BBC Sky at Night Magazine

SCOPE DOCTOR

- With Steve Richards Email your queries to scopedocto­r@skyatnight­magazine.com

I’m considerin­g upgrading my Celestron 9.25 telescope with an EQ6 mount to increase my imaging capacity. What are the pros and cons I should consider before making this investment? CLAIRE WARD

Your Schmidt-Cassegrain Telescope (SCT) and altaz mount are fine for both observing and imaging Solar System objects, but if you want to move into deep-sky imaging, a heavy-duty equatorial mount is a prerequisi­te and the EQ6 would be a good choice.

Another thing to consider is that although an SCT can indeed be used for deep-sky imaging – and on smaller objects like planetary nebulae it can excel – for general deep-sky imaging it does have some drawbacks. The long focal length makes tracking more difficult and extended objects like emission nebulae will be too large to fit in the field of view. There is also the risk of ‘mirror flop’ – movement of the primary mirror during the long exposures required for deep-sky imaging.

It would make sense to consider the purchase of the EQ6 mount as a very important stepping stone towards deep-sky imaging, but keep in mind that in the future you may want to purchase a shorter focal length apochromat­ic refractor for imaging.

 ??  ?? ▲ An EQ6 mount is a good stepping stone to deep-sky observing
▲ An EQ6 mount is a good stepping stone to deep-sky observing
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