Rifle Scopes Losing focus

C

CT Sparky

Private
Minuteman
Nov 25, 2018
18
3
#1
I have been experiencing an issue with losing focus. After around 20 minutes, the sight picture is no longer clear and crisp. I have made adjustments u and down on the cheek rest, changed length of pull and still losing a good sight picture. Once everything becomes blurry, my groupings fall part. Using a FFP scope. Frustrating. Looking to see if anyone else has had this issue and how did you correct it.

Thanks!
 
#2
Not using a suppressor, are you?

Also, it could be an ocular focus issue where you don't have the system set up properly and your eyes are the problem vs the scope.

More background on the setup, the conditions you are seeing it, are you adjusting the parallax at every new range, etc.

Details matter if you want a real answer
 
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#4
What scope?
Its not just a crappy scope thats a strain to look through even in perfect conditions is it?
Are you getting all sweaty and flustered while doing this?
Having to crane your neck down awkwardly because your bipod is too low to comfortably account for your gut?

The only time I really strain with my glasses is with a junky piece of glass or Im uncomfortable looking through someones scope not adjusted for me on someone elses rifle not fit to me.
 
Last edited:
#5
No suppressor.
Have tried with Rx glasses (have a slight astigmatism and really only need readers) and clear lenses
Have reduced magnification.
Have adjusted parallax as well as the ocular focus many times, and I have a hunch that may be the issue.
Seems to be more prevalent while prone than with bench rest.
 
#7
spife7980 said:
What scope?
Its not just a crappy scope thats a strain to look through even in perfect conditions is it?
Are you getting all sweaty and flustered while doing this?
Having to crane your neck down awkwardly because your bipod is too low to comfortably account for your gut?

The only time I really strain is with a junky piece of glass or Im uncomfortable looking through someones scope on someone elses rifle.
Click to expand...

Burris Veracity 3-15 x 50

It is cold in New England; no sweating until late May!
Using good cheek rest; neck is at rest with no strain; could stay in the position for a while
 
#8
Youre looking through your glasses at an angle and causing a slight shift in prescription if its only in prone and the bench is fine. Maybe thats due to your neck craning backwards on itself trying to get your head vertical on a rifle thats too low. Maybe the scope is too far forward or too far back and youre having to stretch or compress your neck and thus straining your entire body to do so, all that wil effect your eyes.

Edit: Im a alow typer, so maybe not muscular straining but that doesnt mean its correctly oriented with your glasses. Thats just an addition lens to collminate.
 
#9
Lowlight said:
The scope is set up wrong ... that is the short answer

it's probably not positioned right as well as not adjusted correctly for you.

what scope is it ?
Click to expand...


Burris Veracity 3-15 x 50.

As far as glasses, I do not need them for distance, just reading. I can see well through Bino's and a scope and I have the same thing happening with clear safety glasses. I can more or less rule them out an issue with my glasses.

Scope is plumb and level and true to rifle. My gut tell me parallax/ocular focus. I have had no luck with these adjustments.
 
#11
Don’t wear reading glasses to shoot if you are okay vision wise at distance. Set your ocular up as noted above with no prescription glasses. Obviously you still need sun glasses or shooting glasses for safety
 
#12
Conrad101st said:
Don’t wear reading glasses to shoot if you are okay vision wise at distance. Set your ocular up as noted above with no prescription glasses. Obviously you still need sun glasses or shooting glasses for safety
Click to expand...

Not readers but regular glasses. I can shoot without them but prefer to use them. If I have to wear glasses at the rannge, then I where my Rx ones. Sun glasses are Rx. I was just making a point that I can rule out the glasses issue as it happen with and without them.
 
#15
How do you set up your diopter? Our eyes can make amazing corrections, for a period of time, then they get tired. Do you set your diopter with or without your glasses?

Does adjusting the diopter help when things fuzz out?

Another possibility is parallax error. Does the reticle or the image appear in focus, either or? Or does everything go fuzzy at once?
 
#16
I have set the diopter with and without glasses. Typically the reticle is clear & crisp. When I first begin my session, the image is clear, then after a period of time I start losing focus. I readjust, it gets clear then lose it again. After reading all of these replies, I believe it to be parallax error.

I followed the setup instructions posted on this site https://www.snipershide.com/shootin...rifle-scope-a-simple-psa-on-diopters.6252841/ . Range day tomorrow, hope this works.
 
