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AO versus side focus ?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 12:26
fairchase View Drop Down
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 I'm looking for a scope to put on my spr ar 15. Gun is used  for target  shooting out to 600 yds. , shooting the ocassional  coyote , etc. I'm leaning towards something in the 4.5-14x44 range .To my eyes a  coyote looks pretty small at 400 yds at 10x. So the extra magnification would be nice when needed.

 All of my other scopes are 3.5-10 x and under with non AO. I never liked AO's on scopes used for big game hunting , and don't think it's a big deal under 10x.

 Now I'm thinking at 14.5 x and with more emphasis on target shooting parallax adjustment is probably worthwhile.

 Now to my question. I've read many articals on parallax adj. , and most if not all have said the old AO is still the best way to deal with parallax. If this is so why are most tatical scopes coming with side focus ? I know the AO requires a little more movement from the shooter, but a little movement from me isn't going to get me shot. Is it just a matter of the side focus being the "tacti cool" thing ?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 12:43
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One is probably not better then the other, specially on high end scopes such as tactical.
 
Side focus makes adjustments easier and I cannot see myself owning an AO for that reason alone.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 14:24
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If easier to adjust means easier to reach then I agree.
Many have stated the larger ring  on the AO has a finer adjustment versus the smaller- coarser dial on the side focus allowing for a more friendly setting. I've also read where you can search back and forth with the ao to find the sweet spot where as with the side focus if you overshoot the sweet spot you need to go back to inf. and start all over.

 Me ? I don't know.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 14:25
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I THINK side focus, although easier, requires more internal lenses.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 14:41
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If easier to adjust means easier to reach then I agree.
 
That is what I meant...easier to reach and therefore easier.
 
Fairchase is correct with what he says about overshooting the adjustment etc. with sidefocus. This is a problem mainly with Leupold. However, most guys I know who have AO just set the AO by either knowing or guessing the distance and set the AO on approx hash mark. Because of difficulty to reach they then do not make finer adjustments whilst looking at the target, but just accept the setting.
 
So overshoot a bit, or be satisfied with once off setting on AO.......................
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 18:58
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All front aos are not created equal, your ar is not accurate enough to justify a really good front ao like an NF br so why fret over it  on the other hand you could get the NF just to  see how inaccurate it is.  side focus can be made  as good with good design if you want to pay for it, on an ar its worth it for ease of use.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/23/2011 at 20:21
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All front aos are not created equal, your ar is not accurate enough to justify a really good front ao like an NF br so why fret over it  on the other hand you could get the NF just to  see how inaccurate it is.  side focus can be made  as good with good design if you want to pay for it, on an ar its worth it for ease of use.

 I don't really understand you statement. I'm sure all AO's aren't created equal , but neather are the sf's.

 I'd love to have a NF, but their out of my budget!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 09:41
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Because the side focus needs another element, the design and assembly (cost) are higher than front ao. As a result most side ao scopes are "better" than their equalvalent front all things being equal counterparts. Also there are very few top end front ao adjustable scopes. Your thinking "then why don't I just get a good front ao and get more pop for the buck". And I'm thinking why-- the gun nor the scope combination will show the accuracy capable of the preceived dollar value of the utility of the side ao.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 12:16
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I like side focus if I'm going to do anything but shoot off a bench at a given distance. It's easier for me to reach it while remaining on target. Just my .02
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 15:20
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One little known fact--many of the more expensive scopes with high end optical systems already have an "extra" lens in the sidefocus location.  So making those scopes sidefocus is more a matter of making a lens movable than adding anything.  So obviously the sidefocus feature does not degrade the optical quality of these scopes as the lens is already there--it's actually there to improve the image.  Fewer lenses = better optics is rather simplistic gunwriter-speak that is wrong as often as not.

Anyway, to the OP's question--the most notable difference you'll see is the differences in depth of field.  An AO scope often has a deeper depth of focus.  While they are not as convenient to adjust (for a right hander) they can be used more as a "set it and forget it" as things stay in focus better at different distances.   Many competition shooters who shoot against the clock at different ranges like this because they can set it for a "middle distance" and everything's in focus enough they don't need to adjust it. 

This is good in some ways but has some disadvantages.  One disadvantage is that if everything is in focus you may be encouraged to take the shot while there is still a decent amount of parallax present.  Also, I like a somewhat shallow depth of focus on high power so I can see mirage in layers at different distances out to the target to help read wind.

Sidefocus systems of course can be made poorly.  On lower end scopes they can make the optics look crappy, you can have a situation where you can't get both the reticle and target in focus while parallax has been eliminate, some have enough backlash you need to "finish your focus" turning the knob only one way, etc.  With some cheaper scopes you might like the performance of an AO better.  Though some of the sidefocus scopes I've seen on relatively inexpesive scopes have worked very well.

Keep in mind all of the above are just generalities and there are exceptions to everything.  But when choosing between the two systems on an otherwise similar scope, those are the types of things you can tend to expect.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 17:57
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Thanks for the info. I think in some ways were getting at the same thing.

 I understand the Ao is not perfect , but what is ? I also think side focus can be very good and probably better than a AO , but it's more complicated , and to do it right ; it's gonna cost you.

 Case in point porro prism versus roof prism binoculars. Quality for quality a pair of roof prisms is going to cost 1/3 more.

 How much more does it cost to make a GOOD side focus over an AO ?

 I have read about the depth of focus being better on tha Ao , and it concerns me. If I'm trying to shoot something that moves the last thing I want to do is ask it to be still while I focus my scope.

 If my parallax is off just a bit I will probably have a better chance of making the shot than if my scope is out of focus.

