corrected finderscope or red dot?

[Jimtheslim]

Thinking of a new scope and if I do there is no way I want to continue with a straight through finder scope. I just cannot get my head round the back-to-front image moving across the sky, especially on my current equatorial mount.

Just curious as to whether people use a red dot finder when looking for DSO's or if a magnified finder scope is essential for these. If so I will look into a corrected upright finder scope.

[Dave In Vermont]

A red-dot finder is one way to go, but these will only show you naked-eye stars visible to your eyes from where you are viewing from. Bad light-pollution? Even more limited. So I go for what is known as an RACI - Right-Angle Correct-Image. Such as an 8 X 50mm RACI. Here's an example of such:

http://www.firstlightoptics.com/finders/skywatcher-9x50-right-angled-erecting-finderscope.html

I hope this helps -

Dave

[Jimtheslim]

5 minutes ago, Dave In Vermont said:

A red-dot finder is one way to go, but these will only show you naked-eye stars visible to your eyes from where you are viewing from. Bad light-pollution? Even more limited. So I go for what is known as an RACI - Right-Angle Correct-Image. Such as an 8 X 50mm RACI. Here's an example of such:

http://www.firstlightoptics.com/finders/skywatcher-9x50-right-angled-erecting-finderscope.html

I hope this helps -

Dave

Thanks, I had seen the red-dot was a naked eye way of lining things up and I've been tempted to try one. My problem is that when I look through a magnified finderscope I have no idea if it's in the place I want it as there are so many more stars visible than with the naked eye. When you then see them travelling back to front I get hopelessly lost, especially when I then look through the scope with a low powered eyepiece! I'm thinking a lower powered corrected finder scope might be the way to go.

As for LP there is some when I look to the East as this looks down the Tyne Valley toward the city of Newcastle. Overhead and toward the West are much better, Milky Way is visible overhead and I have many dark sky sites just a short drive away

[michael.h.f.wilkinson]

The obvious way is to use both: the RDF to get to the right area, and the RACI to find the precise location. I built myself a big RACI (14x70), which is really the only thing I need. The addition of that finder to my scope has transformed my viewing pleasure.

[Linda]

I use the red dot finder for finding my first guide star. I'll give an example. Last weekend I was trying to watch Jupiter. Without using the red dot finder, I tried pointing the scope at Jupiter that was clearly visible with the naked eye. I didn't bother getting my knee on the ground to look properly along the scope, but instead I sat on a bench with the scope at eye height. Then I used the 6x30 finder scope to point exactly at Jupiter. I saw a bright dot and put that in the middle of the finder. It surprised me that I didn't see it as a disk and I didn't see any of the moons. Then I looked into my telescope and I still only saw a bright point. Looked more like a star to me than like a planet.

It took me a while to realize that it was not bad transparency, but that I was indeed just looking at a star. Only when using the red dot finder, I realised that I was looking high above Jupiter. Conclusion: a red dot finder is much more effective in finding the correct naked-eye starter star/planet than a finder scope. On the other hand, when you have found the initial star, starhopping to find a DSO is a lot easier with a finder scope.

Therefore I have both.

The red dot finder is also useful when you are using your finder scope to starhop. I you have an EQ mount, you sometimes lose track of what is up and down when looking through the finder. The red dot then can helps you checking which slow motion control to move in which direction, while looking into your finder.

[Jimtheslim]

Well I do like any excuse to spend more money! Anything has to be better than the back breaking frustration of a straight-through, back-to front search for the correct areas of sky

[Dave In Vermont]

Might I suggest a more complete star-chart instead? Retro-fitting a focal-reducer to a finder-scope (of any description) would be a first!  You might try finding a nearby Astronomy Group and give yourself a chance to talk to the members and try what they have prior to making a purchase. We astro-folks tend to be very supportive to new folks and are happy to field questions and let you try what is used.

Good star-charts are available for free in a software-program called Stellarium. If you'd like a copy - here's a link - Cut & Paste Edition:

On this link is the main page for downloading Stellarium. Choose which version is correct for your computer. Here you go:

http://www.stellarium.org/
 
As for instructions, the most current one's are posted in Wiki due to there being new features & functions being created almost daily. There is also a Pdf. that's almost up-to-date, absolutely enough 'up-to-date' in all needed ways. Here's the Wiki-Link:
 
http://www.stellarium.org/wiki/index.php/Stellarium_User_Guide
 
And the Pdf. is here:
 
http://barry.sarcasmogerdes.com/stellarium/stellarium_user_guide-new.pdf
 
This should help you to find just about everything under the Sun.

Have fun!

Dave

[Jimtheslim]

Thanks,

I already have Stellarium and a copy of 'Star and Planet Spotting', both of which I have read and spent quite a bit of time on. Like I say, I just seem to get lost and find it difficult to stay patient when everything is back-to-front. I don't think trying to move about the sky with an equatorial does me many favours either, hence I am looking into a dob for my next purchase. I see on ebay there are a fair few double finder scope brackets for sale so maybe doubling up with a red dot and corrected upright finder is the way forward

[laudropb]

Many on here use a combination of finders. I have a Rigel to find the general area of a target or guide star and then fine tune with a RACI. Others use a Telrad. This set up made a big difference to my star hopping success.

[Dave In Vermont]

A good solution rears it's head! I do believe you've got the best solution! Do tell us how it works out? Sounds like a plausible suggestion to give - for the files!

Thank you!

Dave

[cloudsweeper]

I use an RDF and a 9x50 finderscope.  The RDF gets me in the right region, but doesn't show faint objects of course.  The finderscope shows a bit more detail, then I take a closer look through the EP.

