Hello,
New to SGP, I’m trying to figure out the best process for doing flats (I have an Alnitak Flat field) at the START of a sequence. Indeed, the ideal would be to park with the scope in vertical position using the Park command. However, I understand you cannot start a sequence with a Park position. So how do others go about doing this. Do you point to a star at the Zenith and stop tracking separately via the mount controller ?
Thank you
We might be able to look into leaving the mount parked until the first light frame is encountered (as opposed to unparking when the sequence starts).
Most people seem to use devices like yours at the end of a sequence.
Just as a thought, I set up as separate sequence for flats. It contains all the exposures and brightness settings for my Alnitak. Whenever I need flats, I just reset all the progress in the sequence, then tick off whichever filters I used that night.
You could manually slew to the proper orientation to balance your Alnitak, then stop tracking and run the sequence.
I am lucky in that my son has a 3d printer and printed me a case for my Alnitak that slips over the end of my dew shield. With that, the Alnitak will hang at lots of angles, including from park position.
One other thought is that you could just leave the mount out of your flat sequence. Then it wouldn’t have to be unparked for the sequence to run. I haven’t ever done this with flats, but I run a sequence to take bias and dark frames in my office where nothing but the camera is connected.
So you have some options to figure out what is best for you.
Best regards,
Craig
Thanks, good ideas. I hadn’t realised you could do one sequence with a profile where the mount is not connected for your flats (or using the simulator ?), then set-up a new sequence with different profile and unpark. In any case, if there is an elegant and simple way to do this (including in a future release) that would simplify things. My main concern is getting something wrong and having the mount move when the flat field is on the top.
Sorry for cutting into ppl Posts but when i saw the word Flats it caught my attention, yesturday i used the Flats wizard in SGP for My DSLR, everything seemed to go well with my light box. then it saved it to my M101 event…So now how does that help the imaging sequence of other targets…i mean how does it apply a flats frame to all other target/events, it seems strange to me…i though it would make me some CR@ flats i could use on my laptop in Nebulosity4???
Mitch ( Lost in SGP land)
Just thought I would add how I handle flats.
I make a separate sequence for them, actually two sequences one for no binning and another for 2x2 but I digress.
I build a flat library and store them for later use. I am very carefull to keep the optical train in the same orientation each session so the flats can be used over and over unless something changes (like a new set of dust motes) or I rotate the camera 90 degrees or something.
I make a set for about 30-40 each filter with no binning and another set for 2x2 binning.
It is kind of a pain with the ATIK383L+ as the light source has to be pretty dim but flat. I shoot for a minimum of 1.5 seconds due to the ATIK’s shutter. T shirt method wont work here. It ends up being like 1.6 seconds for the lum frames and nearly 11 seconds for the blue with the other channels being somewhere in between. I let the calibration wizard figure it out once I am in the ball park for the shortest (lum) frames.
I shoot the flats on cloudy nights, why waste time shooting flats when you could be imaging 
As I understand flats, stacking more than about 10 is overkill. Since they are exposed at about 50%, stacking does little to reduce noise. On the other hand, flats are sensitive to minor changes in the optical chain (eg dust, orientation, focus, etc.). So building a large static library as proposed here is at cross purposes to both these facts. My understanding is it is best to take a small number (e.g. 10) of flats every night you shoot.
Well your half right.
Flats are actually not ‘considered’ at least by DSS when it comes to noise and hot pixel reduction. That’s what the darks ane bias are for.
Flats are considered for mitigation of vigeneting, and dust motes, spots, etc.
I typically match the number of flats to the number of light frames. So if I have 15 light frames I use around 15-20 flats, and other calibration frames. I keep librarys of 30 or so for each color channel so I will usually have enough. Darks and bias are even more extensive with different durations, temps, binning etc. I shoot the dark calibration files with the camera off the scope inside a darkened cool room on cloudy nights 
As long as nothing has really changed in the arrangement of the optical train and its orientation you CAN use the same flats over and over regardless of target, duration, etc.
No need to shoot flats every night you shoot.
I have been successfully using librarys for darks, flats, and bias files. The library gets updated about 3 or 4 times a year unless something changes.
The results speak for themselves 
