double spikes....why? - Page 3

adman (Adam) · #41 02-03-2011, 02:43 PM

I know its not part of the problem this thread relates to - but I have just ordered some prostar flocking....should take care of that!

Adam

multiweb (Marc) · #42 02-03-2011, 02:53 PM

Quote:

Originally Posted by adman

I know its not part of the problem this thread relates to - but I have just ordered some prostar flocking....should take care of that!

Adam

Flocking is good for stray light but any object in a light path, regardless of shape, color, thickness or reflective index will cause diffraction.

One or two vanes in line will give you one line through your star. (the opposite sides overlap - like cables of an hyperstar)

Three vanes at 120deg will give you 6 lines (the opposite sides bisect the angle created by the two other vanes in the middle)

Four vanes at 90deg will give you 8 lines (the opposite sides overlap unless there is a slight angle offset and you then see the 8 distinct lines - problem discussed above)

pmrid (Peter) · #43 03-03-2011, 06:23 AM

Quote:

Originally Posted by adman

EDIT: Looking down the barrel like that with my little catseye red light illuminating things - it could do with a damn good flocking!

Adam, I have a good length of that Spotlight black felt with adhesive backing. I have no use for it now so it's yours if you want it.
Peter

adman (Adam) · #44 03-03-2011, 10:39 AM

Quote:

Originally Posted by pmrid

Adam, I have a good length of that Spotlight black felt with adhesive backing. I have no use for it now so it's yours if you want it.
Peter

Doh! Too late! I ordered some prostar flocking yesterday! Thanks for the offer though. Hold onto it I'm sure there will be a Ten Chainer who could use it.

Adam

peter_4059 (Peter) · #45 03-03-2011, 09:00 PM

Interesting thread. I turned up a rod that fits tight in the secondary centre bolt hole (with the secondary removed) and then measured from the centre of the rod to the inner edge of the tube all around with a micrometer to ensure the secondary was centred. I didn't bother with offset.

adman (Adam) · #46 04-03-2011, 09:20 AM

well - a bit of bad news.

I decided that I would loosen my mirror clips yesterday, so off came the end of the scope. I thought that while I was there, I would shorten my collimation bolts to better suit the moonlite focuser - it reached focus near the end of its outward drawtube travel - a legacy from the old skywatcher focuser.

Anyhoo - a few hacksawing minutes later, I had shorter bolts, and then it took me about a hour to reattach the mirror cell because the springs are now longer relative to the bolts - must be the tightest collimation springs around now!

So, I'm thinking - this is going to be great, we'll get to the bottom of these double spikes now....but of course after you muck around with the mirror, the scope needs collimating again. Out comes the catseye gear, and while I was checking the alignment of the secondary, I thought (well actually I didn't think) - cool - i'll just straighten out those wonky vanes while I'm here....

So I have corrected both problems, and now I will never know which one caused it. Does anyone have a re-wonkifier?

Adam

irwjager (Ivo) · #47 04-03-2011, 11:38 AM

Quote:

Originally Posted by adman

well - a bit of bad news.

I decided that I would loosen my mirror clips yesterday, so off came the end of the scope. I thought that while I was there, I would shorten my collimation bolts to better suit the moonlite focuser - it reached focus near the end of its outward drawtube travel - a legacy from the old skywatcher focuser.

Anyhoo - a few hacksawing minutes later, I had shorter bolts, and then it took me about a hour to reattach the mirror cell because the springs are now longer relative to the bolts - must be the tightest collimation springs around now!

So, I'm thinking - this is going to be great, we'll get to the bottom of these double spikes now....but of course after you muck around with the mirror, the scope needs collimating again. Out comes the catseye gear, and while I was checking the alignment of the secondary, I thought (well actually I didn't think) - cool - i'll just straighten out those wonky vanes while I'm here....

So I have corrected both problems, and now I will never know which one caused it. Does anyone have a re-wonkifier?

Adam

Love to see an 'after' shot of Alnitak now

Oh, and if you ever get nostalgic for double spikes in your images, let me know and I'll re-wonkify ST's Synth module for you.

adman (Adam) · #48 04-03-2011, 12:32 PM

Quote:

Originally Posted by irwjager

Love to see an 'after' shot of Alnitak now

Oh, and if you ever get nostalgic for double spikes in your images, let me know and I'll re-wonkify ST's Synth module for you.

Yep - don't worry - I'll still post an "after" shot. Knowing my luck it won't have changed a bit!

RobF (Rob) · #49 04-03-2011, 08:58 PM

How's that bad news if you've got decent star shapes now Adam!?
I thought you were going to say you dropped the 2ndary on the primary or something at first

Now THAT would be bad news.....

adman (Adam) · #50 07-03-2011, 07:30 PM

Quote:

Originally Posted by RobF

How's that bad news if you've got decent star shapes now Adam!?
I thought you were going to say you dropped the 2ndary on the primary or something at first

Now THAT would be bad news.....

Yep that would be bad news! Although good excuse to buy a new scope....?

Clearing nicely here tonight - should have an "after" shot to show you all later...

adman (Adam) · #51 08-03-2011, 07:26 AM

...and then the clouds rolled in again for a few hours. Cleared up around 9:30 I think - but too late by then to set up

ZeroID (Brent) · #52 08-03-2011, 11:25 AM

The suspense is killing us all ... do we need a De-Wonkifier ? Do we need a Re-Wonkifier ? Will the vanes EVER be straight ? Will the clouds eventually roll away ?
Will Mary-Jane ever find her long lost little brother .....

sorry, wrong program there ...

adman (Adam) · #53 08-03-2011, 11:53 AM

Quote:

Originally Posted by ZeroID

Will the clouds eventually roll away ?

I'm not convinced they will ever go away

adman (Adam) · #54 13-03-2011, 05:31 PM

still waiting for a clear night to test it out........

adman (Adam) · #55 22-03-2011, 10:59 PM

well tonight wasn't a complete waste of time. I did a re-shoot of sirius with mirror cell loosened and vanes de-wonkified and it looks like I have pretty much sorted out the double diffraction spikes. They are still there to a small extent - but much less obvious.

From this I would imagine that the cause was the vanes not being straight / aligned.

EDIT: there is a nasty reflection in there also - would that be off the MPCC??