Hyperstar, Anyone Used Or Have One?

[Mav359]

Im trying to figure out what would be better.....

a) C9.25 with hyperstar kit = 9.25" F2 scope

or

ED80

I am also desperatly trying to justify an ATIK 11000 for one of the two

[carldr]

Go with the Hyperstar kit, and let me how you find it!

I don't know if the FOV would be a bit wide - you'd get something like 4 degrees FOV and 4"/pixel, if my maths are correct. It would be easy enough to mosaic two images for a similar effect if you got a ED80, and you'd get better resolution for smaller objects.

I have considered looking into it, but having to collimate the C9.25 when putting the secondary mirror back for visual use is another thing that puts me off. I guess you would quickly get skilled in doing it, but still ...

[MartinB]

SteveL is a good guy to ask. Hyperstar isn't exactly an easy system to set up and use. It's no easy job imaging at F2.

[Ad Astra]

I have a hyperstar on order for the C-11 at school. From what I understand, installation will be a bit of a challenge, requiring me to remove the corrector plate, then remove the secondary mirror, and reinstall with the hyperstar. I'm looking forward to the challenge!

Imaging at f/1.8 should be brilliant, because the exposures are so fast, tracking is much less of an issue. The folks at Starizona say that you can actually take deep sky images from a parking lot!

We'll see how it goes!

Dan

[SteveL]

Taking out the secondary is dead easy, and after the first time you do it, you will wonder why you stressed about it.

Remove the secondary holder ring

Remove the Secondary mirror (note the postion of the notch on the secondary holder, and the grub screw on the secondary plate)

Place secondary mirror in "pot" supplied

Screw down with ring

Screw Hyperstar into secondary holder until snug. The unit has a 2" filter section (just behind the red cap in the following image), you just unscrew the top of that section, insert the filter, screw the top back on, then attach the camera to the "front" via the T-Threads.

I`ll try to be as unbiased as I can here.

At f/2 the edges of the usable light cone come in at such an angle that interference based filters just cant cope. Almost all LP and NB filters are interference based, and their ability to work correctly are based on the light passing through it passing as near to perpendicular as possible. As the angle of incidence inctreases, the ability of the filter to work with tolerences reuces. Most filters state they work down to a certain "f" number, usuall f/3.5 or f/4.

For small chips, its not so much of a problem, but for larger chips, the light coming at the very edges/corners can experience some weird effects... it is possible that the wavelnegth of the light can actually get shifted by as much as 6nm, so for a 7nm Ha filter, the peak Ha response would be very near the limit of the filter, and in the part that doesnt work that well (i.e <10% passes through).

I always had issues getting my calibration frames to work correctly with my C8 Hyperstar system, it drove me crazy, and yet my images from William Optics 66 calibrated just fine. In hindsight, I am wondering if it was the UV/IR glass window on my QHY8 that was causing the odd flat field over/under calibration issues... i.e the flats and bias were fine, it was the UV/IR window thatw as causing some wavelength shift at the edges that my flats were unable to cope with. I was unable to test that theory as I had sold the kit when I thought of this possible scenario.

Its **VERY** senstive to collimation... silly crazy senstive! Not so bad in an observatory where you can tweak it to perfection and leave it, but I found it a chore to recollimate everytime I had to set up and strip down (secondary removal + hyperstar installation, plus reverse when stripping down).

And focus is even more sensitive... on the C8 hyperstar, the critical focus zone is 6nm. If you want to nail the focus accuartely everytime, you will probably require an electronic focuser. May work OK with a Bahtinov mask, but never tried one at the time.

The hyperstar system can grab a lot of light in a very short time, and with less accurate tracking required. The ability to grab many tens of subs in a session really helped with the signal to noise in the final stacked image. I learnt so much during the time I had my Hyperstar, I went from noob to half decent in one season.

A few things made me sell the Hyperstar system and move to a fast refractor for imaging.

#1 - I had a Nexstar 8 GPS on a wedge, which limited my upgrade path. I needed to move to a GEM of some sort.

#2 - The calibration file issue really did drive me mad.

#3 - I was getting to the point where I wanted to start using multiple night's data to combine into one final image, but getting the camera orientation (and more importantly, the cable locationb) the same for each session, so that the diffraction spikes matched up in both sets was a nightmare.

I hope that has helped a bit...

[Ad Astra]

That is a huge help, Steve. I'm actually close enough to Starizona (about a 5 hour drive) that I have considered taking the scope out there myself and having them help me install it. Maybe I'll save myself the drive.

I'll let you know how mine goes after I get it.

Dan

[SteveL]

I spent about 2 hours with the hyperstar in one hand, and my other hand hovering over the outer ring, thinking about starting the process of removing it... then I chickened out and read the instructions again (for the 100th time!) before I finally got aorund to doing it. Second time was a little faster

[Mav359]

Ive watched the video and because my C.925 is faststar compatible the installation look faily easy, i am an engineer though and do tend to like taking things apart.

I was more conceared about the quality of the imaging against cost, Hyperstar would cost nearly twice the price of an ED80, is it worth the extra? Does it even make a different other then tracking, shorter exposures?

[SteveL]

Personally, I ran into a brick wall with my hyperstar imaging system for whatever reason, and it needed me to sell it all and start again with a GEM and a fast refractor to progress any further. I enjoyed it while I had it, and I learned a lot from it, but (and I know a few people may disagree with me here), if i knew then what I know now, I should have gone straight to a GEM + fast refractor in the first place.

Your mileage may vary, and others may have different opinions, depending how well their system performed.