Watec Video image of Mars (and "interlacing")

[Macavity]

Since I could see *some* surface features on Mars last night, in real time, on the Watec, I decided to try stacking the best 500/1000 frames (in Registax) to see what would happen! The scope setup was my MAK150, plus 2" & 1.25" Barlows, or ~4x multiplication (~f/48, f=7200mm)... At least the Watec rarely suffers from a lack of light? <G> So, a first ever Martian image (enlarged 2x):

The dark rim of Mars seems to have been a bit "eroded" (LOL), perhaps due to miss-setting of camera gain and / or Registax over-processing? (Obviously) no auto-guiding, just a straight HEQ5, whirring away for 1000x 25 fps. Focussing is probably a bit sus too! But overall, I'm pleasantly surprised - "One up" on previous attempts with budget "solar system" cameras...

Aside: Perhaps of more general interest, I discovered that the image is much improved, and stacking facilitated, by setting the "interlacing" to smooth (rather than the default "Off"!) - In the <camera settings> of the (Gstar4) capture software??? I had thought that Video Cams (the Watec) were "progressive scan", but seemingly it's "2:1 interlaced"? Either way, fiddling with this setting seemed to make the image MUCH less "rastery" and smooths the edges of Mars, Sunspots... probably stars too?

[mike.brightmore]

Nice surface detail but why is the edge of the disc so bumpy?

[Macavity]

Nice surface detail but why is the edge of the disc so bumpy?

I think, what happens, Mike, is that the LIMB of Mars is quite dark. If I don't set the "gain" of the Watec exactly right, at the INPUT level, the dark bits get "lost" in the background sky! The "intelligence" of Registax is (genuinely) amazing, but I sense it can "run amok" or be "overdriven" re. Wavelets etc. I have a fair bit to learn...

It seems the hardest thing (with the Watec, anyway) is the "knob twiddling" - Despite the, very convenient, control box. As ever, what I need to do is WRITE things down more... Read a bit more, too. Planetary imaging is, I sense, fairly well documented. Read more too...