mirror lenses are lousy... but what about a GOOD mirror lens?

Started Feb 19, 2014 | Discussions thread
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paulkienitz Veteran Member • Posts: 5,246
mirror lenses are lousy... but what about a GOOD mirror lens?

From all I've heard, most mirror lenses sold for use with cameras, such as the Samyang 800mm, are quite bad by the standards of normal telephoto lenses.  But I've also heard that much of this badness is due to the cheapness of the particular lens models, and the issues might be much reduced if you get a good mirror lens.  (Of course, the donut bokeh is the same regardless of price.)

Does anyone know to what degree this is true?  Is, say, a $4000 Questar really that much better than a $200 Samyang?

I'm wondering if it's possible to get some of that good action by picking up something like, say, a Celestron C90.  They say if you get a good copy it's not much poorer than a Questar.

I am thinking this because I was recently out birding with some people who had spotting scopes, and the birds were all far away, and all my 300mm pictures were crap, but the scopers were seeing everything just fine.  I was thinking I really need longer than 300mm, but then I realized that there's no point in spending tons of money to go mildly longer, like 500mm -- to get into that league requires more like 1200mm.  And a mirror is basically the only realistic option for doing that.

Of course, it's possible that in the end I'll discover that it works, but no better than my current setup of putting a 180/2.8 onto a Q.

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"A good photograph is knowing where to stand." -- Ansel

 paulkienitz's gear list:paulkienitz's gear list
Pentax Q Pentax K-3 Pentax smc DA 55-300mm F4.0-5.8 ED Pentax smc DA* 300mm F4.0 ED (IF) SDM Samyang 8mm F3.5 Aspherical IF MC Fisheye +4 more
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