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My Brand New 130pds - hmm...

Thalestris24

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Thalestris24

Thalestris24

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So, have been trying to pick up the three mirror clips... But this seems to be impossible! Even manually moving the secondary at best I can see two. If I try and get the third into view, the first two go out! Am I missing something? All the guides seem to rely on getting all three in view. Perplexed. Any suggestions gratefully received!

Thanks

Louise

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Starlight 1

Starlight 1

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Well, having spent ages fiddling with secondary adjustment (wish I hadn't touched it but it's all good experience, I suppose...) this is the best I can do without actually tearing my hair out:

attachicon.gifSec_080315.PNG

I know it's not perfectly round and may not be perfectly centred but, the question is, is this good enough??

Also am I right in thinking that it's just the tension of the central bolt spring that holds it in place against the allen keys? There doesn't appear to be any other mechanism that could lock the secondary.

Thanks for any advice or help

Louise

Look to high and go more to the left 1or 2mm  look again on asto baby at the off set of the f5

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Starlight 1

Starlight 1

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So, have been trying to pick up the three mirror clips... But this seems to be impossible! Even manually moving the secondary at best I can see two. If I try and get the third into view, the first two go out! Am I missing something? All the guides seem to rely on getting all three in view. Perplexed. Any suggestions gratefully received!

Thanks

Louise

Is the focuser to far in and hiding the clip.

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Astroscot2

Astroscot2

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Louise, I have the cats eye collimation kit, to centre the secondary and primary reflection I need to rack the focuser out/ back to aid with this proccess.  The Telecat does allow me to set the focal length also but you can get the a similar effect by racking the focuser out . Can you withdraw the Cheshire a tad in the focuser ? 

Mark

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Thalestris24

Thalestris24

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Hi all

Thanks for the replies. I think I might have sussed it now though still not very confident. One thing that's confused me is the various diagrams showing the mirror clips. They are actually low profile so you only just see the hint of an edge. I'm still not sure about getting all three in view. The secondary adjustment mechanism is pants!

Does anyone by any chance have a mod to replace those pesky Allen screws?? I've seen Dion's (Astronomyshed) mod with the custom round plate/washer added but I don't think I could easily make one of those myself.

Anyway, at first opportunity I'll do a star test. Then I'll probably have to go back to the beginning and do it all again!

Cheers

Louise

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russ.will

russ.will

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If you can't see the mirror clips with the focuser racked out, rack it in.

I used to rack the focuser out, so my eyes could actually focus on the secondary and then rack it in to see the mirror clips. Once I could see all three, I'd rack it out a touch until one just disappeared. I'd then adjust secondary tilt until it came back and they all looked equal. I'd then rack it out a bit further until one disappeared and repeat.

Of course, this was after I was sure the focuser had been squared to the tube and I did it in daylight pointing at the sky. This stops your iris down making it easier to focus on close up things.

Russell

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Thalestris24

Thalestris24

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If you can't see the mirror clips with the focuser racked out, rack it in.

I used to rack the focuser out, so my eyes could actually focus on the secondary and then rack it in to see the mirror clips. Once I could see all three, I'd rack it out a touch until one just disappeared. I'd then adjust secondary tilt until it came back and they all looked equal. I'd then rack it out a bit further until one disappeared and repeat.

Of course, this was after I was sure the focuser had been squared to the tube and I did it in daylight pointing at the sky. This stops your iris down making it easier to focus on close up things.

Russell

Hi Russell

Thanks - I can't see anything close up without strong glasses on! I'm hoping to do a star test tonight. If that's ok, I'll leave it alone for now. Otherwise I'll go back and try your tip :)

Last night I put a barlow and a 10mm ep on to catch some glimpses of the Moon between clouds. That was good - the most close up I've seen it with my own eyes! :grin:

Cheers

Louise

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  • 4 weeks later...
Thalestris24

Thalestris24

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Hi Louise

Did you get this sorted? I'm thinking of getting a 130PDS.

Best regards

Alec

Hi Alec

I think so... Lack of clear skies has limited testing. Turbulence prevents collimation star testing anyway... It seems ok though I have a problem with misshapen stars in one corner but I'm not sure what the root cause of that is. It might be a slight tilt with the camera or it might be something to do with the coma corrector or it might be to do with the focuser orthogonality. I'll try and post an example tomorrow. Hopefully someone will recognise the problem!

For the money, I'd say it was a pretty good scope. With the GSO cc it has an effective focal length of ~715mm (F5.5) so not much less than the bigger, heavier 150pds.

Cheers

Louise

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alcol620

alcol620

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Louise.

Thanks. Hope you get it sorted soon and better weather comes your way. Mind boggling this stuff especially when things go wrong, but extremely rewarding when they go right.

Good luck

Alec

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Thalestris24

Thalestris24

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Hi Alec

After a lot of faffing around I eventually discovered that the collimation was out... Tut! When I looked closely I could see that many, if not all, stars were distorted. I don't know how it lost the collimation. I have a 150pds and I've never had to collimate it - it was fine out of the box and has stayed that way for 15 months so far. This 130pds seems less stable. I can only imagine that I've altered the collimation inadvertently when I've been balancing it and grabbing the primary mirror end (it's tricky to balance properly). I'll have to be very careful not to do that in the future! Anyway, easy fix after all and if it happens again at least I'll know what the problem is :). I've lost several night's imaging, though :( It's supposed to be clear again tonight so hopefully I'll be able to do some proper imaging. Fingers crossed my stars are nice and round this time!

Louise

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Thalestris24

Thalestris24

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So, last night's testing didn't go well - still had the same problem! Aaargh! I had to conclude that if it wasn't the primary then it must be a problem with the secondary... On inspection I realised the secondary was slightly loose!! I must have left it like that when I did the secondary collimation a month ago - d'uh! At the same time it's very difficult to tighten the secondary allen bolts without disturbing the mirror position. I hate it!!! Wish I'd bought a frac now... Had a go at adjusting it all again and tightening the bolts. I eventually got to a point where I decided that was it! It's not perfectly collimated but I think it will be good enough (for me). At least stars are now not so distorted and look round. By the time I got to re-testing the humidity had risen and the visibility had dropped :( Still I got a few subs though they were tending to overexpose and even 180s subs were bright pink! So it goes on... It might be clear again tonight so I've put an Ha filter in the TS quick change unit. I focussed on a distant pylon so should be close. Not that there are any emission nebs in my view but I wanted to try the full spectrum 1100d with Ha just to see how it behaves. In fact, I think I might be happy with Ha only images of anything if it successfully defeats the dreadful lp!

Louise

ps My hair is rapidly turning white...

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