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Hi Lyndon,
Also, Re : Is a 100mm APO with a 2x barlow comparable to a Mak Cass for viewing purposes? The 100mm by it self will have an F ratio of 7, maybe 7.5, i havent done the reseach, but close to F7 without being technicle, so, just pointing out that if you added a 2x extender, barlow or what have you, this 2x will in effect slow your ratio down to F14ísh, back to where you started from, , Prob worse as 100mm is 2" less aperture : )
I reccommend any newbies to start off with a shorter F/Length with AP, and visual for that matter, get a good look at the sky with the wider field so can put things into perspective, also easier to find targets, the faster F/ratio will also make targets jump out more, , contrast wise !
Hope this is of help, and all the best ! !
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