#17
Agree with all previous recommendations. If you confirm proper set up and adjustment to your scope, thus ruling out a scope issue. Then I believe your subjective complaints would be primarily due to eye fatigue.
First, realize your eye is not a machine, it is a physiological system that can be prone to fatigue. In order to focus on near objects a muscle in your eye called the ciliary muscle has to contract to allow the lens to change shape and refract light, thus allowing clear focus of near objects. Focusing on far objects in actuality is a resting position for the eye. So, to simplify, looking at the horizon allows the eye to rest and recharge. Looking at small print, while reading for extended time, is extremely fatiguing to the eye. Relating this to shooting, concentrated focus on your reticle will fatigue your eye over time. Ways to remedy this are to ideally get out of the scope give your eyes a break by gazing down range. Once rested get back into the scope. The older you are, the more frequent and longer the rest times need to be. If you don't want to break your position, then simply close your eyelids for a period of time to obtain eye rest. Sometimes, an extended blink is enough to rest the ciliary muscle. If you need to stay in the scope, then direct your focus off the reticle and rest your eye on a distant image. Focus on reticle only as needed. This method in theory will not be as effective as the previous two for eye rest because the reticle and image are supposed to be in the same plane. I personally think it helps slightly from generalized less focused intent. No mistake though, for eye rest, close your eyes or look down range out of your scope.
The shooter needs to understand refined focus on near objects is like bicep curls for the eye--how much weight and how many reps your eye can do is all relative to that individual shooter's eye.
 
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#19
Not sure how bad your astigmatism is, but I had this issue before Lasik. Even with corrective lenses it would be an issue. I did not have astigmatism in my left eye and noticed things cleared up considerably when shooting left handed. After Lasik both eyes are very good and the issue has gone away. Astigmatism will definitely mess with a lot of the vision requirements to necessitate good shooting. Even when dealing with the astigmatism it was still possible to shoot really well. The image was just not as sharp and clear as without. I could tell at times it was a small handicap for hitting targets, but it was usually just more annoying than anything unless we are talking open sights or red dots. I never have explored this, but I know some people have glasses with a special prescription optimised to help them see while shooting. As was mentioned earlier, we are typically trying to view several objects at varying distances. The sights or optics are very close while the targets are not. This can easily cause eye strain especially as we get older.
 
#20
Results from yesterday, reset scope and saw some improvement. In order to get optimum results, I took lots of breaks. Got through the session but as I got around an hour I would lose focus quicker. Other than what has been discussed, I believe that I need to slow down and just give my old tired eyes a test.
 
#21
I agree with you that your eyes are fatigued causing your problems. I have the exact same problem. When it first started happening I went to my optometrist for an eye exam. I still had 20/20 vision so I asked him why this might be happening. He said it happens as we get older and would probably get worse as I got older. He suggested to rest my eyes longer between shots. I did and my groups improved. He was correct as I got older I required a longer interval between shots. And if I took to much time trying to get a shot off I would loose focus as well.:(
 
#22
I
CT Sparky said:
I have set the diopter with and without glasses. Typically the reticle is clear & crisp. When I first begin my session, the image is clear, then after a period of time I start losing focus. I readjust, it gets clear then lose it again. After reading all of these replies, I believe it to be parallax error.

I followed the setup instructions posted on this site https://www.snipershide.com/shootin...rifle-scope-a-simple-psa-on-diopters.6252841/ . Range day tomorrow, hope this works.
Click to expand...
CT Sparky said:
Results from yesterday, reset scope and saw some improvement. In order to get optimum results, I took lots of breaks. Got through the session but as I got around an hour I would lose focus quicker. Other than what has been discussed, I believe that I need to slow down and just give my old tired eyes a test.
Click to expand...


I had this problem for a while with two lower dollar scopes I owned earlier on I just gave up trying to correct it and I don’t wear glasses or anything it took me way longer than I would like to admit that it was happening after more time on the gun because I was heating the barrel up over time and it’s mirage I’m in the northeast as well so when it’s cold it’s just more of a tempature difference between the hot barrel and cool air, I only realized what it was when I made the connection between it going away every time there was a breeze one day maybe this is what’s happening in your case maybe not I just let the gun cool when I notice it now
 
#23
Anderson_A said:
I




I had this problem for a while with two lower dollar scopes I owned earlier on I just gave up trying to correct it and I don’t wear glasses or anything it took me way longer than I would like to admit that it was happening after more time on the gun because I was heating the barrel up over time and it’s mirage I’m in the northeast as well so when it’s cold it’s just more of a tempature difference between the hot barrel and cool air, I only realized what it was when I made the connection between it going away every time there was a breeze one day maybe this is what’s happening in your case maybe not I just let the gun cool when I notice it now
Click to expand...

