In need of a SharpCap tutor

Somewhere to ask questions about the best way to use SharpCap
psy1280
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Re: In need of a SharpCap tutor

Post by psy1280 » Tue Dec 18, 2018 9:20 pm

Don,
What can I say, I find everything you say to be precisely geared to my fledgling struggles. Thank you so much for diluting this enough for even me to understand. It's also quite comforting to know that you are using the same camera and have progressed as far as you have. I shall be reading your post (as well as Dave's) over and over until I can report back with some degree of success. You should write all this for Mike at Orange County Telescope, it's exactly what's needed to go beyond the Revolution's basic instructions.

Yours,
Joe

donstim
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Re: In need of a SharpCap tutor

Post by donstim » Tue Dec 18, 2018 9:22 pm

turfpit wrote:
Tue Dec 18, 2018 1:00 am

The idea of Live Stack is to accumulate faint images and create a stack. The stack will give a better image than the single frame. If you can see the object with a single frame then using those settings for stacking will soon blow out the resultant image. This is where understanding the use of the histogram comes in.
Thanks Dave. I obviously need to pay more attention to the histogram and less attention to what the previewed image looks like before starting live stacking.

Also thanks for the suggestion about using a balun kit to connect the camera and laptop. I think I'll start with the zip ties first, though, since I already have them at hand. Also, the remote you provide the link for is actually the same exact one that comes packaged with the Revolution Imager 2.

Don

psy1280
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Re: In need of a SharpCap tutor

Post by psy1280 » Mon Dec 24, 2018 1:12 pm

Dave and Don,

Last night was the first night I had a glimpse of the full moon rising over the eastern horizon. It was brief (I only had 15 minutes before the clouds rolled in). But during that fifteen minutes I did it! I actually got a decent snapshot of the moon (attached). I feel like I'm officially wedded to this hobby now! I have two questions:

1.) I had very little time and after capturing my moon shot, slewed over to Capella. I'm sure I lowered the exposure or I wouldn't have been able to see Capella (which I did see). However, it was only one star in the field of view. I then tried the Pleiades, and as the clouds were rolling in I only noticed one or two bright stars. My question is how do I penetrate my light-polluted sky and see a few stars rather than one. I realize I can't do Live Stack unless I have three stars...? Well, takes me to my second question,

2.) Now that I've made my bones with the moon, what's my next baby step? How do I view a richer star field in order to begin some live stacking?

Thank you both for getting me to this place...I'm looking forward to any advice or suggestions you may have

Joe
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turfpit
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Re: In need of a SharpCap tutor

Post by turfpit » Tue Dec 25, 2018 10:06 am

Joe

That is a good start - well done! A nearly full moon is a tricky object because of the brightness. As the moon wanes, more features become visible particularly on the terminator.
I'm sure I lowered the exposure or I wouldn't have been able to see Capella
Surely moving from the moon to Capella you would need to increase exposure?

A bright star such as Capella would be visible at 1s (maybe over-exposed at that). For the moon, typical exposures would be more like 50ms. 1.2s is X64 and 50ms is X2 on your camera - see the R2 webpage 'How do I' https://www.revolutionimager.com/pages/menus-r2 for the table which maps seconds to your internal exposure table.

Richer star fields:
  • M45, 7 bright stars and many more dimmer ones to hone your skills. It is a big target so will be easy(ier) to find.
  • M42, the 4 Trapezium stars are brighter fading down to the nebulosity. Again a big target but with plenty of challenges for stacking.
  • Start looking for any globular cluster which is visible to you - plenty of stars in those. Also open clusters such as M52 in Cassiopeia which is fairly high (for me) at the moment.

It would be useful if you started including camera settings such as exposure and AGC (gain). This would help others suggest suitable settings for improving your skills.

Good luck and keep at it.

