Astronomy and DSLR Astrophotography Blog

So let’s continue with the tutorial. The last time we have chosen the object. Today we will take a look at some common camera settings for astrophotography. In this tutorial I will be using modified Canon Rebel XT (350D). Modified means that I have replaced original filter in front of CMOS sensor with replacement filter of Baader. I have listed some good guides how to do it here.

Let’s go back to the topic. The camera is important piece of equipment since it’s capturing the light. Not all the cameras preforms the same but there are some common setting that it’s good to setup before we go out under the stars.

The very first thing is the photography mode of the camera. Here we have just one choice – M (Manual) mode because of one simple reason: DSLRs are not meant to be astrophotography cameras but daylight cameras. So the longest exposition that automatic modes enables us it’s 30s. But that’s far not enough for deep-sky astrophotography. We need longer exposures and the M mode has a “bulb mode”. That means that the exposition is as long as the shutter is pressed on a camera. Of course, we cannot hold the button on a camera for 5 minutes so the wire trigger is necessary.

We select M mode

The second thing is mirror lockup. Almost all the DSLRs enables lockup function. Mirror lockup means that the mirror in the camera, which reflects light to the viewfinder, locks up some seconds before the start of exposition. And why is that so important? Because if you are using telescope with long focal length, then every single tiny movement is noticeable on a picture. And when the mirror “jumps up” it shakes the system and bright stars get tails and that’s what we obiously don’t want to have on the pictures. So the mirror lockup function triggers the mirror some seconds before the start of exposition so the system can settle down before the exposition is started.

Enable the mirror lockup function

Next important thing is ISO speed. This one is still a hot topic among astrophotographers since some claims that lower ISO is better and others who prefers higher ISO settings. Anyway, two years ago I have made a test on Youth Astronomy Camp which revealed that Rebel XT preforms the best at ISO 800.

Selecting the ISO 800

For additional processing it’s the best that we use uncompressed data so the RAW mode is the right decision. If you prefer having JPGs also, then you can select RAW + JPG.

RAW (uncompressed) format

Another not so important thing is LCD brightness. I strongly recommend to set this as low as possible because in the night our eyes are adapted to the dark and if you want to check for example the sharpness of the images on LCD with the full brightness then you’ll get blind for some minutes.

The last but not the least function is information LCD illumination. This function enables you to see the settings specified in the dark. Just press the button.

Info LCD illumination

Thank you for reading. So far we have chosen the object and specified all the camera settings.

Related posts:

1. Astrophotography How-To Tutorial: Part I – Choosing an object
2. Astrophotography How-To Tutorial: intro
3. Astrophotography for beginners: Star trails
4. Astrophotography How-To Tutorial: Part III – The telescope
5. 10 reasons why Canon Rebel is so good for astrophotography

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