Red dot "roundness"

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Post by John McCormick on 10/9/2019, 8:43 am

I've tried the search function but I'm probably not using the right words. Apologies if this has already been talked to death. My Ultra Dots and my Vortex red dot sights all present a distorted dot. It's not a dot at all, really. It's more like a red smudge. I do try to keep the lenses clean. I'm using Rx glasses set for my distance correction (.75) and I'm told by my eye MD that I do not have astigmatism. Is it really all a matter of spending a lot more money on, say, the Aimpoint I see a lot of guys using?

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Post by DA/SA on 10/9/2019, 8:48 am

It sounds like you just need to try different lenses to get a focal length that agrees with the dot.

I sometimes have a similar issue and have found that on different days and different lighting conditions the clarity of the dot can change and different glasses are needed to get a clearly defined dot.

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Post by shootingsight on 10/9/2019, 9:05 am

Actually, it sounds like you do have an astigmatism.

Easy way to test is to create what optometrists call a 'stenopaeic slit'.  You want to create a slit about 1/16" wide.  put two strips of black electrical tape on your glasses, 1/16" apart, and running perpendicular to the direction of the smudge.  ie if the red dot is a horizontal smudge running 3 oclock to 9 oclock, put the tape on your glasses running 12 oclock to 6 oclock, so you create a vertical slit.  If that fixes it, you have an astigmatism.

You can also get an x-acto and a ruler, and cut a slit in a dark piece of paper which you hold up right in front of your glasses.  The benefit here is that it becomes easy to rotate the paper slightly, to tune the direction of the slit.

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Post by expendable on 10/9/2019, 3:33 pm

If the dot has an irregular shape, try rotating the red dot scope.

If the shape stays in the same position the problem is your eyes, if the shape rotates around with the scope it’s the dot.

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Post by jlow on 10/9/2019, 3:51 pm

Agree on astigmatism.  One easy way to tell if it is your eyes or the dot itself is to take a photo of the dot.  You likely will find the dot is perfectly round in the photo.

This may not be true for everyone but some people with astigmatism like me do MUCH better with a laser based holographic sight than a LED based sight.

For instance, Aimpoints are LED based and they always gives me a smudged dot.  On the other hand a holographic sight like an EoTech or Vortex UH-1 both gives me a clear dot.  The only way you can tell is to go to a store and look through some sights.

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Post by CrankyThunder on 10/9/2019, 8:08 pm

Dear John:

As the owner of a number of red dots and always in search of the perfect dot, I suggest that you check out the old tasco pro point scopes.  Specifically, the generation two scopes, the ones with a 30 mm tube and a 1/3 N battery. the battery that is about a half inch long and 3/8 inch in diameter.  Not the generation 1 that has a external battery tube mounted along the side but the generation two scopes.  The Generation 1 scopes suffered from negative magnification issues just like the current ultra dots and when they switched to the coin battery they had issues with battery life.  

This tasco scope has the most purest dot that I have ever seen.  I currently own two aimpoints, a primary arms, a sig, and a nikon red dot and three ultra dots and the tasco has the best dot of the bunch.  The problem with the tasco is that it is very heavy.  

Another option would be to check out the current issue tasco pro point, about 60 bucks, and it is a 36 mm tube with integral scope mounts.  quite a bit lighter but the dot is not as good as the original gen 2 tasco.  I have one of these mounted on my Pardini K22, yes, I got a 60 buck red dot on a pistol that costs more then a grand but that is a pretty good testament to the quality of the tasco.  

For what it is worth, I have a Ultra Dot H1 on my bullseye pistol, the Pardini SP bullseye New.  The tasco pro point gen 2 is too heavy and the current issue tasco does not fit on the pardini mounting groves.  

The tasco gen 2 that I have is mounted on one of my barrels for the SW 41 by the way. 

Sincerely, 
George
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Post by John McCormick on 10/9/2019, 11:28 pm

Thanks for the replies. Good info.

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Post by ser2711 on 10/10/2019, 4:47 am

If you do not solve the problem of astigmatism, it is probably that you have cataract, I solved the problem after surgery.. now I see a perfect round dot

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Post by thessler on 10/10/2019, 6:20 am

Hi John
I have an astigmatism,  my dot looks like a comet with a long tail.
I bought a stick on pin hole . It is just a cheap plastic stick on that goes on your shooting glasses . Not sure but I think it's called "eye pal" . When I shoot I look through it  and the dot is perfectly round.

