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RDF vs Telrad vs Rigel Quikfinder...


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On my 8" Dobsonian, I have a RACI. I like this, found have found it rather limiting... 

With the straight through one, I was easily able to line up the telescope in the direction of the object, but found it sore on my neck. The RACI is easier on my neck, but a pain to align with the target at times. 

It was suggested at the recent New Galloway Star Camp, that I should install a Telrad for sighting the telescope roughly and use the RACI to zero in on it. 

Telrads seem expensive and unavailable at the moment, so I was thinking of alternatives. The Rigel Quikfinder comes to mind, as does a RDF. I could get a twin finderscope mount and put both the RACI and RDF on that. 

Any thoughts? 

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I would recommend a Rigel or a Telrad over an RDF any day. I think anyone who has used one would. I don't think you could go wrong with either a Rigel or a Telrad in that case. I personally have a Telrad. I would argue that the Telrad that runs off of two AA batteries is the better option for me because I always have spare AA batteries laying around. I don't always have a CR2032. A holder for AA batteries for the Rigel is available though, however it costs extra.

Edited by Buzzard75
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9x50 RACI optical and Rigel Quikfinder for me. Telrad would be fine instead but I wanted something lighter.  RDF's are OK but the defined diameter circles of the Rigel and Telrad can really help with star hopping.

 

dobtopp5mm.JPG

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If it's just for lining up to use the RACI then any of those would be fine, but if you want the extra benefit of being able to do some hopping without needing the RACI sometimes then the rigel or telrad can do that much better.

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Regarding the CR 2032 battery for the Rigel.  The battery lasts for ages, and a spare just in case is easily kept in my eyepiece case.  Although I have an AA battery pack for a Rigel I don’t use it.

I also have an unused Telrad, preferring the much more compact Rigel.

Either gets the job done of course.

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RACI and rigel for me.

I really like the compact size of the rigel. It is excellent for lining up you target quickly. I do however find it difficult at time on the back and neck as you have to look through it like the straight finder. I wish I could find a way to mount the rigel so that my back can take it.

Baz

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Here are my thoughts on them:

  • Rigel QuikFinder can be difficult to find the circles and has slight parallax issues.  Small and light.  Battery will last 20+ years with no corrosion.
  • Telrad is huge but I never have trouble locating the thicker circles, plus they go out to 4 degrees, not just 2 degrees as with the QF.  AA batteries can and will corrode inside, ruining the illuminator, unless changed regularly.
  • RDF is cheapest and gets the job done if all you want to do is put the scope on a target.  Haven't used one long enough to declare anything about their battery life.
  • Green laser sight is my preference with my injured neck.  Quickest way to put a scope on a target that I've found (1 to 2 seconds).  Americans have embraced them while Brits have eschewed them.  Just look and listen for aircraft before lighting it up, and you'll be fine.
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arguments for both. If all you are using the finder for is to get it close then jump to a RACI, then a RDf does the job perfectly. 

However if you want to use it as above but have the fall back for star hopping where you use a Telrad to get you close and then a RACI to check and then hone to the object, then I go telrad.

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The combination of a RACI and a Rigel QuiKfinder on an 8" F6 dob as mentioned in above posts, is a compatible set up. I like the Rigel for it is proportionally compact on the length of tube, for sighting, personally I'm not adverse to using a gardening kneel mat, so going down on one knee is OK. For my larger dob, the Telrad on a 4" riser base / RACI combo, is excellent. 

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9x50 RACI and Telrad for me, love the Telrad but need the riser base. It does have a large footprint/base compared to the Rigel. I'd probably be as happy with the Rigel anyway as the Telrad is difficult to mount without riser on the 500p truss dob and 300p flextube due to space limitations. If you have the room for the Telrad, then great, if not, the Rigel is essentially its peer from what I gather...

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The riser base is a good investment. I had the 2" when I used a 300p flextube, the 4" is functional with my 14" dob.  Also treated the Telrad to a Telegizmo canvas cover, which becomes useful at this time of year of potential high condensation, for example pausing for a coffee break.

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It seems that the Telrads are out of stock in most places, at the moment. One thing I have noticed is that in Stellarium, it's possible to alter the Telrad Ocular angles and by removing the 4 degree one, it makes it look like the Rigel Quikfinder one. 

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My aim was haywire the other night. Trying to centre a Newtonian  upside down and back to front I found frustrating. ( I'm sure I'd get used to it given time )but have ordered a Rigal today for my 150P.  I'll leave the finderscope on but hoping it will aid me  as I progress. I use dslr on it's own too and binoculars so hopefully it will help in hopping around  in a mode I'm familiar with. 

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2 minutes ago, Matt61 said:

My aim was haywire the other night. Trying to centre a Newtonian  upside down and back to front I found frustrating. ( I'm sure I'd get used to it given time )but have ordered a Rigal today for my 150P.  I'll leave the finderscope on but hoping it will aid me  as I progress. I use dslr on it's own too and binoculars so hopefully it will help in hopping around  in a mode I'm familiar with. 

I found moving from the supplied straight through finder to a RACI one, quite difficult.  I was able to located targets more easily with the straight through one, but don't miss hurting my neck trying to use it anymore!

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It was worse when my neighbour was having a look ( he kept losing everything !  I'm planning on setting up at my sister's ( minimal light pollution in Cotswolds)  she lacks patience  and probably can't pat her head and rub stomach at same time !

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Telrad. They use proper batteries and last forever. (OK, maybe not forever but my oldest is about 25 years old.) The others I've used require daft little batteries that peg out if you forget to turn them thing off - and you will -  or pack up randomly for some other reason.) Telrad.

Olly

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22 minutes ago, Matt61 said:

Newcomer question . Is it possible to adapt the skywatcher finderscope with an adapter/ prism of some sort to correct the view?

Not to my knowledge.

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33 minutes ago, Matt61 said:

Newcomer question . Is it possible to adapt the skywatcher finderscope with an adapter/ prism of some sort to correct the view?

The prism or diagonal needed to get the right angled view takes up some of the light path of the finder objective which means that finder body needs to be quite a bit shorter for the eyepiece to reach focus. You would need to chop a section off the body of a straight through finder to get it to work with the right angled prism or diagonal.

 

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