Because I didn’t get any further with the lenses I had, I bought a William Optics SpaceCat 51 APO 250 mm F/4.9 which I received on the 29th of this month. The supplied T-mount didn’t lock, so I swapped it for a proper one for the Nikon at the shop. On the 30th, I went back to the spot on the other side of the highway to take pictures of some objects from the Bright And Moderate Beginners Index (BAMBI) list that should be visible at this time of year. Without a tracker, I would have calculated that the maximum exposure time of this combination was ~1.5 seconds.

I pointed the camera at a bright star and tried to focus on it using the included Bahtinov mask. That wasn’t as easy as it seemed on YouTube. However, the lines turned out to be far too small due to the viewfinder of the Nikon. So I took a picture, showed it on the screen and zoomed in on it. Although the photo was out of focus, I could see that the horizontal line was too low, so I was able to adjust it. It was also annoying that I couldn’t figure out how to turn off the screen at that moment, so I saw much less through the viewfinder.

Unfortunately, I was unable to find it with the Stellarium app on my phone, so I pointed the camera upwards again and watched what happened.

CameraNikon D-3000
LensWilliam Optics SpaceCat 51 APO 250 mm F/4.9

The stars seem sharp. Next time, I want to keep taking pictures and only stop when the lines are also zoomed in and sharp on the photo.

The stars are dashes and not dots: I need a tracker or faster shutter speed. The background is purple: the \ shutter speed is probably too low. There are also artefacts in the form of red and blue lines.

I honestly have no idea what I’ve seen. Next time, I need to prepare better (direction and how high).

Categorised as: astro

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