If you're experiencing bokeh issues in the midst of astrophotography--I suggest you dive for cover! Seriously, these are a similar design to mirror telescopes and there are no issues with photographing the moon. I don't think a 500mm lens will be of much use with other astronomical objects.
Originally Posted by Markster
They work absolutely amazingly. Especially when your mirror lens is an 8-inch Celestron with a mirrored Mylar solar filter over the aperture. My father took some astounding sunspot images in his time with that ol' Celestron.
Originally Posted by Markster
Of course, the closest I personally got to astrophotography was taking images of the Orion constellation, and a couple of the moon—all with standard camera lenses.
I was thinking more specifically of the 500mm, rather than attaching the camera directly to a telescope.
I imagine it would work well with the moon (as mentioned).
As far as cheap (or, cheapER) conventional solutions, if you put a 1.4x or 2x converter on it and you can bring that up to 1000mm. Further, I don't think there's anything stopping you from using 2 convertors on the 500mm.
The problem then becomes light sensitivity and shutter speeds required, I suppose.
It does pique the imagination, does it not?
Canon AE-1P 35mm | 50mm/f1.8 FDn | 28mm/2.8 FD | 70-200mm/f4-5 FD | 35-70mm/F2.8-3.5 Sigma FD
I have the Tamron SP 500mm f/8 mirror lens (55B), and I thoroughly enjoy it. Inexpensive these days, it was always reasonably priced. Sharp and with very good contrast for a mirror. I have the Tamron SP 2X teleconverter, (01F) a good performer, which makes it a 1000mm f/16. I bought it mainly for long shots of distant objects, most at infinity, and birds and aircraft against the sky- bokeh issues are nonexistent for those. The whole setup with cases, filters, everything, cost me about $120.
As polyglot says, avoiding specular highlights, or any distinct highlights, will minimize the donut bokeh. Having the background in shadow, or shooting against a very uniform background will minimize it, too. I have found that a very busy background, like dense grasses, will also work, because the doubling of lines is not so noticeable, and if the background is really busy, the doubling actually has the effect of blending, reducing the effect.
One thing I like about the Tamron is the very close focusing ability. It goes to 1:3, and 1:1.5 with the 2X converter. I can get nice shots close up in which the depth of field is so shallow that the background just blurs into a smooth mass. I have been able to take flower shots in which objects which were out of focus did not display objectionable bokeh.
A mirror can be a lot of fun. Avoiding the donuts means choosing shots carefully, and simply avoiding certain types of shots, but to me that's part of the fun. There is no way I would be carrying a regular 500mm, so the trade-offs mean getting shots with a mirror and dealing with its characteristics, or not getting the shots at all.
Last edited by lxdude; 03-01-2013 at 11:38 PM. Click to view previous post history.
I do use a digital device in my photographic pursuits when necessary.
When someone rags on me for using film, I use a middle digit, upraised.