AR Sponsor
Posted: 1/11/2016 4:24:40 PM EDT
I grew up shooting a lot of rifles in regards to target shooting. I did a lot of shooting with my Dad who did not believe in scopes and me and my Brother used open sights. With that said what is the difference between a 3x9x40 scope and a 6x24x50 scopes. Go easy on me being a open sight shooter for 40 years.
|
|
Quoted:
I grew up shooting a lot of rifles in regards to target shooting. I did a lot of shooting with my Dad who did not believe in scopes and me and my Brother used open sights. With that said what is the difference between a 3x9x40 scope and a 6x24x50 scopes. Go easy on me being a open sight shooter for 40 years. How a scope works complete with diagram |
|
Quoted:
I grew up shooting a lot of rifles in regards to target shooting. I did a lot of shooting with my Dad who did not believe in scopes and me and my Brother used open sights. With that said what is the difference between a 3x9x40 scope and a 6x24x50 scopes. Go easy on me being a open sight shooter for 40 years. as the poster above me said, but I will expand on it this way.. the X40 scope will let in less light than the X50 scope therefore, if you're shooting in the early morning or early evening, you will probably have a brighter sight picture with the X50 scope.. (all other things being equal - i.e. glass quality and what not) |
|
There are no bad questions, only bad answers.
Welcome to the world of magnified optics. Some of the above information is accurate, some of it is well-intended but not necessarily accurate. The article link should answer all your questions. I'll offer a perspective. Yes, the first two numbers, separated by a hyphen (2-7, 3-9, etc.) denote the magnification range. The x means "by" and the two digit number following it is the size of the objective lens (the lens at the front of the scope) that lets in light. While generally speaking, a larger objective lens can theoretically allow more light in, that does not mean that the light can actually reach and be used by your eye. That is because of some internal changes that take place affect the shape of the optical beam. The difference is apparent, as stated above, primarily in low light conditions. What gets to your eye is what is called the scope's exit pupil. This is the effective size of the objective lens divided by the magnification power of the scope. So, a 3-9x40mm scope has an exit pupil size, when at 9x of 40 divided by 9, or a little less than 4.5 mm. That is the size of the beam coming out of the back of the scope. That is all the light available for your eye to see. As ambient light gets dimmer, the pupils of our eyes open up to a maximum of somewhere between about 6mm and 7mm, the latter in total darkness, and for many of us, less than that. Because 4.5mm is relatively close to the 6mm or so most of us have in low light hunting conditions, it pretty much allows most, but not all of the full beam from the scope's exit pupil to strike our eye in low light.. If you dial magnification back just a little, to say 7x, you have 40 divided by 7 is 5.7mm, almost perfect for light transmission. It will be brighter at 7x than at 9x in low light. Try it. But, now suppose we consider the 6-24x50mm scope. You would think that it would be brighter in low light at 24x with that bigger 50mm objective. Truth is, it would be dimmer, probably a lot dimmer. Here is why: 50 divided by 24 is barely a 2mm exit pupil (2.08). Thus, much of the surface of your retina is not being exposed to the light beam. Only half or so. Accordingly the image is dimmer by a considerable amount. This assumes that all other factors are equal: equal lens quality, equal lens coatings, equal internal anti-reflection treatment of the scope tube and such. But, here is where that 50mm scope is better in low light: Dial the magnification back to 9x. 50 divided by 9 equals 5.55mm, this is a significant improvement over the 3-9x at the same magnification. At 9x you get pretty much all your retina can receive. In fact, it will be as bright at 9x as the 3-9x40 was at 7x, all other things being equal. In the field you can see this for yourself at dusk by noticing that most scopes will brighten up when you back off on zoom a little bit. In Europe where hunting is permitted after dark, scopes often have even larger 56mm objective lenses, but to make maximum use of them, you have to limit magnification to about 8x. At that point you have 56 divided by 8 equals 7mm exit pupil. That is just about perfect for full darkness. I hope I have not confused you, but it is an oversimplification to assume that a 50mm objective lens will be brighter than a 40mm lens, unless you take actual exit pupil (effect of magnification) into consideration, and the scopes are otherwise of equal quality. Glass quality is incredibly important. No lens passes 100 percent of the light through to the next lens or ultimately to your retina. Each lens subtracts some light. Many manufacturers will tout something like 98 percent light transmission. But that is per lens, not total. A really good scope might reach 93% total light transmission. Most scopes much less. Often, a scope with a smaller objective lens can out perform a scope with a bigger front lens, if the quality of the glass, coatings and internal reflection treatment is superior. One of my best performing low light scopes has an objective lens of "only" 36mm. It is a 2-7x36 Kahles scope. This is some of the best glass money can buy. It is amazing in low light. Also know that as objective lens size goes up, so does the weight of the scope and the height of the scope above your rifle to keep the big front lens from hitting your barrel. Excessive weight and being too high above the bore of the rifle are things you want to avoid if possible. That is why 2-7x32 or 3-9x40mm scopes are so popular. They represent good compromises between size, weight, effective zoom range and power, and adequate exit pupil size for low light performance. Forgive me if I have confused you. Just trying to clarify a few points. |
|
Quoted:
Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. Quoted:
Quoted:
^ very informative Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. If low light performance does not enter into your decision, your options are very wide. What is your budget and how will you use the rifle - distances and type of targets? There are specific features for particular uses. And everything is a compromise of often conflicting features. Long range precision shooting scopes are much different than scopes for close in or for moving targets. General purpose scopes for distances inside 300 yards are different than benchrest scopes, even those used at only 100 yards. |
|
Quoted:
Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. Quoted:
Quoted:
^ very informative Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. ok. can you hunt in the rain or in overcast conditions? (same thing) |
|
Quoted:
Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. Quoted:
Quoted:
^ very informative Very informative but magnification should be what would concern me and not light. You can't hunt here in Fl. during low light in the morning or afternoon. Maybe I missed something. If you are not a hunter, I understand. However, I was curious and for those who are hunters, here is a direct quote from Florida's Regs on legal hunting hours: "Shooting hours for resident game birds, crows and game mammals One-half hour before sunrise to one-half hour after sunset except when hunting turkeys during spring turkey season. Shooting hours during spring turkey season are one-half hour before sunrise to sunset." This is pretty much the same as we have here in Mississippi. One half hour before sunrise is very low light, and one half hour after sunset is too, especially in the winter months when most hunting seasons are open.. I doubt Florida is much different than here on the Mississippi Gulf Coast (old West Florida in colonial days). This also happens to be when most game animals are most active and hunting success better. What happens is not only that the light is dim, but that the rods and cones (the light receptors in our human eyes) start turning colors into shades of muted brown, yellow and gray, making contrast difficult. Telling a deer's antlers, if any, from the tree limbs behind his head can be very difficult and higher magnification alone does not get the job done and can actually hurt by reducing the exit pupil size, but it makes it more difficult to retain good contrast and resolving power, the things most needed. Source: http://myfwc.com/hunting/regulations/general-information/ Those of you who shoot in full sunlight at high contrast paper targets can ignore this, of course. |
AR Sponsor