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Post by jstanfield103 on 10/10/2019, 6:41 am

Cataract surgery took care of mine.
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Post by Bigtrout on 10/10/2019, 8:24 am

Try reducing the intensity.  Doing so makes the dot "clearer" on my Burris FF3.   FWIW.
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Post by jlow on 10/10/2019, 8:25 am

One can in fact "round" the dot if you make your eye look at the dot through a small peep hole.  This is like closing the aperture in a camera which increase your depth of field.  

The only problem with this is it will limit the light that comes to your eye.  May work say if you are shooting in bright sunlight conditions, but on a grey day, it would be like shooting with sunglasses on and may make it hard to see the target.

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Post by David R on 10/10/2019, 9:33 am

I was told to make the dot dim so you can see through it.  I also have MUCH better success with a larger dot.  I have 2 guns with an 8 minute dot.   Its like a circle in a circle from shooting sporter rifle with Peep and Globe. 

The larger dot can be made dimmer and still be easy to see.  I can never get a 1 minute dot to be more than a streak.  
I have a 5 minute dot SRO on my 9 mm 1911.  This has enough settings to get a clear round dot no matter where I am shooting.  

On my Burris FF, sometimes the lowest setting makes it difficult to find the dot on  a well lit target.  The next setting up is too bright and I get a comet.  Again the 8 minute dot is much clearer than the 3 minute.
I have lens corrected astigmatism. 

David
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Post by John McCormick on 10/10/2019, 12:48 pm

Thanks again. I've tried reducing the intensity, especially indoors. That makes it less flare-like. My eye doctor says no to astigmatism and yes to cataracts, but only so far as to say everyone my age has cataracts to one degree or another. He says surgery for me is way down the road, if at all. My uncorrected vision is quite good, the deficiency being the same one most people over forty have: difficulty focusing on things up close. I can read small print outdoors in bright light. Indoors, forget it. The 30mm Leupold scope I have on one of my ARs has what they call a Fire Dot reticle, and that presents as a perfectly round red dot. Of course it's a much smaller dot. Thanks again for the suggestions, guys.

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Post by Dr.Don on 10/10/2019, 5:33 pm

I think I'm going to be way out in the minority here, but I don't believe it really matters what shape the dot has.  The problem is to put the blob, star, smear, or whatever it is in the center of the black and squeeze through the wobble.  I've come to this opinion through decades of dealing with imperfectly formed dots, and doing what I said above generally results in a 10 or better.  If not, it wasn't because of the dot shape.
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Post by jlow on 10/10/2019, 5:40 pm

The problem with doing that is the shape of the blob is not consistent, it changes unpredictbaly depending on many factors which you cannot control.  It is also impossible to know where the center of the blob is (i.e. the POI) from shot to shot.  If you can make it work for you, more power to you, but most people find that difficult.

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Post by James Hensler on 10/10/2019, 6:47 pm

Guys I do have an astigmatism and I do see the star burst or sometimes it’s a blob. I am shooting this season with it and it is definitely a challenge. During CF at Camp Perry my dot was perfectly round and shot a 867 but that’s the last time it has been perfect. Shooting with the blob is distracting but I am dealing with it! Within 3 shots I can dial the clicks needed to make it work for that day or time of day. It varies 3-5 clicks during a match. Moral to my story is yes a person can still shoot ok but get Lasik!!!
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Post by TonyH on 10/11/2019, 7:58 am

Dr.Don wrote:I think I'm going to be way out in the minority here, but I don't believe it really matters what shape the dot has.  The problem is to put the blob, star, smear, or whatever it is in the center of the black and squeeze through the wobble.  I've come to this opinion through decades of dealing with imperfectly formed dots, and doing what I said above generally results in a 10 or better.  If not, it wasn't because of the dot shape.
+1. 
Try using an 1/16" or thereabouts aperture on your shooting glasses. Easily and cheaply made from cling film. Takes a day or two to get used to the aperture but after that one does not notice it.
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Post by -TT- on 10/11/2019, 11:41 am

John McCormick wrote:... I can read small print outdoors in bright light. Indoors, forget it.

