Deleted
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Post by Deleted on May 17, 2020 4:24:15 GMT
Not sure what to make of undersampling. According to astronomy tools, the combination of the Rasa 8 and the imx 432 gives a resolution of over 4.5 arcsec per pixel .This is very undersampled and my stars should appear to be blocky, but they dont seem to be.
The zwo 290 mono should give a resolution of 1.5 arcsec per pixel on the Rasa and therefore better suited to that scope, but I prefer the imx 432.
Does undersampling matter for VA? cheers Paul
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Post by howie1 on May 17, 2020 7:53:10 GMT
In the ol' days with mallincams and SCB2000's no one worried about it, but now with people pretty much doing live-AP, rather than va/eaa, you hear about it all the time. CN has beginners "I'm new to this" threads where they get bamboozled by pixel size considerations before they have a clue what the heck its all about. Shame.
I've never considered it Paul, but those doing AP in my club - who are award winning - have told me they choose oversampling for nebula targets and undersampling for stuff needing finer detail like galaxies and globulars. Or maybe it's the other way around - as I never bother with arcsec/pixel considerations at all, I really dont know which way is best for one or the other. But they do as AP'ers get right into it!! And, they get into it to the point where use the under/over thing depending on the target.
Plus I've heard them exclaim out in the dark "Crap ... the seeing is so bad tonight that the stars are fatter so my shots are under-sampled!" Or maybe they said over-sampled - again I have no idea which way is which.
But my point is, again, that the AP'ers use it to suit their targets and fuss over it when seeing is good .... while the most common VA/EAA forums seem to just state the formula and optimum 1 to 2 arcsecs per pixel as if that is ALWAYS the best and what those doing VA/EAA should aim for all the time. IE I don't think they really don't understand it properly and are just worrying about it for some unclear and invalid reason.
Anyhow thats my take on it.
cheers Howie
ps glad you found that grub screw was the culprit on your HEQ5.
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Post by Deleted on May 17, 2020 9:51:45 GMT
Thanks Howie. Thats how it appears to me as well. I was just wondering what others think.Olecuss on CN talks about it all the time,but I cant see what the fuss is all about. The grub screw thing was surprising. It was loose and I couldnt tighten it at first. I noticed it had 2 washers while the other screws had one.I just removed one of them and the screw tightened up.Not sure what that was all about. I had never done anything to the HEQ5 previously so I dont know why it suddenly decided to start playing up. Just as long as it works. cheers Paul
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Post by Deleted on May 17, 2020 10:30:16 GMT
Rasa8, zwo 290, m65, 10s x18stack. The resolution is 1.5 arcsec per pixel which is about right for normal seeing
This was m65 last night with the rasa and imx432 9s x 20 stack cheers Paul
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