How can I focus my DSLR camera through my telescope?

BBC Sky at Night Magazine's Scope Doctor Steve Richards solves your practical astronomy ailments.

Canon EOS 1000D DSLR camera body

I’m having trouble focusing when using my Canon EOS 1000D DSLR camera on my Meade LX90. Any advice?

The Meade LX90 is a Schmidt-Cassegrain telescope (SCT) mounted on a twin tine fork mount.

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This type of instrument has a visual back with a threaded mounting and a push-fit adaptor for attaching the star diagonal.

For photographic use, the push-fit adaptor and star diagonal should be removed and a Meade Instruments 07352 No. 62 SLR Camera T-Adaptor screwed onto the visual back in its place.

To mount the Canon 1000D onto the adaptor, a standard Canon to ‘T’ mount adaptor will be required.

Focus is best achieved by taking a series of 10-second exposures of a bright star and adjusting the focus position between shots until the smallest star image is produced.

A Bahtinov mask, available from most astronomy retailers, will make this task even simpler.

Viewing the captured images directly on a laptop computer screen, using the EOS Utility software supplied with your camera, will make the task easy and comfortable.

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Email your astronomy queries to Steve at scopedoctor@skyatnightmagazine.com and they could get answered in a future issue of BBC Sky at Night Magazine.