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Why small objectives on the new 1-8x scopes?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 06:01
atp View Drop Down
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Why do the new crop of 1-6x and 1-8x scopes all have objective lenses that are c. 24mm or smaller? On 8x, their exit pupils must be very small, and in dim light they may only be useable on low power. Why not just stick a bigger objective lense on the thing? Sure, it would be of no benefit at all on 1x, but wouldn't that improve light gathering and ease of use on high power? What am I missing? Is their some design or manufacturing reason why a larger objective lense can't work on these true-1x variable scopes?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 09:55
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It might be to keep the scope compact.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 10:23
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Originally posted by BeltFed BeltFed wrote:

It might be to keep the scope compact.

That doesn't make sense. These new 1-8x24 scopes are mostly 12 or 13 inches long and weigh around 26 oz, there's nothing "compact" about them. The Swarovski 1-6x24 Z6i is comparatively svelte at 11.7" and 16 oz. Lots of scopes with 32mm or 40mm objectives are substantially smaller than these new 1-8x24 behemoths.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 10:45
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Didn't say it made sense.
I know what you mean; I use a 1.5-8x26 with a 35mm tube at 22 oz.. My other choice was a 2-12x32 with a 35mm tube at 24 oz., but it was way past huge for my purpose (and other reasons).
I have had the opportunity to play with it (the scope) at night, and really it's not that bad, but I prefer the lower powers at night, and so far have had no issues.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 11:00
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8x-24mm is still 3mm of exit pupil, that is still plenty for day time use, not optimal but it sill works pretty well.  Really it is better than say a 5-20x50mm and pretty much equal to a 4-16x50mm.  If you look at it like that they are not out of line at all. 

Most of them are combat optics so having large exit pupil on high mag is not really needed as they will probably see most of their use on the lower mags.  And in low light chances are you will not be able to identify a target at long distances anyway, so having it on high mag may not be as needed. 

And ontop of all that the Leupold and Premier were built to a spec request by the military.  We are just seeing what they wanted.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 13:02
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getting and using a mid range on high power, usually involves something like using the highest mag for sighting in the gun/load, zooming to that power for a "better look" while using it in the low to mid range 90% of the time making a large objective a negative. If you need a higher mag or use it on high get another type of scope say a 4x16 x50 or something, then the ratio of use switches, say 90% end with an occasional low end use.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 16:40
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For many years the "standards" here in Alaska where the 1.5x5 Leupold VX-III, 3x9 Leupold VX-III, 2x7 Leupold VX-II and the newer 2x8 Leupold VX-III (talking about zooms). Many shots were taken at close range..bear and moose, caribou at longer ranges. Any of those scopes had plenty of eye relief and worked well not because of super light gathering but because folks could shoot under field conditions and could stalk close enough to make the shot. Notice that these scopes might be 4X+ exit pupils but not much over that.
Most shots were taken at less than maximum power for bear and moose. Taking a shot just before nightfall because you have a wide enough exit pupil to see the animal and then loosing it in the brush because it is too dark to find it is illegal...it happens but shouldn't. Not every animal drops at the shot and just because your scope has a large exit pupil does not give you permission to shot under poor conditions.
My Swarovski Z6 1x6 has plenty of light gathering power to shot under cloudy and rainy conditions towards the end of the day, same with my Leupold VX-III 1.5x5. My new Zeiss 1.5x6 will work well for coyote, hogs and such during moonlight where it is legal.
Quality glass and coatings can make a smaller exit pupil much more usable. To large an exit pupil can encourage people to take shots when they shouldn't. Just because you can doesn't mean you should and could land you in jail...here in Alaska the fines can include confiscation of vehicles, airplanes and homes plus the jail time.
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Art

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/17/2012 at 19:56
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Most shots in combat are not going to be made with time.  I have 4 tours in Iraq doing some fun, some scarey, and some dumb sh*t and most of the time on my Leupold M/RT it was on 2.5x and it never went more in a firefight on the M14.  Look at the Aimpoints as the standard US Army sight and it is 1X in the tupe.  We are not teaching both eyes open when we shoot and when you have both eyes open if you shoot one at more than 4X your eyes start to get un focused.  Some get headaches. 
 