This is an interesting concept. I as thinking of bringing a fan to keep the barrel cool or even get a barrel chiller. I have been working on mapping the “cold bore” shot; this could be part of the issue. The 1st question Lowlight asked was if there was a surppessor on the barrel ( trying to rule out mirage from the can).
I will give it a shot!

Thanks!
 
#24
Your best way to distinguish between eye fatigue or if you are seeing mirage from barrel/suppressor heat would be to do a long session of dry fire --focused shooting without firing a single bullet.
 
#25
I begin every session with dry fire. Never had an issue and always have focus. Remember, I am starting with fresh eyes so I may do a closing session as well. I will add this theory to the next range day.

Great stuff! I am glad I asked this question!
 
#28
I started having a similar problem about five years ago. Next time you go shooting start by looking at the target with both your left and right eye. Shoot with your right eye until resolution problem occurs. Switch back to the left eye. My guess is you won't have a resolution problem when viewing the target with the left eye. I would also hazard a guess that you will also see a marked difference right at the beginning when you check with both eyes.

If you wish, shoot left handed for a while. It's good practice anyway. I bet lefty your eye won't fatigue in a similar time frame.
 
#29
I have a similar issue:

Range is 100 yards, indoors, light is not super bright, but adequate. First 20 shots, everything is in focus. I can see both reticle and a target nice and crisp. Shots are slow, may be one in 5-10 seconds. Next 20 shots, best way to describe it is "focus hunting". If you film with SLR camera and a lens that is not super fast to focus, that's similar to what I see. Reticle remains crisp, but the target goes in and out of focus. For all shots after that, the target is very blurry. But the reticle remains focused. I tried to adjust the magnification - no change. It's the same on min and on the max. Interesting bit, on some shots, recoil "snap back" the focus for a split second. Then it goes back to blur. One more detail, I am shooting right-handed, while left is my dominant eye.

I shoot suppressed. Can the mirage be that bad?
 
#30
Nipp said:
I have a similar issue:

Range is 100 yards, indoors, light is not super bright, but adequate. First 20 shots, everything is in focus. I can see both reticle and a target nice and crisp. Shots are slow, may be one in 5-10 seconds. Next 20 shots, best way to describe it is "focus hunting". If you film with SLR camera and a lens that is not super fast to focus, that's similar to what I see. Reticle remains crisp, but the target goes in and out of focus. For all shots after that, the target is very blurry. But the reticle remains focused. I tried to adjust the magnification - no change. It's the same on min and on the max. Interesting bit, on some shots, recoil "snap back" the focus for a split second. Then it goes back to blur. One more detail, I am shooting right-handed, while left is my dominant eye.

I shoot suppressed. Can the mirage be that bad?
Click to expand...
It sounds exactly like mirage. Especially since you’re indoors. We can help you with that!
precisionundergroundriflegear.com

Suppressor Insulator

Please enter your suppressor model and/or size in the notes at the bottom of the first checkout page. 1.59″ is still considered to be in the 1.5″ class.
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908C292E-EA62-48C8-9C46-BCCF46EE65B6.jpeg
 
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#34
I’m 68, a novice to scopes more or less.

if it takes me too long to get a shot off, I need to look up and away from the scope and relax my eyes then come back to the reticle.

I have a mild prescription and the diopter range is enough to correct it so I shoot without Rx lenses.

I also wear strong reading glasses for close up which are required by most as we age since the lenses In our eyes stiffen w age and our muscles can no longer bend it to near focus.

It seems to me it’s this latter situation that causes my focus on the reticle to go blurry if I’m on it too long and why looking off at infinity relives it.
 
#36
Baron23 said:
I’m 68, a novice to scopes more or less.

if it takes me too long to get a shot off, I need to look up and away from the scope and relax my eyes then come back to the reticle.

I have a mild prescription and the diopter range is enough to correct it so I shoot without Rx lenses.

