some F/number questions??

Stephen - 'fast scopes', especially newtonians, are noted for requiring very accurate collimation. I won't go into the maths but with a faster scope, the 'sweet spot' on the primary mirror is smaller than a slower f-ratio scope. Collimating the secondary and primary is therefore critical. But when you get it nailed, the views will be superb.

But note that since the adjustment is so fine on fast scopes, it takes very little to knock the collimation out. I have heard that owners of large, fast newtonians (including dobs) who do planetary imaging, collimate their scopes every hour or so to adjust for temperature changes.

By the way, don't think that your soon to arrive bundle of joy is a lemon - far from it. Just don't be surprised or disappointed if the views are not great - all that that means is you need to recollimate.

I think John Honan posted that f/6 or lower is considered 'fast' but the collimation issues really only start to become a pain in the bum at f/4 or lower. f/5 I'd consider as being medium-fast.

You have a nice range of eyepieces and magnifications there - they'll cover all eventualities.

As for imaging - in general, a faster f ratio is better because you have a shorter exposure time than a slower f ratio.

Clearer still?

Cheers and good luck!

Dave McD

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Its all becoming clearer. I just needed to have all the info on one thread. Thanks a million guys. Now, to learn how to collimate>>>>