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I've created my own darks library for my ASI1600mm Pro. Various gains and various exposure times all at -10 Celsius.
I'm just wondering what people do with them? Once you've taken darks and processed an image you get your master darks.
Do you guys just keep the master dark, in a master darks library, or do you process your darks again each time you stack a new image?
I'm just thinking to save storage, could I discard the dark sub frames and just keep the masters? I don't want to throw them away if that is wrong though.
Also, with this camera I take dark flats rather than bias frames. Because the scope is covered, do I need to do dark flats each time I take flats?
I have an even illuminated flat box which I always use at the same exposure lengths. I guess the only thing that could vary is the gain value.
I understand the need for flats every time you change focus, for each filter etc., but if I'm using the same exposure time can I just use a previous set of dark flats as long as the camera settings are the same?
If this is possible, can I then create a dark flats library for any difference in gain values? Not sure if I gain values affect dark flats though.
I've read that back, and that's a lot of questions! All help greatly received.
I've finally got around to making my flats box.
I decided to go for a cylinder rather than the normal square as I thought it would maximize the amount of reflected light and limit any 'dead' areas. I could also use the Celestrons dust cap retaining pins to lock the flats box onto the 'scope.
I purchased some of the craft board that has a thin foam sheet sandwiched between two sheets of thick paper/thin card. In order to bend the card into a cylinder, I creased the board every 20 mm by pressing the edge of a steel ruler into the board. It took two of the sheets to make a cylinder big enough to fit my C9.25, with only a couple of cm trimmed off.
I then made a reinforcing ring/defuser holder from two strips of the foam board; this time creasing them at 15mm intervals. I stuck these level to the bottom edge so the joins were 90° to the main cylinder joins. These strips were cut wide enough to ensure that the diffuser cleared the secondary housing.
The cylinder was designed to lock into the C9.25s dust cap retaining pins so next I cut two keyways into the bottom outer side. They looked a little weak so I reinforced them with some Christmas chocolate reindeer plastic packaging!
Although the foamboard is quite shiny, I wasn't happy with all the grooves, so I lined the inside with white A4 paper. The Perspex sheet was cut to shape and hot glued into place onto the ledge.
Next, starting at the top, I notched the edge of the cylinder to run the LED string lights cable through and then started to spiral the LEDs around and down the cylinder.
The top cap/reflector was made from two discs of foamboard. One to go inside the cylinder and one to sit proud of the edge. They were glued together before being hot glued onto the top of the cylinder. The LED light string that I bought has an integrated on/off button as well as both up and down brightness buttons with a 3M sticky pad on the back, so I stuck this to the top cap.
As I had previously made myself a 'scope mounted power distribution box with aircraft sockets for power, I removed the 3 pin UK plug/ac-dc converter and soldered on an aircraft plug to match my 12 volt DC supply socket.
The lightbox illuminated.
I shot this over 6 nights. We had an amazing go of clear nights in a row. Now it's all rain until next week. But while it was clear, I managed two nights per filter on my newest scope. A total of ~ 760 3 min images. I think the total imaging time was 37.8 hours. Shot it through my newest scope the RedCat 51mm. It did well, but could have used a belt focuser. I managed to get one together from Moonlite, but only just after imaging this. The scope was able to hold focus a good bit of the night, but the quality curve looked like a swan dive towards the end as the scope lost focus at the end of the night each night. I got out my old trusty AVX to manage the aiming parts of the setup. Guided by an old Orion SSAG I had lying around and a recently acquired ZWO Mini guide scope since it matches the RedCat so well. But I think I'm going to need to swap out the guide cam for something with smaller pixels. Overall though, it worked. Main camera was ZWO ASI 1600 MMC. I used 5nm Astrodon filters.
Hi All, I am posting what I suspect is a newbie mistake question but hoping that someone can assist with the issue of flats.
Although I have been fumbling around the sky, taking snaps at leisure, recently I became serious. I have read up about the different calibration files (flats, darks, bias) and they seemed to make sense; different ways to capture the image defects and extract those from the image of the sky. After a few weeks (months) of further fumbling I went back to the very first target to receive my attention, M42 Orion Nebula.
In short, I took 20x 30s exposures in LRGB and ran these along with 20x LRGB each of darks, bias and flats. To obtain the flats I used a diffuse sheet of perspex (lightbox material) and an LED video lamp that has 180 white LEDs, turned to its lowest setting. Attached below is the stacked Luminance flat and the light image. In the lights I am getting very strong marks from dust and I had thought that the flats would subtract this but looking at the flats the marks are completely different shapes and do nothing to remove them from the lights.
The attached has been further stretched to show the issue. Now, I am obviously doing something wrong but I have no idea what, any pointers from the vast pool of knowledge will be much appreciated.