Scope light transmission quality

This may be old news to some of you but it was new to me. A 3.5X10X50mm Vari-X-III will transmit more light than a 4.5X14X50mm Vari-X-III when set at the SAME power. The folks at Leupold told me this, so I decided that I would check for myself. I have both models so I checked them the other evening at dark. Sure enough, the 3.5x10 was noticibly brighter, in fact it was almost as bright as my relatively new Illuminator 50mm (Jap made)which is the near optic twin of the Weaver GS.

I had figured that any 50mm Vari-X-III Leupold would be have the same light transmission quality regardless of the power range. Taint so. FWIW, the Tech at Leupold told me that all brand scopes were that way as long as you were comparing the same model to model. The Tech at Leupold told me that the advertised 98% light transmission for the VX3's is based on the 2.5x8 model. The 3.5-10 is 97%, the 4.5-14 is 96%, and the 6.5x20 is 95%. I suppose that the greater the power, the more lenses, are needed which reduces light transmission???

I don't know if the Vari-X-III's had the same incremental decrease as the VX3's, but it has made me rethink whether the extra power of the 4.5X14 is worth a sacrifice in light transmission at near dark. I usually set mine on about 7 or 8 power near dark anyway.  (we can legally harvest deer up to 1hr AFTER legal sunset) The bottom line is that I could definitely see a difference and it surprized me.

I would be curious to know if anyone has compared the Nikon Monarch Gold 56mm to any other premium "low light" scopes near dark.  I compared one during daylight to a VX3 50mm and a Swarovski 1 inch 50mm.  The resolution of the Swarovski was unlike anything that I have seen (I could see individual water droplets on leaves at about 80 yards).  The resolution on the Nikon was a reasonably close second and the Leupold was a distand third.  Again, this was daylight so I don't know how that would translate to near dark performance.  Comments/experiences would be appreciated.

Now if I can just find a good pair of "low light" binoculars for under $400..........

hmmm... good info. i figured that the scopes wouldnt be quite as clear if they were high power VS. lower, but i never figured the brightness would be different. try it when they all exert the same exit pupil, it shoudl be about the same, but jim not postive.

cory

That is what I thought too.  The issue here was that I DID compare them at the same power....up to 10 power, and the 3.5X10 was brighter and clearer at every power setting at near dark (about 50 min. after sunset).  During the daytime I can see no difference at all.  I wish that I had done this comparison before I bought my second 4.5X14X50.  I never thought to compare them since they were both 50mm Vari-X-III's.  Oddly enough, the 3.5x10 was my first 50mm Leupold.  Oh well, live and learn!!! 

I am in the market for another scope right now.  Until I did this test, I had ruled out the Nikon Monarch Gold 56mm, because it was "only" 10 power.  Now I am looking for comments from folks that have had some real life experiences with this scope in low light conditions.

have you looked at the ziess conquests? there an awfuel fine scope.

cory

Yes, I looked at the 30mm 3x12 and was impressed, but the one that astounded me was the Swarovski 4x12x50mm w 1 inch tube.  WOW!!! I have never seen that degree of resolution before.  It costs a bit over $800 locally, which is on the outside edge of my price range.  I looked at a number of the 1 inch tube Conquests.  They were OK and better than the Leupold, but they had a bit of glare in them.  I hate glare!

hmmm, yeah, i have noticed a little glare, but for the value, ill get used to it

cory

One reason, with the two models you compared, is that the 3.5-10 Leupold does not have an adjustable objective as opposed to the 4.5-14 which does. When a scope has a adjustable objective to correct for parallax it requires an additional lens to do this. The more internal lens a scope has causes a loss of light transmission as light passes through each internal lens. This is one of the reasons why lens coating formulas are such guarded secrets. A variable scope can have between 6-10 internal lens, so I think you can begin to get the picture. By the way, if you have occasion to speak with the Leupold tech in the future, ask him why they don't claim to be the new brightest scopes in the world. S&B advertises that their scopes can transmit up to 95% light transmission. I would love to hear their answer.