Confusion over file location and nomenclature

[PetePeterson]

After 4 months I’m still climbing the learning curve for using a new ASI2400MC Pro and SharpCap 3.2 Pro. Right now I’m having issues with a couple of things that could be better addressed knowing how to juggle flat files. Could somewone give me some guidance please?

Right from the start I haven’t been able to figure out where the desktop SharpCap Captures desktop shortcut actually stores files. (Think it’s at C:\Users\Pete\desktop\sharpcap captures.) Needing it to be readily accessible a dedicated folder was created and captured files are set to save at C:\0 SharpCap Images with sortable date and subfolder options selected. And this works fine except for my confusion over flats.

When capturing dark frames the capture routine allows a choice between Dark Library and Capture Folder. Selecting Dark Library and running 15 second darks, darks load to C:\0 SharpCap\Images\Darks\ASI2600\RAW16@6248X4176\4\15s. I can identify the darks and work with them.

Flat files are my problem. There is no flat library option. Flats load into the Capture Folder for the current date.

Here are the four flats for 1X 2X 3X & 4X binning run Nov 24. Except for the file size there’s no indication of which is which. Or if there is a more current flat.


Back on the SharpCap main screen:


At first there was nothing under the drop down. And browse only showed the old flat from Nov 20. I had to go searching and know that the correct flat was taken on Nov 24. When I selected it and held the cursor over the box next to Browse the new selection showed itself with more detail that the windows files did. But there’s still no indication of what bin mode is selected.

Can someone please help me get my head straight on this? I find this very confusing and am undoubtedly overlooking something.

[admin]

Hi,

my usual experience has been that you don't save and reuse flat frames in the same way that you do for dark frames – there are a couple of reasons for that:

1) flat frames are much quicker to take since you can take them with short exposures
2) any adjustment to the optical side of things means that need to redo your flat frames – that includes removing and replacing the camera, rotating it or even adjusting focus.

That means that the expectation is that you capture your flat frames immediately before the capture of your actual images – in which case the fact that the newly created flat frame is automatically selected for you means that you don't really need to worry about where the frame get saved.

I can see a couple of points of interest though for improvement – firstly it's currently not possible to use the binning level as part of the filename template, which would be a good thing to add. Secondly the filename template parameters may not get filled in correctly when creating flat frames, which would again be something that is worth correcting.

Cheers, Robin

[PetePeterson]

Guess I'm unusual in that I do T shirt twilight flats rather than using a luminescent board. Can't fit a board into the observatory.

I'm running a Meade 14" and minor temperature induced focusing adjustments have never been a problem for my flats in the past. So my camera setup is left alone for weeks at a time. The only thing that may change is binning. Am I wrong about needing different flats for 1X, 2X, 3X and 4X binning?

The work-around being used is to copy the stacked flat field out of the capture date file into a separate flats folder where it's renamed in descriptive detail.

Haven't had the ASI2600MC Pro all that long and although my flats are being applied they are very bad. So a primary reason for carrying several flats is to enable experimentation. A secondary reason for being able to identify flats is to use them in other processing. The stacked processed displayed SharpCap image only saves in a PNG format that I'm not familiar with and can't convert to FITs. And I'm not aware that the stacked unprocessed FITs file and the individual frame FITs files save without having darks and flats applied. So it's necessary to identify darks & flats so that they can be used in situations where I want to completely process the unstacked individual frames in other software.

While this is off topic, Is it possible to somehow save the displayed stacked stretched image in FITs as well as in PNG?

Pete Peterson

[admin]

Hi,

You will definitely need to collect the four different sizes of flat frame for different binning levels. Remember to either check the checkbox to allow SharpCap to take bias frames or to use a dark flat when capturing your flats otherwise the flat correction will less than optimal. Note that when the capture of the flat frames are complete, the filename and path of the created flat frame are shown in the green notification bar at the top of the SharpCap window. You can click on the filename to open the flat file automatically and also click on the folder name to the left of the filename to open that folder.

The reason that you can only save the image as seen on the screen in PNG format is that the final image that is displayed on screen is only at a bit depth of eight bits of colour depth. This means not only is there no point in saving in fits format, but in fact fits support for 8-bit images is pretty dodgy and a lot of applications, so is best avoided if at all possible. PNG files are lossless, so you don't lose any image information by saving them that way.

Cheers, Robin