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Align secondary on 200p

PostPosted: Mon Dec 07, 2015 7:00 pm
by Alonsos
Hi, I have a Skywatcher 200p dob ( with all settings out of kilter) I've got a (Cheshire) , (bobs nobs fitted) ,(a Laser collimator) I've read & read how to collimate the thing,watched videos etc (yes it was my pride & joy now it's the thing) I've lots of patience but even that is dwindling ,I can do the paper opposite the focuser ,the paper in tube, and now understand what ime looking at BUT
THE SECONDARY is my thorn in the side it is adjustable up down, side to side,around,and so on,
I thought I had it right several times only to find it's not right,ime thinking I will never do it !
I think the main thing is how do I know the correct adjustment re the middle screw ? Too high too low & tilt to compensate
The whole secondary thing gr !!! Shed now locked after another unsuccessful few hours :crying:
Take care you lot

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 4:08 pm
by jmfdiver
I can only tell you from my experience that at first I had no clue what I was doing and watched the video and spoke to Dion and all the guys on chat. Now I don't know why it always sound so complicated because once I got my head round it I found it easy, I just generally have a look at the secondary through the cheshire first ( stick the paper behind it first as per video) and twiddle it about then stick the laser in and fiddle about with the primary. Not very technical but it works for me. I will probably be shot down in flames for this but I think it is made to sound more complicated than it is. Just my opinion. Make yourself a cuppa do some deep breathing and give it another shot. If you can't do it walk away for a bit.I hope you figure it out.
:coffee:

Jen

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 4:58 pm
by carastro
Have you seen Astrobaby's page on collimation, it was my bible when I had a Newtonian,

http://www.astro-baby.com/collimation/a ... 0guide.htm

Carole

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 5:38 pm
by Alonsos
Hi
Yes walked away from it & back refreshed today,watched Dions videos through ,that answered a lot of questions,and ground ends flat on bobs nobs( they were a bit rough ) then made simple card to hide secondary from primary that's better than stuffing a large Jiffy bag down tube ,and put the card opposite the focuser,
Then put in the 2 bits of card & adjust secondary spot on as per Dions video (it's looking good me thinks )
Next take the bits of card out & look in the cap / Cheshire and I see ime looking @ 2/3rds of my primary, ???
To see all of primary & the 3 mirror clips i have to adjust the secondary quite a bit and undo all the fine settings I made In the first place !
This is the bit ime having probs with
Thanks for taking the time to answer my initial post ( very kind ) :))

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 6:29 pm
by Dion
The 2/3rds of the primary your seeing, are you saying it's a full circle only 23/rds the size or it's lop sided and your seeing 2/3rds of the side of the primary?

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 7:12 pm
by Alonsos
2/3ds of primary

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 7:13 pm
by Alonsos
Lop sided

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 8:29 pm
by Dion
then you need to rotate or tilt to bring it in

Re: Align secondary on 200p

PostPosted: Tue Dec 08, 2015 9:21 pm
by Alonsos
Hi
If you rotate or tilt surely your altering the initial setting you did ie rotate to get a near as you can circle ?

Re: Align secondary on 200p

PostPosted: Wed Dec 09, 2015 3:28 pm
by Alonsos
Got it @ last I think re collimated
Next problem the primary adjustment , the 3 adjusting screws if slightly loosened you can move mirror maybe 1 - 2 mm with your fingertip so tighten slightly and the mirror cell holder sits on three O- rings , these three o rings have not got enough give in them to take more than 3/4 of a turn before they bottom out I can't adjust primary on that but if I put a turn on lock screw I can get the adjustment I need , so adjusting the primary for me is a case of screwing in lock screws and gently locking with adjusting screws, that's back to front but works ,
Springs in there would make sense or do I fit fatter O-rings to give me adjustment ?
Anyone else had this problem , are my O- rings past there sell by ?