Quote:
Originally Posted by Atmos
Ken is right, narrowband filters cut the band enough that bloating isn’t an issue as long as you refocus in between. As the focus shift is only on the order of maybe 100 microns or a bit more, registration isn’t an issue.
Where an APO really does well in narrowband imaging however is that most APOs have a considerably better optical figure than most achromats because they’re built to a much cheaper standard. THIS is where an APO will be better, smaller tighter stars and a better corrected field with less spherical aberration.
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I saw somewhere where they are selling individual optics for refrctor scopes so maybe there is one or two that is very good quality better than the standard or stock achcromatic scopes that are being sold as mass production in markets, so that might do some improvements or not?
Also about stars, so if using a high quality filters, won't help to bring that achromatic scopes to somehow near APO level? For example 6nm or 5nm/3nm NB filters.