Originally Posted by Igilligan 
I get similar results with the zooms and my 1.4x tamron. But like you found with the tamron 90mm... the tc's do work better with the primes.
The atmospheric conditions and phase of the moon really make a huge difference. The night after I got the shot below,
I tried again and could not even get close to that detail, because of conditions in the upper atmosphere
Here is a moonshot with an old 400mm vivitar F5.6 and the tamron 1.4 tc
this is probably the most detail I got on a moonshot.. I gave up trying not long after this...
Your shots are quite good for such a short focal length. Lots of detail and very good contrast. I never got such a good result with a humble photo lens!
Ben