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130P-DS Complete Strip Down and Rebuild


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Hi

Hopefully I have started this in the right section :icon_biggrin:

After getting some left side distortion while imaging with my 130P-DS and DSLR (see attached) I am starting from scratch trying to get everything square and aligned.

I used the strips of card method to attempt to find the spot directly opposite the focuser. This is what I can see through the sight tube after placing a hole reinforcer over the spot. It obiously looks out and my best guess is that it would appear to explain the apparent tilt in the images I am getting.

Opinions please.

Many thanks

Here's the problem I am getting

Single__2017-01-02_21-49-52_0002_ISO800_60s__19C.JPG

This is the view through the sight tube

IMG_20170107_084333.jpg

 

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I am no expert in this but from the what I can see it looks like the secondary is slightly out and needs moving (to the left in the picture). Maybe move the primary a bit more to get it central. Your best bet is to wind in the secondary wind back the primary and start again. I had massive issues with my 150pds but once I put it back to the start it took no time to get it right.

You also need to check you colimation using an out of focus star to be 100%.

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I doubt you aren't already aware of these:

You could also refer to Astro Baby's Collimation guide at Astro Baby's Collimation Guide.pdf (thanks to @Davey-T for posting this after Astrobaby's website one toff line at the moment)

AstronomyShed has a tutorial too on Youtube 

and yes, I do have a certificate "Teaching Grannies to suck eggs 101")

and, also, yes, I am stalking this issue :)

 

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Hi

I have read your original thread on this , I had pretty much the same problem after flocking my 150pds and like youself many, many hours of frustration. I found that my problem was focuser alignment,  but it took about half a dozen goes using the card measuring method to get it right. Obviously this also means a full collimation each time. The other problem I had which compounded the problem was a little slack in the eos t mount adapter (not sure what camera you are using). 

I fully sympathise with your frustration , you may have a different set of issues to me but keep going and bear in mind it maybe a combination of problems.  

Not much help in solving your specific problem(s) , but hopefully a bit of moral support.

Good luck

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23 hours ago, iapa said:

I doubt you aren't already aware of these:

You could also refer to Astro Baby's Collimation guide at Astro Baby's Collimation Guide.pdf (thanks to @Davey-T for posting this after Astrobaby's website one toff line at the moment)

AstronomyShed has a tutorial too on Youtube 

and yes, I do have a certificate "Teaching Grannies to suck eggs 101")

and, also, yes, I am stalking this issue :)

 

Thanks for the link to Astro Baby's collimation guide via Davey-T, I noticed the site was down.

I'm going to take this slow and be sure of every step, although tomorrow could give a little clear sky for testing so it would be good to get it done for then.

 

 

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6 hours ago, Grimbles said:

Hi

I have read your original thread on this , I had pretty much the same problem after flocking my 150pds and like youself many, many hours of frustration. I found that my problem was focuser alignment,  but it took about half a dozen goes using the card measuring method to get it right. Obviously this also means a full collimation each time. The other problem I had which compounded the problem was a little slack in the eos t mount adapter (not sure what camera you are using). 

I fully sympathise with your frustration , you may have a different set of issues to me but keep going and bear in mind it maybe a combination of problems.  

Not much help in solving your specific problem(s) , but hopefully a bit of moral support.

Good luck

I do think it is likely a combination of issues.

If my calculations are correct, the focuser is not square and adjustment has been made the best I can using the tilt adjustment screws on the focuser. A properly collimated laser would have been useful. It's not easy focusing on the sight tube crosshairs and the ring to see if it's aligned.

Why this has become a problem when it wasn't before is puzzling. Trying to get the MPCC properly square in the focuser is difficult with that awful undercut so it's possible it was being tilted and cancelling out the focuser tilt may be?

I ended up getting a zero tolerance t-ring for my 600D to rule out any slack there.

 

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Well it's collimated, as far as I can tell. I've seen pics of the ideal but it's proving elusive.

I had to settle for aligning the secondary by getting the sight tube cross hairs(actual) aligned with the doughnut and then the primary aligned with the crosshairs reflection/eye hole.

The secondary is reasonably round under the focuser. I just couldn't get it perfect and get a full view of the primary in it at the same time. I tried getting a photo of it but couldn't get it to focus on the primary.

Looks like a bit of clear sky early tomorrow so will have to test it out.

I hope it's right, I'll be gutted if it's still wrong.

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3 minutes ago, Skyline said:

Interesting, thanks.

Anything to make it easier, I really don't want a frac!

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