100-400 Z for astro anyone?

Started 6 months ago | Discussions thread
OP BasilG Forum Pro • Posts: 10,035
Re: 100-400 Z for astro anyone?

Andy Lucy wrote:

Yes, I have a tracker and am currently looking for a multi-purpose telephoto for some of the imaging. I have the 100-400, 400/4.5, and 500 PF on the shortlist. It is clear that the 400/4.5 would probably be best for astro (prime and no PF), but if the 100-400 is close enough, it would be great because it could additionally serve as a general purpose telephoto and even for some telephoto macro work. The 500 PF should be pretty good too, yes. There are a few good examples, and I've seen one or two where the PF element reared its head with "very bright" (relatively speaking) light sources in the image.

The best evidence on the quality of a lens for astro would be some actual astrophotography images. However, a second best is a night shot with near-pinpoint light sources across the frame. Fortunately, Gordon Laing of Camera Labs now includes just such a shot in his lens reviews. For the 100-400 Z lens he took an image at 100mm focal length and there was little evidence of coma or colour artifacts.

Thanks for pointing this out. I was quite surprised to see that the 100-400 at 400/5.6 and and the 400/4.5 +TC at 560/8 have better corners than the 500 PF at f/5.6 in the chart test. Wonder if they got a not-quite-perfect 500 PF or if it's a matter of focus distance (up close vs. infinity).

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