Green Dot, any advantage over Red Dot finder

[glass]

Hello. what is the  difference between a Red Dot finder and a Green Dot finder? Thanks.

[Uranium235]

One has a red laser dot, the other is green..... thats about it! (they both still do the same job)

[Spacedout]

Hello Glass, 

The Green dot finder is better visually but is useless in cold weather.  The red dot finder is not so bright visually but will withstand much colder temperatures.  The other thing about the red dot finder for me is my camera picks it up really well though my neigbours will hardly notice it if at all.  The green one would raise a few eyebrows for sure!  This video shows the my red dot finder in use pointing at M42.  Now that is the simple difference but I'm sure someone else better qualified will have a more technical explanation.

Cheers

[Steve Ward]

Red/Green dot reflex sights are designed more for rifle sights than astro finding , the green dot is much easier to see in daylight but is generally too bright for nighttime use.

In much the same way as red laser levels usually need red glasses to be seen clearly in daylight , whereas the newer green laser levels are easily seen in daylight without the need for glasses.

[Floater]

I read somewhere that green light is a no-no for night vision. Can't remember where but definitely online, so should be treated with extreme caution - I mean it might even have been on an astronomy forum, so doubly worrying!

Seriously, anyone have an input on this? Green is bad for night vision? Something to do with colour receptors in the eye(s).

[stu640]

Colour receptors - Rods at night, cones in daylight. Rods work best under red light conditions and are sensitive to bright lights and less effective under illumination of other colours. Not sure about green, but most night vision equipment gives green/black pictures and in my experience I found they harmed my own night vision. Hope this makes sense - the bright iPhone screen is hurting my eyes as I'm writing this in the dark!

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[D4N]

The rods are most sensitive to green light and fairly insensitive to red, your brain interprets their information as grey regardless of wavelength.

The rods get worn out quickly when you look at a bright light source they are sensitive to, this will ruin your night vision until they regenerate.

By using a red light it is detected by your red cones but not by the rods, this will preserve your night vision.

So your eyes are most sensitive to green light but if you want to preserve that sensitivity for looking at faint things use a red light for everything else.

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[glass]

Thanks all for your replies, so I think I'll  get a green dot as well as red, it seems they are better in daylight.

[D4N]

What are you trying to find in the day? This type of finder would be useless for the sun. Solar finders are easy to make though as you can use the light from the sun to project a dot from a pinhole.

Or are you birding? Sights I've seen for that have just been plain unmagnified reticules, no need for a light.

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[glass]

I'll use the green dot in daylight for bird watching and the red at night rather than having separate finders, I wouldn't use it for the sun. I like this particular finder, it is smaller and much better built than the finder that came with my skywatcher (battery kept disconnecting / on switch often wouldn't work)  I think these rifle finders/sights are better value than the telescopic ones, although I paid probably twice as much as I need to have done, so would rather forget about price now.

[D4N]

Fair enough, the Skywatcher stock RDF is a common cause of dissatisfaction. Not sure why they can't get a simple on/off switch to work properly.

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[glass]

If I were to buy a telescope again I'd just buy it with as little add ons as I could, then check reviews on these and add when I needed. I must have spent a further £150 + on replacing finder, and mount both of which came with my Startravel 120mm and soon turned out to be pretty awful to operate as they should.

[paul mc c]

http://www.ebay.co.uk/itm/Airsoft-Reflex-Holographic-Red-Green-Dot-Sight-Scope-4-Reticles-Fit-20mm-Rail-UK-/391089348196?pt=LH_DefaultDomain_3&hash=item5b0ebdde64

What about this,has both red and green.

[glass]

I'd rather not look at that again, I've got one very similar but paid a lot more, just hoping mine is better in some way.!