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#26 Hikescdnrckys

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Posted 08 September 2014 - 04:35 PM

Roy,

 

The Celestron 8SE is based on an altaz mount. For long exposure video or photography (exp>30 sec), you would need a wedge to eliminate field rotation. The SE was not designed with a wedge in mind. Due to tripod stability issues, it is difficult to outfit it with a wedge, if you live South of latitude 60 (Anchorage, AK).

 

The alternative is to go with a camera that has a modern Super HAD II sensor. These sensors are much more sensitive and hence give good results with shorter exposures (30 sec or less). This eliminates the need for a wedge. The following cameras have Super HAD II sensors. Entry level: Mallincam Micro, AVS DSO, Samsung SCB-2000. More advanced: AVS MK-IV. Non-video: Lodestar x2.

 

To enjoy DSO's with an altaz mount you will need a focal reducer that gets you close to f/3, as one of the following: Meade 3.3 reducer/corrector, AVS Vario-reducer, Mallincam MFR-5.

 

On the software side you may consider AstoLive for the video cameras or LodestarLive for the Lodestar. Both of these have stacking algorithms that compensate for field rotation. Using them you can stack several shorter exposures. You can also control most cameras from these software packages. (At this point AstroLive cannot control the Mallincam Pro Jr and the Samsung SCB-2000.)

 

--Dom

 

Hi Dom. I am new to video astronomy so have been reading as many posts here as possible. I have an opportunity to pick up a new scope for a significant big birthday next year and was looking at the Celestron Evolution 9.25 along with an Astro-video APU1 or Mallincam Jr. Pro. Given the Celestron Evolution is Fastar capable, does Fastar serve the same purpose as a focal reducer or would you still need one? Do these video cameras APU1 etc. mount directly to the Hyperstar lens which replaces the secondary or  are they only meant to slide into the focal tube?

 

Thanks for your help!



#27 A. Viegas

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Posted 08 September 2014 - 04:42 PM

If you buy the new Evo 9.25 you can easily get down to F3.3-4 with the jr pro and mallincam mfr5 reducer. The vario reducer sold by AVS can get you to F2 with the APU 1 or the Mk4 cameras as its designed to be optimally paired with the 1/3" chip in those cameras. In either combination you really don't need hyperstar which costs close to $600-800 vs $250 for the Mfr5 or $100 for the vario reducer. Hence hyperstar is overkill for
These video cameras.

Only reason to buy the hyperstar is for larger chip CCD astronomy and then the Evo mount is probably not the best idea.

Al
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#28 core

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Posted 08 September 2014 - 09:39 PM

The vario reducer sold by AVS can get you to F2 

 

fwiw, AVS website states that the reducer's ratios are .63, .56, .5, .43, .36, and .29.  The f/2 or f/1.8 2 reducer (for f/10 SCT) had been announced a while back with no updates.

 

 

I just purchased my first telescope, a nexstar 8se. I would like to get into video astronomy. Looking to get the mallincam Jr pro pc. 

 

From my experience with a 6SE (and occasionally mounting a 8SE OTA on the same mount), here are some observations:

 

- you will most likely run into problems with the camera hitting the base of the mount if you just let the video imaging train hang straight off the back.

- you can set the slew limits in the Hand Controller to avoid that, but you will be missing out on objects closer to the zenith (quite a large swath), where skies are darker.

- alt-az tracking very near the zenith can be sloppy for long exposure (> ~10sec).

- even with proper backlash settings, it takes patience (no more than 20sec or so) for tracking to settle in and track an object after a goto. 

- goto's may not be accurate enough to place objects in the camera's FOV; I've set up so that I can quickly swap out with an eyepiece.

- that said, it's not complicated and you'll be amazed at how quickly you can get good results.

- once you're familiar with the quirks that the setup (mainly acquisition and tracking) will entail, you can get by with just the 0.63x alone for larger image scale on some of the brighter DSO's (globs, planetary).

- last thing to add - you should do initial alignment of the mount via the video output, much easier than using an eyepiece, and it makes certain you're centered on the small imaging chip.

 

My suggestion would be to get a 0.63x SCT FR (which also works fantastic for visual on the C8, if you haven't gotten one yet), followed by the stock diagonal, and then the camera with a regular 1.25" 0.5x FR.  This combination allows for 1) camera clearing the base at zenith 2) resulting FR of around 0.4x-.3x or more, depending on spacing.  You should also setup a framing eyepiece (in my case, a 25mm crosshair) with extension tube that you can quickly swap out with the camera portion for a quick visual confirmation without needing to refocus - I've found this little extra works wonders when using the SE mount for video astronomy.  Here's a quick pic of the described setup, after the 0.63x FR - focus is set for the camera, and eyepiece view is close to parfocal.

Attached Files


Edited by core, 08 September 2014 - 10:58 PM.

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#29 Dom543

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Posted 08 September 2014 - 10:36 PM

Hikescdnrckys,

Al and Peter gave you very good advice.

The only thought that I could add is to reiterate the importance of a modern, high sensitivity sensor, if you are using am altaz mount, like the Celestron Evolution. This allows you to keep exposure (a.k.a. integration) times short, that is key for users of altaz mounts. The unlimited integration capability of the Mallincam Jr Pro and of the AVS APU-1 is less important for you, as you will not want to do long exposures.

The APU-1 has the same type of modern high sensitivity sensor, as the cameras listed in my post replying to Roy. But there may be a waiting list for the APU-1. Inquire with AVS. The other cameras are available for immediate shipping.

Clear Skies!
--Dom
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#30 CA Curtis 17

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Posted 08 September 2014 - 11:10 PM

Hikescdnrckys,

 

The video camera will screw onto the Hyperstar once you get the adaptor from Starizona for the video camera.  The same adaptor works for the MC and AVS cameras as well as the Samsung and most others which use the C-Mount threads on the front.  I have taken pictures with my C14 in Hyperstar mode with the MC Xtreme, Micro, Samsung SCB 2000 (posted in another recent thread on CN) and the DSO-1.  You can find images I took with the MC Xtreme at f/2 using the Hyperstar in the presentation I referenced here:  http://www.trivalley.../2014-02-21.pdf.

 

Al is correct, the Hyperstar is rather expensive and may not be worth your while if you can get down to f/2 without it.   I have the MFR 5 and it only gets me down to ~ f/4.5.  I tried adding another focal reducer, the Celestron f/6.3 in front, but then I got vignetting with the Xtreme.  I haven't tried it with the 1/3" camera yet.  But you won't get vignetting with the Hyperstar.  The fact that it works for a larger sensor isn't any reason to dismiss it for a smaller sensor since it works perfectly for them as well.  Another advantage of the Hyperstar is you won't have to worry about clearing the base of the mount.

 

My point is, Hyperstar is a sure fire way to get to f/2, but you have to decide if it is worth the expense to you.

 

Regards,

Curtis


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#31 Hikescdnrckys

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Posted 09 September 2014 - 02:14 PM

Thanks Al, Peter, Dom and Curtis. Your advice has been very helpful. Sound like Hyperstar is overkill, so I will likely just start with a focal reducer, diagonal and either the Mallincam Jr. Pro or the AVS APU1.

 

First steps first though, I need to get my hands on the evo 9.25!



#32 CA Curtis 17

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Posted 09 September 2014 - 06:54 PM

Good luck!

 

 

Curtis








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