First time success... well, not quite. Need help

Discussions of Electronically Assisted Astronomy using the Live Stacking feature.
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psy1280
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Joined: Wed Oct 24, 2018 4:52 pm

First time success... well, not quite. Need help

Post by psy1280 » Sat Dec 08, 2018 2:32 pm

I've progressed from seeing nothing in Sharpcap (my focusing was way off) to last night where I was able to see a star (Hey, it's a start!), unfortunately, that's all I was able to see! Using my Celestron Evolution 8, with StarSense, I had no trouble zeroing in on some bright stars, i.e., Capella, Vega,etc. Using the Bahtinov focuser, I did achieve great focus. This was quite exciting, however, no mater where else I looked (clusters, nebula, etc.) I wasn't able to see anything (I was using 2 sec frame rate) except one star and the rest black. Although, one time when trying to see a cluster, I was able to see three, extremely faint (almost overlooked them at first) stars.

I quite literally, played with every control, both on my Revolution Imager (I know the camera is a starter camera, but from the photos I've seen, you can see more than one star) and with SharpCap. I must have spent three hours moving the values of everything in the menus. I tried live stacking numerous times on different objects, only to get one stacked frame and the rest rejected (obviously, I wasn't picking up alignment stars for Live Stacking).

After seeing some of the post photos, I know there's more to see than one star at a time. I'm very frustrated, but still encouraged knowing that I at least captured a star! :D

I refuse to give up, but I must say, I didn't sleep well last night

Thanks for any help/suggestions
Joe

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turfpit
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Re: First time success... well, not quite. Need help

Post by turfpit » Sat Dec 08, 2018 2:50 pm

Joe

See my links in this post viewtopic.php?f=12&t=1253 and this https://docs.sharpcap.co.uk/3.2/#A%20Co ... %20Example.

The controls you need are in the Revolution menu system - I don't think there is much to help you in the SharpCap controls for this type of system.

Try an object like M31 or M42 or M45 as they are both big and fairly bright. Turn up the exposure and gain (AGC) to at least ensure you hit the target. Then step down the settings to get a better image. Posting some settings (from the internal camera menu) and corresponding screenshots will help with giving you some pointers.

Dave

donstim
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Joined: Wed Sep 19, 2018 5:35 am

Re: First time success... well, not quite. Need help

Post by donstim » Fri Dec 14, 2018 7:51 am

Joe,
Have you had any luck in being able to image anything besides bright stars with your Revolution Imager and Sharpcap? I have the same telescope/imager as you (but without Starsense). The key items for me in achieving an image to start working with in Sharpcap (either preview or Live Stacking) are: 1) ensuring the object is in the field of view of the imager; 2) having an adequate combination of shutter speed and AGC (gain) in the camera menu to see the object; and 3) achieving an adequate focus to see the object. Having 2 out of the 3 is not good enough!

There should be no need to change any of the settings in the Revolution Imager menu other than the exposure time (shutter speed) and AGC level. (You can make adjustments to other settings later after you first get an image to work with -- although in my limited experience I have yet to change any of the other settings yet anyway.) For the exposure setting, as Dave said, if you're trying to image a deep sky object, be sure to start off with something nice and high to make sure you get an image. It sounds like you did that if you were using a 2 second frame rate, which would be X128 on the camera menu. Try coupling that with an AGC Max of 24 dB to start with. Once you get an image, you can vary the exposure and gain to improve the image.

Other than exposure, some of the issues that cause difficulty are: 1) the field of view of the imager is very limited, especially compared to the eyepieces you may use for visual observation. and 2) the focus point for the imager will likely be very different than for an eyepiece. So it is very difficult to swap eyepiece and imager to make sure you have the object in view. If you are sure your telescope is extremely well aligned, you can use the image to focus on a nearby star and then use the telescope's goto capability center the object. Then, if your focus and your positioning is correct, you can vary the exposure if need be to image the object. Alternatively, if you know about how many turns of the focus knob (and which direction it needs to go in), you can center the object using an eyepiece with a tight field of view ( for example, a 7-9 mm eyepiece if you have one), then swap the eyepiece for the imager and adjust the focus as necessary. For me, I think it takes around 21 full turns of the focus knob counterclockwise for the eyepiece I use for this.

Let us know if you have made any progress. Dave is quite knowledgeable and helpful.

Don

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