Thursday, September 27, 2012

My first photos on Messier objects!

The first two nights I got enough time and good enough weather I went out and just took a lot of photos on different objects. I really should plan these things ahead. Now I just take a look at a star chart, point the camera somewhere I might get something interesting on screen and shoot. I like to think this as practicing the finding of objects, but it's really not that. It's just me trying to do everything at once...

I took photos of several Messier objects. At least 20 photos on each object but some photos were off focus or off target.

M57 - The Ring Nebula

I started collecting photons on 9th September and continued on 15th. First I didn't think I could actually get anything and my intention was just to shoot some stars and practice stacking on Deepskystacker. I was surprised to see this:

The Ring Nebula is quite easy to find. It's in Lyra, between Lyra γ and Lyra β. Total exposure of this photo is about 8 minutes.

I also have an entry on this in Astrobin.

M13 - Hercules Globular Cluster

This one was easy to find. I took one test photo and already the cluster was on finder. 30 more photos and on to finding the next object. With exposure time of 15 seconds the whole stack comes to 7 min 30 s.

You can definitely see it's a globular cluster. That's about it. No Mercedes-sign, not many pixels, but still a beautiful globular cluster. Quite nice for my first, I think.

M51 - Whirlpool Galaxy

Well... I got it on camera. Kind of. You really can't recognize it if you didn't know it's M51. I took a lot of photos on this but got the galaxy only on a few. So there's light from about 30 seconds here.

In case you don't believe there's something in the upper photo, I dug it out more with Darktable:

Yeah... I got it on camera...

M31 - Andromeda Galaxy

...and of course M32 and M110.

After M51 I tried M29. It looked quite easy to find on a star chart, but I really can't see anything on my photos. The rest of the evening I had my camera pointed on Andromeda. I took perhaps 30minutes of photos but what I didn't notice was that I had dew on the lens. 20 minutes of photos spoiled. Also the first 10 minutes aren't that great except the very first ones. Next time I'll take a blow dryer with me so I can dry the dew...

Since 15th of September it has been cloudy and rainy. Soon I'll have two weeks of paternity leave and perhaps there will be couple of good nights. I'll probably start with Andromeda since my failure last time bugs me quite a lot.

Wednesday, September 19, 2012

Deep sky objects and stacking

I've seen lots of awesome photos of deep sky objects. I always thought they are so small that you can't see them with your naked eye... But no. They're huge. Sky is full of galaxies and nebulae and many of them are bigger than the Moon. The problem is, they're too dim to see.

A telescope collects light from a bigger area than your eye, so it helps to see some objects. An other way to collect more light is long exposure photos. Ok... no news to people who knows about astrophotography, but I don't know who I'm writing this for. Problem with long exposures is the rotation of Earth, or the apparent movement of the sky. You can compensate it with a tracking mount, but better mounts cost more...

I'm still doing this with budget equipment. My kit:
  • Canon EOS 1100D - 300e
  • 75-300mm lens - 100e
  • EQ 3-2 with one motor - I bought it used for 200e
  • Stuff to put this all together - ~50e
Camera and lens are something one might already have and use for other stuff as well. So if you think of the total price, it would be here about 250e.

Now to the point: stacking pictures. With this budget kit, I can take 15 second exposures. Longer than that and the stars would trail. With better alignment for the mount I could probably go as high as 1 minute, but for now I settle for 15 s. A deep sky object might require several minutes exposure to be seen and perhaps hours to look good. I take a lot of photos with short exposures and then stack them together with specialized software. I've been using Deepskystacker but there are others as well.

To demonstrate the difference between a single 15 second exposure and 15 minutes of them stacked together, I'll show my first "masterpiece": Andromeda galaxy:

A single 15 second exposure

15 minute stack of 15 second exposures
Is there a difference? You can definitely see more of the galaxy. I am going to shoot the galaxy some more the next time it's possible and post an updated version. Perhaps this time I don't fail and adjust the focus in the middle of session so that the rest 30 minutes of exposures are out of focus...

Thursday, September 13, 2012

Testing the tracking mount

Finally there was a bright enough night to test EQ3-2. I needed to learn how to adjust it for this latitude and how to align it to Polaris. I have a polarscope but using that turned out to be more difficult than I thought. I got started with crude aligning to north without a compass. The idea was to take some photos with long exposures so I could see how long exposures I'm able to take.

First a test image without tracking:

The photo is taken with 300mm lens and 30s exposure and it looks like the lens was out of focus and the mount wasn't stationary all the time. However it gives an idea how much the stars trail with 30s exposures.

Another one with the tracking on:

Its about the same direction with 300mm lens (now with better focus!) and 30s exposure. Stars still trail a bit too much. Maybe 10s exposure is short enough?

Couple nights later I was able to photograph some more. And succeeded to align the mount better. This time I looked from a map where north is. :) 30s exposure looks like this:

Otherwise everything might be worse than the picture before, but I see no trailing at all. I wish I'd learn to align the mount like this every time.

Saturday, September 8, 2012

Camera and EQ3-2 tracking mount

I bought an used EQ3-2 tracking mount mainly for camera. Then I also had to buy a DSLR since I only had a pocket camera (Canon PowerShot SX200 IS). Internet said it would be fairly easy to mount a camera to EQ3-2, but I failed to notice there are several types of EQ3-2 connection plates. The one I bought wasn't the type for cameras...

It looked like this

and it's supposed to look like this

I bought a dovetail adapter for EQ3-2 and dovetail plate for camera

The final set up looks like this:

Next I'll have to learn how to align the mount properly. I have a polar scope so it should be easy but then I saw this: Maybe I'll prepare for a bigger operation...