First Timer...Need Help with Viewing Through ASI120MC-S :(

[judasentinel]

Hello,

My name is Munib, and I am from the USA (Wisconsin for now). I have recently caught the astro-imaging bug and have bought an ASI 120MC-S as my first camera. Being new to this world, I am a long way from even understanding the basic terms, but am quite well-versed with astronomy. My equipment list is as follows:

Celestron 8SE GoTo telescope, with an equatorial wedge
Meade F6.3 Focal Reducer
2" diagonal and eyepieces
2X Barlow
ASI 120MC-S camera
Sharp Cap

Everything is being run remotely via a dedicated laptop.

As far as live viewing is concerned, I have zero issues with alignment, and am able to have great views of stars, planets and DSOs. However, as soon as I switch to the ASI camera, I am not able to see ANYTHING at all. I have tried to understand how to use SHarpCap, and am scouring the manual right now. I am at the stage where I am ready to pull the trigger on the SharpCap Pro, but want to be sure that I can actually use the software properly. I have tried focusing on the telescope, and do not get much, except for when I am looking at the moon, which shows up alright. Not the sharpest though. To top it off, I only see a small portion of the moon in SharpCap. When I put the eyepiece back on, the moon is smack in the center, but with this camera, it is to one side, and that too, only partially. Stars and nebulae are out of the question, as all I see is darkness, and no amount of focusing brings ANY bright speck on the screen. I know the camera works, as I have been able to use it for terrestrial viewing through my telescope (focusing in the distance on a tree or something). My question is perhaps more about what I should be doing in SharpCap, so I can at least see the damn objects on my computer screen. I play around with Gain and Exposure, but do not understand what settings to use, which one to do first, how to adjust the different colors, etc.. So many questions....the manual is quite detailed, and I am going to get through the whole thing, but perhaps what I am looking for, is some basic guidance on where to start, how to start and pitfalls to watch out for.

I am sorry for the long-winded explanation above, but winter is ending here and the weather has finally started to warm up. Today was the FIRST day since November 2020 that we saw clear skies, and I am disappointed that due to my ignorance and lack of skill, I could not see ANYTHING through the camera.

Hope people here will be able to guide.

Thanks for reading.

Munib

[admin]

Hi Munib,

Let's start by talking about how much of the moon you can see with your telescope and camera, because that leads into everything else that you are asking about.

You're using a telescope with a long focal length – 2 m if you use it without any Barlow or reducing lenses. 1.3 m if you use your focal reducer. Combining this with your ASI 120 camera (which has a small sensor) gives a very small field-of-view (about 0.15 x 0.1°). This is much smaller than the size of the moon in the sky, explaining why you only see a small chunk of the moon through your camera. You can use this website to calculate the effective field-of-view of your equipment in other combinations : https://astronomy.tools/calculators/field_of_view/

The small field-of-view is also giving you difficulties when looking for deep sky targets – you are looking at such a small amount of the sky at any one time that the likelihood of finding bright stars or the object of interest in view is small. This is made worse by the fact that you are trying to get three things right at once – focusing, camera settings, and pointing in the right direction.

Unfortunately, an SCT is a tricky scope to use for beginning astrophotography, particularly when coupled with a small sensor camera. Persistence will slowly get you in the right direction (for instance try things like focusing on the moon first and then moving to another target as you will know you are in focus). Another option is to consider adding a short focal length refractor to your kit – one possibility would be to buy a decent quality 50mm or 60mm finder guider, which will slot into the finder dovetail on your SCT. When you connect your camera to this telescope you will get a much wider field of view and it will be easier to get going. If you proceed to take astrophotography further then this could become a guide scope. For instance something like this : https://www.altairastro.com/starwave-50 ... 2496-p.asp (I'm sure there will be equivalent products sold in the US - do not buy the really cheap versions as they are low quality - for example avoid https://uk.telescope.com/Orion-Mini-50m ... 109903.uts)

Robin

[judasentinel]

Thank you, Robin, for your detailed reply and explanation. Now I see why the manual you wrote is so detailed - there is so much wealth contained therein.

I have used the astronomy tools website in the past, but only for my Canon T3i DSLR. Based on what you shared, I looked into the various combinations of cameras (ZWO brand) with my scope and unless I go with a $1300 one, I am not going to be able to see much of the DSOs, especially things as large as M42 or the Andromeda Galaxy. I do, however see both through my Canon DSLR when attached to the prime focus of the scope. Net conclusion is that I have the wrong telescope for imaging. When I bought it last year, I refused to get drawn into astro-imaging, arrogantly thinking that I only wanted to do live viewing and that would be enough. Boy, was I wrong!! I can hardly see ANY details in my live views, unless I am looking at the moon or the sun.

As regards the guide scope, that is perhaps out of the question, as I already have StarSense camera that I am using for alignment. Once aligned, not sure what the purpose of a guide scope is, since my mount is on a wedge and it can track the sky fairly well. I guess I do not understand what a guide scope is for, and what relevance it has to doing astro-imaging through my primary telescope. Or is it that you are saying I should completely switch to a smaller F-ratio refractor for astro-imaging, and keep the 8SE for live viewing? If so, I might be waiting a while to cough up enough money for another decent telescope and mount to go with it.

Coming back to what I already have, Robin, and others, where would you suggest I start, as regards SharpCap is concerned? I am going to try and do the moon focus tonight and then slew to something else, and see if it works with the camera. But in addition to that, how do I ensure that SharpCap doesn't freeze up on me (it froze up thrice last night - too cold?), and I can at least see something in the window, while i bring it into focus?

Robin, do you suggest buying the Pro right now at the stage that I am, or should I wait? If buying the Pro version is going to help me learn things better and faster, that can be the reason for it. But if SharpCap is like most other applications, where you need to have your basics right first, then maybe wait?

Awaiting your inputs.

Thanks.

Munib

[admin]

Hi Munib,

I'd say don't buy the pro version yet (I'll never be a sales person...). Do that when you find one of the pro features that you try out and find useful.

My point with the guide scope is that they are relatively cheap (if medium-low quality) short focal length refractors. Pop your ZWO camera in one and you have a field of view 2x the size of the moon... Fun to play with for imaging for about the lowest outlay you could choose (even if you bought a cheap refractor the mount would be a problem, but the guide scope will mount off your SCT). If you do go down the astrophotography route you will find yourself with an EQ mount and a bigger refractor in a few years and the guide scope will still be handy then for autoguiding.

As for freezing up of the camera, not usually caused by the cold! More often USB issues - see this page for advice : viewtopic.php?f=18&t=349&p=1556#p1556

cheers,

Robin