[Slawomir (Suavi)]

Interesting reports, thank you Lewis.

I have quickly made a rough comparison (see the attached files) using data from here: http://www.airylab.fr/AirylabUS/index.php?option=com_content&view=a rticle&id=52&Itemid=57

The website did not have a report for Esprit, thus I used data from the report for Skywatcher's Equinox, but of course Esprit, being more expensive and more refined than Equinox, should yield better results.

The reason why I am interested in this discussion is that even with narrowband imaging, light at a range of wavelengths and with longer exposures will slowly leak through a filter, in particular around bright stars, creating halos and enlarging stars to some degree. I have noticed that with my ED doublet and 3nm filters. And although I am not in a rush, I have been looking at possible reasonable future replacement for my TS doublet.

Going back to the original question, if one is after the best possible astro-images, then perhaps FSQ might be better to some degree (than Esprit). But whether Jeremy’s mount (HEQ5) will allow to fully capitalise on FSQ’s excellent optics – I do not know.