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Red/green dot rifle scope as finder?

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16 replies to this topic

#1 SamplingNature

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Posted 10 September 2019 - 10:10 PM

So, a few weeks ago, I took delivery of a Meade ETX-80. I love the scope, despite the fact that the red-dot finder was DOA. Excited to get the scope set up for first light, I ran out to Walmart and picked up a green-dot sight for an air rifle.

The sight is "Gammo" brand. It's essentially the same design as the finder that shipped with the scope, and identical to other dot finders on the market.

It aligned well the first time I tried it (against a tower about
1 1/3 mile away), but took it off the bracket to when adding other accessories. The second time I attempted to align it, it didn't go so well. It is, after all, a $12 accessory for a kid's bb gun. And it fogs up almost instantly!

As such, I'm considering replacing it with a green dot 'scope' sold for firearms and crossbows, such as this: https://www.amazon.c...=gateway&sr=8-4

As the one I can purchase locally is 1x, I see no reason why it will not function well. It also seems that it would be easier to warm with hand warmers to ward off dew than the original finder.

Does anybody have experience doing this? If so, how well does it work?

#2 Bozemandob

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Posted 10 September 2019 - 10:38 PM

the mount would cause you trouble with rifle open sight.  Anyhow i've been through the telrad and rigel open sight systems, which are the most popular sighting systems for scopes.  I disliked them both.  Then i found the ultimate answer, using a laser pointer.  You'll need to check your style mount, but i use the Orion skyline deluxe bracket system, along with the dual finder scope mounting bracket so i can still use my finder scope as well.  dont buy a finder scope with a red dot, its too bright even on the dimmest setting, and drowns out the celestial bodies.  Also the laser that comes with the orion deluxe only works in temperatures down to 40°F.  you can just buy the bracket if your going to be observing in colder temps.  then i bought the z-bolt low temp laser, good till 14°F.  This is the best set up and i enjoy observing so much more now.  and the laser is the coolest thing you can show your friends.  Z-bolt sells a complete set-up actually, https://www.custom-l...stronomy-kit.  



#3 SamplingNature

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Posted 10 September 2019 - 11:23 PM

I actually have a pistol laser sight mounted on my telescope. It mounts to a Weaver plate secured to the scope with Gorilla Mounting Tape. Its likely how I'd mount the scope as well.

#4 Tony Flanders

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Posted 11 September 2019 - 04:48 AM

In general, unmodified red-dot or green-dot gun finders are way too bright for an astronomical telescope; they will utterly destroy your night vision. Telescope red-dot finders are usually just gun finders with an extra resistor to reduce the brightness down to manageable levels. Which is to say, about 1% as bright as a daytime finder.

 

Do you have any idea why the red-dot that came with your scope doesn't work? Can you fix it? Can you return it and ask for a replacement that works better?


Edited by Tony Flanders, 11 September 2019 - 04:50 AM.

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#5 Richie2shoes

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Posted 11 September 2019 - 06:50 AM

As Tony said, anything bright enough to be used in daylight is too bright for your scope.  I'd go with a Rigel Quikfinder, Telrad or some other red dot finder designed for astronomy use.


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#6 epee

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Posted 11 September 2019 - 07:58 AM

Firearm red-dots are bright as stated. If you plan on using the scope terrestrially, that can be a good thing. Red-dots are also good for aligning go-to mounts. You are likely to have difficulty mounting a firearm sight; especially high enough off of the optical tube to be comfortable to use. Both the Telrad and Rigel are best for star-hopping, with the Telrad being superior. The Telrad is large and the Rigel fits a small scope better.

 

Instead of dropping $30 on a sight that is not well suited to astro-use that will be difficult to mount, spend $40 and get something really nice at can be transferred from scope to scope.


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#7 John Fitzgerald

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Posted 11 September 2019 - 08:08 AM

The Rigel comes with two bases so can be used on two scopes, but I have found it difficult to snap and unsnap from the base. People with weak grips might find it impossible.

#8 Ed D

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Posted 11 September 2019 - 08:16 AM

I owned and used several firearm red dot sights, which I also tried on my scopes.  One big negative was that the lenses on these have a light gray tint, which makes them work very well in daylight by enhancing contrast.  It's subtle, but it's there.  That same tint will darken the night time views of the sky considerably.  They work well in the subdued lighting of an indoor range, which is exponentially brighter than the night sky.  If you shoot pistols or action carbine and have these sights, try them at night against the sky and see how you like them.  Please be discreet about it, preferably removing the sight from the gun.  I don't want any of your neighbors having a heart attack, or you in jail for careless display of a firearm.

