Lens suggestions for Canon 40D - multiple choices

[g__day]

Hi Guys,

Many years ago I spent much time with modded Canon 40Ds with BYE on SCTs and Refractors, then I switched to ZWO cameras.  Recently I thought my mount has plenty of carrying capacity so I decided to re-mount my 40D on top of my main SCT with a 30 - 70mm Canon lens (first time I will have ever used it not connected to an OTA)!  I have decent a range of Canon lens I  can attach to the camera, of varying focal length - I simply wondered if any folk could offer a suggestion as which to use.  I am not really sure what I expect it to do as I often image dim targets from my astro-lab .  But I guess I wanted to see what a wider field shot actually looks like thru a Canon camera lens.

Any advice on what lens / targets / image durations make for good choices would be much appreciated - as its strange to find after a decade I am trying something with astro-imaging!

Many thanks,

  Matthew

 

[dkerber]

Well, the Milky Way likes really wide angles, such as 11 - 14mm. The Orion molecular cloud complex (HorseHead, Flame, etc) wants a little narrower. Your 70mm might be good for that. I've gotten some nice shots of M51 and M101 with a 400L.

 

[s3igell]

If you are AutoGuiding, you should have all the time in the world for your exposures.  If not, the 70mm will likely show minor Star Trailing after about 45-60 seconds piggybacked on your SCT.  That should be decent Exposure Time for any Target...

If you have a Choice, try one of your Prime Lens - they are usually easier to set and maintain Focus AND likely to have fewer Aberrations (that last depends on Price Category of Lens of course).

For a pleasant surprise, try your 50mm f/1.8 (if you have one).  They don't call them "Nifty Fifty" for nothing...