Submitted: Monday, 14th October 2013 by Hugh Esmond
After hearing Anthony Wesley give a talk on planetary imaging at the recent 2013 Astrofest in Queensland I was inspired to find out more. His images of Saturn and Jupiter were very impressive and he was using basic equipment that anyone could afford. The main factor in getting great images was fast frame rates and good seeing conditions. After the talk was over I asked him what camera he was currently using. He replied ZWO which didn’t mean anything to me at the time.
I have always been a fan of video imaging mainly from the image intensifying side of things. I like the instant gratification of seeing a deep sky object live on the screen plus you have the option of taking a quick a photo of what you are seeing without the need for long exposures or processing. Some video cameras enable you to see things live on screen that are impossible to see with your eye at the eyepiece. Any humble 8 inch telescope will show live video images on a computer screen better than you can see through the eyepiece of a telescope three times the aperture.
I have owned both the GSTAR EX the GSTAR EX2 a Malincam Extreme and an Orion StarShoot Deep Space Video Camera II. In fact I had all four at the one time and did my own sensitivity tests on all four under the same conditions to see which performed the best.
Being a Photographer I often did my own tests on lenses of different manufacturer to see which was the sharpest and this habit has followed me into Astronomy. Half the fun is trying out and comparing equipment. I think most of us are equipment junkies at heart and it can get out of control until “the wife” puts her little foot down. I have thinned the herd since then & now only have the GSTAR EX2 and Malincam Extreme.
I often find the claims of the manufacturer and some reviewers to be a “little” exaggerated or biased. For instance the Orion Star Shoot Deep Space Video Camera II, AKA the color GSTAR-EX CLR Deep Sky Video Camera which is the same thing just rebadged, are a waste of time and money, poor color and not that sensitive. Unless you have it connected to a 20 inch light bucket you won’t see much.
Upon returning home from Astrofest I looked up ZWO Optical on Google & read some of the reviews. ZWO is a relatively new company only founded in 2011 apparently by amateur astronomers.
These little cameras seemed to be great value for money so I discussed them with Matt from Sirius Optics and he said he that he would get several units to evaluate.
By the end of the day Matt informed me that two of both the ZWO ASI130MM and the new ZWO ASI120MC cameras were on their way across the ocean. It wasn’t long before they arrived and Matt asked me to take two home and give him an unbiased appraisal. As Matt said, if we intend to sell them, were going to need to know how they perform in the real world.
The ZWO ASI130MM is monochrome and uses the Micron MT9M001 CMOS sensor, the same sensor as used in the QHY5. The sensor is ½” at 1.3 megapixels with an impressive choice of frame rates. Frame rates can be selected from 30FPS at a resolution of 1280X1024 to 320FPS at a resolution of 320X240.
The new ZWO ASI120MC Camera is color and comes with a cute little 2.1mm fish eye lens that turns it into an All Sky Camera as well. It uses a 1/3” CMOS sensor at 1.2 megapixels with 20 different frame rates selectable from 35FPS at a resolution of 1280X960 to 215FPS at a resolution of 320X240.
What I like most about both cameras was the easy setup and use. Everything worked straight out of the box & the software loaded without problems, I’m using Windows 7 64bit. I didn’t have to go chasing all over the internet for obscure ASCOM or NET FRAMEWORK drivers.
Everything you need to use the camera is on the disk that comes with it including two capture programs SharpCap™ and FireCapture™ and a stacking program, AutoStakkert 2™. You even get instructions in PDF form on how to use the camera. No need for endless hours reading forums for best settings or chasing drivers to get the camera to work, with these cameras it’s all done for you. Load the software & plug in the USB cable, select the camera from the drop down menu & bingo, a live view of whatever you’re pointed at. The software really is that easy to use.
Capturing an image is straight forward. Focus the image, adjust the shutter speed & other controls if required & you can see the effect on screen. Then you can take either a snapshot (single exposure) or video. In either case, the image is deposited in a folder you select with the capture information beside it, (a nice little bonus) & you can even name each image as you take it if you want.
