I've been batting this idea around for a year or two after posting here and discovering that companies do not make H-alpha filters that can be mounted on a normal camera lens (e.g., a 77mm threaded narrow-band Ha filter). While I'm quite pleased with the outcome of of my solar eclipse photos and subsequent movie that I did with an 800mm lens equivalent (400mm + 2x) with a solar filter equivalent (two stacked ND filters), for general astrophotography of the sun and especially for the upcoming Transit of Venus event, I'm still thinking about doing this (a small black dot moving across a solid yellow surface with maybe a sunspot or two is not nearly as interesting as one that shows supergranularity, flares, filaments, etc.).
I'll start out by saying that I still have reservations about doing this because:
- I already have a good system going for a 400mm or 800mm lens that hooks directly to my camera because, well, it's a camera lens.
- Solar telescopes are friggin' expensive.
- The solar 'scopes I see have a 1.25" eyepiece barrel that I'd need to use a T-ring and -mount for my camera, and ...
- ... I've read some bad things about the stability of the focusing mechanism and am not sure how it would behave with a 5-lb camera body attached.
- I don't have a good mount system other than my tripod and AstroTrack that could be both stable and handle the weight of both the telescope and an attached camera.
With those stated, can anyone allay my fears for the third, fourth, and/or fifth items?
I'm currently looking into the Coronado SolarMax II telescopes as those seem to be all that's out there for consumer-grade systems. My current 400mm lens is an f/5.6, while with the extender I generally shoot at f/11 for best sharpness. With a 1.25" eyepiece barrel, my understanding is that I'm going to get an effective focal length that's longer than that quoted by the product, but I'm not sure what that "crop factor" will be. That also means (I think) that I'll get a slower system with the camera attached.
Thus, my starting point is looking at the SolarMax II 60 (the SMT60-10 model versus the -15 model). Which also happens to be more than I would like to spend at $1.5k. I mean, that's more than I paid for my 400mm camera lens.
But then re-reading the older thread about an H-alpha filter for a normal camera lens, I'm thinking that I may almost be better off getting a dedicated astronomical CCD for once. SBIGs seem like the way to go for amateur imaging, and the ST-8300M appears to be popular and has a good QE ... and while I could use that for other imaging I do, it tacks another $1800 onto the price. And its minimum shutter speed of 0.12 seconds makes me wonder whether it could handle the sun just through an Ha filter.
So I guess this is more of a stream-of-consciousness "Please give me advice" thread. So ... can anyone please give me advice?