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TAKA FC100DZ for sun?

Posted: Mon Jun 07, 2021 9:02 pm
by fedele
is the doublet FC100DZ, with Fluorite internal side, a good choice for SUN observation and imaging?
Any risk? is a good choice in general?

Re: TAKA FC100DZ for sun?

Posted: Tue Jun 08, 2021 11:14 am
by marktownley
Hi there,

The Tak seems an 'OK' performer for Ha and white light. For CaK there will be quite a bit of spherical aberration at full aperture and would only really recommend using at 50mm aperture.
fc-100dz-aberration.jpg (26.2 KiB) Viewed 111 times
fc-100dz-strehlratio.jpg (28.5 KiB) Viewed 111 times
If you have a cheap achro you would probably get better results. If you already have the Tak try it and see how you get on!