Sky Watcher 102 Startravel Refractor - Focusing Problems

[Chris81]

Hi there

I have been using a refelctor scope for some time now and had a fair amount of success with it. However! having just recently purchased a  small (ish) refractor which I am intending on using mainly for Guiding later on (once a larger mount is purchased).

I had been testing it out recently and on both occassions I could not get any clear images in the EP whatsoever, and when I finally managed to get a brief look at the moon, it was blurred and again I could not get any focus. Is it maybe that the Lens is too close or too far from the optics? any suggestions would be appreciated. no doubt at all that it is probably an easy fix and i'll kick myself once I know.

Thanks in advance.

Chris

[Alien 13]

Most refractors are designed to be used with a diagonal that adds about 2" to the image train are you using one?

Alan

[Thalestris24]

Hi there

I have been using a refelctor scope for some time now and had a fair amount of success with it. However! having just recently purchased a  small (ish) refractor which I am intending on using mainly for Guiding later on (once a larger mount is purchased).

I had been testing it out recently and on both occassions I could not get any clear images in the EP whatsoever, and when I finally managed to get a brief look at the moon, it was blurred and again I could not get any focus. Is it maybe that the Lens is too close or too far from the optics? any suggestions would be appreciated. no doubt at all that it is probably an easy fix and i'll kick myself once I know.

Thanks in advance.

Chris

Hi

It might be because it's an achromat. I have similar difficulties with my ST80. Also the focussing mechanism isn't that good anyway. I'm going to clean mine and put some white lithium grease on it. The stock grease is very sticky! Astronomyshed on YouTube have a tips and tweaks video for the ST80. I imagine the 102 is very similar.

Louise

[m37]

102 focuser could definitely do with a strip and rebuild with some nicer grease as mentioned above. The focuser is not great but if you're not imaging anything then you will probably be able to put up with the image shift you will get on focusing.

Also as mentioned above you will need to use the diagonal to get enough distance with the added bonus of a corrected image. If this is still looking blurred no matter what you do, shine a torch down the objective and see if you are getting dew. Also try this on the eyepiece. Mine used to dew up quite quickly.

cheers

[Chris81]

Thanks everyone, in fairness I hadn't even tried it with the diagonal, so that is probably the most obvious solution initially I guess. too used to using a reflector! I will give this a go firstly and if the issue still arises I will try the other advice suggested above. much appreciated! 

[JulianFR]

I have to say I find the focuser on my ST 120 quite 'sticky' and imprecise. Looks like this could be a common ST issue then. Are there any solutions apart from stripping it down and re-greasing (I'm rubbish at DIY)? It would be nice to have a bit more fine control over the focuser, but without spending more cash on a micro-focuser.

[Thalestris24]

I have to say I find the focuser on my ST 120 quite 'sticky' and imprecise. Looks like this could be a common ST issue then. Are there any solutions apart from stripping it down and re-greasing (I'm rubbish at DIY)? It would be nice to have a bit more fine control over the focuser, but without spending more cash on a micro-focuser.

Hi

I just did my ST80 the other day. I didn't go as far as stripping it down - I just racked out the drawtube and cleaned the sticky stuff off the rack with some nail polish remover (acetone) and then applied a very thin coating of white lithium grease (http://www.amazon.co.uk/gp/product/B003JAG55W/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1).

Seemed to improve the movement quite a lot!

If you fancy having a go at stripping down the focusser it's very straightforward and there's a vid for the ST80 here:

https://www.youtube.com/watch?v=Ylb7xnc_03U

The focusser tweaks are towards the end. I expect the ST102 is very similar.

Hth

Louise

[Tinker1947]

Using a ST-80 with a Lodestar requires a lengthy extension to gain focus.........

[JulianFR]

Thanks Louise!

[Thalestris24]

Thanks Louise!

Hi

Further Tinker's post - it would be a good idea to check which particular extender/adaptor you need. As I said above, you have to make sure you can comfortably reach the 400mm focal length.

Cheers

Louise

[JulianFR]

Just an update... I did clean the focuser assembly... And was taken aback by the 'grease' inside it. This gunk was more like thick, non-adhesive glue than grease. Bizarre stuff really. I replaced it   with lithium grease.... Much better!