Sunday, April 1, 2012


I've never done very well with Mars, and my best views--never that good--have been with an aperture mask.  With full aperture, I just get a red and white blob of chromatic aberration.

I had a 75mm single-hole aperture mask that I was planning to use in my 8" F/4.5 Coulter for solar projection, but tonight I added another hole to it.  Both holes miss the two-vane spider.  The views of Mars with the aperture mask and a 5mm ortho are great--best I've had.  Two dark areas (one was probably Mare Acidalium) and a bit of polar cap.  I don't know if they're better with two holes than with one--there may be better contrast with one--but they are a bit brighter with two, and I love the easy focusing (with the mask, you see double and you focus by merging the images).

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