Reflex sights - Image quality of aiming dot?

[Bill_Rights]

I just received my new Burris Fastfire II reflex sight and have some questions for those having experience with reflex sights. First, here is what it looks like:


http://www.burrisoptics.com/fastfire.html

This sight projects a red light beam from an LED (light emitting diode) onto the curved glass lens/screen. The screen has a coating on it that reflects only the wavelength of the light beam back toward your eye while letting all other light pass in either direction, so you can sight through it. The projected dot is supposed to be 4 MoA size. Put the red dot on the target, pull the trigger, bullet goes there (once zeroed). Simple, cool.

Questions:
1) The projected dot on the screen is a little "fuzzy". Actually, the edges look sharply, irregularly jagged. Is this normal? I think it is distracting, at least, for aiming. I guess I am spoiled by the sharpness of scope reticles. My first thought was, the jaggedness is due to reflections off small scratches on the glass screen. But I guess it could be from the LED lens/projection assembly. How to tell and what to do?

2) Mfgr says the intensity of the LED beam uses an ambient light sensor and brightens or dims the dot to suit light level - the sensor is in that little hole you can see in the photo centered just beneath the lens. Supposed to measure light in the direction of your target. Q: Could the fuzzy dot image be because the intensity is too bright? Maybe the intensity control is stuck on high? I can't see any difference, whatever the lighting (I guess that's the point of the sensor, but it may be too bright overall).

Do I call Burris or where I bought the unit (MidwayUSA)? How would I know that any replacement unit is any better?

Overall its a cool little unit - I think I'll like it once set to my liking.

 

[Hostile Amish]

Fuzzy dot appears on any reflex sight.

 

[dave from mesa]

I have a J-Point and the dot is fuzzy also. Sure wish someone could make them with a nice round clear dot.

 

[stubbicatt]

Howabout on an aimpoint? Is the dot any better defined?

 

[H2O MAN]

I had one of those and did not like the distorted view through the curved glass.
The dot was a little fuzzy and did not appear perfectly round.

The dot on my Aimpoint T-1 is clear until I crank up the brightness and the dot/reticle on my EOTech is crystal clear.

 

[hardluk1]

Find one that has and ajustment for brightness like all the tube tyoe have so you can dail in the amount of light needed. I to ordered a reflex type and would not get must again without the dial.

 

[briansmithwins]

Astigmatism in your eye can also effect the sharpness of the dot. Try rotating the whole sight: If the jaggies stay in the same place, it's your eye. If they rotate with the sight, it's the sight.

I agree that your Burris sounds like it's too bright for ambient conditions, which is another reason I don't like auto adjusting sights. BSW

 

[Walkalong]

Howabout on an aimpoint? Is the dot any better defined?

Just about a perfect circle until turned up too much.

 

[heron]

I never noticed any irregularity of the dot in mine (cheapo Sightmark), but what I do have a problem with is lining up the dot with the proper portion of my prescription glasses.

 

[desidog]

So the overall opinion I'm getting here is that the Burris isn't that good? I was thinking about getting one at some point, but am more inclined to go with the Leupold, since it doesn't require batteries to function...and the batteries always go too quick!

 

[Cohibra45]

'Red Dot' sights are not meant for 'precision' shooting......they are used for accurate 'fast' fire. In other words, if you want precision MOA shooting, get yourself a good scope. If your needs are MOM/A (minute of man/animal) and need to get off shots quickly, then the 'red dot' sights are what you need (or just a good set of irons)!!!

 

[Bill_Rights]

Thanks.

BSW: Thanks for the idea to rotate, check my own eyes.

H2O Man: OK, OK - Aimpoint and EOTech: I paid $209 for the Burris Fastfire II and I thought I was doing good not to cheap out but to pay 4X more than the $50 bottom-rung units, and buy from Burris, a family-owned USA (Colorado) company I trust and have seen good things from (although, the sight itself is marked "Made in Philippines", which I also 10X prefer over something made in China). But the Aimpoint and EOTech, aren't they $1000-1500? They damn well better be better! But I always assumed they got a premium price because they had the military contracts, and you could get just as good stuff, made in the USA, from those who don't have the big contracts. Not true?

Several of You: You seem to agree that overly intense dot makes the fuzzy-ness happen, or at least makes it worse. It gave me the idea to look around for a sliver of neutral density filter material/plate and stick it between the projector and the screen, to see if that cures the fuzz, i.e., by knocking down the intensity impinging on the screen. But of course, I need to be able to put the filter in the beam without blocking my eye-view of the screen, hence the "sliver" idea. Let you know....

 

[heron]

If you're going to do something with a neutral-density filter, I'd try putting a bit of it over the sensor hole first. BTW, have you tested to see if that's working? Block the hole and the image should change intensity (dimmer), shine extra light at it, and it should get brighter.

 

[mattw]

Try focusing on the target instead of the image of the dot. That is how EoTechs are designed to be used, maybe it would apply to this optic as well.

