Step by step

STEP 1

Choose a lens appropriate to the view of the Double Cluster you want to portray. A 35mm format sensor camera coupled to a telescope with a 1,000mm focal length will cover an area 2° by 1.3° giving you a good close-up on the pair. If using a smaller APS-C sensor, a 600mm focal length achieves a similar field of view.

STEP 3

A tracking mount will give the best results. A polar-aligned tracker can be used for cameras with lenses attached. If you’re attaching your camera to a telescope, an equatorial mount will help carry the extra weight. If you have this setup already, you could piggy-back a camera with a lens fitted on the telescope.

STEP 5

Open the lens wide, perhaps closing by a stop or two if you see frame edge distortion. Set focus to manual, centre the Double Cluster and use ‘Live View’ focus assist to focus as accurately as possible. If you can’t see stars, try setting the ISO higher. Using maximum zoom, adjust focus so the stars are crisp and sharp.

STEP 2

A wider view of the Double Cluster field will be less demanding on tracking accuracy and potentially show the area of Milky Way where they sit. A 35mm lens with an APS-C sensor or 60mm lens with a 35mm sensor will give enough of a field of view to include the whole of Cassiopeia as well as the Double Cluster.

STEP 4

A low ISO (200–400) will capture the Double Cluster’s colours in the best way. Increasing the ISO gives an apparent increase in sensitivity but the higher you go, the more noise appears and the colours will start to wash out. Ensure the mount’s polar alignment is as accurate as possible so you can take longer exposures.

STEP 6

Set your exposure time for 30 seconds and take several shots. If you have a shutter-release cable, set the camera to ‘Bulb’ and take longer shots. Basic tracking mounts are limited to around 90 seconds for a close-up shot. The sweet spot is when you can use the longest exposure without signs of star trailing.