RDF Replacement

[Langy]

I have the Astromaster 130 EQ with the wonderful RDF, which although I can get within 5 degrees of an object isn't really that much help. I've not got the best of eyesight so even like last night when pointing up at Jupiter you bend down below the scope, close one eye and first try to align the two dots in your sight to see how far out you are, then you tend to fix your eyes on the object and keep in line with the scope and move around until you get a match with the two dots. The first night I used this I left the battery switched on for 24 hours, however I think it was a benefit as the lights are far too bright, even now they are a bit bright.

So I've decided to take a look at what may be more useful. I've read some previous forum posts and the Rigel QuikFinder Compact Reflex Sight came up. So after reading up on it at http://www.firstlightoptics.com/finders/rigel-quikfinder-compact-reflex-sight.html I decided to ask some questions. A couple of emails later they came back with a link to this review http://www.cloudynights.com/documents/finders.pdf to compare it with the Telrad Finder here http://www.firstlightoptics.com/finders/telrad-finder-astronomy.html.

Now I know my scope is quite small as it goes so wondered if the Rigel stickup up 4.5 inches would be the better option compared to the longer telrad at 20cm long. I don't like the idea of something sticking up so high on the scope as I suspect at some point it will get knocked.

I'm still a little confused as to how these both work. For example the RDF relies on two LEDs located at different distance within a lens where you have to have you eye lined up to see what it points at. If you were to look from the side or above the direct line of view with either of these finders would you still get the alignment rings still showing in the eye to point at the same object in the sky?

As I said I don't have the best eyesight and am looking for something that will suit and work far better than the RDF that is currently on the scope.

Reading the review the Telrad came out on top but I'm interested in peoples opinions, especially if you have used both and which may be the best for me.

[Fozzie]

Morning........

I can add a positive for the Rigel QF, great piece of kit..  Last year I also had the astromaster before I upgraded, one of my biggest cons for the scope was the RDF..

The rigel is a good piece of kit, it will stand about as high as the focuser on the astromaster, so assuming you place it around the top of the focuser then that will offer it some protection against being hit, which I guess inevitably it will, at some point...

I actually use my glasses during alignment so the height off the tube is an advantage, you look at the projected circles with one eye, sky with the other, its easy  to align, controllable brightness... actually I love it... its helped no end in finding objects, sometimes it's like I cant miss..

The best thing is the circles on both are only visible if your looking somewhere near directly through, unlike the one that comes with the astromaster, so if your not aligning right, you wont see the circles.. if that makes sense..

Hope this helps, just my humble opinion...

Clear skys...

[Langy]

Thanks Fozzie

I've just found the full specs on the Telrad and looking at those it would be just as tall, a lot longer and several times heavier than the Rigel.

I think I'm getting sold on the Rigel, which I would prefer to attach to the scope with cable ties to start with.

TELRAD SIGHT SPECIFICATIONS

SPECIFICATIONS

Window dimension (from observers vantage): 1-5/8 x 1-3/8 inch (41.3 x 35 mm)

Magnification: 1x (zero power)

Housing: Black finish, ABS plastic construction

Retaining thumbscrews (two on the Base): 6-32, ½ inch long

Length overall length: 8-3/8 inch (21.3 cm)

Height overall (on Base): 5 inch (12.7 cm)

Weight with Base and batteries: 10.9 oz. / 308 g

Batteries required: Two "AA" 1.5 Volt, in series

Packing box dimensions: 10-1/4 x 6-1/2 x 4 inches (26 x 16.5 x 10 cm)

Package/Shipping weight: 14.9 oz. (0.42 kg)

Rigel Specs

SPECIFICATIONS

Housing: ABS Plastic construction

Height: 4-1/2" (115mm)

Width, and Depth: 1.4" (36mm)

Maximum Height (incl. Base): 5" (127mm)

Base Dimensions: 2.5" (61mm) long, 2" (51mm) wide, 1/2" (12.7mm)

Weight with battery and Base: 2.75 ounces (75 g)

Battery: One 3 volt, Eveready ECR2032/Duracell DL2032

Draw/Avg. Battery Life: 1 milliamp, 250 hours

[Killie]

I just bought a Rigel QF and have attached it to my scope.. I just need some clear nights to see if does make it easier to align my scope!

[Kirscovitch]

I hated my RDF the first couple times I had my SLT out. Lately though I fallen in love with it. (To each his own!)

