Carole's Flattener

[Carole]

Thought I had better start a new thread before I get accused of highjacking again.

Quotes from George's Flattener thread>

Just before Kelling I had been supplied with an extension ring for my flattener as some-one had suggested the distance wasn't right (on UKAI), and at Kelling I was getting these really strange shaped stars which I've never had before.  

I was wondering if this could be the reason.  
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An extension ring for your flattener?  Which flattener have you got?  As far as I'm aware, the Williams Optics flatteners are designed with DSLRs in mind.  They take a Canon adapter ring and then the DSLR attaches directly to give the precise distance (56mm).  If you add anything else then, yes, you will get odd shaped stars.

Be careful of advice you get on forums!  (Yes I know that comment is self referential!)

Mark

Hi Mark, I have a W0 X0.8 Flattener 111
I discussed this with Ian King and he sent me the extension piece on a trial basis.  So I have not paid for it yet.  Just need  to get out there (clouds permitting) and do a "with and without" image to check the difference, I don't have the skills to work it out how you have explained to George.
But looks like I'll be returning the said expension piece.

thanks Mark once again.

Carole

[MarkS]

If the flattener has not been designed for your specific scope then it is quite possible that it will need a slightly different spacing to achieve the best performance for that scope.  So definitely do "before and after" images to check.

But when flatteners are closely matched to the scope (e.g. the range of flatteners for the Skywatcher ED80, ED100, ED120) then it is important to achieve the correct quoted distance.  It is interesting to note that Skywatcher have created a different flattener for each scope rather than adopting a "one size fits all" approach.  I think this Skywatcher approach will ultimately give better imaging results because the flattener is more closely matched to the optics of the scope.   I wish Celestron had done the same for their SCT flatteners!

Mark

[Carole]

These are the stars I got in the CORNER of my previous image WITHOUT the flattener extension piece>


these were the stars I got in the CORNERS of my M13 at Kelling Heath WITH the extension piece on the flattener.


the middle was OK.

I saw this at Kelling Heath on the Saturday when I was also having problems with alignment and just thought it was something to do with the tracking/ALIGNMENT, but it wasn't until I got home and examined my M13 image taken on the previous night that I realised that they were on that too.

Now I've read your thread with George I am convinced it is the extension piece to the Flattener.  

So if the spacing from the flattener to CCD is critical, am I right in assuming a Barlow can be put on so long as it is between the flattener and the scope.

Carole

[mickw]

Are those space ships in all the corners or just one ?
Are they all pointing in the same direction ?

It looks like something is out of alignment, if you're using DSLR is the camera seated firmly on the T Ring and the T ring firmly screwed to the adapters ?

[Carole]

I have a meade x2 barlow you could borrow for a short while.  If you get on with that then you might consider the Celestron 1.25" x2 I have for sale, it's in mint condition with end caps and box.

Yes everything is screwed on OK Mick, I think it's just the extra extension piece that is causing the problem, it was supposed to reduce vignetting and coma but seems to have done the opposite.

The centre of the image was fine.

How are you getting on with your venture into imaging?

Carole

[Carole]

Are those space ships in all the corners or just one ?

Yes, all four corners, although there are not so many stars bottom right so a bit difficult to see properly.

Are they all pointing in the same direction ?

As you go around the image they all seem to point towards the centre of the image (i.e. tail of "space ship" pointing outwards).

Carole