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Question/Issue with Athlon...shrinking eye box?

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catorres1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote catorres1 Quote  Post ReplyReply Direct Link To This Post Topic: Question/Issue with Athlon...shrinking eye box?
    Posted: October/21/2016 at 22:52
I have a question about low light scope performance, and perhaps I am just expecting too much, but I wanted some opinions.  I recently got an Athlon Midas 4.5-27 and finally got it mounted on a multi-use 6.5 Grendel....a primary use being pig and coyote hunting at night.

Went out two weeks ago with my son to hunt pigs and sat in a spot watching deer as the sun went down, and when I looked through my scope, it was as though a white curtain was pulled across the view.  Sun was behind the trees to the left.  I could not see hardly at all.  I found by dialing mag all the way down, I could see.  I also noted that if I pulled the rifle up to view the brighter horizon, I could see, but as I moved down to look into the trees, I could not.

Last week, went out again to the same place, intending to test a little more carefully, which did not happen, but did have the same thing happen...somewhere between sundown and about half an hour after sundown.  Again, it was as though everything went white and I could barely see.  Once it went totally dark and the full moon came up (or if we used a spotlight), we could see just fine.  In fact, the full moon was so bright that at near midnight, we could see telephone poles and metal gates at 350 plus yards with no lights through the scope.  

So today, I took the rifle out to a ranch for more testing (in between being made a fool by speeding doves).  What I found is that the effect is like when your eye is slightly off center, just starting to leave the eyebox by looking vertically too low in the scope.  I could actually simulate the effect by moving my head in a certain way inside the eyebox, even in regular light.   I found that as the sun went down, that it seemed the eyebox got smaller and smaller, and if I moved my head around sometimes I could find a spot where it worked.  So it seems like the eyebox shrinks in the twilight hours, which makes no sense to me.  

I decided to check mags from top to bottom and found at minimum, it was fine, at 10, it was tight, at 15 it worked if you had it juusst right, and at 20 plus, it is as though the eye box shrunk to 0, and you just could not find the spot to make the image clear.  So all this leads me to think it is indeed the eye box, which corresponds with the tighter box at higher mags as one would expect.  Oddly, I also noticed that the 'sweet spot' that works when this problem occurs, seems to be slightly off center, that is the 'black' around the image is thicker at the bottom than it is at the top.  If I move my head so that the black circle around the image is even, it goes white.

I did test against another rifle I have with a different scope, it did not exhibit this problem.  It is a 3-15x 42, and it seems uneffected.

So do I have a defective scope, or is this due to the optical design?  I was reading Ilya's article on scopes, and he mentioned a kind of flare...could this be it?  Hopefully, he'll read this and can educate me.

I have contacted Athlon.  They seemed very cooperative and are willing to replace it, but they don't know if this is just the way it is, whether my expectations are too high (as my other scope may have spoiled me) etc.  Hate to bother swapping around and just having the same, but as this rifle will see a lot of use in low light, I sure hope I did not make a mistake here.


Thanks!

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catorres1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote catorres1 Quote  Post ReplyReply Direct Link To This Post Posted: October/21/2016 at 23:02
Okay, I just did a search on veiling flare, the term in Ilya's document, and while most images were not what I am experiencing, this one is fairly close.  Here is the url:


http://static1.davidkennardphotography.com/wp-uploads/834-kodak-1a-pocket-jr-digital-mod/Veiling-flare-Kodak-Pocket-Jr.-Digital.jpg

Hope that helps!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3_tens Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2016 at 10:01
First off I would never recommend a scope with, or in this magnification range for hunting in low light. 50 Objective but with lower magnification. 1-6 range. Glass quality trumps magnification every time. The first thing magnified by high magnification is the defects of the scope. Even shooting out to 1000 yards rarely is 15X needed. Money spent on better glass gives better results than spending a lot for magnification that does more harm than good.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote catorres1 Quote  Post ReplyReply Direct Link To This Post Posted: October/22/2016 at 11:44
Yeah, I did not really care too much about the top end mag, except that I liked the idea that my sweet spot should be in the 15 or so range, where I really intended to use it most of the time.  I have a Vortex HST on a purely target rifle, and I find that it drops off steeply in clarity after 18 or so.  So I figured I would get higher mag than I needed to have a strong centerpoint in mag that corresponds with what I wanted, if that makes sense.

As for the quality, I read alot on the boards before taking a risk, and it seemed like an opportunity to jump in on higher quality before it got too famous.  And the rifle it went on was to be a varied use rifle, from shooting targets at long range at mid-day, to hunting hogs etc. at night.  When I bought it, there was a 'try it for some period and if you don't like it, we'll buy it back' guarantee.  May need to invoke that if I can, not sure yet.

For twilight, a good useable 10-15 power is probably what I was hoping for, and I still may be able to get that out of this scope, not sure.  For dark, considerably less, but the odd thing is, in real dark, this problem goes away, I can use any mag and see fine.  It's just that period from just after sundown to dark where the problem shows itself, which is certainly within legal hunting hours even for deer where I live.  And for pigs, anytime is legal.  So I don't get it, honestly, maybe it's some sort of stray light issue, or something is misaligned, I don't know.  But I have already had one person on another board tell me they  have the same exact problem, but theirs is the 2.5-15.

For the higher mags, would not use that after sunset anyway, so hopefully it is not an issue, but I need more testing opportunity to be sure.