 Everyone (me included) wants the very best scope with all the bells and whistles for 400-800 bucks. I don't think it's possible ; if it was no one would be buying the  Nightforce and the other high dollar scopes.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 18:56
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Originally posted by Jon A Jon A wrote:

One little known fact--many of the more expensive scopes with high end optical systems already have an "extra" lens in the sidefocus location.  So making those scopes sidefocus is more a matter of making a lens movable than adding anything.  So obviously the sidefocus feature does not degrade the optical quality of these scopes as the lens is already there--it's actually there to improve the image.  Fewer lenses = better optics is rather simplistic gunwriter-speak that is wrong as often as not.

Anyway, to the OP's question--the most notable difference you'll see is the differences in depth of field.  An AO scope often has a deeper depth of focus.  While they are not as convenient to adjust (for a right hander) they can be used more as a "set it and forget it" as things stay in focus better at different distances.   Many competition shooters who shoot against the clock at different ranges like this because they can set it for a "middle distance" and everything's in focus enough they don't need to adjust it. 

This is good in some ways but has some disadvantages.  One disadvantage is that if everything is in focus you may be encouraged to take the shot while there is still a decent amount of parallax present.  Also, I like a somewhat shallow depth of focus on high power so I can see mirage in layers at different distances out to the target to help read wind.

Sidefocus systems of course can be made poorly.  On lower end scopes they can make the optics look crappy, you can have a situation where you can't get both the reticle and target in focus while parallax has been eliminate, some have enough backlash you need to "finish your focus" turning the knob only one way, etc.  With some cheaper scopes you might like the performance of an AO better.  Though some of the sidefocus scopes I've seen on relatively inexpesive scopes have worked very well.

Keep in mind all of the above are just generalities and there are exceptions to everything.  But when choosing between the two systems on an otherwise similar scope, those are the types of things you can tend to expect.

Good info.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 19:33
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I do own several scopes with A.O. focus, but I use them for keeping the parallax down when shooting for groups. With targets instead of animals you have the time to set the scope. I have had scopes that sucked in the parallax department, set for 150 yards or so, when trying for a 100 yard group. For my hunting needs the scope gets set on 150 yards and left alone unless the opportunity for a long shot with lots of time presents itself. My guess would be the long range hunting  crowd would make more use of the side parallax adjustment. It's simply not needed for my hunting at 400 yards or less unless we are trying for those itty bitty groups on sight in!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 20:58
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Originally posted by 8shots 8shots wrote:

This is a problem mainly with Leupold.
 
I don't follow you on this one.  I have SF parallax adjustable scopes in Nikon, Leupold and Zeiss and they all adjust back and forth the same.  I have read on this forum (some where a while back) that the early SF Leupolds had to be reset (turned if you wiil) back to infinity if the parallax adjustment was over shot.  I can't say for sure about those but I can say the VX3 line doesn't have this problem.
 
Jim
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 21:10
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The SF vs AO comes down to a personal prefernce.  One thing with SF is the adjustments are very course (small knob movement equals a lot of adjustment) in comparision with AO (more AO movement with smaller/fine adjustment).
 
To the OP, here is a link that describes each one;
 
 
HTH,
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 21:33
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Yep already read that one , but thanks for the post.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/24/2011 at 23:46
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Originally posted by tjtjwdad tjtjwdad wrote:

I can't say for sure about those but I can say the VX3 line doesn't have this problem.

Unfortunately I believe they still do with some regularity.  In fact if you caught ILya's High End Tactical II:  http://opticsthoughts.com/index.php?option=com_content&view=article&id=81:high-end-tactical-scopes-part-ii&catid=4:rifle-scope-reviews&Itemid=4 , of all the scopes he tested the only one with noticeable backlash in the sidefocus was the Leupold.  And this was a $2k+ MK IV which you might expect to be a bit better than a $500 VX3.  A quick google of "'side focus' backlash" shows one name pops up way too often to be coincidence.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2011 at 03:37
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I have a nikon monarch one with an AO and one with a sf as well as a bushnell 4200 one with the AO and one with the SF. I've noticed that the AO scopes are less prone to hazing or whitish glare even without sunshades, with the SF scopes at high or max magnification, say 16x and up I get sun or light glare bouncing off the front end of the scope moreso than the AO set at the same power pointed in the same direction considering my sf scopes already have sunshades and there seems to be a matte antireflective finish on the inside of the scope tube objective. I think it may have something to do with the springs behind the objective of AO scopes serving as an antiglare????? 
I also noticed on a clear day with no haze or fog where you can see the mountainside clearly 20km away, I can see more or better details on a tree 20km or more away on that mountainside using my AO scopes. Even my old simmons 44mag focuses better at 20x than the nikon on far off objects, although the nikon definitely is brighter.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/25/2011 at 18:04
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Originally posted by Jon A Jon A wrote:

Originally posted by tjtjwdad tjtjwdad wrote:

I can't say for sure about those but I can say the VX3 line doesn't have this problem.

Unfortunately I believe they still do with some regularity.  In fact if you caught ILya's High End Tactical II:  http://opticsthoughts.com/index.php?option=com_content&view=article&id=81:high-end-tactical-scopes-part-ii&catid=4:rifle-scope-reviews&Itemid=4 , of all the scopes he tested the only one with noticeable backlash in the sidefocus was the Leupold.  And this was a $2k+ MK IV which you might expect to be a bit better than a $500 VX3.  A quick google of "'side focus' backlash" shows one name pops up way too often to be coincidence.
Haven't noticed it in my VX3.  I'll read over the posted link though, sure looks interesting.
 
JW
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