startravel 102 service

[steviebee]

Anybody know roughly how much a optical service would cost on a SW Startravel 102!

 

Steve.

[Peter Drew]

Can you describe the service that it needs?    

[steviebee]

Hi Peter, I think it needs the optics (?) looked at. I took the lens out to clean them and since then it seems slightly blurred and I have a ghosting effect!

[Peter Drew]

Hello Steve. Sounds like you may have assembled them incorrectly. The front component is biconvex with the shallower curve facing outwards towards the sky, easy to get this wrong as there is not much difference in the curves. Worth checking as this could cause the effect you describe.

[Knighty2112]

Saw a tip on a YouTube video if taking your lenses out to first mark them at the edges with a fine permanent marker with an arrow pointing in to each other so that you can get the lenses lined back up in the correct way. A little late now I know, but one to note for any future cleaning perhaps. Also, did you make sure when you screwed the lenses back together in their housing that you don't over tighten them which will put stress on the lenses and cause issues too? 

[ronin]

Skywatcher site says the lens are air spaced. So the biggest chance is that they are assembled put back wrong. Easy enough trap to fall into.

Generally the front lens will have the most curved face facing out towards the stars. So the flatter surface is "inwards". Both surfaces will be curved.

Then the spacer, then the rear element. The rear element is likely only able to go in one way without hitting the rear face of the front element. Difficult to put into words,

Simple diagram is here: http://starizona.com/acb/basics/equip_telescopes_refractors.aspx

BUT the picture dipicted shows the front lens as equiconvex, they are not equi as a rule. As said it is normal for the more curved surface (less flat) to face out - the ratio of the radaii is around 1:6 to reduce spherical aberration.

[steviebee]

Thank you Peter, I will have a look at that. Everything was ok (apart from dirty) before I touched it. I have striped it down again now, cleaned both lenses and replaced them, as per ronin's link.. They do seem to fit better. I have looked through it and it does not seem as misty/blurry as it was with daylight view yesterday. I will have to wait till Wednesday to check in darkness. Many thanks for all your comments/suggestions. Hopefully it was just a case of me getting it a tad wrong.

 

Regards.

 

Steve.

[steviebee]

On 11/09/2016 at 10:09, Peter Drew said:

Hello Steve. Sounds like you may have assembled them incorrectly. The front component is biconvex with the shallower curve facing outwards towards the sky, easy to get this wrong as there is not much difference in the curves. Worth checking as this could cause the effect you describe.

You was spot on, thank you.