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Newbie needs fine focus

Norrin Radd

By Norrin Radd
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Norrin Radd

Norrin Radd

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Hi to all on SGL !

Hi I'm Rick, please go easy on me all you cats out there that might read this as I am a compete luddite with all this posting stuff and the interweb :-) I've been checking out SGL for about a year whilst trying to decide what scope to buy and this seems like a very inclusive place for all levels of astronomers to chat etc. I APOLOGISE NOW IF THIS IS A BIT OF A JACKONORY SOZ !!

Im a lifelong sci-fi fan amongst many interests and wanted to buy a scope last year as a treat for myself on my 40th but was in process of new house so it didn't happen until this year.

I knew I wanted an entry level refractor that would be robust and small enough to grab n go and take places in the car and was tempted to buy celestrons 102 SLT with GOTO but I decided I want the challenge of learning the sky and finding DSOs on my own so I've recently bought the skywatcher 120 star travel for a bit more aperture for same sort of money as the nexstar.

I'm pleased with the scope in general and was aware before buying that the scope would benefit from a couple of better quality lenses than those supplied however the one issue that I'm a bit dissapointed with is the focusing. I thought the scope would have a fine focus ability as well as the coarse focus... As a dilettante I am hoping anyone reading this who's more in the know can help with a bit of tech advice. I'm thinking that my solution could be something like the Baader focusing eyepiece holder which will give me fine focus but can I still use the 45° erect image diagonal in said holder which will fit but will I have issues with this for example once I add a Barlow and a lense to the 45° ?? Again well done if you stayed the course and read all that lol !! Any advise will be gratefully received..

Rick

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RT65CB-SWL

RT65CB-SWL

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Hi Rick / 'Norrin Radd' and welcome to SGL.

Assuming you 'scope is a refractor, I always pull out my main focus tube to get approximate focus, then focus using the narrower focus tube. You can, I believe get a helical focusser as an 'add-on' accessory.

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JamesM

JamesM

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Hi Rick and welcome to the forum. You might want to consider posting your equipment question over on the beginners equipment section as more people are likely to visit there than here in the welcome section.

Cl;ear skies and hope you enjoy your stay here.

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Norrin Radd

Norrin Radd

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Thx Philip R and slim80. And yes my ota is a frac and yeah the baader eyepiece is a helical focuser that I'm thinking of getting but I don't know if I can use the 45° in it as the 45° will then possibly have a Barlow and a lense in it too,so will that create issues not just of centre of balance but focus as well ??

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swag72

swag72

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Hi Rick and welcome to SGL - Just thought I'd say hi as sadly what I know about actually looking through a scope is as close to zero as is possible to get :D

Look forward to seeing you around :)

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rwilkey

rwilkey

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Hi Rick, a warm welcome to SGL, the 45° diagonal is more for daytime/terrestrial use, for astronomy you need a 90° diagonal as it is more practical for looking at the stars and other astonomical objects.  On the focuser issue you should be able to get fine focus by careful adjustment, but you need to be patient.  Failing this you can get replacement focusers that have 10:1 ratio twin focuser knobs that allows you to make finer adjustments as needed, the only thing is some of these tend to be a bit on the expensive side, it depends on how much the issue bothers you.  Of course, you must be able to acheive fine focus.

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opticalpath

opticalpath

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Hi Rick.

A simple thing that might help is if you can somehow fix or clamp a 'wand' on to the flat face of one of the focusing knobs - something light and rigid, say about the size of a chopstick.  The idea is that this long lever gives you much finer control of the focuser knob.  I have even used a light-weight mini bar-clamp (see attached) clamped on to the focuser knob.

It's also important to have the focuser tension screw(s) adjusted to allow the drawtube to move smoothly without binding, but not so loose as to allow it to slip.

Adrian

post-8730-0-16984900-1433149352.jpg

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glowjet

glowjet

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Hi Rick and welcome to SGL, focus control is often a problem with refractors off the shelf, extra sensitive control can be had by fitting large rubber tyres to the focusing knobs, if you take measurements and visit your local model shop you might find some to fit. I have decent sized ED Refractor, but in the end fitted it with a MoonLite unit, it is now a dream to use. Enjoy your Astronomy and the forum :)

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