 

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#9 hiMike

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Posted 11 September 2019 - 03:33 PM

Here's the one that came with my scope:

https://www.amazon.c...=gateway&sr=8-3

 

The pros are that its only $15, has standard mounting mechanisms, is easily adjustable, and has an analog power control meaning you can make it as dim or as bright as you'd like. The dot is small enough that you can dial it in really precisely and aligning with targets is quick and easy. It holds zero well enough, collimation will require a re-zero anyways.

 

The cons are that it doesn't have an automatic shutoff, so if you accidentally leave it on it will be dead the next time you go to use it. To make matters worse the battery is a pain to replace if you want to leave it mounted on your scope. It usually takes me two minutes to do (compared to 2 seconds to replace batteries on most other devices). It would be much faster if you took it off the scope to do, but then you'd lose your zero.

 

As others mentioned, laser pointers are the way to go. They're quick and easy and will help you learn locations in the sky much better (red dots always seem to be at an awful angle). That being said, many star parties do not allow laser pointers so you'll want to have both.



#10 hiMike

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Posted 11 September 2019 - 03:37 PM

I should also mention all the green firearm optics advertise how green is much brighter to the eye, so you may want to stick with the red option to preserve night vision. Not sure what the science says though, could just be marketing.



#11 Jon Isaacs

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Posted 11 September 2019 - 06:52 PM

I should also mention all the green firearm optics advertise how green is much brighter to the eye, so you may want to stick with the red option to preserve night vision. Not sure what the science says though, could just be marketing.

 

It's not marketing. The eye, particularly the dark adapted eye, has it's peak sensitivity in the green and has very little sensitivity in the red. 

 

Jon



#12 SamplingNature

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Posted 11 September 2019 - 10:19 PM

The scope I'm looking at has a variable intensity for both colors. I'll most likely purchase at the local Walmart, so return is easy if it doesn't work out.

I love the concept and look of the Telrad (not so much the Rigel) but I think it's overkill on this little telescope. I think the dot (or crosshairs if that were an option) would make for more precise two-star alignment.

#13 SamplingNature

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Posted 11 September 2019 - 10:23 PM

As for mounting, my laser sight (mounted top dead center) actually has a Weaver rail built into the top. Or I could mount it to the riser my existing finder is mounted on (possibly requiring a Weaver plate).

#14 Jon Isaacs

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Posted 12 September 2019 - 05:19 AM

The scope I'm looking at has a variable intensity for both colors. I'll most likely purchase at the local Walmart, so return is easy if it doesn't work out.

I love the concept and look of the Telrad (not so much the Rigel) but I think it's overkill on this little telescope. I think the dot (or crosshairs if that were an option) would make for more precise two-star alignment.

 

Variable intensity for a rifle sight is almost certainly too bright for astronomy.  A Telrad can be turned down to the point where it is essentiallyinvisible to the dark adapted eye under dark skies, you turn it up from there.  

 

Jon



#15 Tony Flanders

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Posted 12 September 2019 - 05:29 AM

The Rigel comes with two bases so can be used on two scopes, but I have found it difficult to snap and unsnap from the base. People with weak grips might find it impossible.


Yeah, I detest that base. It's the big weak spot in an otherwise excellent finder. Mine is now attached to the scope semi-permanently with duct tape.


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#16 Tony Flanders

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Posted 12 September 2019 - 05:33 AM

I love the concept and look of the Telrad (not so much the Rigel) but I think it's overkill on this little telescope.


I agree. I prefer red-dot finders on my small scopes because of their small physical size. Especially a wide-field scope like the ETX-80.
 

I think the dot (or crosshairs if that were an option) would make for more precise two-star alignment.


Actually the opposite, in my experience. It's very easy to center a star quite accurately inside the half-degree innermost circle of a Telrad or Quikfinder. It's much harder to overlay a dot on a star, because either the dot tends to overwhelm the star or vice versa.



#17 SamplingNature

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Posted 14 September 2019 - 11:18 PM

I went ahead and popped on the scope/finder I was considering at the local Walmart. No problem mounting it to the riser that the original RDF was affixed to when I received the ETX-80. I tried it out in the back yard (hand-held) and it looks like it should work out fine. I'll align it with the scope tomorrow, and hopefully get a short session in tomorrow night.


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