Hello everyone,
I am currently building a wide-angle setup, but I am facing serious issues with my Askar FMA180 Pro. Firstly, there is a problem with focusing: I am unable to reach focus at the manufacturer’s specified 55 mm backfocus distance. Instead, I need to increase the backfocus by approximately 6 mm to achieve focus at the very end of the focuser ring. At this point, there is absolutely no focusing travel left, and I have no margin for fine adjustments. This shift of the optical plane leads to severe coma and elongated star shapes, starting from roughly half of the image and becoming even worse towards the corners. This is especially problematic given that I am using an APS-H sensor, with 2 mm filters, so the scope is not even at full-frame coverage. I have attached some pictures showing the issue.
Am I expecting too much from this scope, or is it likely that I am simply unlucky with this particular copy? Should I contact my dealer to request a replacement unit, since the backfocus offset prevents proper use of the telescope according to the manufacturer’s specifications?
Thank you so much for your advice.
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