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Scope light transmission
bassassassin007
Member Posts: 87 ✭✭
I am interested in a new scope for a brush gun that may occasionally have to shoot 250 yards or so. I am torn between the Leupold VX3 1.5-5x20mm and the Leupold vx2 EFR 3-9x33.
I like the magnification flexability of the 3-9. My thought is about light transmission. Though the vx3 has better lens coatings, the vx2's lens has a lot more surface area for light gethering.
Which one would you choose and why?
Dave
I like the magnification flexability of the 3-9. My thought is about light transmission. Though the vx3 has better lens coatings, the vx2's lens has a lot more surface area for light gethering.
Which one would you choose and why?
Dave
Comments
I would choose the 1.5x5 for your use if shots are not going to over 250 or so. However, you should understand that I shoot (and hunt) primarily with handguns and have gotten very accustom to using low power scopes. A 4-5X seems totally adequate out to 250-300 yds for me. Also, the VX3 is a little higher quality scope, INMO, than is the VX2. I also like the smaller size of the 1.5x5. The 20mm objective should provide adequate light transmission for the lower powers of the scope. (20/5=4. 20/4=5. 33/9=3.67. 33/5=6.6) Thus, you might roughly expect the same light transmission from the 3-9 set at 6.6 power that would be obtained with the 1.5-5 set a 4 power.
Good luck.
The vx2 has a larger exit pupil diameter than the vx3s at any comparable magnification. So if they were both vx2s or vx3s the 33 mm objective would clearly be better as far as how bright they would appear to be. My concern/question has more to do with the light transmission coatings of the vx3 vs the vx2 at the same magnification, Say 3-5 x since this is where they overlap. I guess the question is, Do images appear brighter through a 20mm vx3 lens @3x or through a 33mm vx2 lens @ the same magnification?
Sorry for my confusion,
Dave
The VX-3. At both extreme ends of magnification, the exit pupil of the VX-3 is greater which means more light getting to your eye.
Intersting... but at 5X the exit pupil of the VX3 would be 4 while the the VX2 would be 6.6. How significant is this? Would the better lense coatings compensate?
Pointing each out my back yard into the woods with essentially only the moonlight for illimination, they all appeared to be equally bright (as least as far as my eyes are concerned). Actually the M8 probably could have been considered the brightest, but I think that was because it has the lowest magnification and more trees were in the field of view reflecting moonlight. I will test this again but closer to sunset which won't be pitch black.
Today I went to the Leupold website, and unless I mis read it, they write that the new vx2 line is optically similar to the vx3/vari-x 3 lines. The lens coating system they use for each might be different, but optically they are comparable. Perhaps the difference in price isn't for brightness, but other features and/or cunstruction ruggedness.
Dave
I did a little testing last night in my back yard at about 9PM. Using a M8 fixed 4x w/28mm lens, Vari x3 4.5-14 w/50mm lens, and a vx2 3-9 w/33mm lens, I set each up so the pupil diameter would be 7.
Pointing each out my back yard into the woods with essentially only the moonlight for illimination, they all appeared to be equally bright (as least as far as my eyes are concerned). Actually the M8 probably could have been considered the brightest, but I think that was because it has the lowest magnification and more trees were in the field of view reflecting moonlight. I will test this again but closer to sunset which won't be pitch black.
Today I went to the Leupold website, and unless I mis read it, they write that the new vx2 line is optically similar to the vx3/vari-x 3 lines. The lens coating system they use for each might be different, but optically they are comparable. Perhaps the difference in price isn't for brightness, but other features and/or cunstruction ruggedness.
Dave
It is those coatings you are talking about that are the apple in the pie. I would get either a 2-7x or 3-9 x variable. The human eye can only dialate to about 5-6mm. You can adjust a variable to get there, a fixed you can,t, and a low power variable like the 1.5-5x is still to small of an objective lense diameter.
Back to those coatings. They are the very thing that increases light transmision thru the lens, versus reflection off the lens. The more transmission, the more light you are piping thru that 5mm hole called the exit pupil.