 

[Bill_Rights]

Further tests

BSW said:

Astigmatism in your eye can also effect the sharpness of the dot. Try rotating the whole sight: If the jaggies stay in the same place, it's your eye. If they rotate with the sight, it's the sight.

The "jaggies" do stay in the same place when I rotate the sight, so I tend to agree that the effect is in my eye. Actually, that would be another good test. Look at it with my other (non-dominant) eye - the two eyes couldn't have the exact same patern of jaggies. That said, if I dim the projection light, as heron said, the jaggies nearly go away. Mattw, your idea didn't work. Somehow the jaggies look the same no matter how far out I focus my eye(s). I guess that's the "magic" of 1X reflex sights - that's why they work.

 

[chris in va]

I have two red dots, both look like a coronal discharge from the sun.


If I lower the brightness, they appear nice and round. It's all in my eyes.

 

[Coal Dragger]

My Aimpoint has a fairly clean dot on lower power settings, but it is slightly elongated due to the angle it is projected on the glass.

 

[lipadj46]

Turn down the brightness it will appear fuzzy when cranked up. Also if you focus on the dot it can look fuzzy but if you focus past the dot it will sharpen up. You could have a bad one though.

 

[Bill_Rights]

Optics of reflex sights

Coal Dragger,
Your eyes are not fooling you about the elongated dot. I see the same thing on the Burris unit. I think this particular undesirable imperfection is due to the inherent optical output nature of the solid-state light-emitting diode (LED) or the laser diode (LD) being used to generate the light for the dot. These guys (LEDs and LDs) both put out an elliptical beam. See the figure below with the big blue oval in front and its label wording to the immediate left of it. This is entirely typical of these devices and a figure like this appears in every optics textbook relating to the matter:



The light-emitting material is built up in thin layers ( about 1 micro-meter = 0.039 mils = 0.000039") thick, in stacks, on semiconductor wafers, then the diode devices are cleaved out of the flat wafer into "chips" and the emitted light comes out of the edges of the chips. The chip is represented by the rectangular elongated-perspective box in the drawing. The emitting layer is wider than it is thick, so you get an elliptical beam (though note that the sense of the ellipse is 90° from what you'd expect). Turns out, it is a bear of a job to "circularize" these elliptical output beams. So most cheap optical systems just take a half-hearted stab at it and leave the output beam kinda not circular. More than you wanted to know, but this is what Burris and the others are fighting to get it right....

 

[sinistr]

i like the trijicon reflex myself,doesn't require batteries and is very tough.will washout in real bright light though.the small triangle redicle seems to work the best, imo.

 

[Hungry Seagull]

My sightmark reflex isnt that bad, however no auto light here, just a big knob setting the intensity.

Ask me again a month from now after the cataract is removed from the eye that will be using that sight.

 

[dillynfw]

I hope this isn't off topic but what's the max. effective range for a sight like this?

Obviously, there's no magnification. So is it merely then a matter of zeroing the sight at any reasonable distance you want?

 

[H2O MAN]

dillynfw

I hope this isn't off topic but what's the max. effective range for a sight like this?

I was able to deliver consistent hits to the head of a steel target
at 400 yards off hand with my EOTech equipped MK14 SEI Mod 0.

 

[Bill_Rights]

useful range and reticles?

dillynfw:
I don't mind (as OP) talking about range. I've looked at targets 200 yds away with mine and see no reason I couldn't put a (rifle) bullet into an 8" box with this sight (4 MOA dot size). But I think Cohibra45 (yesterday) has the right idea....

sinistr:
A triangular dot, eh? That could NOT be a raw LED beam of any sort. See my posting above about the elliptical beam and the difficulty of even making it just circular.

NEW SUB-TOPIC: Who knows if their reflex sight uses a reticle (or some kind of equivalent) to shape the "dot" or whether the dot you see is just the raw light beam, reflected off the screen?

I am beginning to think that the Burris Fastfire I have just has me looking straight into the output of the LED. Well, if so, no wonder the dot is fuzzy, jaggy or whatever!? Even looked at the filament of a light bulb up close? Or looked at the sun? Even looking into a flashlight too close is, uh, non-productive. The receptors in your eye are overwhelmed by the light intensity and all sorts of image distortions result.

Anybody know?

 

[briansmithwins]

Unity power sights (1X) shine for close up, fast work. They can be used for longer ranges (I've shot and got hits on man sized steel at 400 yards) but they have problems at range. The primary problem is that unity power sights don't help you SEE the target the way a magnified optic can: That tan smudge is just a tan smudge, not visable as a face...

The shaped reticles on a Trijicon Reflex sight are formed by the emitter. If you look at the emitter you'll see a little wee triangle, or chevron, or dot. I like the Reflex, but 2 batteries in a modern Aimpoint get you longer life (always on) than the tritium in a Reflex sight. Plus the battery is field replaceable. BSW