I also wear strong reading glasses for close up which are required by most as we age since the lenses In our eyes stiffen w age and our muscles can no longer bend it to near focus.

It seems to me it’s this latter situation that causes my focus on the reticle to go blurry if I’m on it too long and why looking off at infinity relives it.
Click to expand...

sounds like whilst your occular lens is adjusted so you can see, it isnt adjusted properly, its just adjusted close enough that your eye can correct the image but this can cause significant eyestrain.

theres a sticky at the top of the forum about scope adjustments - have you gone through the whole process? **(EDIT - just noticed you said you just did this, how did it go?)** do your glasses ONLY have spherical correction, or do they also have cylindrical correction - because if they do have a significany cyl value, no adjustment of the scope will fix it you will need to get glasses for shooting with (basically glasses with the right correction but the center of correction not at the center of the lens but where you look through it when on the scope) or (probably the expensive option, I've heard of it but very rare) have a special lens ground to fit to your eyepiece with the right correction
 
#37
mick243 said:
sounds like whilst your occular lens is adjusted so you can see, it isnt adjusted properly, its just adjusted close enough that your eye can correct the image but this can cause significant eyestrain.

theres a sticky at the top of the forum about scope adjustments - have you gone through the whole process? **(EDIT - just noticed you said you just did this, how did it go?)** do your glasses ONLY have spherical correction, or do they also have cylindrical correction - because if they do have a significany cyl value, no adjustment of the scope will fix it you will need to get glasses for shooting with (basically glasses with the right correction but the center of correction not at the center of the lens but where you look through it when on the scope) or (probably the expensive option, I've heard of it but very rare) have a special lens ground to fit to your eyepiece with the right correction
Click to expand...
I have a very light prescription and it falls well within the diopter adjustment range of my scopes.

Yes, I set my diopter using the generally accepted method of looking at a clear sky or solid white wall and adjusting until my reticle is crystal clear.

But completely independent of any of that, I use 3x magnification reading glasses in normal life and when focusing on a reticle focal plane (Cause we hard focus on the reticle, not the target, right) that’s only inches from my eyes for too long, it is a reading glass situation, I believe. And holding it for too long results in muscle fatigue from bending the lens in my eye to that close focus.

or, at least that’s my story and I’m sticking to it! Haha

I have prescription shooting glasses lens (Randolph Rangers) that I used for a very long time shooting registered skeet. But, I don’t like corrective glasses when on a scope for reasons that include what you mentioned, the center of correction isn’t really where I need it for scoped rifles.

thank you so very much for taking an interest and replying.
 
#38
Baron23 said:
I’m 68, a novice to scopes more or less.

if it takes me too long to get a shot off, I need to look up and away from the scope and relax my eyes then come back to the reticle.

I have a mild prescription and the diopter range is enough to correct it so I shoot without Rx lenses.

I also wear strong reading glasses for close up which are required by most as we age since the lenses In our eyes stiffen w age and our muscles can no longer bend it to near focus.

It seems to me it’s this latter situation that causes my focus on the reticle to go blurry if I’m on it too long and why looking off at infinity relives it.
Click to expand...

sounds like a classic case of improper reticle focus.
your eye compensates for a while until strain takes over.
it happens frequently and usually from looking through the eyepiece too long to acquire focus, if you look more than 10 seconds or so, your eye compensates & you defeat the whole process.
when you set your reticle it has to be instantly in focus, look away, then back, etc. preferably against a neutral background, sky, etc.
it happens far more than you’d guess.
 
#39
Tim7139 said:
sounds like a classic case of improper reticle focus.
your eye compensates for a while until strain takes over.
it happens frequently and usually from looking through the eyepiece too long to acquire focus, if you look more than 10 seconds or so, your eye compensates & you defeat the whole process.
when you set your reticle it has to be instantly in focus, look away, then back, etc. preferably against a neutral background, sky, etc.
it happens far more than you’d guess.
Click to expand...
Thanks Tim, please see the post right above yours. Does this perhaps change your view?
 
#41
Baron23 said:
Thanks Tim, please see the post right above yours. Does this perhaps change your view?
Click to expand...

nope. If can see well with lenses you should not lose focus with a properly adjusted scope.
with compromised vision, it really is tougher to get it properly done.
it is easier having somebody well versed watch you, internet solutions are often less than ideal.
 
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