While imaging the recent eclipse i ran into some issues. My rig consisted of a ZWO ASI294 on a ZWO AM3 mount. scope was Tak60cb. SharpCap was running on an I7 NUC.
I was running "remotely" using windows RDP on an iPad. During the event, I did several screen captures on the iPad that were quite good.
But when I got home and went to process the .FITS files, they are very blown out. Nothing I have done seems to make a difference.
I've been able to crop the screen captures, so all was not lost.
Two questions -
Is there anyway to recover the FITS files. I'm reasonably certain the exposure was set too high, but the iPad displays seem to have dealt with it. What secret sauce did you sprinkle on the live images to do this ?
Secondly, what to do next time to avoid this problem ?
examples can be found here:
https://drive.google.com/file/d/1jlFo36 ... sp=sharing
https://drive.google.com/file/d/15rib6W ... sp=sharing
https://drive.google.com/file/d/17Ij8lt ... sp=sharing
Thanks
john
What's your secret sauce ?
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Re: What's your secret sauce ?
Hi John,
I can see from the screenshot that the sequencer was in action when you were imaging - I guess you might have been running some sort of exposure bracketing sequence? How many frames were you capturing at each exposure length? I would recommend a minimum of 10 for short exposures (or a 1s delay between changing the exposure and capturing) to allow the camera to change to the new exposure that it has been sent.
Delaying 1s should allow any frames of the old exposure that are still 'in flight' between the camera and SharpCap to pass by , capturing 10 frames is enough to ensure that if there are any frames of the old exposure still arriving, you would capture some of the new one too.
cheers,
Robin
I can see from the screenshot that the sequencer was in action when you were imaging - I guess you might have been running some sort of exposure bracketing sequence? How many frames were you capturing at each exposure length? I would recommend a minimum of 10 for short exposures (or a 1s delay between changing the exposure and capturing) to allow the camera to change to the new exposure that it has been sent.
Delaying 1s should allow any frames of the old exposure that are still 'in flight' between the camera and SharpCap to pass by , capturing 10 frames is enough to ensure that if there are any frames of the old exposure still arriving, you would capture some of the new one too.
cheers,
Robin
Re: What's your secret sauce ?
Thanks for the reply
I did not run a bracketing sequence - I started the sequence using auto exposure, which severely over exposed the images - 250 ms or so.. SO during the initial part of the partial phase I fiddled with exposure to find something that would work for the partial phase and redid the sequencer on the fly. I doubled the exposure - from 1 to 2 ms for the totality phase.
All seemed well, as the screen captures were coming out good.
But the FITS were a mess. I did not use the SER format as I always use FITS . My bad!
Maybe the FITS files were packed too closely together and somehow corrupted one another ?
Interestingly, the first file in the final phase - after fourth contact - shows up as a very nice shot of totality, even though it was taken - in theory - well after totality.
C'est La Vie.
john
I did not run a bracketing sequence - I started the sequence using auto exposure, which severely over exposed the images - 250 ms or so.. SO during the initial part of the partial phase I fiddled with exposure to find something that would work for the partial phase and redid the sequencer on the fly. I doubled the exposure - from 1 to 2 ms for the totality phase.
All seemed well, as the screen captures were coming out good.
But the FITS were a mess. I did not use the SER format as I always use FITS . My bad!
Maybe the FITS files were packed too closely together and somehow corrupted one another ?
Interestingly, the first file in the final phase - after fourth contact - shows up as a very nice shot of totality, even though it was taken - in theory - well after totality.
C'est La Vie.
john
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Re: What's your secret sauce ?
Hi John,
well, FITS is significantly slower to write than SER, so if you were taking lots of saved frames quickly then you could build up a queue of frames ready to be written to disk. In the worst case, if the SharpCap memory buffer fills up completely then frames would get dropped without saving because the disk is busy saving earlier frames and there is no space to store the new ones any more. Even so, I'm struggling to see how a frame captured in the post-totality sequence would show totality in that case.
Do you still have the sequence that you used that you could share? Perhaps after reviewing that I might be able to understand a bit more about what happened. The log from the session would help too!
cheers,
Robin
well, FITS is significantly slower to write than SER, so if you were taking lots of saved frames quickly then you could build up a queue of frames ready to be written to disk. In the worst case, if the SharpCap memory buffer fills up completely then frames would get dropped without saving because the disk is busy saving earlier frames and there is no space to store the new ones any more. Even so, I'm struggling to see how a frame captured in the post-totality sequence would show totality in that case.
Do you still have the sequence that you used that you could share? Perhaps after reviewing that I might be able to understand a bit more about what happened. The log from the session would help too!
cheers,
Robin