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Thursday, February 14, 2008
Color data: only 3x600s with UHC-s filter
I shoot California nebula as well. Elevation was very low at the end of the exposures,
only about 28 degrees.
H-alpha 4x900s, same setup.
3x600s trough UHC-filter added.
for astro photography.
I was expecting severe distortion in the image edges, there is none!
I was expecting severe color aberration, there is none!!!
This lens was unexpencive, doe the old FD model, about 120€.
The front lens aperature is 72mm.FOCUSING Fast lenses are very difficult to focus manually, it's pure luck to reach sharp focus. 200mm f2.8 lens has about 20 microns sharp focus area! I build a simple autofocuser to my lens by using TCF-s temperature compensating focuser. I'll send real pictures about that later. Here is a picture about principle. This system solves allso problems with focus temperature shift! TCF-s focuser is easy to move back to the main telescope at anytime. I was able to use FocusMax with the lens and reach sharp focus in 30 seconds.