3 replies to this topic

[JazzyCabbages]

I’m in the process of transitioning from shooting with a DSLR (Nikon D750) for 5 years, to a ZWO ASI294mm pro.  I’ve snooped around the forums here and other places to make sure I’m doing this correctly with getting all of my accessories I need and crossing my I’s and dotting my T’s…
Here’s what I’ve been using:

- Celestron CGX mount
- Celestron 8” EdgeHD
- .7 focal reducer
- Celestron T-Adapter for my DSLR (93644)
- Celestron StarSense (rarely use it anymore, but I see that people often use it with the ASI AIR)
- Celestron Powertank (18771)

Here’s what I’ve recently bought/ordered:

- ZWO ASI 294mm pro (arriving today)
- ZWO ASI AIR Pro (backorder)
- ZWO ASI EAF (backorder)
- Samsung Galaxy Tab S7+ to run my ASI AIR

 

Here’s where my confusion starts – I know I need to get my filter wheel & filters.  I also want to get the Hyperstar.  I’m hoping that I can get one set of filters that will fit both – shooting 1420mm  at F7 with the .7 reducer and  390mm at F1.9 with the Hyperstar. Is that possible and if so, what size?  Would 1.25” work for both?  The one that worries me is with the Hyperstar.

Other questions that have popped up –

1. What’s a good/compatible power supply/tank?  I plan on using my powertank I already have to run my CGX mount.  Would the Jackery 240 or 500 be good for the EAF, the ASI294, the ASI AIR and possibly a dew heater? I’d also want to run my laptop from time to time as well.

2. Back focus – My scope has a back focus of 105mm with the reducer.  Am I able to use my T-Adapter to help get correct back focus for this?

3. I only live an hour from Cherry Springs.  I’ll be imaging 90% of the time from the Overnight Astronomy Observation Field.  What filters other than the LRGB  should I look into?

Thanks for any advice/help.  This is a great community! 

[rhart426]

The OAOF @ Cherry Springs has AC power.  If you'll be there 90% of the time, just get an AC>12VDC converter (Pyramid is a good brand), stick it in a plastic box with a power strip, and call it a day.  If the other 10% is at your house, then absolutely don't bother with battery power.  Bonus points if you weather-seal the box and drill holes to place sockets for power in/out.

 

As for the filters, go to astronomy.tools, click on calculators from the top toolbar, select CCD Filter Size.  Select aperture (8" = 203mm), enter focal length, etc etc. It will calculate the minimum filter size for you.  You can go smaller, but you'll see vignetting from the filter.  From what I can see, the Hyperstar is going to need 2" filters.

 

SHO is always popular (S2, alpha H, O3).  I'd start with those, they'll give you the most bang for your buck.  Other wavelengths are available, but less useful.

Edited by rhart426, 01 March 2021 - 02:51 PM.

[t-ara-fan]

 

Here’s where my confusion starts – I know I need to get my filter wheel & filters.  I also want to get the Hyperstar.  I’m hoping that I can get one set of filters that will fit both – shooting 1420mm  at F7 with the .7 reducer and  390mm at F1.9 with the Hyperstar. Is that possible and if so, what size?  Would 1.25” work for both?  The one that worries me is with the Hyperstar.

 

There are special narrowband filters for very fast (> f/3) systems.  I think what they do is widen the bandpass so light hitting the filter at a steep angle still gets through. So these might be less than ideal for your f/7 setup. You should look into this before spending the big bucks.
 

[rhart426]

There are special narrowband filters for very fast (> f/3) systems.  I think what they do is widen the bandpass so light hitting the filter at a steep angle still gets through. So these might be less than ideal for your f/7 setup. You should look into this before spending the big bucks.
 

I knew there was some other consideration but couldn't remember what it was and I've been thinking about it ever since. Thank you!