Quote:
Originally Posted by Startrek
Stephane,
Goto , framing and focus are excellent as this object is a tough one to attempt.The bright star Alnitak has a double diffraction spike on one side due to one plane of your spider vane slightly offset from centre. From my experiences with newts I’d say one screw on one side is screwed in too tight pulling the opposing vane upward slightly. When you get time you can test on a bright star and make tiny adjustments until it’s perfect. Before that have a visual look at the spider vanes to see if you can see an offset on one side. If your not confident, just leave it , the double spikes will only appear on the brighter stars ( if any ) in your images.Yours is not that bad I’ve seen worse.
Image is great for a first attempt but noisy.
Did you use calibration frames ? (At least darks )
How was your guiding ?
We’re conditions humid last night ? Your DSLR could have been running quite warm +25deg ( thermal noise ) which also adds noise
We’re seeing conditions good, nice and stable or poor ?
From the info I have , the Nikon D7000 when used for Astro has a sweet spot at ISO100 and ISO200 ( high dynamic range) What setting did you use ?
For a DSLR with short exposures and OSC NB filter, a great effort
Well done !!
Martin
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Hi Martin, thanks for the feedback. I will have a good look at the spider vane. Should be a reasonably easy fix. The night I took the shots, it was indeed about 25 degrees (got bitten to death by mosquitoes - added mosquito repellent to my shopping list). I used 20 darks, 20 flats, 40 biases, but still very noisy. Either my camera does not like the heat, or I am not doing my darks properly, or both…
Guiding was again fabulous at total < 0.6. I haven’t changed any settings, but it looks like it’s improving from one night to the next.
Seeing conditions were okay, on the humid side though. ISO was set at 800. I have since seen your message re 100 or 200 and will try that next time.
I am currently studying denoise techniques on Youtube and will see if they make any difference. From what I’ve seen so far though, is that they make only incremental improvements and that calibration frames are by far the best way for reducing noise. It will be interesting to see if noise is reduced on cooler nights.
Thanks again,
Stéphane