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Red dot finder

Eyeball

By Eyeball
in The Astro Lounge

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Demonperformer

Demonperformer

Posted
Posted

You use it by keeping both eyes open, looking through the finder with one eye at the red dot, and at the sky with the other eye, superimposing the dot over the required object.

That presupposes that you can actually find the red dot when you look through the finder, which is a whole different story!!

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Demonperformer

Demonperformer

Posted
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When I can find the dot it is a wonderful system. I have come to the conclusion that there is a relationship between the amount of extraneous light pollution and the difficulty of finding the dot. Unfortunately the LP in my garden is quite high, so I can have loads of trouble. Often, if the moon is visible, I just use that as a first alignment object with a long fl eyepiece and just go from there. But as I say, on the occasions I do find the dot it is great.

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jgs001

jgs001

Posted
Posted

That about sums it up. The RDF has some leeway on where you look through it, but outside of that you can't see the dot. However, you don't need to get one eye up right against it, and squint, which for me at least, makes it much easier to use. And you don't get the inverse view of finder scopes (I couldn't get my head around that one..) I'm a fan :D

I have a SkySurfer III and the dot has variable brightness to the point I can make it bright enough to see it against the daytime sky (for the moon).

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jgs001

jgs001

Posted
Posted

I have a 6x30 (I think) finder on my Skymax, and I really don't like using it, needing to squint into a tiny eyepiece at awkward angles. I only have that on there as the FOV is so small as to need the extra magnification, but even then, if the finder is even marginally out, even locating the moon becomes a chore.

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Brinders

Brinders

Posted
Posted

I have an RDF on three of my scopes (and a finderscope on the CPC 925). I prefer it to the finderscope and have no problem seeing the red dot superimposed on the sky even in bright daylight with the brightness turned up. You don't put your eye up to it like in a finderscope, but look through the RDF screen at a short distance, as though looking through a window, and onto the night sky. You should be able to see the red dot, and once properly aligned with the scope (easier to do than a finderscope) you should be able to bring the red dot and your telescope onto the object you wish to observe. I wouldn't be without mine.

A word of caution regarding a laser: the authorities (Police, CAA etc) apparently take a dim view of them (no pun intended) as they have caused temporary blindness to pilots when the thing is shined into the cockpit, whether done intentionally or not. Personally, I think they should be banned and have no place in the arsenal of a responible astronomer.

Brinders

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Astro_Baby

Astro_Baby

Posted
Posted

I have both on my main scope. A red dot for general location and for star hopping and an 8x50 for finding stuff once i am in the right area. Some objects are easier to spot with an optical finder rather than a red dot.

If I had to choose just one I'd pick the RDF though.

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Iris

Iris

Posted
Posted

I got my first scope a few weeks ago - just a little ETX80 but one of the first annoyances was getting it ligned up with my chosen target - the amount of time spend flailing around the sky was really getting ridiculous - now this is probably partly down to inexperience I expect.

Now the ETX80 is a GOTO and one might figure that once aligned you could just rely on that to point in the right direction of the target - even it if is less than perfectly aligned it ought to put your target reasonably close to the FOV.

The first few times I used the scope - mainly on Jupter and the moon I had mixed results - the moon being so darn big is easy enough to hit - but even jupiter in all its brightness proved to be elusive and trying to line the tube up with anything else - even bits of Orion with which I am fairly familiar was a job an a half!

The first time I managed to align the GOTO it was pretty close and I was quite impressed but that was likely luck because the next time I tried it was a wash out and I ended up giving up.

So I decided to get an RDF to help. I took it out for the first time on Saturday, I think, and it was like night and day - alignment was a snap and star hopping was a joy in comparison to my previous wave and hope approach - I definitlely wouldnt be without it now (even having only used it properly once) - now that I know that I can put the scope on my target (at least those which are visible to the naked eye that is) I will have the opportunity to build confidence in navigating the sky for those objects that one cannot see so easily.

I would echo the earlier comments about sometimes having trouble finding the dot in the viewer but once set up it is quite easy to find a spot on the back of the finder to align your eye to ensure a fix every time (at least this is true of mine) - and I found after just a short while that using the finder with both eyes a short distance behind the scope became second nature.

My blog has some of the gory details of my early experiences both with and without the RDF.

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Talitha

Talitha

Posted
Posted

Hi Colin, i've never had a problem with my RDF either. All you have to do is make sure you're right behind it.. prety intuitive, actually. I got one a long time ago when they were first offered by the 'Orion' company here in the States and haven't used a regular finderscope since.. yes, they're that good. :)

What you see is a red light (on your end of the RDF) reflected on a small piece of plastic (on the sky end of the RDF). The dot looks like it's in the sky, but it's really not. :D

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jgs001

jgs001

Posted
Posted

Steve, I've compared a Celestron included with scope RDF with the SkySurfer III. There isn't a lot of difference, except the SkySurfer has a larger aperture which makes it a little easier. I've heard the SkySurfer V is even better by a very large margin, but it ought to be given how much more it costs :D.

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Astro_Baby

Astro_Baby

Posted
Posted

The Sky-Surfer V is a HUGE jump over most RDFs. Its a really well made and solid bit of kit. In that class of RDF though you also have the Telrad (very popular bit of hardware) and some other high quality types like the Rigel one and also the Revelation one - some of those are a good deal less expensive as well.

I have a Sky Surfer V and like it lots - its very robust, gives a good clear view and doesnt use reflective coatings so it doesnt dim down the view and mask faint objects as badly as the small red dots I have used before.

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mint_mark

mint_mark

Posted
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I've just fitted a Rigel quick finder to my small 72mm scope. This finder stands up from the scope so its base is only 6cm by 5cm. You can attach the base to the scope using supplied sticky pads or you can use a screw. I screwed mine on and added a piece of old cycle inner tube to protect the scope and add grip. The finder clips into the base (quite firmly!)

When you look through you see two concentric circles. You can see these with your eye close up or quite far away... back up too far and the circles become larger than the window. You can adjust brightness and have them flashing if you like. There are three small knobs to move the circles for lining up with your scope... very easy.

I've practiced through the window on street lights, but no stars tonight... we've got lightning, thunder and hail :D Still, I could find street lights at ~1200mm with no problem, so it's looking good. I didn't have a finder at all before, so even finding the moon was tricky!

The Rigel is quite cheap, all plastic, maybe a bit fragile. On the plus side it is very light, won't affect your scope's balance and is hopefully resistant to dew. It uses a CR2032 button cell... don't know how long it lasts. There is an optional 2xAA holder too which requires a little effort to fit. I'll wait and see if I need it.

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timefortea

timefortea

Posted
Posted

Like Mark I've just fitted a Rigel finder with 2 concentric rings rather than a dot. The design of the Rigel makes it stand 3-4" proud of the scope body, this makes it ideal for my my less than flexible neck. Also the "normal" view on the reticle and the double ring targeting system make it really intuitive.

I think my ordinary finderscope may soon be made redundant.

Got my Rigel from FLO and the service was superb :)(grovel creep grovel :D)

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John

John

Posted
Posted

Another vote for the Rigel Quikfinder here :D

I've tried many RDF's including the Telrad but for me the Quickfinder is the best all round. The 2 concentric circles (reticules) it projects (as apposed to a dot) are 2 degrees and half a degree in diameter (against the sky) so they really help with star hopping. It also has an adjustable frequency pulsing reticule option as standard (it's an extra with the Telrad) which can be useful as well. Add to that it's lightness, ease of fitting and alignment and low cost and I think it's a real winner :)

That said there are times when a decent 50mm optical finder is useful as well so my optimum setup is one of each on the scope.

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