All ZWO cameras are specifically designed for Lunar, Solar and Planetary Imaging but I found you can also to do deep sky imaging as well. The cameras will expose as long as 1000 seconds. If you do use long exposures it’s important to use the Dark Frame Subtraction option otherwise the picture degrades from noise. I could successfully take photos of 60 seconds and I have seen other examples on the internet where 200 second exposures have been made. A lot depends on the ambient temperature; obviously the colder it is the longer the exposure you can successfully take. The dark frame subtraction is not easily found at first, it’s in Options - Video Capture Filter - ROI Misc - Stack Dark Frames with options from 2 – 50. I left it at 2 and it worked well. If you use the dark frame option it is automatically applied to all the frames you take afterwards. If you dramatically increase the exposure time you will need to do a longer dark frame.
You will also find the Sensor Temp information in the same drop down menu. The chip isn’t cooled but it has temperature information which would be handy for those experimenters who like to make their own coolers. The only other control that may leave you wondering what it does is the Frame Divisor slide control; this is the adjustment to stop the camera dropping frames. All the frame info is displayed in the bottom left hand corner of the screen. Most other controls are easy to use and named accordingly.
Once captured, your video can then be stacked using AutoStakkert 2™. I tried using Registax™ because I am familiar with it but it didn’t like the AVI files created by SharpCap™.
There are ways around this but that involves trolling the internet, which I did and I found the solution, but I decided to give AutoStakkert 2™ a try instead.
I’m happy I did because I found AutoStakkert 2™ much easier to use than Registax™ and it did a better job in my opinion but, maybe you will disagree.
So first night out using these cameras on a very average seeing night I was able to capture Saturn and get a very acceptable image, actually the best I have taken so far. I have often captured Saturn, Mars and Jupiter with the GSTAR and Malincam and processed in Registax™. However I found the whole process much simpler using these cameras & the software that came with them.
To my surprise I found I liked the ZWO ASI120MC Color Camera better than the monochrome camera. The smaller chip makes it easier to fill with an image of Saturn. The color is superb and seems just right for planetary imaging. Other color cameras I have used produced images that have either been too washed out or too red.
After Saturn was getting too low in the sky I tried out the longer exposure times on some deep sky objects, Omega Centauri, Centaurs A, The Triffid & Lagoon Nebula’s. I found I was able to produce quite acceptable images, obviously not as detailed as cameras specifically made for deep sky imaging. However you can have a lot of fun honing your expertise using these cameras.
When the moon rose that night around 10pm the live views were as good as the GSTAR or Malincam and very detailed images were able to be produced by stacking them in AutoStakkert 2™
Cameras are like telescopes, each type is designed to fulfill a specific purpose, ZWO cameras are designed for Lunar, Solar and Planetary Imaging & they do it extremely well at a very affordable price. As a bonus these cameras can be used for guiding and come with the usual cable for auto guiding. As an auto guider they are every bit as good as the cameras that only auto guide and they cost less.
If you are looking for a camera that will do a little more than the usual offering then you have it in these cameras, planetary, lunar, solar, auto guiding and a little deep space as well.
If you are new to Astrophotography and want a cheap way of getting into it without having to sell your first born child or incur the wrath of the “first lady”, either of these cameras are a dream come true. Even if you decide to upgrade to more advanced equipment later, you will never want to sell them because for planetary imaging, they are as good as any with the added bonus of being able to double as an auto guider. It’s really a no brainer, why buy an expensive guide camera that just does auto guiding when for less money you can have a superb planetary camera that will do both. They are compatible with PHD Guiding, GM (Guidemaster), Maxim-DL, Metaguide and Astroart.
Bottom line, they are great little cameras and very versatile if you are willing to experiment with them.
Many thanks to team from Sirius Optics as I am now the proud owner of arguably one of the finest planetary cameras available & without doubt, certainly the cheapest, the ZWO ASI120MC.