Also there is probally an issue with the PVS14s when you mount them behind an optic. 
 
This is just me talking I am not a hunter, competition shooter (unless M1 Garands), just a shooter that does the tactical thing and coyotee thing. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2012 at 01:43
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I apologize for typing a response for the hunting scope forum.
The new tactical scopes work very well with the clip on night vision, night vision goggles and thermal sights in use.
Most designated marksman, snipers and crew served weapons have one of those sights available.
The Leupold 1.1x8 was developed for use on the M 240B if memory serves as a day sight.
Since it is used with a night sight, low light/night capability was not a priority.
You are using a $56,000.00 weapon with a $4,000.00 day sight and a $25,000.00 night sight or thermal imaging sight. The day sight is just that.
I very rarely hear of a unit using pop up flares or requesting anything but infrared flares that work with their night vision goggles and night sights.
A thermal imaging system works very well for detecting enemy in buildings, even when you can't see them.
So the Leupold and S&B are dedicated day sights for military use, not really designed for civilian use at all. (note that they have illumination settings for use with night vision)
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Art

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/18/2012 at 17:56
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Forgot about the weight thing.  I would have to think the smaller the objective the lighter the weight at least a few ounces.
 
Art,
 
Thanks for the info.  That is partly what I was trying to convey but you said it a lot better than I did and with more detail.
 
Thanks,
Scott
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 11:01
atp View Drop Down
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So to summarize, so far nobody here knows why the manufacturers have chosen 24mm or smaller objectives for all the current true 1x variable scopes (1-8x, 1-6x, 1-4x, etc.), nor what the engineering constraints are that might lead to such a decision. Now that Shot Show is over, maybe Koshkin or others can fill us in...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 13:09
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atp..I am confused, I thought we were discussing the military scopes.
The Leupold and S&B 1.1X8 were designed specifically to used on the M-240B machine gun as a "day sight".
They were designed to be integrated with various night vision equipment for low light or night time use.
The 1.1X6 scopes were designed for use on the M-4 style carbines, smaller objectives mean they can be mounted lower with a better cheek weld.
That is what the Leupold LE rep said in response to an inquiry by a dept armor.
I do not have an answer why others have done it on their civilian scopes.
I have a Swaro Z6 1x6 and on 6x with the illuminated cross hair it is usable at dawn and dusk.
I have two 1.5x6 scopes with 42mm objectives and they can be used during half moon to full moon especially if there is snow on the ground.
Go to a S&B or Zeiss 1.5x6 with illuminated cross hairs if you want to shoot at night.
Thanks
Art

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 13:49
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Thanks for your Service & time ffhounddog.Welcome to the OT Excellent
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 13:59
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Originally posted by gulf1263 gulf1263 wrote:

I am confused, I thought we were discussing the military scopes.

The higher a scope's top-end magnification, the more useful a larger objective is going to be, so my question is more relevant to the latest 1-8x scopes, which happen to currently be marketed largely at the military. But as it happens, all the true-1x variables on the market have only 20 or 24 mm size objectives, so the same question still applies to them, although (due to their lower magnification), perhaps to a lesser extent. No one here has yet answered that question in any convincing way.

Originally posted by gulf1263 gulf1263 wrote:

The Leupold and S&B 1.1X8 were designed specifically to used on the M-240B machine gun as a "day sight".

Which doesn't really answer the question of, "Heh, wouldn't a 32mm objective do a better job at 8x on that scope than a 24mm?" Maybe it wouldn't, I don't know. But even ignoring low-light performance, I'd think that a larger exit pupil would still make eye positioning and rapid sight picture aquisition a bit better. (Btw, although it doesn't really matter here, I very much doubt that the M-240B GPMG is where we're going to see the majority of those 1-8x scopes used. Sure, they'll be used there, but if the scope works as well as claimed most of them will end up on rifles, which of course Leupold and S&B knew all along.)