Dave

donstim
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Re: In need of a SharpCap tutor

Post by donstim » Thu Dec 27, 2018 2:15 am

Nice shot! You're making progress! Unfortunately, our skies have not allowed me the chance to do any observing for quite some time.

One of the limitations of a camera like ours in a long focal length telescope like we have is that yields a pretty small field of view. Notice that you cannot even get close to the entire full moon in the field of view even though I am sure you are using the supplied 0.5x focal reducer. This small field of view can also affect the number of stars you can see in it depending on what part of the sky you are looking in. I haven't even tried to image M45, the Pleiades with my camera/scope, primarily because it covers an area about 4 times greater than the diameter of the full Moon. You will only be able to get maybe 2 or 3 of the Seven Sisters in the field of view at a time. Personally, I consider the Pleiades to be more of a binocular target.

If you want to image larger numbers of stars, I suggest sticking with globular clusters. However, I don't have any suggestions as to which ones in your limited South to Southeast view at this time of year

Don.

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turfpit
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Re: In need of a SharpCap tutor

Post by turfpit » Thu Dec 27, 2018 11:22 am

Folks

A graphical demonstration of all this.

Using the Sky at Night magazine field of view calculator
http://www.skyatnightmagazine.com/astro ... calculator. Specs will need to be added by hand. Moon selected for demo.

R2 camera: pixel size 5.0um (is actually 5.0x6.25 in Sony IXCX811 spec sheet), 720 (H) x 576 (V)
Celestron Evo 8 scope: aperture 203.2mm, focal length 2032mm, use 0.5x reducer
66ED refractor: aperture 66mm, focal length 400mm, no reducer (1.0x)

Images below are for the moon. Repeating the exercise for M42 will be educational.

Dave
EVO8+R2+0.5x.JPG
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66ED+R2+1.0x.JPG
66ED+R2+1.0x.JPG (107.64 KiB) Viewed 1022 times

psy1280
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Re: StarSense alignment issue

Post by psy1280 » Thu Dec 27, 2018 1:31 pm

Beautiful shot of the full moon Dave. Thanks for sharing the information. I see you were using the R2. Here's a question for anyone using Celestron StarSense with SkySafari 6 Pro, although I think the question is more generic.

Last night I was trying to obtain a manual three-star alignment. Only one time out of twenty-five attempts was I successful! I kept getting: "Pointing error too large, alignment failed." This was followed by the app freezing/hanging up (the wheel kept spinning, I had to turn off the ipad and back on to refresh the app). I tried to vary the distance I slewed between alignment stars, would get one star, maybe two, but only once did I get aligned. And every time the app would freeze???

Does anyone know specifically what a 'pointing error too large' means? FYI: I did not have this problem the last two times I observed...very strange!

Joe

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turfpit
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Re: In need of a SharpCap tutor

Post by turfpit » Thu Dec 27, 2018 1:44 pm

Joe

You don't understand. Not my moon, I didn't use a telescope, I do not own an R2 - it came as output from the Sky at Night FOV calculator. What I was trying to do is show you how you can find out yourself what your camera is actually capable of. I listed all the technical details for your equipment and also use my refractor properties to show a comparison.

You are also mixing up different questions in the same thread - now moved onto StarSense and SkySafari 6 Pro - this is a forum about the capture software SharpCap.

Dave

psy1280
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Re: In need of a SharpCap tutor

Post by psy1280 » Thu Dec 27, 2018 1:52 pm

Sorry Dave I apologize. And again, thank you for trying to work with my issues. I've never been involved in any forum before and didn't realize I was breaking protocol. I'm new to all of this and will be sure to stay on topic going forward.

Joe

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turfpit
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Re: In need of a SharpCap tutor

Post by turfpit » Thu Dec 27, 2018 2:17 pm

Joe

No need to apologise. Its a learning thing - one topic in a thread - the topic title should say it all. The forum is a useful place for others to find answers to problems. Just a small amount of organisation makes the whole forum useful to many people as the search tool then becomes effective.

Dave

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