Im looking for a new scope and would like to know your experience with the best light transmission from scopes. Ive long heard S&B to be one of the best. While not ruling out a PM2 I was in market for something like a k624, zp5, actar, or march. Somthing in the 3k range. I'm looking at the zp5 and like reticle, but have heard it isnt the best at light transmission and dims a little at higher power. I do a lot of longish range hunting for feral hogs often in late evening or early morning with low light and shadowing so light is a major factor in my decision. Thanks for posting your experience.
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Rifle Scopes Light transmission
- Thread starter rcparker
- Start date
The 624i has long been known for very high light transmission. I have both S&B and Kahles and both are very good in low light. The other I have never used just looked through so no real world. Like a lot of thing it comes down to what you are willing to spend.
All of the better brands have very similar light transmission.
Generally, with modern scopes, light transmission is not a good predictor of low light performance (or optical performance overall).
ILya
Generally, with modern scopes, light transmission is not a good predictor of low light performance (or optical performance overall).
ILya
I understand may thing including contrast and resolution play their part in image quality. I am not trying to quantify light transmission with a number. Maybe light transmission was not the best or even correct term. Im just asking for a comparison of low light performance from people who have owned mentioned scopes. I have a march 3-24×42 that's great for my light weight backpack gun but suffers at high magnification low light conditions.
Your March suffers in low light at high magnification because it has a relatively small objective size. Light transmission has a very specific definition: it is a ratio of how much light makes it out of the scope compared to how much light makes it into the scope. That is not the same as how much light overall makes it through the scope.
If your primary concern is low light, make sure you choose something with a large objective lens. Once you get magnification into the equation, you have to think in terms of exit pupil size, which is just objective lens diameter divided by the magnification. Between March, Minox, Kahles, S&B, etc the performance in low light is broadly similar for all scope that are equipped with a 56mm objective. There are some small difference brand to brand, however. Traditionally, Kahles really emphasizes low light performance, but I found it to be more true for K312 than for K624. With the high magnificaiton models with 56mm objectives, I would probably be looking at Minox and S&B.
That having been said, if your primary concern is indeed low light, you should really look at the 6-24x72 Zeiss or Hensoldt. I just did a quick look and you can pick one up from EuroOptics for less than $3k. It is SFP and the reticle is not the most modern thing out there. However, if you primary concern is low light performance, this scope with its 72mm objective runs circles aorund just about everything else.
https://www.eurooptic.com/carl-zeiss-optronics-hensoldt-zf-6-24x72-mildot-riflescope.aspx
If your primary concern is low light, make sure you choose something with a large objective lens. Once you get magnification into the equation, you have to think in terms of exit pupil size, which is just objective lens diameter divided by the magnification. Between March, Minox, Kahles, S&B, etc the performance in low light is broadly similar for all scope that are equipped with a 56mm objective. There are some small difference brand to brand, however. Traditionally, Kahles really emphasizes low light performance, but I found it to be more true for K312 than for K624. With the high magnificaiton models with 56mm objectives, I would probably be looking at Minox and S&B.
That having been said, if your primary concern is indeed low light, you should really look at the 6-24x72 Zeiss or Hensoldt. I just did a quick look and you can pick one up from EuroOptics for less than $3k. It is SFP and the reticle is not the most modern thing out there. However, if you primary concern is low light performance, this scope with its 72mm objective runs circles aorund just about everything else.
https://www.eurooptic.com/carl-zeiss-optronics-hensoldt-zf-6-24x72-mildot-riflescope.aspx
Excellent information from koshkin. Indeed at the higher end, or even not so high these days, light transmission are quite comparable. Light transmission is a product of lens coating and ever since riflescope manufacturers followed the camera lens manufactuters lead on this, overall light transmission has increased dramatically. Just to shock everyone here, but one of the leaders, if not THE leader in over light transmission is riflescopes is Nikon. This is of course, due to its long time experience in camera lenses and the fact Nikon was a pioneer in lens coating and has been at the fore front of that and glass in general, ever since.
I have a Nikon Tactical 2.5-10X44 with illuminated reticle that I have used to excellent effect hunting wild pigs at midnight in south Texas.
As koshkin says, the objective lens diameter dictates the exit pupil size, but I will add that the overall illuminance that comes to your eye is a combination of objective lens size, light transmission and magnification. At night, you want to have the exit pupil at 5 or 6 (or greater) mm in diameter,to match the pupil size of your eye in those conditions; in other words, your pupil is large to accept as much light as possible, give it the exit pupil to match. So a 25X56 scope will have an exit pupil of 2 (still small,) but if you crank if down to 10X, the exit pupil will be 5.5 or some such. Add in great light transmission and you have decent illuminance to see what you want to see. Of course, at night, color and contrast will be diminished, because a scope will not create what it doesn't receive.
Remember, unlike what some gunwriters say, bigger glass is the only way to have more light going through a scope. Do not expect to use full magnification on riflescopes at night and expect to see very well. A 3-24X42 will do quite well until about 6X after which it will rapidly get darker. In order to use 24X, you would need a 100MM objective or bigger.
I have a Nikon Tactical 2.5-10X44 with illuminated reticle that I have used to excellent effect hunting wild pigs at midnight in south Texas.
As koshkin says, the objective lens diameter dictates the exit pupil size, but I will add that the overall illuminance that comes to your eye is a combination of objective lens size, light transmission and magnification. At night, you want to have the exit pupil at 5 or 6 (or greater) mm in diameter,to match the pupil size of your eye in those conditions; in other words, your pupil is large to accept as much light as possible, give it the exit pupil to match. So a 25X56 scope will have an exit pupil of 2 (still small,) but if you crank if down to 10X, the exit pupil will be 5.5 or some such. Add in great light transmission and you have decent illuminance to see what you want to see. Of course, at night, color and contrast will be diminished, because a scope will not create what it doesn't receive.
Remember, unlike what some gunwriters say, bigger glass is the only way to have more light going through a scope. Do not expect to use full magnification on riflescopes at night and expect to see very well. A 3-24X42 will do quite well until about 6X after which it will rapidly get darker. In order to use 24X, you would need a 100MM objective or bigger.
