Saturday, 1 August 2020

AR12768 in CaK 31st July

ar12768-cak-colour
Taken with the 118mm scope at f27 (127mm scope stopped down to 118mm to give f10, and then 2.7x telecentric) I was keen to remind myself how this performed at these shorter wavelengths.  It is considerably softer than my 100mm Tal, but it does just about work, at 656nm it is a much stronger performer and does well when the seeing allows it.  I still think a 150mm f8 scope stopped down to 120mm would give better results and this is on the radar of my shopping list.