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Parallax Distance markings

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 15:08
martinv View Drop Down
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I just received a SWFA model SS10X42MQ but found to eliminate the parallax at a target over 1000 meters I have to dial the focus ring to ~175 meters. Why is this? This is the rear focus model and the max distance labels on the focus ring are 500 meters, then infinite. I would have assumed infinite would have been correct. Is there any adjustment to calibrate the focus ring? Is something wrong with the scope? This scope came with no user manual.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 15:11
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Welcome to the OT, I'd call customer service tomorrow am!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 15:43
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Most common reason for such a disagreement between the parallax marking and target distance is an incorrectly adjusted eyepiece.

Did you carefully adjust the eyepiece for your eye?

The basic procedure is listed elsewhere in painstaking detail, but basically, you should set parallax at infinity, look at something featureless, like the sky and slowly adjust the eyepiece so that the reticle is as sharp as possible, making sure you frequently look away at some distant object to let your eye rest and reset.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 16:21
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The eyepiece adjustment appears to have NO effect on the amount of parallax.  Is this not normal for a first focal plane scope?   I just retested the eyepiece through its entire range.  With the focus ring set to infinite, and looking at a target over 1000 meters, the amount of parallax deviation seems to only be affected by the focus ring.

I am slightly nearsighted (still good enough to pass the eye test at the DMV).  Could this be a factor? 
If I ignore the numbers on the focus ring, the scope appears to work otherwise.  This is my only decent quality scope, however my $89 UTG scope seems to adjust much closer to its labeled distance values on the focus ring.  (The UTG is 2nd focal plane and adjustable power, so I don't know if this is a factor).
The SWFA SS is fixed power 1st focal plane.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 16:45
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You are looking at it the wrong way.  Do not try to dial out parallax with the eyepiece.  Your eye continually adjusts and adapts, so that will give you very little.

Look at something featureless and make the reticle as sharp as humanly possible.  Make sure you do not stare through the eyepiece more than a few seconds at a time.

Screw the eyepiece adjustment ring out to the end of its adjustment range.  The reticle should be blurry.  Look away at something distant.  While doing that, adjust the eyepiece slightly.  Glance through the scope and if the reticle is still blurry at first glance, look away again and make another adjustment.

Keep doing it, until you are past the point of perfect reticle sharpness, so you have to dial back a little.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 18:38
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I did the eyepiece adjustment you described.  I made sure my eyes were focusing to infinity and adjusted the eyepiece from all the way out, to the point the reticle was just into focus with my eyes focused to infinity.

Regardless of the method, with the focus set to infinity, shouldn't there be some point where there is no parallax when looking at a target 1200 meters away?  The only change in parallax I see is when I adjust the focus.  It's as though the scope works fine, but the focus range is not calibrated to the indicated numbers. 

For example: I had the focus set to infinity and was looking at a target at 1200 meters away.  There was no way to get rid of the parallax except for dialing the focus to ~175 meters.   Even after trying every possible eyepiece position the parallax would appear to remain exactly the same.




Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 19:26
koshkin View Drop Down
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If you set up the eyepiece correctly and parallax dials out at 1200 meters when the setting is 175, then, there was likely a calibration error at the factory and you should indeed call SWFA for a repair or replacement.

Everyone's eyes are a little different so the marking on the parallax control are often not dead on, but they should not be quite that far off.

If you are parallax free at 1200m with a 175 yard setting, chances are you can not get a parallax free setting at 10m.  Have you checked close distance parallax?

To answer your other question: eyepiece focus does effect parallax (obviously), but using it for adjustment i difficult since your eyes start playing tricks on you.  As you adjust the eyepiece, reticle focus changes and your eye tries to compensate for that by changing its focus.

That makes everything inconsistent since your eye is continuously under strain.  The least strained operating mode for your eye is looking toward infinity, so you want to set up your eyepiece in such a way that your infinity focused eye does not have to strain.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 20:01
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Originally posted by martinv martinv wrote:


Regardless of the method, with the focus set to infinity, shouldn't there be some point where there is no parallax when looking at a target 1200 meters away?  

What does "focus set to infinity" mean?  Once the ocular is correctly set, it shouldn't have to be touched again.  And, once the ocular is set, adjusting parallax should not be equated with focus.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 21:16
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Quote What does "focus set to infinity" mean?
 The focus control has markings from 20 meters to 500 meters, followed by the infinity symbol "".  I assume this means every distance at some point above 500 meters.  


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 21:38
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Correction the focus range on my scope starts at 10 meters (not 20).

Originally posted by koshkin koshkin wrote:

If you are parallax free at 1200m with a 175 yard setting, chances are you can not get a parallax free setting at 10m.  Have you checked close distance parallax?

Good question.  I just tested this and it cannot quite get to parallax free at 10 meters.  At 20 meters a setting of ~15 is parallax free.   
I think i will contact support tomorrow.  I am now curious what the factory calibration procedure involves.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2015 at 21:53
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(I need to preview before posting since I have no editing permissions.)
Note the text on the post above starts off to the right side of the quote.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/01/2015 at 12:25
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I think we need to decide on a vocabulary before we continue.

"Focus" is generally used to define setting the reticle for maximum sharpness to your eye.  Once this is achieved, you shouldn't have to mess with the reticle focus again, it should be clear and well defined in all applications.

"Parallax" is defined as an apparent shift in the position of the target caused by a shift in the position of the shooter's view of the target.  Or something close to that.

Yes, as you get further way from a parallax-free image, the target does get blurry; however, the function of the parallax adjustment is much more about removing parallax than it is about focusing on the target.

To focus the reticle, look at a blank sky and make small adjustments, looking away often, then looking back at the reticle.  If you stare at the reticle and make adjustments, your eye will also be making very small adjustments; and the end result will be pulling the rifle scope up and the reticle not being focused at first glance.  That is bad.

Once reticle focus is set, parallax should be much easier to deal with.

If you find you are adjusting both, or cannot get a good view with the parallax adjustment once the reticle is focused and set, then something is wrong with your scope.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/01/2015 at 17:21
martinv View Drop Down
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Sorry about the terms confusion. 
I used the term focus as SWFA indicated it as a "Rear Focus" control:
Stock # - SS10X42MQ
  • Matte Finish
  • Patented Mil-Quad Reticle
  • 30mm Tube
  • Rear Focus
  • OK for .50 cal
  • .10 Mrad"

I do agree calling it a "Parallax control" is much less confusing.

I called SWFA service and I have now sent the scope back for service.  I'll report back the results once I find out. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/02/2015 at 08:45
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/15/2015 at 18:41
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RESULT OF THE PARALLAX ISSUE: 

My scope is "lost in the mail".  

Not getting a tracking number was a major mistake on my part.  I suspect no tracking number = invitation for theft.  

Do these scopes have serial number?  Another thing I failed to capture if there was one.

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