Every amateur astronomer knows that the clouds will roll in as the delivery man’s van leaves your front door. This happened to me again these last two weeks.
I treated myself to a new ZWO ASI224MC camera with a Canon lens adapter, all purchased online from Bintel. Very small and compact and it is intended to help me with my polar alignment, guiding and some planetary imaging. It’s main advantage is its very low read noise which means that you can take many short images and add the individual image frames in post processing to form a longer duration image without adding significant noise in the process. I’m not planning any huge expansion into planetary astrophotography but it would be nice to have something to do when the moon is up and I cannot do long exposure, deep sky stuff.
Last night was clear with the Moon and Jupiter right overhead and I started everything up; EQ6-R mount with the ZWO ASI224MC camera on a Canon 60mm EFS lens. For the software I used Sharpcap Pro, it will cost you 10 pounds annually to get the Pro version that lets you do polar alignment. This works very well and will work with any camera that is recognized by Sharpcap. Also read one of my previous posts about SparkoCam.
You just follow instructions and move the mount az and alt adjustments to get the polar axis of the mount perfectly on the celestial pole. No guessing or frustration and a perfect result. That’s worth more than 10 pounds!
My first attempts at using the ASI224MC camera with an Orion EON 80ED on the moon and Jupiter was not great, I have a lot of learning to do and I did not spend a lot of time trying. Just a quick picture of the moon…
I then took a number of images of the Milky Way with my modified Canon 600D with a Canon 60mm EFS lens directly on the mount and took a series of 60 images of (quite short) 30 seconds exposures at f3.2 and 400ASA as well as a number of dark frames of whatever was directly overhead at the time. It happened to be the center of our galaxy. As usual, combined with Deep Sky Stacker and processed with LR4. I was sitting inside on the sofa nice and warm, watching a movie while Magic Lantern was managing the camera outside in the cold. Did I mention that it was cold?
After a number of cloudy, wet and cold winter months we had a clear night on 3/4 August to take the cameras out for a few photos. The moon only set at about 11:15pm so it was quite a wait in the cold. This was the coldest night in Adelaide for something like 125 years! It did not bother me too much as I was dressed as if I was going to Antartica. Luckily there was no dew and that made everything easier.
I used the Canon 600D on the iOptron SkyTracker on my photographic tripod.
This image is of the Milky Way with a 60mm prime lens at f/3.2 and ISO 800. I used 11 light frames of 60 seconds each with 3 dark frames. The image is showing the Sagitarius region with the Lagoon nebula (M8) at the lower right and the M6 cluster in Scorpius at the lower left. This is a very rich star field and larger apertures will reveal incredible detail. It is also the location of the centre or core of the Milky Way Galaxy.
The next wide field image is of the Milky Way with a 11-16mm Tokina lens at 14mm and f/3.2 and ISO 800. I used 9 light frames of 60 seconds each with 2 dark frames.
I also took a quick image of the Small Magellanic Cloud with a 60mm prime lens at f/3.2 and ISO 1600. I used 11 light frames of 60 seconds each with 2 dark frames.
Images was stacked with DSS and stretched in PS CS2 and finished up in LR4.
I think that I need to make my exposures longer than 1 minute to get more detail. I don’t like to raise the ISO level higher as it will also increase the amount of noise. I will try and get to 3 minutes per frame next time. It just makes it harder to get the tracking done well so that the stars don’t turn out to be lines! This should be easy with the Tokina 11-16mm lens but when using the longer focal lengths it will be a bigger challenge.
I went out to a site about 35km east of Adelaide last night, trying to get a few photos of a dark night sky. I was quite dissappointed by the conditions. Although there were no visible clouds, the seeing was poor. There must have been some thin high altitude clouds and conditions at ground level was quite gusty at times. I managed to get a few images and tried a “long” exposure of 10 minutes for the first time. The camera was on the iOptron SkyTracker on my normal camera tripod and I aligned the setup to the south celestial pole with a green laser. To legally use one of these lasers in South Australia you need a permit from your local Astronomy Association. This image is a single exposure of 603 seconds with a Tokina 11-16mm lens at f/3.5 at 15mm using ISO-200.
I took a risk with the long exposure as the misalignment of the camera on the tracker would have showed up as star trails which would not have been attractive in this case. The Canon custom function that performs long exposure noise reduction was used to subtract a dark frame from the light frame in the camera. This meant that the camera took 20 minutes before I could see if it worked.
I used f/3.5 rather than the lens’ capability of f/2.8 to reduce chromatic aberrations which tend to smear the stars in the corners into lines. Taking photos of stars (pinpoint light sources) across a wide field is the most difficult test possible for a camera lens. Stopping down the lens by one or two stops will make the image much sharper with less distortion. The image was cropped and rotated a bit to create a banner type image with the milky way centered on it. (It also got rid of the worst distorted stars in the corners)
ISO-200 is not normally used for deep sky astrophotography but I wanted to get a low noise image and I had enough light with the milky way directly overhead. It worked quite well and there is minimal noise in the image. I did a bit of noise cancellation in Lightroom 4 as well.
I spent a few days in Hawker, in the Flinders Ranges, South Australia. It happened to be New Moon and it was very dark. This image is taken of the Milky Way with Sagitarius making up most of the image. South is up.
The final image is made up of 13 light frames and four dark frames of 60 seconds each. I used a Canon EF 50mm lens at f/2.0 at ISO-400. Combined the 17 frames with Deep Sky Stacker and stretched with Photoshop CS2 and cleaned up with LR4.
The current weather is not really good for astronomy but I am getting good at spotting a break in the clouds.
I travelled to Lake Alexandrina last Friday night and took some photos from about 6pm on Friday till around 3am on Saturday. It was quite dark with some clouds around to make it interesting. Later the dew started having an impact and then the fog rolled in to make it really challenging.
The evening started with total cloud cover and the stars started appearing from the west. A most welcoming sight. This was taken on a static tripod (20 seconds, f/2.8, 16mm, ISO800).
When it turned dark so that I could find the southern celestial pole I could align my tracker and start. The Milky Way was a 120 second exposure, f/3.2, 14mm, and ISO800. I am not keen on using the high ISO capability of the camera if I dont need it. It adds a lot of noise that you have to try to get rid of in post processing. I prefer taking a high quality image up front if I can. I used Lightroom 4 to clean up a bit and change levels and curves.
The image of the Milky Way diving into the lake (clouds) was taken at 60 seconds, f/3.2, 14mm, ISO1600.
When I started losing feeling in my toes due to the cold, I packed up and headed home.
This is my current star tracker that I use to take widefield astrophotos. It kept me busy and out of trouble for a while…. I use a green laser pointer to help me to do a perfect polar alignment. So far I have done 3 minute exposures with a 14mm lens with round stars. Let me know if you are interested in more detail.
I took this photo of the Milky Way (Scorpius region) last Sunday morning at about 2am just after the moon set and before the clouds came in. Taken with Canon 600D and a Tokina 11-16mm lens at 14mm, f/2.8, 120 seconds. Levels and curves was adjusted with LR4.
I took a handfull of images with the idea of stacking them but I found that the sharpest result was achieved with a single image. I did not even subtract a dark frame but I did some noise cancellation with LR4.
I used a home built tracker on a solid tripod to avoid getting star trails in a single exposure. Magic Lantern was used on the Canon to provide a bulb function.