Unfortunately you do lose light putting a NVD behind a large piece of day glass, especially when you crank up the magnification.  This is why da torch or another IR illuminator is needed for these requirements especially with a Gen 2 system.  Hope this helps.

Vic

The main equation is the the Generation tube you're using, magnification and range to target.  I can look at an OLD spotting scope I have from Redfield (A MK IV to be exact) versus my Swarovski STS-80HD with a PVS-14 via a universal adpater at 15x with virtually no difference in the NV image at 100m. Now I am sure with a VERY cheap spotting scope I see laying around my local shooting range for rent would give lower viewing resolution with a Gen 3 device.  Now put a GEN 2 device and crank up with magnification to 15x and no matter what scope I use, the image is very dim and not capapble of good resolution....and yes the rental range cheap scope above mentioned would show the diminished gain of the Gen 2 even more versus the Gen 3.  I guess I'm not used to very cheap spotting scope glass.  Even though my Redfield MKIV is considered old and "cheap", I rate it pretty darn well with my 2K glass! I'm not to sold on the "qaulity optics" that cost thousands versus the cheap ones at $500-700. (My Redfield MKIV was $425.00 when I bought in 1994) I also have a so-called cheap set of Minolta's 10x50 I paid $350 for, and I still am amazed at the razor sharp image versus some 1K+ glass.  

Quoted: Quoted: I agree completely with Vic's statement above.  I have a gen3 MUM and a universal adapter for it that I use (and will be using ALOT this summer ) and I was shocked to find that nearly all of my riflescopes (given similar power) looked indistinguishable from one another.  Whether it was on a cheapo tasco or my personal favorite $40 simmons 3-9x40 or one of my uber nice Burris (the ones made here in the US) scopes, the image was sharp and I was easily able to watch furry critters at 150-200+ w/ and w/o a torch.  But I can't imagine gen2 would provide a very useable image, never tried it, but doesn't seem likely.  My $0.02 I don't want to sound like an optics snob but if your calling simmons (40$) cheap and a burris uber nice then you haven't played with quality glass. I'm not saying simmons or burris are not suitable for the job but they can't hold a candle to a NightForce, S&B, or USO scope.  Their is a reason we use NF, S&B, USO, and Leupold in the military. Durability is one major difference, but I bet you would be suprised if you got to use some of the nicer optics.  I used all cheap optics until I bought a ACOG and a Nightforce for 2 of my rifles.  Now I won't buy anything but top tier optics (so I don't buy much stuff now it seems!!)

While I agree with you on "day" optical qaulity glass, I think the initial point of the issue was day optics in combination with a NOD.  Lower qaulity optics I have found in front of a Gen 3 device is much less forgiving for night time ops except with the use of a high power IR illuminator of some sort. We do not have this luxury during the day of course or low light, (i.e. still too bright for a NOD). but help here might be from a white light to improve the lower qaulity glass light gathering ability.   Hope this helps.

Vic

Quoted: Quoted: My original post was if respect to the light gathering ability of large-aperture objectives, and whether that enhanced or assisted an older generation NOD. Alas I have not found anything with magnification in the F1.2 or F1.0 range. With big glass your lucky to get F2.8 or F2.0 and anytime you are limiting light... the image quality goes down. That is why adding supplimental light to the scene helps. Then however, you have crossed from passive night vision to active night vision and while most people are hunting critters and that is not a concern, some people in the LEo and Military need to remain "unannounced" as it were. IPSC_GUY SIERRA II ALPHA

For those folks whom need to remain "unannounced",  that is why I sell a good amount IR lasers and illuminators to these qualified folk.  Hope this helps.