Imaging With ZWO ASI178MC

[brenski]

Hi

recently bought one of these cameras. i'm completely new to imaging, but really keen to make progress.

at the moment I've got the ZWO ASI178MC connected to a Netbook PC and a Bresser 75/350 (i intend to use my SkyWatcher 200p) and have used the default ASI software to get the image below  - i would like to think i can do much better than this.

■ better software to use for capturing images and video - for lunar, solar, planetary and dso

■ best settings for images and clips

■ what video filetype VLC will recognise and playback (ASI's .avi is incompatible with VLC - it will work in Windows Med Player)

■ how to "know" you've got DSOs worth processing, when these can't actually be seen onscreen

[brenski]

just a quick update, the .avi file properties:

length: 00:00:36

frame width: 3096 

frame height:  2080

data rate:  772787 kbps

total bitrate: 772787 kbps

frame rate:  5.00 frames/second

file size: 3,516,180,992  (3.27gb)

 

would there be a valid reason for VLC refusing to play this?

 

 

[PeterCPC]

You may find Sharpcap to be better to acquire images.

Got this regarding VLC - may help.

Peter

 

[johngm]

Hi Brenski,

+1 for sharpcap. I would also recommend for lunar and planetary imaging you crank up the frame rate.  5 fps is a bit slow. I've just checked the spec of your camera on FLO website, and at 3096 X 2080, your max frame rate can achieve up to 30 fps, is suggest you use this setting. And on Lunar, try taking a 1 minute capture, stacking in Autostakkert, and keeping the best 50% of frames. I've not used Autostakkert in a while, but there are plenty of online guides.

John

[brenski]

@PeterCPC thanks - tried - but no joy. I think this could be down to the frame rate - as @johngm suggests. i'll try again on next clear evening and see what happens.

[johngm]

4 hours ago, brenski said:

@PeterCPC thanks - tried - but no joy. I think this could be down to the frame rate - as @johngm suggests. i'll try again on next clear evening and see what happens.

Keep us posted and let us know how you get on 👍

John

[symmetal]

You can experiment on getting the best framerate indoors with just the camera on its own sitting next to the PC. You don't need an actual image to be seen. I use Firecapture for video imaging though Sharpcap as mentioned is just as good.

Your maximum framerate possible is dependent on the exposure time. Aim for the shortest exposure time you can manage. The shorter the exposure the more likelyhood of getting a sharp image as you capture short moments of good 'seeing' For the moon you should manage 5mS or less and still get a bright image.

Max framerate = 1 / (exposure time in seconds)

Exposure = 100mS. Max frame rate = 1 / 0.1 = 10fps

Exposure = 5mS. Max frame rate = 1 / 0.005 = 200fps

However your actual max frame rate achieveable is limited by your hardware and how fast it can mange the data rate coming from the camera. You need a short good quality USB3 cable, (less than 3m) to get the maximum out of USB3. I assume your netbook has USB3 ports. If you have to use USB2 then that would limit your maximum framerate more. Having plenty of RAM and/or having an SSD drive helps with longer videos. Running out of RAM during recording and then relying on writing 'direct' to a standard hard disk drops your frame rate right down. Disabling, or limiting the update rate, of the preview screen during recording can give more processing power to the actual video capture if you have a lower spec processor.

If your subject doesn't fill the frame then select a ROI (region of interest) in the capture software that just covers the target. This will reduce the amount of data needed to be sent per frame so hardware limiting is less critical. Very useful for planets where 200fps can be achieved. (The usual maximum limit of ASI 'planetary' cameras.)

Having a high framerate isn't required to get a higher quality stacked image. (Still keep the frame exposure as short as possible though to hopefully 'freeze the seeing' conditions.) It just means your recording time for each video is reduced to get the necessary number of frames to stack. This means less likelyhood of the subject image changing throughout the recording (particularly for solar, and to a degree Jupiter due to its fast rotation), and/or clouds, leading to a more blurred stacked image.

For the moon or solar you can double the camera framerate by doing two recordings of the top and bottom half and stiching them together. Select a ROI that covers half of the target. Only the height of the ROI affects the camera frame rate not the width so you can keep the width at maximum if you wish.

For the moon you can record for 5 mins or more as long as it doesn't drift outside the ROI or clouds pass by.

Alan