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birddog
Optics GrassHopper Joined: August/25/2004 Location: United States Status: Offline Points: 1 |
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Posted: August/25/2004 at 22:14 |
got a question for you guys why do some or most shotgun scopes have that small end on the front of the scope? its like someone cut the front of the scope off! this style scope cuts down on light getting in so yo cant see well at dusk at all. you need to get out of your stand before you want to. if your in the woods you need to get out around when the deer are on the move. a field edge is not to bad but even still you loose light fast with this type of scope. i shoot a mos.835 ulti-mag with a simmons pro dimond shotgun scope. the gun is great! the scope is also when you have lots of light. no prob. killing 100+ yards with it, in one side and out the other. i would like to pull it off but i use the gun for turkey hunting also and it works well for that. maybe go with a new gun rem.870 or ithica has a new deer gun i hear is good, a free floating barel on it. i forget the name but then i could have a set up just for deer and get a real scope put on
any one has a good reason for why these scopes are made this way please enlighten me! |
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Chris Farris
TEAM SWFA - Admin swfa.com Joined: October/01/2003 Location: Texas Status: Offline Points: 8024 |
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You do not have to have a 50-56mm scope to hunt in the dark. You do have to have a 7mm exit pupil (or close to it, depending on your age). For those reading this thread that don't know what I am talking about I will explain.
Exit pupil is the amount of light your scope emits out of the eye piece. Hold your scope at arms length and you will see a circle of light on the ocular lens, this is the exit pupil. The pupil of your eye can only take in a maximum 7mm's of light when it is completely dilated and of course your pupils dilate when it gets dark. Because the exit pupil changes with power, we need to know how to determine when it is 7. This is done by dividing the objective lens size by what power the scope is set on. IE; a 3-9x40 set on 5.7x will have a 7mm exit pupil (40/7=5.7). A 3-9x50 set on 7.1x will have a 7mm exit pupil (50/7=7.1). This is why many optics makers offer a 6x42 scope or an 8x56 binocular.
The most important aspects of a good low light scope are glass and coatings not objective lens size. The only advantage to a larger objective lens is that it will produce the magic 7mm on a higher power.
Shotgun scopes are generally low power and do not need a large objective lens to produce a 7mm exit pupil. IE: A 2.5x shot gun scope only needs a 17.5mm objective to do the job. The most popular shot gun scope is the Leupold 1-4x20 and it transmits perfect light on 2.9x. |
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uaw003
Optics Apprentice Joined: December/07/2004 Location: United States Status: Offline Points: 14 |
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Chris ... I am not positive that you are wrong about the 7mm pupil of a human eye but I think you are. From all the information that I have, the average human pupil dialation is 4.5 to 5.5 mm. If you have info stating otherwise, feel free to post again.
The other stuff is correct in theory but wrong with the 7mm, I believe. A scope with superior optics/coatings like the Nikon Monarche UCC 3.5 X 10 X 50 being set on 10X will give the full range of light that a human eye can receive. |
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uaw003
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Chris Farris
TEAM SWFA - Admin swfa.com Joined: October/01/2003 Location: Texas Status: Offline Points: 8024 |
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Barring any hereditary or environmental factors the human eye pupil dilates to a maximum of 7-8mm and starts to slowly decrease as age increases. At age 50 your pupil will dilate to a maximum of 5-6mm. In bright day light your pupils will be about 2-3mm.
This is why extreme low light binoculars are made in 7x50, 8x56 and 9x63 because they all transmit a 7mm exit pupil. Also the reason U.S. troops get a 7x50, because they are mostly around 20 years old.
There are other benefits to having a slightly larger exit pupil that what your eye is dilated to as well. Your eye does not have to be perfectly lined up making the eye relief more forgiving and it allows you to get on target quicker. |
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uaw003
Optics Apprentice Joined: December/07/2004 Location: United States Status: Offline Points: 14 |
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Hold on, I'll grab my digital caliper...turn off the light in the bathroom and measure...doh!!! Alright, that was a very bad idea and my shooting eye!!!
