Hyperstar test

[RobertM]

This is my first real test of the C11 Hyperstar after collimation.  I tried using a number of methods but in the end using a defocused star in live view seems the quickest (though not necessarily the most accurate).  The image is 10 x 60s uncalibrated so has plenty of warts and issues but I'm very happy that I managed collimation to such a good degree after only 10 mins.  Flats are the next problem though hopefully not so bad.

Reduced size:


Full size 450D image (560mm f/l f/2) :
http://farm6.static.flickr.com/5212/5408930284_66b2d46509_o.jpg

[Carole]

Going down the hyperstar route then Robert.  I read about this once as I wanted to know what it was when Daniel kept talking about it.  Sounds like a bit of an initial challenge but will produce good results once set up.

Carole

[Fay]

Looking good Robert, bet you are glad to have tried it out, I am envious of the 10x1 min subs!!

[Mac]

Looking good,

Mac

[PhilB]

That's not at all bad. Nice to see the investment is paying off.

[MarkS]

Looking very promising Robert!  I'm sure this is going to be a great rig.

Did you use a filter for this image? 
Is the 450D unmodified? Or have you taken the plunge!

I look forward to seeing a properly calibrated result.

Mark

[Rocket Pooch]

Can I borrow it and put my QSI on the front please, oh please!!!!

[RobertM]

Camera still unmodded and the filter was an IDAS LPS-P2.  I did get a 1000D to mod but after Err 99's had to go back.

There are very strange gradients which I need to investigate ... another day.

Chris, if you have a Canon adaptor then that idea might be a goer

[MarkS]

There are very strange gradients which I need to investigate ... another day.

Do you mean the dark strip along the bottom of the frame?  If so, it's caused by the mirror interrupting the light path and casting a "shadow".  It's bad enough at F2.8 on the bananascope - you'll have it even worse at F2.  It also causes a diffraction spike on the stars that fall within that strip.

I'm planning to rip the mirror out some time.  Won't be able to use the viewfinder any more but that is not a huge issue.

Mark

[RobertM]

Thanks Mark, that's what I thought it was and that'll be my solution too.  I'm also planning on buying one of the MkIII Canon 1.4 tele extenders to use with it but that's part of a longer term consolidation project.

Robert

[Daniel]

That's a great result Robert, I've been waiting for a first light of this for a while. you can see the mirror issue your getting in this image

http://www.flickr.com/photos/23188472@N02/3178909495/

those stars are looking lovely and round, amazed you got the collimation that good in just 10 minutes!

Daniel
:O)

[RobertM]

Hi Daniel,

Thanks and yes the flats are just like yours.  Collimation would actually have taken less than 5 minutes but it was miles out from previous duff attempts with CCD Inspector and manually recentering (don't ask).  I can also see two improvements that would make the system better - a) blackening the edges of the flattener optics and b) spring loading the adjusters.  Certainly the current push/pull arrangement of screws is the weak link when collimating, especially on a star as low as Sirius.

I made a 120mm mask to fit over the secondary housing to remove artifacts due to the shape of the camera and that certainly helped to produce a good out of focus dougnut for collimation.

Will do some flats and bias tonight and try stacking the other 30 subs.

Robert

[Daniel]

By the way, what's this about using a tele extender, is that with the hyperstar?

[RobertM]

That's one of its uses but I'm waiting for someone to review the 1.4 MkIII before deciding.

[mickw]

Cunning

784mm @ f3