense or tube diameter.
Take a look at the Leupold VX-3 series of scopes. The 1.5-5x20mm, 1.75-6x32mm and 2.5-8x36mm scopes are very bright and will extend the trigger time. Be aware of your state's shooting hours as these scopes will allow you to exceed these time limits!
JD338
Take a look at the Leupold VX-3 series of scopes. The 1.5-5x20mm, 1.75-6x32mm and 2.5-8x36mm scopes are very bright and will extend the trigger time. Be aware of your state's shooting hours as these scopes will allow you to exceed these time limits!
JD338
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336ER and JD338 have it right. Scopes do NOT gather light. They are just glass, nothing in them is designed to "gather" light. They simply transfer light.
I've heard many people say that 30mm tubes are superior to 1" tubes in this regard but I'm out of my league to even approach that subject.
I've heard many people say that 30mm tubes are superior to 1" tubes in this regard but I'm out of my league to even approach that subject.
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It's a term used in optics that is confusing, at best. That's why I posted the definition from the telescope industry. They, and the scope manufacturers, use this term, I think to purposely confuse folks into thinking that their optics can actually make the dark look light. That's why we have night vision optics.
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Eli, The 30mm "thing" is not an easy one to decipher, there is no doubt of that. I own a couple of Leupolds with 30mm tubes and really like them. Will they transfer more light than a 1" counterpart? Yes and no. All things being equal the larger tube will allow more light to pass through, but again it's other factors that actually are more important, glass and coatings. In other words the miniscule amount more (of light) will quite likely not even be useable to one's eye.Eli Chaps said:
The best features of a 30mm scope are their greater strength, generally larger allowance for adjustment and also what many feel is a more forgiving "eyebox" (include me among them). Is that enough reason to offset larger physical size and weight? How the heck would I know.... ;D. I will simply say that personally I am very happy with the two 30mm scopes I own and would purchase another driven by need.
In a side by side comparison with the 30mm Leupold (2-7x33) and a 1" Zeiss Conquest (3-9x40) my old eyes see more clarity in low light from the Conquest, but an easier sight picture from the Leupold, due to it's excellent for low light reticle, a #4 type. Better glass and coatings from the Zeiss product and a better choice of reticle for certain applications for the Leupold. Both are extraordinary at the end of legal shooting, IMHO.
Which is better? I don't reckon I'm smart enough to know for sure...... ???
Ed
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