SkyWatcher 9x50 Finderscope Issues

[AweSIM]

Hi,

I have a SkyWatcher 9x50 finderscope that came with my SkyWatcher 200 DS OTA. The other day, I was disassembling the eyepiece of the finderscope to clean its lenses and I kind of messed up. When I unscrewed the crosshair retainer ring, I flipped it over to pop out the lens, expecting it to have only a single lens. Contrary to my expectations, two lenses and two spacers popped out. Since it happened very quickly, I don't know the order these lenses are supposed to go back. Although I have tried assembling back a couple of possible combinations of these elements, I am unable to properly focus my finderscope.

The eyepiece of the finderscope has the following elements inside it:

1. A retainer ring with crosshair stretched across it with a screw thread to lock everything in place. I know this is the last element in the assembly. I'll denote this with [ # ].

2. A small spacer (maybe 2mm), denoted by [ = ]

3. A large spacer (maybe 10mm), denoted by [ === ]

4. Two double-element lenses with one side flat and the other side convex, denoted by [ |) ]

I've tried the following combinations without success:

A. [ #  ===  |)  =  (| ]

B. [ #  ===  (|  =  |) ]

C. [ # . ===  = (|  |) ]

But none of these combinations are working. I remember how much I had to screw the objective lens in or out to reach visual focus for the finderscope, but now the focus is occurring near or just outside the limits of the primary lens threads. Also, the view through the finderscope show strange halos which aren't centered.

I'm hoping that someone here might possess the same finderscope and can tell me what order do these elements go inside the eyepiece assembly.

Thanks a lot!

Asim

[John]

Hello Asim.

I have just had a look at the internal componants of my 9x50 right angled correct image Skywatcher finder eyepiece and it seems to be the same as your arrangement A.

Having put mine back together the finder works fine. I think the eyepiece of your 9x50 should be a similar design ?. I think the only difference with the RACI finder is the prism diagonal and the shorter finderscope body.

Perhaps try that configuration again ?

Maybe the objective of your finder has shifted as well ?. Worth checking at least.

Edit: also worth checking that the lenses and spacers in the eyepiece have seated properly - it can be a bit tricky to get them all in a neat stack so that they go back into the eyepiece body neatly and properly seated.

 

[AweSIM]

On 20/01/2020 at 04:18, John said:

Hello Asim.

I have just had a look at the internal componants of my 9x50 right angled correct image Skywatcher finder eyepiece and it seems to be the same as your arrangement A.

Having put mine back together the finder works fine. I think the eyepiece of your 9x50 should be a similar design ?. I think the only difference with the RACI finder is the prism diagonal and the shorter finderscope body.

Perhaps try that configuration again ?

Maybe the objective of your finder has shifted as well ?. Worth checking at least.

Edit: also worth checking that the lenses and spacers in the eyepiece have seated properly - it can be a bit tricky to get them all in a neat stack so that they go back into the eyepiece body neatly and properly seated.

 

Hi John. Thank you so much for your response. I'll try that configuration again and let you know how it goes. Your point regarding seating of the elements is a good point. I'll double check that too. I'll also try to post an image of what the finderscope shows.

Thanks. 🙂