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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/20/2007 at 23:35
jackG View Drop Down
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This has probably been pummled into puree, but nevertheless, I'll ask it.  I've never used a scope with an adjustable objective.  My brother had one at one time and got rid of it.  He complained that for him it did not work.   He would have it focused for say a couple of hundred yards out, and a critter would wander into view at half that distance.  He  was constantly forgetting to adjust it, and was missing shots or having them run off while he was fussing around trying to get it properly adjusted.  He's been known to overcook things, so it's possible he's making more of it than it needs to be.

 

For hunting, how many of you use scopes with an AO?   Or is their use better suited for target shooting?   This year's hunting trips had deer popping up at ranges just of about 100 yards out to over 300 and pretty much everything in between.  In a couple of cases, had I had to play around with focus, I think they've have gone before I could have gotten around to shooting. 

 

Is this an issue?  Or, do you just get pretty good with practice and simply incorporate the adjustments into the hunting procedure?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/21/2007 at 01:33
8shots View Drop Down
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If you are shooting at varying distances and need to take the shot quickly, an AO is not going to work. Your brother is absolutely coorect. An AO set for 100yds renders a 300yds target out of focus.

AO works for target shooting and situations where you have enough time to adjust the AO.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/21/2007 at 09:25
cyborg View Drop Down
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I must be a rare one, I use an AO on my 300 wm and have never missed, even on quick shots at varying distances. I guess everyone's different. Bottom line use what works for you.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/21/2007 at 11:04
jackG View Drop Down
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Cyborg - when I talked to him last night, he claimed that if it the AO was not dialed in, he missed shots.   Not having used one I have no idea how things appear through the scope if it's not adjusted.  I had these questions for him:

 

1.   If the thing is properly adjusted at say, 50 yards and a target appears at say 200 yards, can you see it clearly at the 50 yard setting?

2.   If you take that shot without adjusting the thing, would the sight be off enough to miss?

3.   Does it change the point of aim when the adjustment is changed?

 

He had no definitive answers, but sort of blamed the AO for his missed shots. 

 

I'm a bit skeptical of his pronouncements, because I've seen him tank some pretty simple shots with no contribution from an AO at all.

 

I'm considering purchasing another hunting scope.   My hunting has been in open country with shots of over 300 yards on occassion.   I've got a Sightron II in 3-9, and I could use a little better glass (shot a small buck because I couldn't see the antlers - or just didn't notice) and more power.  More power may seem like overkill, but with a 270 WSM the rifle can exceed my skills with this scope.  

 

I'm enamored with the Kahles 4-12, even though it has a 50 mm O lense, which is kind of a whopper and I don't know how that would be to see sitting atop the rifle, as well as how my reduced bank account will feel.   Also recommended is a Bushnell 4200.  However in the higher power range models they have a AO.  I like being able to just pull up on a target with no screwing around, be in focus, put the cross hairs where they belong and let fly. 

 

I've watched fellow hunters monkeying around with  the O lens on long shots using an AO.  But the animal was standing around and had no idea we were there.   The shooter had all the time he wanted.    I'm seldom so fortunate. 

 

By the way, thanks to both of you for the interest. 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/21/2007 at 11:51
Dale Clifford View Drop Down
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depends

 

on the scope, in a way its like depth of field on a camera, some scopes go thru their ao range very quick with just a small turn of the ring, because their mag range is shallow say 3x9, and the "focus" doesn't change much

ao has more effect on close ranges just like depth of field than distance shooting were the rays of light are more parallel.

 

on the shooter,  generally ao's are more for 1)either close shooting 2) determing the difference in target as in precision load work up--

 

you didn't mention the power range of the scope, but--- the likely hood of a miss was due more to the missuse of the power range than the ao. in other words, if the scope has and was on a higher power setting the ao appear to be more critical (in this case bothersome would be a better word) than on a low power.



