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Samir Kharusi | all galleries >> Galleries >> Dump for Disconnected Photos > Saturn 09jan05
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Samir Kharusi

Saturn 09jan05

Azaiba, Muscat. Oman

Taken through a C14 at about f28, using a ToUcam webcam. Below it is a JPL simulated view. I added the annotations and also what a couple of stars separated at the Rayleigh diffraction limit should look like through a C14. Now, is that the Encke Gap that you see a hint of at the left edge of the rings? The very thin line near the outer edge. Also appears on the right side, though more subtle, and at about the correct spacing. I'll have to keep on trying to nail it down ever more convincingly, hoping for ever more steady seeing :-) An interesting aside: It is often recommended that to sharpen up planetary images on the ToUcam one should use an Ultra Violet / Infra Red blocking filter. This filter is stuck to the lens of the ToUcam, so when you remove the lens you shoot with unfiltered light. I bought a Baader UV/IR blocker, shot 2 videos with the filter and 2 without. The ones without the filter show the Encke as above, the ones with the filter do not. I had refocused between each capture, so I do not believe focus is the issue. Perhaps the filter is not as high quality as Baader claims? Perhaps the extra UV+IR without the filter allows for slightly more aggressive post-processing? Perhaps the IR or UV defines the Encke better? No idea. One day I plan to experiment further... Let's also have a quick look at so-called diffraction limits. The Rayleigh Limit for a C14 is 0.4 arc-seconds (refer the 2 simulated stars in the corner), but both visually and in imaging one can go much finer if there is a pattern of some kind, eg. a line, like the Cassini or the Encke. The Cassini Division is some 4700 km at its widest, subtending less than an arc-second at Earth's distance, yet it is possible to see it in quite small telescopes. The Encke Gap is only 325 km at its widest, subtending less than 0.1 arc-second, or under a quarter of the Rayleigh Limit for a C14! For more stuff visit my primary website:

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