When aligning the scope, I have no problem putting the dot on a star and with a 9mm ep having it just off center.

[itmo]

use both of your eyes with the RDF, one looks through the rdf and the other at the sky. you should see a floating dot which you then align. 

[AstroTux]

+1 for the Rigel QuickFinder - especially on this 'scope. The Telrad and the Rigel do very similar things, but the footprint of the Telrad is massive as it uses much larger batteries. It looks good on a 12" Dob but is just too big for an AstroMaster 130 IMHO.

I use the Rigel as it's small enough to sit near the focuser without getting in the way or unbalancing the 'scope. Whilst it only runs on a single CR2032 battery, I have yet to replace the original after 18+ months of use. Replacing the battery is a simple case of slotting a new one into the base, and as these are cheap you can always carry a spare in your pocket should it be needed.

To use either the Rigel or the Telrad is simplicity itself compared to the dreaded RDF, I just couldn't get along with mine and have removed it completely. On first use find Polaris through your eyepiece ( as it doesn't move very much ) then keeping both eyes open use one to look through the device. To reduce the parallax effect you can even stand quite a way back from it. If the illumination is set correctly you will see two ( or three in the case of the Telrad ) circles imposed on the sky. Use the adjusters to centre these on Polaris and you're fit to go.

I also use the Rigel on my 10" Dob as it comes with two bases, and find it very useful for getting into the correct area and then using the finder 'scope to fine tune the position.

hope this helps,

Alan

[Killie]

and find it very useful for getting into the correct area and then using the finder 'scope to fine tune the position.

That is exactly what I am hoping to use the Rigel QF and my finderscope for. As a note,  I looked at the Telrad on my 127 and just thought it looked way to big... I would imagine the same on a 130 as has been mentioned above.

[TractionMan]

Rigel and Telrad are most likely the top 2 contestants. Both options should work. I for one is more than happy with the Telrad (got two of them). Sure it's big, but not that heavy really. Here are a couple size comparisons, Telrad vs 130mm and 150mm newts:

http://stargazerslounge.com/topic/158617-telradquikfinder-on-a-heritage-130p/#entry1603514

http://stargazerslounge.com/topic/107109-pictures-of-your-set-up/page-19#entry2015251

Hope it helps.

/Stellan

[Astro Imp]

I use a Telrad and am very pleased with it but I found using it on a 4" riser made it even better.

Considering the Rigel has a smaller footprint and is itself higher I would think this would be ideal.

As has been said above you use either with both eyes open and move the scope until the view through the finder is superimposed on the view of the sky.

After a little practice I'm sure either will be an improvement on what you have.

Good luck.

[Langy]

Ordered the Rigel this afternoon.

Now for placement, I may take the RDF off and using cable ties hold it in place where the RDF is, or should I mount it near the rear of the scope?

[pel]

Mounting it near the top is the norm.

I had the same scope as you to start with, the RDF is truly terrible :-)

Good luck with the Rigel, I had the telrad on the 130EQ, it looked very big but it worked very well.

[bambuko]

I use Rigel and like it a lot, but if I had bigger scope I would try Telrad.

If you don't like Telrad size, there were at least two threads on CN about shortening them.

Here is one of them:

cut my telrad in half

it results in quite funky Telrad (certainly a lot better than original).

[Langy]

Thought I would give an update as the Rigel was delivered today and I fitted it as soon as I got home.

I decided I didn't like the idea of something that was permanent to start with, so I decided to remove the current RDF as it will not be used and using the sticky pads just stuck those under the base leaving them to be free where they hit the scope. Then using a batch of cable ties wrapped those around the scope and used a smaller cable tie to pinch them together as they EP mechanism mounting pushed them apart.

It doesn't look pretty but it works a treat, where if I want to take it off a couple of snips and you would never know it had been on there.

With limited viewing tonight I pointed the scope to the hazy moon and lined up the finder. Only had to adjust it up a couple of degrees. Then I spun the scope round to Jupiter using the finder and looking through the EP there was Jupiter. A very well worthwhile investment, just need some clear skies to put it to the test.

Who knows I may eventually get properly polar aligned if I ever get to see polaris again.

[AstroTux]

Glad you find it a worthwhile investment. You'll probably upgrade your 'scope many times in the years to come, but I bet the Rigel sticks with you all the time :grin: .

Alan