Quote:
Originally Posted by Merlin66
Tareq,
Not all AP guys are just using just narrowband filters - you have to consider the use of L filters and RGB filters if you're really "serious"
This puts extra demands on the already very good ED type achromats.
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I understand, and that is a good point, but does ED APO let's say doublets for example be good enough for imaging then or it must be a triplet? So is an ED APO scope small one for example about $300-600 nice for imaging or this is not bad but it won't do better as well?
What is the problem of L filter if using with an achro refractor?