|
A mirror lens shouldn't be too bad for photographing the moon as you won't have the depth of field problems. It's pretty much an SCT scope after all! I'd double check that the mirror design doesn't have any implications when used with the smaller than 35 mm chip in the 400d - I don't see why it would.
Don't think that it will be a great 500 mm lens in general though... If you use the camera lot for a range of subjects (day and night!), I think you'd be better off spending the money on the 300mm zoom. That will be nearly the equivalent of 500 mm at 35 mm, and be a more generally useful lens.
Finally, the big chip on the 400d, will mean that the moon still covers quite a few pixels and will be more than enough for on screen images and quite printable I should think. Someone else would probably know the maths for that!
|