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nobody

15 Sep 2022 19:13



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Atasez si un scurt articol scris de cine altcineva, Damian Peach, in care atinge problemele discutate pe aici.

Citez:
Choosing Your Tools
- The first is an electric focuser. You don’t want to touch the telescope when focusing, as vibrations from your hand are greatly magnified, and you’ll simply be fighting with a jiggling image.

Cameras, Computers, and Control
- You can even use a DSLR camera with HD video capabilities, though they weigh much more than the video cameras shown above and require a very sturdy focuser.

At the Telescope
- First and foremost is making sure your telescope is in perfect collimation. Even a slight misalignment can noticeably degrade the image being recorded.
- Another consideration is ensuring your telescope has reached thermal equilibrium. If your scope is warmer than the outside air, it will radiate heat, producing a blurry image that is virtually impossible to focus.

Focus, Focus, Focus
- Focusing in good seeing is usually easy, but under poor seeing it can be extremely difficult, so don’t be discouraged ... Simply take your time and practice. The more you do it, the better you’ll get at it.
- When you start recording video, you’ll typically be operating your camera at about 30 to 80 frames per second or more, depending on the brightness of your target, capturing a minimum of 1,000 frames for a single image stack.

Video Reduction
- The number of usable frames you stack varies depending on the seeing conditions. Under good seeing you can stack a great many frames (maybe 75% or more), but in poor conditions this goes down to maybe about 30%. Stacking more frames taken under poor seeing simply produces a blurrier result, because more subpar frames are included in the final stack. That said, don’t be fooled into thinking just selecting the 100 best frames will work. It may well deliver a sharper result, but it will be extremely noisy when sharpened.