NEW SeeSTAR S30 Pro User Here

Can't see where to get notifications so replying. I am an S50 and S30PRO user. I uploaded some Seestar files when I couldn't get them stacked for Mabula but I never got any notification he'd replied.

David (@dpfaulk61)

The forum is a bit quiet at the moment, but I expect it will liven up when Mabula releases the next beta.

I've never used a SeeStar, but I can give you a brief introduction to using calibration frames.

Darks are used to correct anomalies in the camera sensor - mainly hot and cold pixels and amp glow (in older sensors), Flats are used to correct some anomalies in the optical path, such as lens vignetting or dust on the sensor, Darkflats are needed to mathematically adjust the data from the flats so that they can be correctly applied to the image.

I'm assuming that the SeeStar will give you access to the raw, unprocessed frames. If that is not true then most of what I will say below will probably be useless.

Darks

These are basically just images taken with the same settings and conditions as the lights, but with the lens cap left on. If the lights are 30 sec exposures then the darks should also be 30 sec. If there is a gain or offset setting available these should match the lights. Ideally the temperature should also match. I believe the SeeStar uses an uncooled sensor, so the darks should ideally be taken on the same night as the lights. Take about 20 - 30 exposures (I usually take 30). It is important that there are no light leaks into the camera.

There is a recent view that a modern sensor with aggressive dithering does not need dark frame calibration. My view is that they are easy to take and should always be used.

Flats

These are images taken with a uniform light field giving about 50% illumination at the sensor. There are several ways to do this, but I would recommend getting one of those cheap light panels that artists use for tracing. Point the SeeStar straight up, put the panel on top and adjust brightness and exposure time until the histogram is about 50%. If the SeeStar does not have a histogram function then you will need to experiment. Start with the panel at its lowest brightness setting, set the exposure time to about 2 secs and take 20-30 exposures. Check them back at the computer - anywhere from about 25%-75% illumination is probably ok.

Flats can be done the next day - the temperature doesn't really matter. With modern sensors it is important that the exposure time is not too short  - at least 1-2 secs is ideal.

Darkflats

These are images taken with the same settings as the flats - but with the lens cap on. Exposure time, gain and offset should exactly match the flats. Take about 20-30 exposures.

You will see (especially in older literature) that some people recommend bias frames instead of darkflats. My experience is that darkflats will work with all sensors, but bias frames do not work with some modern sensors. I recommend darkflats, but if you decide to use bias frames remember that they are used instead of darkflats - not in addition to darkflats.

Once you have all the frames just start APP and load the lights, darks, flats and darkflats into tab 1)Load, then go to tab 5)Normalize. Hit the 'normalize lights' button and APP will perform calibration, registration and normalization. If there are any data errors they will need to be corrected. If not then the analytical graph will allow you to check if there are any bad frames (clouds etc) that should be deleted before integration.

The calibration step will produce a MasterFlat, MasterDark and Bad Pixel Map (BPM). These are reusable, and can be used in place of the darks, flats, etc, if the conditions are unchanged. I reuse mine for months - sometime years. However, with an uncooled sensor you will probably want to do new darks for each session so that the temperature matches.

I hope this all works for you. Learning to use calibration frames is one of the important steps in astrophotography.

JC

@connor231 thank you so much for the thorough reply. After doing some online searching, I found that the Darks and Flats the S30 Pro produces are not available to the user. They are pre-built into the output. I did find the following last night on Gemini:

1. Open Astro Pixel Processor.
2. Go to Tab 0) RAW/FITS.
3. Locate the Bayer / X-Trans CFA patterns setting.
4. Set the pattern to GRBG (the default pattern used by the Seestar S30 Pro's sensor). [1, 2, 3]

1. Go to Tab 1) LOAD.
2. Click the Light button.
3. Navigate to your Seestar sub-frames directory, select all of your individual .fits light files, and load them.
4. Leave the Flat, Dark, and Bias file sections empty. [1, 2, 3]

1. Completely skip Tab 2) CALIBRATE.
2. Go straight to Tab 3) ANALYSE STARS.
3. Click Analyse Stars at the bottom of the menu to let APP map the stars across your individual pre-calibrated sub-frames. [1]

1. Go to Tab 4) REGISTER. Click Start Registration to align your frames.
2. Go to Tab 5) NORMALISE. Click Normalize to equalize the background brightness and control gradients across your exposures.

• Note: If you are combining data across multiple separate nights, you can use APP's Multi-Session processing feature by assigning frames to individual session folders during the initial load step. [1, 2]

1. Go to Tab 6) INTEGRATE.
2. Adjust your Composition boundary mode (such as setting it to Full to keep the wider outer edges resulting from field rotation or imperfect tracking).
3. Choose your quality filter (e.g., setting Lights to Stack to 90–95% to discard frames with passing clouds or severe tracking glitches).
4. Click Integrate at the bottom of the screen. [1, 2, 3, 4]

David (@dpfaulk61)

Interesting that the SeeStar doesn't allow access to the raw images. Perhaps that will come with a future firmware update.

The workflow you found looks fine to me, I have a few minor comments that you can feel free to ignore if you wish.

1. You can load the 'precalibrated' frames in tab 1 and then go straight to tab 5. You don't need to do the individual steps unless you want to (or unless you are doing something more complicated - like a mosaic registration). APP will automatically do the intermediate steps (although the calibration step won't change the data without calibration frames).
2. If your setup is unchanged and you are loading 'precalibrated' frames you do not need to use multiple sessions unless that is more convenient. When I shoot with a colour camera I usually combine data from multiple nights into a single session - it works fine.
3. Because of field rotation and dithering you final image may have some lower quality regions around the edges. Enabling 'Multi Band Blending' (MBB) in tab 6 will help reduce this. Try it at 10%-15%. Of course you will still probably want to crop the image a bit.
4. If there are varying illumination levels, eg where the data comes from several nights and there is some moonlight, then enabling 'Local Normalization Correction' (which is different to 'Local Normalization Rejection') can improve the image somewhat, although it does slow down the integration. Try 1st degree, 3 iterations.
5. After the stack is integrated, but before saving the stretched version, definitely go into the tools menu and use the 'remove light pollution' and 'calibrate star colors' tools. These are excellent tools and I use them all the time. One trick is that after using the first tool you need to select its output file before applying the second tool. I'm not sure why this doesn't happen by default.

Good luck

JC

Thanks again, John, for your input. I finally ran a few stacks through APP this evening, and the workflow has changed from what I listed previously. It's nothing major, and I think I figured it out, but it is different.

Here are two of my photos from the other night. The first is of M81 and M82. 1. The first photo is the processed final from the S30 Pro. 2. The second is running the stack of photos through APP using all the settings as is, and the third 3. is the APP image with Noise Exterminator applied.

The other image is of NGC-7000. 1. The first photo is the stacked image out of the S30 Pro, the second 2. is after applying APP, and the third 3. is after applying Noise Exterminator to the APP image.

Is there somewhere I can get details on what all the settings mean and which I should be adjusting, etc.?

David (@dpfaulk61)

Congrats on your first stacks. I can't see any of those targets from my location - I'm too far south (Australia).

I believe Mabula has been working on a manual for some time, but its not available yet.

APP has been designed so that it will generally work well with the default settings. Just remember to sometimes reset the menus so that you know you are using the default settings. Beyond that I think most of us have learned by reading the tooltips and asking the occasional question on this forum.

For questions relating to astrophotography theory the Cloudy Nights website is quite good, although there is a bit of a bias towards Pixinsight.

JC