 I confess (if that's the right word!) to not doing much star-hopping, but relying on GoTo.  It really is good.  When I align with say Jupiter, the 'scope is spot-on target.  Even with a one-star alignment, it puts me within 10 or 15 arcmin of target, which is of course within the FOV in the low power EP.  

Doug.

[Jimtheslim]

26 minutes ago, Dave In Vermont said:

A good solution rears it's head! I do believe you've got the best solution! Do tell us how it works out? Sounds like a plausible suggestion to give - for the files!

Thank you!

Dave

Thanks, if I end up with enough $$$'s at the end of the month to take the plunge on a new scope I will keep you updated. Maybe part with one of the Lego Star Wars sets I have in the loft. 

[F15Rules]

2 hours ago, Dave In Vermont said:

A red-dot finder is one way to go, but these will only show you naked-eye stars visible to your eyes from where you are viewing from. Bad light-pollution? Even more limited. So I go for what is known as an RACI - Right-Angle Correct-Image. Such as an 8 X 50mm RACI. Here's an example of such:

http://www.firstlightoptics.com/finders/skywatcher-9x50-right-angled-erecting-finderscope.html

I hope this helps -

Dave

+1 for the RACI finder from me:-)

 

Dave

[cuivenion]

2 hours ago, michael.h.f.wilkinson said:

The obvious way is to use both: the RDF to get to the right area, and the RACI to find the precise location. I built myself a big RACI (14x70), which is really the only thing I need. The addition of that finder to my scope has transformed my viewing pleasure.

Hi Michael, can you tell me what that scope and mount is please? I would also second using both a red dot finder and a RACI.

[michael.h.f.wilkinson]

3 minutes ago, cuivenion said:

Hi Michael, can you tell me what that scope and mount is please? I would also second using both a red dot finder and a RACI.

My main scope is a Celestron C-8 on a Vixen Great Polaris mount. The finder is based on a department store 70mm F/5 refractor. I added a 1.25" 90 deg Amici prism after a while. It came with a 45 deg, but the 90 degree SkyWatcher Amici prism is more comfortable and better quality. The EP is an Antares 25mm 70 deg with second-hand Edmund optics 34.8mm reticle from the Surplus Shed. I recently modded that further by adding an illuminator:

 

I bought a set of finderscope rings from Robtics and mounted that with a standard finder-shoe.

 

[cuivenion]

Surplus Shed, Interesting. My wife may not be happy with you Michael lol. I'm thinking that the vixen mount might be my next upgrade at some point. I hear it's a lot smoother and can take more weight than the EQ5 while still being able to take EQ5 accessories like goto etc.

[michael.h.f.wilkinson]

I thank that holds true for the old EQ5 mounts, which were a pretty rough copy. Newer ones are closer, I gather

[Jimtheslim]

Is there an awful lot of difference/advantage of a 9x50 over a 6x30 finder? Given that DSO's probably won't show in either?

[cuivenion]

8 minutes ago, Jimtheslim said:

Is there an awful lot of difference/advantage of a 9x50 over a 6x30 finder? Given that DSO's probably won't show in either?

Stars will though and you can check with stellarium to see if the view in the finder corresponds to the simulated view in your software. If you don't like using pc's outside do a printout of the view and use that.

[John]

I find the 9x50 right angle, correct image finder and the Rigel Quikfinder zero magnification illuminated reticule finder (similar to a Telrad) a killer combination on my 12" dobsonian when used in conjunction with a good sky chart such as the Sky & Telescope Pocket Star Atlas.

Since having these tools I've found dozens of new-to-me deep sky objects down to magnitude 14. The Star Atlas shows stars similar to the fainter ones that the 50mm finder will show and in the same orientation which makes locating objects more straightforward.

I do have a 6x30 RACI finder as well but I use that when chasing double stars with my ED120 refractor.

With regards to software, I find the Cartes du Ciel planetarium software very good for producing printed star charts to use out in the field if required.

 

[michael.h.f.wilkinson]

I must say I personally don't like using a Telrad or other RDF, possibly because I have a ton of experience with binoculars and finder scopes, and very little with Telrads. I was operating Olly's 20" Dob a summer or two ago, and just relied on the 9x50 finder scope, ignoring the Telrad right next to it. Apart from long experience, my reliance on the finder alone may be due to the fact that I tend to use the 15x70 binoculars in a game I call "Messier Hole-in-One": Estimate where in the sky a particular Messier object is located, point the bins at that location, and see if it is in the FOV. Extra points if it is slap in the centre. M42 is of course easy, as is M31. M81 and M82 are a bit harder, and I am getting pretty good at nailing M3, M13, M51, and M92 every time.

[John]

Once you get comfortable with a method that works for you - keep on using it !

With the fainter objects the final "finding" is done at the eyepiece - half a degree is still a lot of sky when you get up close and personal with it !

It's astounding to think that the whole true field area covered by the famous Hubble Deep Field images is just 2.5 arc minutes in extent

[F15Rules]

2 hours ago, michael.h.f.wilkinson said:

I thank that holds true for the old EQ5 mounts, which were a pretty rough copy. Newer ones are closer, I gather

I think it still holds true Michael. I used (and still have) a Celestron CG-5 which is just over 5 years old. Its a nice mount.

These newer ones came with better 2" tubular legs than EQ5s, and also have proper ball bearings in each axis. Even so, my new to me Vixen GP, which is c 20 years old is far better, smoother and with zero backlash..when I move the mount by hand and lock the axes, there is no backlash or movement whatsoever. These old mounts are so well engineered, I'd far rather have one of these than any of the clones:-)..I think I'd have to spend well over £1k now to get something as well made.

Dave