Anyone got a good used lefthanded rifle? |
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uaw003
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Dale Clifford
Optics Jedi Knight Joined: July/04/2004 Location: United States Status: Offline Points: 5087 |
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There are two ways to mount a shotgun scope, as a "regular" rifle type mount or as a "scout" mount. Regular mounts can use a "saddle" over the receiver or a cantiliver that brings the scope back to the shooter , but the mount is on the barrel. check out Remingtons 11-87 slug gun on their sight. This sounds like your set up. A rifle type mount needs the stock cheek piece raised to accomadate the drop normally built into shotguns. A Scout or forward mount doesn't need this and allows the shooter to use with both eyes open. A very fast set up. I use a a 4X pistol scope (sometimes a 2x) with a modifed Taurus pistol mount on the rib of an 11/87 with a 26 in. barrel with remchokes. . 3" Brenneke slugs will "pattern" about 4 inch on an 8" plate at 100 yards, without the use of a "rifled slug" barrel. I have witnessed rifled slug shotguns set up with rifle scopes that will do better, but they loose the quick handling characteristics of a shotgun. (One of my requirements is that it must be semi-auto) Then if the opportunity arises, bird loads can be changed out on the spot without loss of utility. The point of aim is within tolerences for shot as to point of impact. I got really lucky on this one, and Win double XX 000 buck shoots to the same point of impact as the slugs. The point is-- It takes a lot of experimental trial and error to get were you are going but well worth it.
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interzone
Optics GrassHopper Joined: January/10/2005 Status: Offline Points: 2 |
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Question-Currently I have a Leupold 4x28 scope on a shotgun, the gun has been used for deer hunting. I would like to make it a multipurpose, deer,turkey gun. For turkey hunting, I would prefer having no magnification, or little magnification, so I am considering switching to a low power variable scope. Found a Leupold Vari x3, 1.5x5x20 pretty cheap at a locl gun store. Considering the math you suggested, the 4x28 will have a perfect 7mm pupil. The varix3, set at 4x, will have an exit pupil 5mm-considerably smaller than the 4x leupold. So which is the better scope at 4x-I realize that the coatings are more advanced in the varix3 line, compared to leupold fixed scopes. Will the coating on the varix3 make fora better "light gathering" scope than the 4x? |
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Chris Farris
TEAM SWFA - Admin swfa.com Joined: October/01/2003 Location: Texas Status: Offline Points: 8024 |
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Yes, coatings and glass will win almost every time except in extreme comparisons where the better scope is below a 4 mm exit pupil. Keep in mind as you get older your pupil will not dilate to 7mm it will only go to 5 or 6 depending on your age, plus any ambient light will cause your pupil to get smaller. 5mm is still very good. You can also just turn the power down a tad on the variable if need be to get a larger exit pupil.
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Urimaginaryfrnd
MODERATOR Resident Redneck Joined: June/20/2005 Location: Iowa Status: Offline Points: 14964 |
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Edited by Urimaginaryfrnd |
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"Always do the right thing, just because it is the right thing to do". Bobby Paul Doherty Texas Ranger |
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Stud Duck
Optics Journeyman Joined: May/20/2005 Location: WV Status: Offline Points: 508 |
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I'm faced with a similar situation, I'm starting to hunt Ohio, Iowa & Illinois and was trying to decide shotgun or muzzleloader. If I went with a shotgun, I'd be sacrificing approx. 50yds on maximum effective range, correct? Shotguns are good to ~150yds. If I go with a shotgun, I'm assuming I need to mount my base directly to the receiver & stay away from the cantaleiver mounts, correct?
What is the maximum effective range of the load you quoted above? I'll be using a TC Omega if I go with the muzzleloader. Edited by Stud Duck |
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