Edited by Dale Clifford
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/21/2007 at 11:55
cyborg View Drop Down
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I don't have any problem with the focus I set mine at 300 and rock on, from 300 down there's no problem with the focus and I always hit the kill zone. Of course a consistent cheek wield is essential. Let's consider this, most scopes with no parralax adjustment are set to be free fromm 100 yrds down, so any thing over is gonna be a suggested area anyways. Consistent cheek wield is the only thing that will tighten up the area.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 00:49
jackG View Drop Down
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I've got another question.   I've noted that many scope manufacturers have AO versions and non-AO versions of scopes in the same power range.  Other than that the scopes would appear to be the same. If the two were compared side by side, would there be any observable difference in the sharpness of focus between the two?  Does the AO scope have an advantage?

 

My youngest brother who posesses a fleet of them, as well as some eyesight limitations, argues that it is not possible for a non-AO scope to remain in proper focus particularly at long range and with magnification over say 9X.  That does not seem to hold true in my case, which suggests the problem my be in his eyes and not the scope.  And finally, even though it has been explained to me, I don't understand why binoculars for example, require focal adjustment with distance changes, when my VX-11 in 4-12, and my Sightron in 3-9, do not.   Can anyone please illuminate that?  Thanks.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 01:07
8shots View Drop Down
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I cannot speak for all scope brands, but certainly the scope that I have is very sensitive to correct AO focussing. If the AO focus is out then the sight picture is blurry. I certainly cannot use a 300 yds setting and shoot/see at say 150 yds. If the AO is not adjusted correctly, parralax error is obvious on my scope, in other words the reticule appears to move if I move my head.The reticule can easily jump about 1 to 1,5 inches on a bad setting at 100 yds.

The only reason, in my humble opinion, to use a AO scope is in order to eliminate paralax error by means other then keeping cheek weld consistant. So AO is ideal for target shooting and hunting where the animal is stationary. If your need is for moving targets/distances, then an AO is not of any benefit.

The paralax of a normal scope is usually set at 100yds. On any target closer then 100yds paralax error is naturally worsened, and on any target further then 100 yds the paralax error is naturally reduced.

 

I think that on binoculars you have a very short focal plane, and on a telescope a more forgiving longer focal plane.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 01:21
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Below is some-one elses wisdom on the subject:

If you buy the scope with the adjustable objective, you will not be able to just leave it set for 100 yards and use it down at ranges of 25 yards at 9X magnification simply because the target will be out of focus. In this respect it is not like a simply 3X9 scope without the AO feature.

If you have a 4.5X to 14X and you set it to 4.5X chances are that you would not see enough of an out of focus condition between 25 to 100 yards to actually have to make a focus adjustment, but at 9X you would.

The error in point of aim would grow as well down at 25 yards if you are set to 100 yards if and only if your eyeball is not centered down the tube. However you would notice that the target of interest in and around the 25 yard range was out of focus and somewhat blurry and you would be going for the focus ring to clear up the image anyway, especially at the higher magnification range.

So if you are thinking you want to use the higher power scope for hunting and targets may be appearing from 100 yards down to 25 yards, A: you wouldn't (shouldn't) be set to 9X, but if you were, you would have a hard time using the scope and B: To answer your direct question the parallax error of a 4.5X14 set to 9X and focused at 100 yards should have no greater than a 3X9 scope at 9X if you were using them both side by side at only 25 yards (assuming the 3X9) scope is the type that is parallax corrected for 100 yards and not one for 22 rifles or shotguns set to a closer range).

the advantage of the AO scope is that you can adjust the focus and thereby null out the parallax at 25 yards if needed to shoot at very small targets to obtain maximum accuracy from the scope/rifle combo.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 09:59
Dale Clifford View Drop Down
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the appearance of sharpness would depend on what range the parallex was set in the non ao scope, if say 100 yds the ao when set to 100 would be the same as the non ao, but at 25 yds the non ao would be out. ao becomes more important as the distance shortens and the magnification increases.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 11:19
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Another follow up.    I hunted MT this year and it is open country.  You get some shots in the 100-150 range in the coulies, but most of the shots are beyond that range.   We marched all over the place searching for pronghorn as well as mule deer.  I  use a compact Nikon binocular to assist in finding them.   It's not like a spotting scope in that it's only 10X, but it helps a great deal in locating those suckers that are bedded in the sage brush.   As the range changes, that is looking at say 50 yards or so, then out to a hundred or more, adjustment of the focus is essential to provide a clear image through the binocular. 

