Using a Refractor

[MJP]

I'm new to astronomy and have recently bought a Celestron Omni 120mm refractor.

The scope ticks all the right boxes but I have a problem using the finderscope to locate items right overhead. When I point the telescope in that direction the finderscope is only about 18 inches from the ground (the tripod is fully extended). To look through it I almost need to lie down as I cannot bend sufficiently to twist my head around to look through the finderscope. The main scope is fine as I have a star diagonal. There does not seem to be anywhere else to locate the finderscope.

Is this a common problem or is there a simple solution?

Hopefully this is not a silly question and there is a simple solution. Any help will be appreciated.

Mike

[Moonshane]

hi Mike

I have the same scope and had exactly the same problem. there are two solutions you could try. one is a right angled finder. these are not as 'intuitive' as a straight through finder but less craning on the neck. the other is to raise your mount higher up. I tried the 90 degree finder but don't really get on with it and am considering selling it - this is not a sales email as I have not made up my mind yet ;0)

there are a few options in how to raise your mount height.

your could get some longer section stainless tubing and replace the ones on the tripod. this might be the easier and cheaper option possibly. the other is the one I adopted which is to replace the tripod legs on another aluminium tripod with hardwood. I am 6'3" and made my tripod to measure. the mount now stands about 5'6" off the ground now and is much easier to use I still need to kneel occasionally but it's a lot better and I can use the main eyepiece sitting down in my chair while looking at the zenith.

I suppose another still is to mount a telrad or rigel quickfinder onto the tube and this would have the same effect?

hope this helps. I gree it's an excellent scope.

[SteveP]

Hi MJP

You've learnt an important lesson - astronomy was never designed to be easy!

Seriously, if you used up all the extension on the tripod's legs and you've positioned the finderscope as far forward in its holder as you can, you're running out of options. You can buy right angle (RA) finderscopes with an in-built diagonal but that will mean more expense unfortunately. Or just stop looking at the zenith!

Steve

[pvaz]

You can replace the finder scope with a Right angle one. It's a finder scope with a diagonal in it.

Finders - Skywatcher 9x50 Right-Angled, Erecting Finderscope

EDIT: Hehe lots of posts at the same time.

[Moonshane]

ha ha

indeed Paulo - at least we all broadly agreed!

[John]

I have a 150mm F/8 refractor and have the same issue. On the mounts they supply with these scopes eyepiece height when viewing the zenith area is always an issue. The simplest (and lowest cost !) approach that I have found is to add a red-dot type finder further up the tube - it can be right up near the objective lens in fact. The Rigel Quikfinder is ideal for this purpose as it used a self-adhesive base (no drilling), is lightweight and low cost (£30). It also happens to be one of the best RDF's IMHO.

[Moonshane]

I agree John,

an excellent little finder and I have just got one to fit onto the crayford I have also fitted to the 120. this makes a big difference too to the enjoyment of the scope allowing much faster/more accurate focusing.

[Wurzil]

Another trick to raise the finderscope a little is to make the eyepiece end of the scope heavier so that there is less scope sticking out at that end when balanced. Ive heard that those strap-on ankle weights can be used for this.

I have the same scope too and am considering one of those Rigel quickfinders to help me find things more easily - I never really condsidered that it would have the added bonus of me not having to lie on the floor anymore

Have any of my fellow OMNI 120 users tried low power 2" EPs yet (my next purchase so just interested) - and what are you finding is your top useful mag (say, on mars - mine handles 200x quite happily).

Warren

[Blackheart]

Hi Mike

I have a problem with my neck so straight-through finders have always been a prob for me. I find the Skywatcher right_angle 9x50 is excellent on my 12" dob. Yes it takes a little to get used to it, but your brain soon adjusts... There's one on ebay right now.... Skywatcher Finderscope 9x50 rightangle on eBay (end time 20-Feb-10 20:45:23 GMT)

Is it all right to post links like this... PLease just let me know if it's not...

Also, I am considering buying a scope similar to yours so I wonder if you could let me know what the performance is like and the false colour...

[old codger]

I had a similar problem with my 5ins. Bresser refractor, and replaced the straight through finder with a right angled one, and also increased the height of the mount by adiing a 'Widescreen' extension pillar between it and the tripod head. It makes it heavier to handle but is much more comfortable.

Old Codger

[Mark at Beaufort]

We have all been there with fracs. Keith (old codger) refers to the pillar extension sold by Widescreen Centre. I attach a photo showing a 6" Meade on a standard skywatcher tripod with pillar extension attached. Believe me without the extension the scope would nearly touch the floor!!

Mark

[GazOC]

I've got an extension pillar for my EQ6 and HEQ5 and they are great when using long refractors.

[Moonshane]

hi Wurzil

so we don't get spanked for knicking the thread, I'll PM you as I have just bought such a lens - although not used yet!