Uranium235
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Everything posted by Uranium235
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In me back garden I've recently moved to the edge of town and in a northerly direction there is nothing for miles so that part of the sky is quite good. West is awful though, South is a bit "meh" and East is good(ish). Plus the bodes were near the zenith - so not too hard to get a good image.
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I'm familiar with the nyquist theory in both imaging and sound engineering (though its more obvious in sound) - but I suppose if you go past the rayleigh limit and into oversampling its capability then there really isnt much of a win or lose, as youre always going to be limited by the aperture (a bit like having a limiter on your car). Especially when you take into account that for long exposures, the sky in the UK is never good enough to support that kind of resolution. Perhaps futher tweaks could be made, the 130 has been through a house move and hasnt had its collimation checked for about 6 months - so tweaking that (or at least checking it) is probably worth it. But for now the biggest issue remains the dark frame calibration of the ASI178, as it seems to prefer darks taken in the same session (though not too difficult due to the short exposures required). However, those tiny pixels seem to have turned the 130 into a very unlikely galaxy smasher (only 20x2min)
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I only had to check it becuase its not very often you come across a camera with such small pixels (2.4 microns) - 99% of the time DSO imagers dont have to think about it becuase they usually never get close to the resolving limits of their telescope. Though I've not really seen any negative consequences of breaking that limit, there must be some penalty - but there arent that many discussions on the subject that I have found. I did find a sensor with 1.6micron pixels, but I cant see any practical application for it... you'd need a large aperture and a short short focal legth to satisfy that - and we all know that would be insanely expensive!
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Use the telescope capability calculator found here: https://astronomy.tools/ All you need to do is punch in the aperture size and it will tell you the limits for your telescope.
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Now properly calibrated: Still a bit noisy, but what do you expect for just over 1 hr exposure! Its alright, but its not a miracle worker...lol BTW: This was shot at just beyond the Rayleigh limit of the telescope (0.85" p/p)
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M81 - 36x120s (L) - shot with the ZWO ASI178MM (test camera) Rough process only - and no flats applied.... brace yourself Full frame: Crop:
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Ummm guess what? The 130 is sitting outside and collecting photons.... currently testing to see what happens when you push this telescope to its rayleigh limit
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130pds back in action!
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Ok, try removing the lens while the camera is switched on. It shouldn't break anything, though the camera will report an error. I've no experience with nikon lenses, but with canon lenses that have no manual aperture setting, that's the way I would set it (setting up with dslr, then remove).
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Try this: Attach the lens to your DSLR camera as normal, set the aperture. Turn the camera off, remove the lens.... done!
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Apologies for naff weather... just ordered another Samyang 135 f2
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Deep sky imaging showcase 2017
Uranium235 replied to Uranium235's topic in Imaging - Showcase Threads
Another year of mosaics! Rho Ophiuchi from 52 degrees North Bubble to Cave Pelican to North America IC1396 Cone to Rosette- 23 replies
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Finally, it's here! (my apologies for the delayed start of this one) Please use this thread to showcase your best images captured during 2017. Just one post per member but you can include up to 5 images if you want. The thread is for all imagers, both novices and advanced. Please keep details to a minimum - scope and camera possibly along with a few comments. The thread needs to be packed with images so please don't respond to the postings
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Running the 383 at -30... now thats a first!
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-12 tonite... brass monkey time!
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Hurrah! SII filter now arrived, time for some updates to existing projects....
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Back on my warm-up target (CTB1).... must bonkers with the Moon the way it is!
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Heh somehow I don't think you will be ditching that 130 anytime soon, you're getting some good stuff out of it! A victory for the bargain basement of telescopes
not calibrated properly yet, but its the largest M81 Ive ever put out....lol.
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