Hi all,
I'm trying to decide between a couple of different Cassegrain designs to replace my SCT. I have many years experience with the SCT design, but one Cassegrain design I have no idea about in terms of practical use, is the Takahashi Mewlon. I know they are a Dall Kirkham, so no corrector lenses, and have a superb image, but that is it.
My questions then are:
1, How do they deal with dew? Any particular precautions to take?
2, The mirrors are exposed, so are they overcoated to give more protection?
3, Being exposed, how susceptible are they to getting dirty? This I guess is an additional part to the dew factor. I live on the coast in Sydney, so I am concerned.
4, With regular use, how often is it necessary to clean the mirrors?
So you know, the Cassegrain I end up with will be principally as a visual scope for my sketching of the Moon and planets. Photography will only be of the planets and Moon too, and this will be minimal. I'm looking for a Cassegrain in the range of 7" to 8" for my purposes.
I think that's it for now that I can recall. Hopefully as discussion progresses here other questions will come to mind, or will be answered even though I didn't ask them...
Cheers,
Alex.