Birdwatching Dot Com










The Scopes Advisor

Binocular Advisor

Sign up for our FREE Email Newsletter

BDC Red Dot Sight for Spotting Scope

Getting the most out of your spotting scope

Red Dot SightWhen you're trying to aim your spotting scope at a bird, seconds count.

Adding a red dot sight to your scope lets you zero in on the bird instantly.

Say you're at 60 power and the bird has moved to a different branch, you can glance up from the eyepiece, reposition the red dot on the bird, and immediately find the bird in your scope again.

The red dot sight does not project a beam of light out to the target. A clever mirror positions a tiny, low-power LED light dot over the target. You see it, but the bird does not.

Battery consumption is minuscule, even with heavy use. The battery will last for months. The kit includes an extra battery and the battery is a standard size available at any hardware store.

What's the catch?

Astronomical telescopes often have mounting points for red dot sights, but spotting scopes don't. You have to glue the mount to the top of the scope.

This takes a little derring-do, so if you're up to the challenge, Birdwatching Dot Com has put together a kit with the parts you need.

If you buy and use our kit, you will be agreeing to take full responsibility for the results. You will be gluing the mount directly onto the top of the sunshade on your scope. This is not a risk-free venture. If you get glue all over the place or have other mishaps, these are not our fault. OK?

We include an extra base plate in the kit, just in case your first effort at gluing doesn't go exactly right. You'll have a second chance.

The BDC Red Dot Sight Kit

We've been attaching red dot sights to our scopes for years, and have tested many kinds of sights. We found what we think is the best solution and put all the parts together into the BDC Red Dot Sight Kit. It comes with the sight and mounting hardware already assembled and ready to mount.

The sight is manufactured by Sightmark, one of the largest makers of red dot sights. The sight comes with a three-year warranty from Sightmark. It's designed to mount on firearms so it can stand up to heavy use.

We selected this sight because it's ultra small and light. And it's bright enough to be seen outdoors in full sunlight. And it has an on-off switch, so you can shut it off and conserve the battery when you're not using it. And it's reasonably priced.

Red Dot Sight ViewThe vertical and horizontal adjustment of the actual red dot itself uses a small screwdriver, which makes it easy to make adjustments when you're in the field. Other models that we've tried use tiny allen wrenches that are sooo easy to drop and lose in the grass.

We've also found the right combination of mounting hardware that will raise the sight up to just the right height so that you can see it over the top of an angled eyepiece.

The BDC Red Dot Sight Kit includes:

  • Red dot sight with battery
  • Spare battery
  • Manual for using the sight
  • Mounting brackets
  • Small screwdriver and allen wrenches
  • Spare mounting bracket
  • Loctite adhesive
  • Complete mounting instructions

So that you can see just what you're getting into, we're including here the full instructions for how to mount the red dot sight on your scope.


Where to mount

The best place to mount the red-dot sight is on the sunshade of the scope.  On a scope with an angled eyepiece (like most birding scopes have) this will allow you to quickly switch back and forth from looking through the eyepiece to aiming with the red-dot sight. You won’t need to reposition your head, just glance up and down. This setup makes for quick aiming of the scope.

Many scope sunshades have some markings on them that give aiming assistance. To use with angled scopes, they need to be rotated off top dead center.  I recommend you rotate the sunshade so that the markings are about 45 degrees from top dead center before you mount your red-dot sight.

Also, you will be able to use the sight even if you have a digiscoping camera mounted on the eyepiece that would otherwise block the sight.  You can rotate the shade and sight into whatever position is easiest to use.  You will discover that the red-dot sight will stay on target even when rotated.

Mounting instructions

1. You need a steady tripod that you can firmly lock down to keep the scope in the same position while you are mounting the sight.  This is very important. If you don’t have a sturdy tripod, buy one or borrow one. You need to own a sturdy tripod anyway to see the best image in your scope. Set up the tripod at the height you would usually use it and attach the scope. Do this indoors with the scope looking out a window in a place where the tripod and scope can stay undisturbed while the glue sets.

2. Pick an object at the range you most often use when birding with the scope. Center this object in the field of view of the scope and tighten up the tripod head adjustments so that the object will stay in the center of the field of view while you are glueing on the red-dot sight.

3. Turn the red-dot sight on. The switch is on the back top of the sight. It has three settings. Bright, Dim, and Off. You can use the middle, dim setting to conserve the battery as long as you can still see the red-dot clearly. Since you are doing this indoors and looking out a window, the dimmer, middle setting should be plenty bright enough.

4. Set the sight on the top of the sunshade of the scope. The sight kit comes with its mounting hardware already attached. Slide the sight around on the top of the sunshade until the red-dot aligns to the sighting object as well as you can get it.

It’s OK if you can’t get a perfect alignment vertically.  You will be adjusting the red-dot on the sight to correct for this after you mount the scope. Just do the best you can.  Try not to have any of the sight extend out beyond the front of the sunshade.

When you find the best position, hold down the sight and mark the four edges of the mounting plate on the sunshade. I find a soft pencil works, but you could also use a Sharpie marker pen. You are marking the area that you will cover with adhesive.

Optional tip. Put masking tape on the sunshade just outside this marked area. This will help you remove any misplaced glue that gets on the scope during the mounting process.

5. Make sure both the sunshade surface and the bottom of the mount are clean and free from grease and dust.

Put the Loctite adhesive on both surfaces, on the bottom of the mount and on the scope sunshade where you have marked the area.  Too much is better than too little. You want to be sure you have enough adhesive to fill in whatever gap there is between the curved surface of the sunshade and the curved surface of the mount.

I like to squeeze out a blob of adhesive onto the center of the area and drag it out to the edges of the mark with a small tool. A  toothpick has worked well for me.

Let the adhesive sit on both the sight mount and the sunshade for the full timed five minutes as per the instructions on the Loctite adhesive package.

6. Put the sight on the scope sunshade and press the two parts together. Keep checking the red-dot and scope alignment as you do this, and try to get them aligned as well as you can.

However, you don’t have to get this perfect, because after the ahesive sets you will be able to adjust the red-dot sight. The sight comes with a small screwdriver that will let you adjust the red-dot alignment.

Optional tip. At this point I like to add a bit of extra adhesive over the holes in the sight mount and push it gently into the holes with a toothpick. This will help strengthen the adhesion to better resist side-to-side or twisting forces.

7. Let the joint sit undisturbed for the full 24 hours. It’s a great temptation to try to adjust the windage and elevation before then, but not disturbing the bonding process is important for a long-lasting mount. I even go so far as to not turn off the sight. The battery usage is small enough to not matter compared with getting a strong bond.  

8. After 24 hours, the adhesive is fully set and you can adjust the red-dot on the sight with the included small screwdriver to match up with your scope. The adjustmen screws have small screwdriver slots and are located on the top back and right rear of the sight. The top screw makes the dot move up and down. The right screw makes the dot move left and right.

Adjustment strategy

I like to sight in at a mid-range distance. The red-dot will be right on at that distance, a little high at closer distances, and a little low at long distances. I quickly learn to adjust my aiming accordingly so that the setting works at all distances.

At long distances, it matters less, because the object you are aiming at with the red-dot will still be in the field of view of the scope. A little experimentation will allow you to tune the red dot alignment to suit your personal preference.

Price info



Birdwatching Dot Com

Please call us toll free 800-779-7256 for advice on choosing scopes or other birding products.
FAX 641-472-7256
Birdwatching Dot Com Store
2197 236th Blvd.
Fairfield, IA 52556

Copyright 2013 Michael and Diane Porter.