So, this is the same principle as the iris. In bright light, your pupil contracts, this brings the light through a much smaller radius of your eye's lens, in effect pre-focusing for you.

One big advantage of using an iris, for me anyway, is that it forces you to hold your head in the same position for every shot. It does get in the way of dot acquisition in timed/rapid however. That can be overcome with practice. I suggest giving it a try!

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Post by airedale on 10/11/2019, 2:52 pm

I have used various red dots for over a decade because of my "old" eyes.  While on occasion I have a single near perfect dot, most of the time I don't.  I had cataract surgery both to fix the cataracts and to improve my astigmatism.  My left eye, not my shooting eye, came out perfect, always a round dot.  My right, shooting eye, not so much.  Doesn't matter what sight.  Some days I have a cloverleaf, other days just two dots slightly merged.  Other than being a distraction on days when I irrationally strive for perfection in everything not having a perfect dot doesn't seem to matter.  If you allow it it can became a distraction.  Anyway I try hard not to look at the dot but the target.  Once upon a time I had as close to perfect vision as one can have.  Intense computer work was the beginning of having vision problems.

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Post by BHeintz on 10/11/2019, 4:30 pm

Dr.Don wrote:I think I'm going to be way out in the minority here, but I don't believe it really matters what shape the dot has.  The problem is to put the blob, star, smear, or whatever it is in the center of the black and squeeze through the wobble.  I've come to this opinion through decades of dealing with imperfectly formed dots, and doing what I said above generally results in a 10 or better.  If not, it wasn't because of the dot shape.

I have always done this myself. I never see a clean round dot, and at times it is not round at all. What ever you are seeing, if it is in the black when the shot breaks, you should be fine. I did switch from a 4MOA dot, to 2MOA, and the smaller dot for me seems to help with this issue.

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Post by mikemyers on 10/11/2019, 11:39 pm

Why not go for an eye exam and get a pair of prescription shooting glasses designed to eliminate the astigmatism?

This video explains (near the end) what the problem is, and gives three ways to correct it.  Since we all need to wear shooting glasses anyway, they can be given a prescription to correct the problem, as long as you're wearing the glasses.  (There are other options too.)

https://www.youtube.com/watch?time_continue=5&v=9oNvqpM8PcA
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Post by jlow on 10/12/2019, 11:14 am

I wear contact that corrects for astigmatism, it does absolutely nothing for the blurred red dots.  I suspect it is because either a slight degree of astigmatism still exists since it is impossible to get 100% correction, or as an earlier poster mentioned, it might have something to do with a small degree of cataract which most of us have.

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Post by mikemyers on 10/12/2019, 11:28 am

I didn't think that was possible - the main feature of a cataract is that the lens gradually becomes more and more opaque, but I was wrong.  According to the American Academy of Ophthalmology:  

  •  "As the lens thickens and changes shape while developing a cataract there can be induced astigmatism due to these changes."

Another option is "contact lenses":

  • https://www.lenspure.com/articles/what-you-need-to-know-astigmatism-and-contacts


I haven't found anything on the. web about this, but while I don't have astigmatism, while wearing my progressive lenses (in my regular glasses), if I look through the wrong part of the glasses the nice round red dot seems to take all sorts of different fuzzy shapes.  My shooting glasses are not progressive, so this never happens while shooting, only dry-firing when I often wear my regular glasses.  I'm not sure if any red dot sights permit this, but would be nice if it was possible to add an extra lens to a tube-style red dot sight, where a corrective lens could be built into the sight.....
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Post by jlow on 10/12/2019, 11:36 am

Adding a lens to the tube to correct the fuzzy red dot was something I was interested in and I actually broached this question to my ophthalmologist but she unfortunately told me "no".

Really only two thing has helped in this quest.  One a peep sight that I installed in the rear iron sight of my AR where the RDS was installed.  Worked except for the loss in brightness.

The second thing is switching from an LED-based RDS to a holographic/laser-based RDS.  Unfortuately, there are limited choices i.e. a EoTech or a Vortex UH-1.

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