It's clear from many common scope designs on the market that the additional cost and bulk of going from a 24mm to a 32 or 40mm objective is fairly small. So on a very high-end do nearly everything at all ranges and damn the cost and weight scope - which is clearly the niche that the new 1-8x designs are aimed at - why the small 24mm objective? Is there truly no advantage at all to going to a bigger objective, for some opto-mechanical reason? Or is there an advantage but for some reason it's not practical to make a larger objective work? Or what?

Originally posted by gulf1263 gulf1263 wrote:

The 1.1X6 scopes were designed for use on the M-4 style carbines, smaller objectives mean they can be mounted lower with a better cheek weld. That is what the Leupold LE rep said in response to an inquiry by a dept armor.

That's obvious nonsense, as the M4 carbine has such a high sight line that mounting larger-than-24mm objective scopes is trivial. That Leupold LE rep was blowing marketing smoke. Nobody low-mounts scopes on any AR-15 design because they'd be totally unusable in that position. Now yes, on rifles with a more traditional low sight line, you often want to get the scope as low as possible. However, except in unusual situations like scoping a Kalashnikov, the limiting factor on how low you can get the scope is typically the diameter of the eyepiece, not the objective. Most rifles will probably mount a 32mm or maybe even 40mm objective just as low as a 20mm objective.

Originally posted by gulf1263 gulf1263 wrote:

I have a Swaro Z6 1x6 and on 6x with the illuminated cross hair it is usable at dawn and dusk.
I have two 1.5x6 scopes with 42mm objectives and they can be used during half moon to full moon especially if there is snow on the ground.

That's an excellent practical example. There likely isn't any rifle scope in the world with better quality 24mm optics than the Swarovski Z6i, so it should be the best case for low-light use in small objective scopes. The fact that you notice a clear low-light improvement with your other 42mm scopes is definitely interesting.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 14:33
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I only know enough about optical design to fill a thimble 1/2 full, but my guess is it may be partly due to the fact of how extremely difficult and complicated it is to make a 1-8X with decent image quality throughout the power range.  A larger objective may have required them to make the scope longer in order to maintain image quality.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2012 at 16:03
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Originally posted by atp atp wrote:

That's obvious nonsense, as the M4 carbine has such a high sight line that mounting larger-than-24mm objective scopes is trivial. That Leupold LE rep was blowing marketing smoke. Nobody low-mounts scopes on any AR-15 design because they'd be totally unusable in that position.


Really???

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 08:31
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The questin is a very valid one, since there difinitely would be a market for, let's say a 1-8x50. You could pretty much dominate the high end of the European hunting market with such a design, because it would cover everything from driven hunts to hunting by moonlight quite well.

The relatively simple (but hard to overcome) technical reason why such an optic does not exist is the fact that with a given objective focal length, you cannot increase the objective diameter beyond a certain point without running into huge optical problems. A scope with ~1x starting magnification has an objective focal length of about 50mm. At a given focal length, increasing the objective diameter will lead to incresingly steep ray angles and more aberrations, with "more" meaning something like to the power of three or four with increasing f-number (ratio of focal length/objective diameter). A 24mm objective with a focal length of 50mm has an f-number of about 2. Increasing the objective diameter to 50mm leads to an f-number of 1. Two-fold doesn't sound too bad, but to the power of three, the optical difficulties will increase by a factor of eight, to the power of four, it's a factor of sixteen, so every additional millimeter of objective diameter comes at a higher price or incresingly crappy image quality.

Anyone who is into photography knows that "faster" lenses (higher f-number) tend to be extremely expensive when compared to "slower" lenses (low f-number) of comparable quality. This is caused by the same optical restraints.