I will say that my hunting scope that I have on my 300 has none of these issues, completely useable and bright all through the range, and it's a 42mm.  Cost was more than a bit different though, and it does not have a 'real' zero stop, which I wanted for the Grendel as I will be using it at longer range on steel quite a bit.

I wonder if a sun shade would help here, or if it's just a failure in the design....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: October/23/2016 at 15:28
This is a pretty classic veiling flare problem.  All other thing being equal, it is generally more pronounced in scopes with larger objective lenses.

This issue is most pronounced when you are trying to see somethign comparatively dark, while there is still a dominant light source in the image somewhere.

As far as the exit pupil shrinking in low light goes, that is obviously impossible.  The optical system of the scope does not change regardless of the light levels.  

What is happening is that as the light goes down the pupil of eye gets bigger, so the alignment of your eye to the exit pupil of the scope gets more critical as the relative size of the eye pupil with respect to the exit pupil changes.

Lastly, on the quality of the Midas scope: I have not tested one, so I do not know how it stacks up.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dw0229 Quote  Post ReplyReply Direct Link To This Post Posted: October/23/2016 at 19:46
I had a problem last hunting season that cost me a deer. I was way up a tree (about 50 ft ). I was watching a field in the middle of 15 feet high pine plantations. There was a lot of skylight all around me as I was perched way above those small trees. I had a deer on the field which was easily seen through my binos. I was using a Trijicon Accupoint 2.5-10x56 and was on 4 power. When I shouldered all I could see was a washed out white. Kinda like a snowy tv screen. Try as I must I never could make the shot. I blamed it on the quality of the glass-coatings. Which may or may not have been the case. I always wondered if I had been up there with a high quality European scope what the outcome would have been.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: October/23/2016 at 20:07
Just out of curiosity, did you try changing the magnification? And did it have any effect?

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dw0229 Quote  Post ReplyReply Direct Link To This Post Posted: October/23/2016 at 20:26
No. Just left it at 4 power. Didn't think to do that.I forgot to add thatddarkness was falling. It was about 5:30 in the evening .
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Post Options Post Options   Thanks (0) Thanks(0)   Quote catorres1 Quote  Post ReplyReply Direct Link To This Post Posted: October/23/2016 at 22:03
Hey guys, thanks for the responses!  DW, sounds like what I am seeing.

Ilya, so I did some more testing last night as the sun went down.  First of all, my 42 mm HD5 exhibited no problems whatsoever, at any mag.

Back to the Midas, I noticed that if I very carefully aligned my eye through the scope, with everything perfectly centered, it was extremely white.

However, if I broke my cheek weld and pulled my head higher so that the 'dark ring' around the image started to protrude into the image, ie not looking through the scope directly through the middle, but looking at it more through the top half than the lower, I could just find a spot that worked.  The darker it got (until full dark) the more I had to move my high off center and the harder it was to find that spot.  If I pointed the scope into the bright sky, the problem went away, as I lowered it into the dark trees, it got worse.  As I raised mag, it got to the point that it was impossible to see at all.  As I lowered mag, the problem lessened.

But it was definitely effected by eye position, and it required me to look more and more through the top end of the scope to the point where the 'black ring' started to protrude quite alot for me to be able to see without the white.

I need to test with my sons, who have better eyes than me, maybe it is not the same for them.

So I guess my question is, what is the solution?  Is this just a fact of 50mm life? Or do I have to get a different brand/design?  I am considering selling it or trying to return it to Athlon and picking up something else, but I don't want to move to another 50mm and having the same issue.  

BTW, a sunshade did nothing to help.

BTW, otherwise, I like the scope for what it is.  The reticle is great, clicks seem dead on, in good light, it seems pretty crisp until the top mags, though I have not tested it too much.  At night, under a full moon, I can see very far very clearly without additional illumination...the other night, we were easily able to make out telephone poles, gates, fence posts, etc.  out past 350 yards.  

If it were not for this problem, I would be very very happy with it considering the cost.

Thanks for your help here!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Snack_Attack Quote  Post ReplyReply Direct Link To This Post Posted: November/11/2016 at 18:52
Many scopes tend to do this. I see it in scopes with 32mm and 40mm objectives, and always becomes worse the more you increase magnification. Oddly enough the only scope that i have seen that didn't was an older nikon prostaff 3-9x50. I believe larger exit pupil eases the problem, and on 9x a scope with 50mm objective will still have a respectable exit pupil size. As koshkin said, it's a problem of light getting into the scope that isn't coming from the target area. Thats why it went away when you looked at the sky, but came back when you looked at the dark tree line. A replacement from Athlon will be the same. You could get rid of it and buy another one of the scope you say was unaffected. 3-15 was it? Otherwise, just keep the scope and live with dialing back the magnification. I wouldn't consider it too bad if you can still get around 10x without seeing it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote catorres1 Quote  Post ReplyReply Direct Link To This Post Posted: November/12/2016 at 21:31
Thanks for the post!  I sent the scope back to Athlon.  They told me it should not be doing that so wanted it back.  When they got it, they told me that they tested it and were able to duplicate the problem.  Interestingly, I also sent them an account of another person having the same issue, and they said that another person had just called them with a scope from the same batch with the same problem.  

They said that they had identified the problem and it is due to some kind of non-reflective coatings being applied incorrectly.  They were testing the new batch they had just gotten in to ensure there were no problems and then were going to send me a new one.

So hopefully, all good.  We'll see when it gets here.  
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