Hyperstar on Celestron C11 Edge with Atik 490EX

[pyrasanth]

Hi everybody- finally I got a clear night last week & managed to see a star (wish I was in Florida-lol)

I've ordered some new toys to play with on my Celestron C11 Edge. "Toys" should arrive in a week or so.

These are:

Hyperstar

Atik 490 Ex colour

Microfocuser with motor drive

I'm curious about image scale. I know that the setup above will catch great swathes of nebula under the right conditions but does anybody know how the Hyperstar & Atik camera will fare for imaging objects like M57 & the gobular clusters. I know its down to image scale so for these objects I might be forced to image through the 0.7 focal reducer which I also have available for visual & photographic use if required. It should be really good however for M42 & M31 & possibly M33.

I've managed to sort out a lot of the previous CGEM DX mount issues by paying very careful attention to balance. I've had to put an additional 7 pounds of weight on the dec axis & an additional 10 Kgs on the RA. The telescope is now on a permanent Altair-Astro pier under 3 feet of concrete which has again helped. I'm totally hooked on this hobby so I've ordered a paramount MX+ which should arrive in the 2 months so I can really get stuck into some serious deep sky work. The most damning issue I will need to deal with is sky pollution so i'm hoping the Hyperstar will help in that direction.

[nmoushon]

The hyperstar will and will not help in regards to the LP. Yes your sub will be shorter but with its fast f/ratio it will just over saturate b/c of the LP that much faster. Your best bet is to combat LP is either narrowband or a pellet gun One of those Im pretty sure could get the police called on you though.

[admin]

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[ollypenrice]

You have picked a difficult route for yourself so far as getting into AP goes. If you don't use the Hyperstar the difficulty arises from the long focal length of the SCT which will need very accurate guiding. Since you've gone for one shot colour you cannot elect to make things easier and faster by binning 2x2 either. If you do use the Hyperstar the difficulties arise from the fast F ratio, which may be great on paper but which will be difficult simply because it is so fast. The depth of field is incredibly shallow so focus is ultra critical. A Fearthertouch conversion would probably meke life easier. Also collimation is ultra critical. None of these problems is insurmountable but you might as well be prepared for them. Yours will never be a plug and play system but hang in there.

I can see the advantage of OSC from the Hyperstar point of view but defeating LP is best done with narrowband filters and these work best with mono cameras.

How to know what field of view each system will give you? Very easy; most of the software planetarium packages allow you to plug in your chip dimensions in mm (x and y) and your focal length (ie the FL of whatever variant you are wanting to model). This then throws up a frame which you place over your target and move around, rotate, etc, to see how to frame it. I believe the free Stellarium offers this though I use SkyMap Pro out of long habit. This, for me, is the first step in taking a picture.

Olly

[Gedan]

Hi, as stated autofocus really helps here. Either maxim with focusmax or SGPro will work. I used a bahtinov mask for close focus then let SGPro take over.

Another issue is diffraction spikes...by chance I found that by forming an S shape with the cables which were taped together seemed to do away with these.

Although I think hyperstar has definite merit I was plagued by issues...ccd had to be sent back and mount needed a new motor control board...which took months to sort. I am going another route at the moment and hope to return to hyperstar later.

It may also be worth getting the filter drawer which allows you to add an idas lp filter or even an Ha filter...I read somewhere that 12nm are good for hyperstar and can be used along with your osc.

Good luck!

[ollypenrice]

Ouch, I have just seen that you went for a 490, not a 460. These really are small pixels for your scope. Is this decision set in stone?

Olly

[pyrasanth]

Ouch, I have just seen that you went for a 490, not a 460. These really are small pixels for your scope. Is this decision set in stone?

Oll

The reason behind this is explained in the following FAQ on the First Light Website. My work with this CCD will be with the Faststar optics so this will suit me well. I have a Skyris 618C which I will use for high res planetary work http://www.firstlightoptics.com/blog/atik-460ex-v-atik-490ex.html

[ollypenrice]

The reason behind this is explained in the following FAQ on the First Light Website. My work with this CCD will be with the Faststar optics so this will suit me well. I have a Skyris 618C which I will use for high res planetary work http://www.firstlightoptics.com/blog/atik-460ex-v-atik-490ex.html

OK, if you stick to the Hyoerstar you have a reasonable sampling rate (quick check on my part, not guaranteed) of 1.36 arcsecs per pixel. That is optimistic but not silly and since I have never imaged in UK skies I'm not competent to judge beyond that. A mono version of the camera would be useful binned 2x2 at F7 but if that is not your objective then no worries. In your case my main concern would be how to focus. In order to exploit your fine sampling rate you will need seriously excellent focus. This doesn't fall off the tree like an apple! However, it can be done. I haven't used a Hyperstar but there is a plenty of info out there.

Olly

[ChrisLX200]

A 490EX OSC will be something of a one-trick-pony though, if you can't bin it (?) it won't be much use other than at Hyperstar focal plane. Mine is the mono 490EX and I need to bin it 2x2 with my SCT otherwise it is working at a silly over-sample resolution. It works well @ 1:1 in my refractor though.

ChrisH

[ollypenrice]

A 490EX OSC will be something of a one-trick-pony though, if you can't bin it (?) it won't be much use other than at Hyperstar focal plane. Mine is the mono 490EX and I need to bin it 2x2 with my SCT otherwise it is working at a silly over-sample resolution. It works well @ 1:1 in my refractor though.

ChrisH

Exactly so.

Olly

[pyrasanth]

OK, if you stick to the Hyoerstar you have a reasonable sampling rate (quick check on my part, not guaranteed) of 1.36 arcsecs per pixel. That is optimistic but not silly and since I have never imaged in UK skies I'm not competent to judge beyond that. A mono version of the camera would be useful binned 2x2 at F7 but if that is not your objective then no worries. In your case my main concern would be how to focus. In order to exploit your fine sampling rate you will need seriously excellent focus. This doesn't fall off the tree like an apple! However, it can be done. I haven't used a Hyperstar but there is a plenty of info out there.

Olly

These 2 items will I hope address the focus issue:- I understood right away that focus & colimation of the Hyperstar is critical

http://starizona.com/acb/MicroTouch-Autofocuser---Wireless-P1041C745.aspx

http://starizona.com/acb/Feathertouch-SCT-MicroFocuser---Celestron-Edge-HD-11CPC-1100CGEM-1100-P2518C654.aspx

I will see how I get on with the 490 EX colour- it's no big deal to get another 460 EX mono for any other work if this combination limits me. My main interest is nebula currently.

Thanks everybody for the great advice. What is the effective of narrow-band filters on a colour CDD?

[ollypenrice]

The Bayer matrix on an OSC limlits you to one pixel in four on Ha and two in four, probably, in O111 - though it might be that the blue and green filters both block some of the O111. You'd need to see the bandpass for the Bayer Matrix in question and compare it with that for a variety of 0111 filters to see how they overlap.

For nebulae the Ha is by far the most important NB filter, with O111 second. It enhances the red channel enormously. However, the speed of the Hyperstar does mean that the broad red filter will pick up a lot of signal.

Since changing filters is an issue with the Hyperstar a mono camera with a single filter fitted would be a great bonus. You can use NB filters through an OSC but you lose masses of signal and resolution, which is a pity because the resolution in nebulae often comes from the Ha layer.

Olly

[Gedan]

You can get the hyperstar filter drawer.

This may be helpful..http://www.astrograph.de/artikel/Comparison%20of%203%20Ha%20Filters%20for%20F2.pdf