Increasing the objective diameter is possible when the starting magnifications is increased at the same time. Basically, exchanging the objective system of a 1-8x24 with an objective with a focal length of 100m and an objective diameter of 50mm would turn it into a 2-16x50, and that would be optically feasible because the f-number is still 2.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 10:59
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These scopes are designed for an enviroment where people shoot back at youSemi Auto
 
One reason the objective size is kept small is that the sun reflects off the front objective and gives away your position this is usualy addressed with a kill flash.  large objectives tend to be sh*t magnets under rough conditions  gathering dirt. Good lens caps help.  Another factor is the strength of the tube as a smaller tube tends to not get banged around as much on everything one goes past.  The other factor is that most people are ignorant and fail to understand that to have a 7mm exit eye pupil one has to have larger objective sizes.  Most people who purchase scopes have no idea how bright a  scope will be in low light if they did all scopes would be  6x42 fixed power scopes.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 11:23
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Wow, I didn't really understand a lot of that, but it is interesting to know that there are very difficult optical engineering problems preventing a 1-8x50mm scope.

Originally posted by dcjs dcjs wrote:

Anyone who is into photography knows that "faster" lenses (higher f-number) tend to be extremely expensive

I think you go that backwards. A "faster" lens (one that that gathers more light) is one with a higher numerical aperture, or a lower f-number. High NA (low f-number) lenses definitely do get very expensive.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 11:33
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Those are very good points to bring up Wes. Not being familiar with tactical scopes, I was paying more attention to the other mechanical/optical reasons mentioned. I never paid much attention to the reason for a kill flash. I also did not consider crud magnets.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 11:47
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The F stop discussion is history a F 1.4 opens wider than a F 1.8 allowing more light to enter striking the film quickly.  The variable factors are speed of film + F stop + aperture opening size.
FOR 100asa   bright daylight F16   1/250 sec is typical but todays digital does not hold to the same constraints as the limits of film, look at a digital video with night mode its like having night vision. 
 
 
Please realize that the military does not always know what they are doing Shockedoften decisions are made by a guy in an office who has no personal knowledge of the factors actually existing in the field.  I know a lot of dumb decisions that have come down simply because the guy making the decision has no subject matter knowledge but he has the rank and responsibility to decide and God forbid he would ask someone doing the job.

Edited by Urimaginaryfrnd - January/25/2012 at 14:13
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 11:50
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Folks, read the answer dcjs gave above. If he is correct, then the reason we see only small 24mm objectives on these 1-8x scopes is because the manufactuer's can't build a 50mm objective for these scopes that actually works, and even going up to a 32mm objective would likely be very difficult.

I strongly suspect that dcjs's explanation (or something very similar to it) is basically correct, and that the optics engineers designing riflescopes know that. So for now let's assume that's the case...

Now go back and skim through all the just-so-stories people were making up to "explain" why all the true-1x variable scopes have small objectives. Those explanations are all completely wrong. This is a small lesson in how people don't like to admit, "I don't know why the world is that way", and sometimes don't even seem to notice that they don't know. Instead they make sh*t up.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 11:54
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Bite the hand that feeds you why don't you.  I would not bother asking any more questions if you are just going to sh*t on the people who try to help.  Loco
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2012 at 12:04
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Originally posted by supertool73 supertool73 wrote:

Bite the hand that feeds you why don't you.  I would not bother asking any more questions if you are just going to sh*t on the people who try to help.  Loco
Ditto
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Aw, did I hurt your poor little feelings?

Higher standards lead to better understanding. You'd rather have low standards, and not point out when answers are confusing and make no sense?

Yes yes, many of the "explanations" offered in this thread are potentially legitimate reasons why somebody might decide that, on balance, for their purposes they'd rather go with a scope with a 24mm rather than a 32mm or 40mm objective. That's fine, and of course there's nothing wrong with bringing them up and discussing them in this thread.

But the facts appear to say that those points have nothing to do with why no one is offering a 1-8x40mm scope right now. If a manufacturer could build a 1-8x40mm scope for the same price and quality as the 1-8x24 scopes, it would definitely work better in some ways and it would sell. Furthermore, many of the "problems" suggested are very minor, and most people would completely ignore them and cease to even notice them as problems if you put an actual working 1-8x40mm scope in their hands. Apparently physics makes that 1-8x40mm scope too hard for anyone to build, at least right now. Most of other putative problems are just noise distracting us from that main point.
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