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Deflavio

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About Deflavio

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  1. Interesting experiment, why not to increase photons by binning up a bit? Flavio
  2. When you say "it seems like the mount points, stops, waits and then moves" does the noise from the mount motors also stops, changes in intensity or stays the same? I'm just checking if some of your gear is slipping, maybe two years without use may have loosened something in your gears. Other possibility, what is the voltage range for this mount? You may want to make sure you are not just close to the limit. I suggest to post in the equipment/mount section. I'm sure you will get more answers. Flavio
  3. Eh, that would be really nice. This could be the base for a full EAA/AP simulator ..including noise, optics and sky, etc. Ok, I'm dreaming now but I saw some time ago Aberrator software. It was nice to simulate the effect of optics on planets and doubles, no noise though. Regarding SNR, I think it should be possible to adapt the point source algorithm to extended object by changing how the number of photon are computed for the pixel, the rest hopefully should be similar. I'll try to get more reading on it. Flavio
  4. Hi Martin, I think the reason Borg+Lodestart results are strange for FWHM 2 and 3 is because you are well past the 0.83xFWHM threshold (i.e. when you are under-sampled but SNR is maximum according to Raab's paper) and your pixel is now bigger than the whole star so you don't have benefit by going bigger than that. Specifically with FWHM=2,3,4 you are sampling at 0.44x, 0.66x and 0.89x FWHM. These results replicate pretty well what said in the paper.[Just checking, FWHM =2 and 3 seem the same plot but I can follow the pattern on the rest]. Also it is interesting that by using la
  5. Thanks Martin! I think your last message finally cleared my doubts. SNR is aperture, exposure and QE, yep I fully agree with this. What got me confused was the story of the "equivalent" time required by equivalent f-ratio systems I read around. I see now, this works IF I don't change pixel size. Like a photographer changing lenses but keeping the same camera body. Longer focal lengths give bigger pictures on the focal plane spreading more the photons on a larger surface but density will stay the same for constant focal-ratio. So yes, by using the same pixel size, you can get same SN
  6. I have not used myself ASIair but looking at few videos on youtube it seems that all you need to get your "evoscope" functionalities is just install the ASIair, connect mount and camera(s) and install the app on your ipad. Looking at screenshots the equivalent of ASIstudio is somehow already built inside ASIair and the app so no need to install on any computer. That's in theory, but in practice I would make sure that your mount is working fine with ASIAIR and that you wifi signal is good enough! Also you may want to consider a ZWO focuser for this to be completely automatic. Regardi
  7. Hi Mike, For 1.5x FWHM I mean a sampling rate that is 1.5 times higher than the actual Full Width Half Maximum of your final "star disk". This star disk would be the combined effects of seeing (main factor), Airy disk and tracking errors. In practice, this means that you need to cover the central part (or most luminous portion) of your star with at least 1.5 pixels. In the tables I posted above, I just took 8 different FWHMs to represent different sky conditions or star sizes and tried to see what would be the ideal focal length given 3 different pixel sizes. If I look at your s
  8. wow that's a lot of hours in a year. I like to do the "theory" but I definitely do less practice I completely agree regarding bigger pixels and seeing condition. Given a fixed focal length (and aperture) the larger sensor would go always deeper. However, what about details and object features/contrast? As you say, average or bad sky conditions would actually push to use binning but the same angular sampling can be achieved using a shorter focal length. Even more if I also consider a smaller pixel size. I'm curious to know if someone has tried this. Clearly the C11 or 15’’ will
  9. Hi Martin, Very interesting paper, it covers quite lot. Interesting that max SNR is achieved at 0.83x FWHM assuming a centred voxel...and accepting bad under-sampling and aliasing of course, but at least, no need to go further than that for more SNR. It also confirms that to preserve details and still have good SNR, sampling should be between 1.5 to 2.0x FWHM which is in line with what has been said before on this and other forums. Unfortunately, the formula and the script are as you said for point sources. At fix angular resolution (pixel value in your python script) SNR goes up with ap
  10. Hi Everyone, Sorry for the long post but it's cloudy outside... I have started thinking about different options on how to optimise/improve resolution while still using moderate focal lengths for travel. At the end, it seems that it all comes down to the final arcsec/pixel value and a good sampling of the final FWHM (combining seeing, AIRY disk and tracking errors). A sampling rate between 1.6x to 2x of the FWHM seems “ideal” according recent posts from @vlaiv. Or maybe even less considering the more noisy nature EAA images compared to AP. I guess many high frequency details are prob
  11. Hi Toadeh, If you are looking for a cheaper but still a good option considering your equipment, I would also suggest the classic ASI224MC for about £220. It's not the latest camera but it is very sensitive colour camera and it has been one of the most used for EAA so you will find a lot of info and examples online. The 244 has a smaller field of view compared to 533 or 294 but considering your 150p with a focal length of 750mm you will get a good 1.05''/pixel resolution and a "nice frame" of 0.4x0.3 degrees zooming on most of the major bright objects. I'm thinking myself to get the 1
  12. Thanks Martin and Mike, The observations of remote galaxies you are showing in this forum are really impressive and clearly show that your two approaches are working very well. Aligning to a closer star and then a small goto jump to the target seems a really good idea. Now I feel like I'm cheating with my continuous use of plate solving but I guess with a much lighter mount and under the sky of London it's a way to make things a bit simpler... it may be professional deformation but the truth is I quite like the geekiness of it and that's part of the fun!
  13. I agree, now that I have seen the improvement using the GOTO on EQ I can see the value of good alignment. Although I'm still not sure if just levelling with the bubble on the AZ-GTi is precise enough for AZ...That's why I'm never got mad about it. I mean the bubble is always within the marks but how good is it? On a EQ mount aligning to polar seems to me more objective and quantitative (especially using SharpCap or similar tools). If I got it right, with a good polar alignment, levelling becomes more about stability of the scope but it is not really affecting goto or tracking because RA
  14. ...and here some old images using the 130p and AZ-GTi. This was a couple of years ago so that was just basic setting (Sharpcap, SynScan and manual focus). I'm now trying to get the SW focuser working on the 130. Hopefully that would improve things further. M51 (Gain 350, 15sec x 40 frames, SW130p + ASI224) - AZ mode and the firework galaxy NGC6946 (Gain 373, 5sec x 80 frames, SW130p + ASI224) - AZ mode
  15. Hi Keltoi, Yes, this is my main setup for most of my observations, I alternate between ED72 and 130p. Just last night I did some EAA using the 72ED + ASI224 and AZ GTi in EQ mode. It was a pleasing and fun night with everything working well. I recently added the SW focuser + HitecAstro DC controller to improve my focus and I can see the difference. My software combination is SynScan app on windows, together with Sharpcap, HitecAstro focuser software and Cartes du ciel. It is a bit overkill but the long term goal for me is to learn how to control everything remotely. As basic setup
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