 

Using a 3-9X42 Sightron SII,with no focus adjustment, I'm obliged to take what I get when peering through the thing.  Nevertheless, with no adjusmemt, to my eye, the image is crisp and clear.   For this trip all shots were taken on 9X.  The first was around 125 yards, the second 150, then a 95-100, followed by a 322, and topping it off was a 225, downhill into a coolie.  If I had been looking at those animals with my bioncular, I would have had to adjust every time for a focused image.  Why is the scope able to provide a sufficiently clear image to hit the desired point of aim on every animal, without the ability or need to focus?   How is that optically possible?  Or is comparing a binocular and a scope, optically apples and oranges?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/22/2007 at 11:36
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Silly question, did your brother have the scope focused properly and sighted in per the manual before using the AO?

I used to have a vari-xII 4-12, thin duplex, and really liked the AO myself. I usually had it set for 100 yards unless on point with a long shot; then I'd dial 'er in to the expected shot. I had a lot of confidence and long shot success with that scope!!  

Since then, I''ve checked out some of the Leupold LR's with the parallax side focus and they seem to be much more sensitive than the AO at the end of a scope.

Happy Thanksgiving!!

-Mike 

Edited by mike650
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/23/2007 at 06:19
8shots View Drop Down
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JackG, the answer as to why a rifle scope and binoculars focus differently can be complex. The short answer is that rifle scopes have a greater hyper focal distance then binoculars. In other words through the clever use of lenses and lense configurations a rifle scope has a greater hyperfocal distance then a pair of binoculars. Like taxes, nothing is for free, so by giving you a longer hyperfocal distance, you loose a 100% sharp focal point on all areas other then that what the telescope was set for at the factory. The human eye, being a wonderfull thing, compensates somewhat for the fixed focus inefficiencies. Binoculars, through the process of focussing, or moving the focal point, can give you the 100% focus on whatever distance you choose to focus on. In the process you give up the ease of use, ie just to look at any object and it will be in focus. There are some binoculars with fixed focus and long hyperfocal focal distances. 

 

Read below and never look at a scope in the same way again, or ignore the below and just enjoy the optical experience!!!


 

< =text/> < src="http://pagead2.googlesyndication.com/pagead/show_ads.js " =text/> < name=google_ads_ marginWidth=0 marginHeight=0 src="http://pagead2.googlesyndication.com/pagead/ads?client= ca-pub-2966239032434067&dt=1195819252671&lmt=1195819 252&alt_color=FFFFFF&at=336x280_as&output=&c orrelator=1195819252656&url=http%3A%2F%2Fwww.dofmaster.c om%2Fhyperfocal.&color_bg=FFFFFF&color_text=000000&a mp;a mp;a mp;color_link=1111CC&color_url=008000&color_border=F FFFFF&ad_=text&ref=http%3A%F%2Fwww.google.co.za%2Fse arch%3Fhl%3Den%26q%3Dhyperfocal%2Bdistance%26btnG%3DSearch%2 6%3D&cc=3356&ga_vid=1868796279.1195819142&ga_sid =1195819142&ga_hid=1040730035&ga_fc=true&flash=9 &u_h=1024&u_w=1280&u_ah=990&u_aw=1280&u_ cd=32&u_tz=120&u_java=true" Border=0 width=336 scrolling=no height=280 allowTransparency>

The concept of hyperfocal distance is easy to understand: focus a lens at the hyperfocal distance and everything in the photograph from some near distance to infinity will be sharp. Landscape photographs are often taken with the lens focused at the hyperfocal distance; near and distant objects are sharp in the photos.

Application of the concept leads to many questions: Which lenses are best for using hyperfocal distance focusing? What is the hyperfocal distance for a lens? How do I focus at the hyperfocal distance? Do I have to focus exactly at the hyperfocal distance? In this article we'll look at the basics of using hyperfocal distance to maximize depth of field in a photograph.

Hyperfocal Distance Definition


Hyperfocal distance


 

When the lens is focused on the hyperfocal distance, the depth of field extends from half the hyperfocal distance to infinity.

Photography, Phil Davis, 1972.

 



Edited by 8shots
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/23/2007 at 06:23
cyborg View Drop Down
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EXCELLENT 8Shots. That helps clear up some things I've sometimes wondered about. Thanks 
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