Which Mono camera for Solar Imaging ?

[sandconp]

I currently have a ZWO 178MC OSC planetary camera.  Everybody tells me that I need to get a mono chrome camera for solar imaging. I have narrowed it down to two cameras the ZWO ASI178MM or the ASI174MM.  The ASI174MM is quite a bit more expensive and I am not sure why?

 

I have a Lunt 60MM HA f/7 Solar scope and looking for recommendations.

 

[Hughsie]

With solar imaging it is important to understand that the ‘surface’ is dynamic and constantly changing. To render an image of the Sun or, say the Moon, you would typically capture a short video and stack the frames to create the image. With the Moon I would typically take a 10,000 frame video but with the Sun so much can change over 10,000 frames that it’s pointless taking it so a much shorter video is needed, say 500 or 1,000 frames.

You can further improve the image by having a fast capture rate. If you compare the 178 with the 174 you will see the frames per second for the 174 is so much better. As a result the 174 will capture 1,000 frames much quicker than a 178 over which time the surface of the Sun will have not changed that much.

There are however restrictions, for instance, can your computer download speed keep up with a high frame rate? USB2.0 will limit download speed compared to USB3.0 and are the images being written to an SSD or mechanical hard disk? 

I use a 174mm connected to a Intel i3 laptop, USB 3.0 connection writing to a Crucial 500GB SSD. Using my Lunt 60mm and 174mm at full resolution (Mono8) with SharpCap at 2.5ms exposures and zero gain I achieve a frame rate of c150FPS on a full solar disc image. I should add that I use SharpCap Pro (£10 per year fee) and with that you can also adjust up to 50% of you installed RAM towards buffering and so reducing the number of dropped frames.

So, this is my take on the 174mm. Others here will have an opinion on the 178 or indeed what I have said here. Overall I am happy with the 174mm and if you want to see what a 174mm can do have a look at some of the Solar images I have posted on this site.

Good luck.

John

Edited March 23, 2021 by Hughsie

[Merlin66]

The fast frame and USB3 is definitely needed, as well as a SSD drive.

The ASI 178 is OK, but a small chip, not sure you’ll get full disk images.

I use both the ASI 174MM and the ASI 1600MM for solar imaging with a DS SM60 on the ED80.