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Old April 30, 2012, 09:59 PM   #1
Crosshair
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Bushnell TRS-25, is this normal? (photos)

So I took my Ruger Gunsite scout rifle out to sight in the Bushnell TRS-25 that I mounted on it. I got it sighted in, but by that time the sun was giving me issues. Sunlight was obviously bouncing around inside the scope and screwing with the dot.

What I want to know is if this is normal or if my sight is messed up? If it is normal then I'll just have to deal with it, my irons would be even more problematic in such conditions anyway. If it's not normal then I'll just return the sight.

Here is a picture with the camera zoomed out to give you an idea as to where the sun is in relation to the sight. You can see the dot being washed out by sunlight bouncing around inside the optic.



Wide Angle HQ

Here it is close up when it is really bad.



Closeup 1 HQ

Here it is close up when it's not so bad, but still quite noticeable when shooting and partially obscures the target.



Closeup 2 HQ

What do the people who know more than me think? Is this normal for such a compact sight or do I need to exchange it?
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Old May 1, 2012, 08:06 AM   #2
wogpotter
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What you're seeing is "Flare" or more accurately "Ghosting" an extreme form of flare, where the flare actually has a distinct image of the reflection.
It is caused by poor design, specifically a lack of "baffles" (light trapping devices within the optic). Basically "extra stray light" gets trapped in between the glasses & bounces back & forth destroying optical quality. It is a design feature, not a manufacturing defect.

You won't usually see flare until the sun is shining more or less directly into the front of an optic, & the closer to being directly in line it is the worse it gets. One of the things that drives up the price of an optic is it's ability to retain contrast between light & dark & suppress flare & ghosts as the angle decreases.

It can be reduced by adding a shade (a tubular, opaque extension of the front of the tube) but never 100% eliminated. This is one I made from flexible black plastic sheeting & Velcro, but you probably won't need anything this huge for the optic you have. Even a 1/2" long one might help, you'll have to experiment & see what works for your exact optic. Tip, old plastic bottles, film cans & so on make great 1/2 completed shades.


There is always some flare in any optic, but the better designs will tighten the angle at which it occurs in relation to the sun & reduce the severity when it does. Try using a wrapped round piece of black paper to see how big a shade you need & once you figure it out you can make a permanent one form aluminum, plastic or something else more permanent. It may only need to be an inch or so long. Shades are sold pre-made in many sizes & lengths, but I don't know if one exists to fit your exact sight.
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Last edited by wogpotter; May 1, 2012 at 08:39 AM.
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Old May 1, 2012, 01:07 PM   #3
Crosshair
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Thanks for the very good writeup. In this case the cause not poor design, but the desire to get as small an optic as possible, thus there isn't any room for baffles in the optic.

So now that I know this is "normal" for an optic of this type, I have to ask myself if this drawback is worth it vs the small size and weight of the sight. In this case the answer is "Yes". I'll do what you said and look around at the possibility of devising some sort of shade, as putting by hand over the sight would make the ghosting disappear.

I now realize what the heck I am seeing in the sight, sunlight is getting into the sight and illuminating the diode, which is at at 4' of clock on the sight. That light then reflects onto the objective which I then see as part of the dot.

I should have tried tilting the sight to see if that made a difference, but as long as I know about the problem and why it happens I can work around it.
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Old May 1, 2012, 03:32 PM   #4
wogpotter
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How about one of those ARD honeycombs attached to the front of the tube?
That's worth looking at & they come in many different sizes.
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