Monday, September 15, 2014

Dumbbell nebula, Ring nebula and exposure tests

The sky was clear on September 13th and I planned to shoot some stars before Moon rises. I thought I had prepared everything, but turned out I hadn't charged cameras battery. Luckily there was enough power to last until Moon lit up the sky. Maybe 15 minutes more had been possible but nevertheless... everything went better than I expected.

First some more tests about exposure times. 80 second was easily possible the last time, now I tried some more.

100 second exposure (left) and 150 second exposure (right)
100 seconds looked good so I took 150 second. When I look at the photo on computer screen I'm not sure about 150s. Most stars look ok, but maybe some show some trailing. I have to run final tests about this on a better ground. This time the mount was a bit unstable. So I'm not sure whether the trail is caused by mount shifting on ground or incorrect alignment.

Result was something between 100 and 150 seconds so I chose 120 as exposure time for shooting the Triangulum Galaxy.

Triangulum Galaxy M33

This failed. Moon was rising and it's glow had lit the eastern sky. Air humidity was also quite high and some fog did form a while later so all that made Triangulum a wrong target for that night. Still I spent 10 x 120 seconds worth of time and battery on what you see above. Also I managed to tilt the camera couple times so only seven photos were usable.

Well... You can see it and maybe even recognize it as M33. Bigger photo (if really necessary) in

Ring nebula M57

After the Triangulum failure, I realized the sky was more clear of light pollution right in zenith. Lyra and Ring nebula was the first thing that came in mind. Couple of photos there and only one of them was not tilted during exposure. I really have to stay away from the mount during shooting...

This is a single 120 second exposure. Quite nice. Although focal length of 200 mm is quite short for M57. Bigger photo in

Dumbbell Nebula M27

Battery indicator was blinking red but I thought I'd use all the remaining power to shoot the Dumbbell nebula. It was also in a dark spot of the sky. Now the exposures are only 30 second and I took 10 of them but still this is what I got:

I'm impressed. Last time I tried M27 was with my old 75-300/4-5.6 zoom lens. I got a faint gray smugde. Now the aperture was 2.8 and my faint smudge has some real color! Can't wait to take some longer exposures of this.

Here's one a bit zoomed to show in the preview on Facebook or G+. :)

Bigger photo in and one with more stars around it in There's also open cluster of NCG6830 on the bottom if this image.

Tuesday, September 9, 2014

Proper alignment of EQ3-2 and first photos of the season

I've had problems with aligning the EQ3-2 even though I have a polar scope. For some reason I misunderstood the instructions totally. I always assumed the scope shows some kind of fish eye view and the constellations visible should cover the real stars. Nope.

View from polar scope. Image linked from
The scope shows Big Dipper and Cassiopeia from northern hemisphere and Octans from the south. Place polaris here circle is exactly as it says, but the rest are just directions where the constellation should be. This was the information I was lacking.

Now I made a somewhat good alignment and started to look through the scope. Polaris was by chance quite close to the circle. With couple of minutes of screwing and unscrewing the legs I got Polaris right where it should be. Now the tests...

With rough alingment I got maybe 20 second exposures with 200 mm optics without the stars trailing. Once or twice 25 to 30 seconds was possible close to celestial pole. Now I tried 30 s, 45 s, 60 s, 70 s and when that worked I took 20 exposures with 80 second time.

Here's an single shot to how the stars don't trail with 80 second exposure.

The Moon was up and almost half so sky was kind of lit. Before this it has never bothered me too much since my exposures were so short, but now it was a problem. I tried to stack my Andromeda photos and the result was worse than my previous best one (with 25s exposures). There's really no point of posting that image here.

After Andromeda photos were shot I decided to try the Whirpool galaxy. I knew the Moon makes that difficult so the result won't be good. Before this I haven't had any image of it. Now I got this

From nothing to this. Now I'll just wait for a better conditions (no Moon) and try again.