Short answer;
Mirror lens; Advantages; Size. Weight. Usually, cost.
Disadvantages; Optical performance, at times, lack of
'convenient' means of stopping down, odd 'bokeh' that generally occurs with
them.
Refractor lens; Advantages; Optical performance, at times. Normal
settable F stops. More normal 'bokeh' produced.
Disadvantages; Size, Weight, usually cost.
I.E. The 500mm mirror lenses that are fairly prolific out there (Zuiko,
Tokina, Soligor et al) are all amazingly small in length, and relatively
compact in diameter as well (3-4 inches in each direction), but they're
almost all fixed F8 lenses.
I've a 500mm refractor for my P*ntax gear that is a real beast. It's fast
at F4.5, but my gosh, the camera looks like a complete afterthought dangling
off the back. It's almost 18 inches long, about 5 inches in diameter, and
weighs 7.5 pounds.
Then there's the cost factor. The mirror lenses can be had for a song, if
you shop diligently (100-125), and even the Zuiko can be had for around 300
with careful shopping. The aforementioned P*ntax lens is still available
from B&H for the paltry sum of 2300 and change. Even on the evil one,
they're usually still 1000 or more.
-----Original Message-----
From: Charles Monroe
What are the pros and cons of a long focus versus a mirror lens of
the same effective mm length?
Charles Monroe
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