Hi everyone,
Here's my second Mars observation for this apparition, I did the first one with the usual 3x apochromatic Barlow but the camera couldn't cope with the atmospheric dispersion that goes with the current altitude of around 45 degrees, resulting in double edges and lineair artefacts.
Since I had good experiences with using a 30 mm Kellner eyepiece off-axis on Mercury, I was trying to find a simular solution on Mars, but needed a bit more magnification without using a longer extension. In other words, I needed a good quality 25 mm Kellner with a 24 mm barrel, which nowadays is very hard to find. Luckily this was exactly one of the last remaining 24 mm eyepieces in the shop, a Tasco brand made in Taiwan with good coatings and baffling!
This gives me a focal ratio of f/34.5.
There is a solid NPH visible plus a lot of haze near the terminator.
See
http://www.erwinvandervelden.id.au/2005-09-09-erv.htm
Cheers,
Erwin van der Velden