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Context : I came to Lucky Imaging given the poor quality of my site: Bortle 7, lots of turbulence, mediocre Seing The Lucky Imagine has many advantages for me: • We free ourselves from the breast with poses < 500ms • We improve the resolution to -1” with exposures < 5s because it is less sensitive to turbulence. By posing very short we freeze the turbulence and eliminate small tracking defects. • Simplicity of the photo process with the Shapcap stacking tool. No need for autoguiding up to 30”. • Image stacking and alignment is automatic with SharpCap. The histogram stack function helps improve the brightness of dark areas of the image and improve the contrast in brighter areas of the image. • The most important: the pleasure because you can see the image forming live over the seconds. • We can access 80% of interesting planetary nebulae and galaxies without problems. It’s trickier for the Nebulae. • The surface brightness of the target is limited but I observe in my photos magnitudes greater than 17 in 15’ • You must set the Gain between 50% and 90% of the maximum gain in order to benefit from the lowest reading noise. • With high gain it is preferable to add offset so as not to "eat" the very weak signals. My uncertainties: The recommendations explain that we must do Darks but that Offsets (Bias) and Flats (PLU) are not essential. I'm not convinced: 1. Darks do not seem essential to me given that my camera (ASI533) produces only 0.0005 electrons/second/Pixel or 0.0015e/s/Pixel with an exposure of 3” and cooling of -10°C. (0.15e/s/Pixel with an exposure of 300’’, i.e. 100 times more electrons. 2. On the other hand, the reading noise of the camera (1e) with a Gain of 500 is not negligible / thermal noise (0.0015e) so it seems essential to me to do Offsets (Bias) 3. Regarding the Flats (PLU) I think that when in doubt you should do them. Question: Can anyone advise me on DOF and share their experience in Lucky Imaging? |
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| I moved this topic to the Electronically-Assisted Astronomy (EAA), as I think it would be more relevant here. I hope that's alright! |
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| No problem |
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| It all depends on how you make your acquisitions: if you use 8b (gain >500ms) you have to do simple stacking in sum mode, so darks are mandatory (no offset, they are contained in the darks) . For flats, it depends on the size of your sensor, with my 290mm no flats, with the 533 flats. On the other hand, if your gain is lower than 500, 16b is (maybe to think about it) possible, so you can take the stacking mode with rejection. At this time no darks (let's say it's not obligatory), and offset possible. |
