Month: March 2019

Learning My Telescope, Focusing

Learning My Telescope, Focusing

If like me, you are new to Telescopes and using it for Astrophotography then you too are struggling with a tricky learning curve.

I’m writing this in the hope maybe I can help you with some of the issues I’ve had to try and overcome.

I want to mainly use my telescope for astrophotography. My 2 main issues have been polar alignment of my eg5 mount and focusing to get sharp photos.

My first problem was polar alignment, but I got away with it for shorter exposures, so I concentrated on trying to solve the focusing and getting pin point sharp stars.

I was amazed with my first ever Orion Nebula photo, but on closer inspection I notice it wasn’t fully in focus.

Now to me, when I took it, I thought it was in focus. I’d been told to use Live View on the camera and to zoom in 10x. It was tricky to see, but I thought it was in focus.

I learned a few things here.

1. Zooming in 10x on Live View still isn’t enough to get perfect focus
2. I need some extra help focusing.

Needing glasses for reading, I’d already thought to put those on for looking at the screen to know I’m focused, but I had been told that a Bahtinov Mask would really help as doing it by eye is not enough.

You can buy these, but you can also make them. So I made one from a downloadable template on the web.

Now when you look through a scope with this on at a bright star, you’ll see a 6 pointed star burst. Now you can adjust the focus to get the middle, ’12 to 6′ (top to bottom) line to be exactly in the middle of the other 2 lines. It’s easy enough to do and then you have perfect focus!

So now I had a lot sharper stars. As you can see from this image.

But now the star trails started and this was down to my polar alignment. This image was a 30s exposure, but I wanted more.

Polar alignment took me a lot longer to sort. My next post will talk about how I worked it all out.