Newbie trying to figure out StarTools,

General discussion about StarTools.
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Re: Newbie trying to figure out StarTools,

Post by Therodir »

almcl wrote: Sun Nov 15, 2020 9:34 pm First of all, non-expert disclaimer here, but while we wait for Ivo who will be able to give a much more informed opinion, here are some thoughts.

M42 is quite a difficult target, I find. There's a very bright core round the Trapezium but also some wonderful fainter detail in the outer cloud. You have captured this and I have tried processing to bring out some of both aspects, but you may find getting a second set of data with a much shorter exposure where you expose just for the trapezium and then, after separately processing this, layering it in, gives a more satisfying result.

Anyway, I loaded your data, Auto dev'd it once, binned, cropped and wiped it, then Autodev'd it again using a 'Region of interest' on the red nebulosity, used the HDR module with the reveal core preset, then shrunk the stars using the shrink module (they looked a little bit soft) used the colour module which bought out some nice colours, and the turned the tracking off. The result is below. If you want more detail (you may not!) just ask?
Oh maybe i'm not doing something right. I took 10 exposures at 4m, 20 @ 3m, 20 @ 1m and 20 @ 30s. I took the same amount of darks and 20 bias. I did not get any flats (yes I know it says they are pretty much necessary) because I can never get it right and they end up just ruining my images. Anyways I stacked all of those together. Should I be stacking them separately, as in stacking the 4m together, then the 3m, 1m and so on?
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Re: Newbie trying to figure out StarTools,

Post by almcl »

I think it would definitely be worth stacking the different exposure lengths separately - almost uniquely for this target this seems to work.
But normally settle on an exposure length that doesn't blow out the star cores and gives a histogram (if your camera and software support that) somewhere between a quarter and half way from the left.
Skywatcher 190MN, ASI 2600 or astro modded Canon 700d, guided by OAG, ASI120, PHD2
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Re: Newbie trying to figure out StarTools,

Post by admin »

Therodir wrote: Sun Nov 15, 2020 8:56 pm I took 10 exposures at 4m, 20 @ 3m, 20 @ 1m and 20 @ 30s. I took the same amount of darks and 20 bias.

Please have a thorough read of this checklist and important pre-processing do's and don'ts. There is a lot of advice there.

Also please have a look here for the correct settings when stacking and saving a dataset in Deep Sky Stacker.

Before getting into post-processing, please give yourself the best possible shot by making sure that what you are processing, is the most optimal and easiest to process.

For example, mixing exposure times is not recommended, particularly when working in StarTools. You can make a HDR composite by processing two stacks of different exposure times separately, and then combine them later. Do not, however, give your stacker multiple exposure times or frames shot with different ISO settings. It will causes noise signatures to vary all over the place and will also cause artefacts.
Therodir wrote: Sun Nov 15, 2020 8:56 pm Basically, i'm just following the tutorial and not understanding and randomly moving things hoping it will do something.
Also, as of a couple days ago, I had no idea what a dataset was. I could still be wrong, i'm assuming it is my final stacked image without any processing.
A post-processing application, like StarTools, is made to convert recorded photon counts (a dataset, consisting of a stack of multiple RAW frames) into a pleasing, scientifically valuable image. As such, the act of post-processing a dataset, is transforming something that is barely usable/visible into something that is readily visible and usable.

The most basic steps involve;
  • Removing parts of the image that are not part of the picture (for example stacking artifacts introduced by the stacker) (in ST; Crop)
  • Removing light pollution and any other unwanted constants from the signal (in ST; Wipe)
  • Applying a non-linear transformation "stretch" to the entire image, to make linear photon counts visible for our human vision (the human eye does not perceive changes in light level in a linear manner). (in ST; AutoDev)
Beyond that, many modules in ST deal with teasing out more detail, or matters of aesthetics.

If you do not know what a particular step is supposed to do or why it is done, click the Help button, which will open up your browser with details on what a module is doing, and/or Google a term if it is unfamiliar to you (e.g. "astrophotography dataset").

@almcl already gave a good introduction workflow with the dataset as-is, and if you have any specific questions or things that require clarification, please do ask.
Ivo Jager
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Re: Newbie trying to figure out StarTools,

Post by Therodir »

I'll probably just stick with DSS and have to be happy with the images I get. I basically need an ELI5 tutorial if I'm going to learn anything.
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Re: Newbie trying to figure out StarTools,

Post by Burly »

Basically after loading file and choosing Data from a one shot camera (dslr) osc ,option two button
1/ auto devo is stretching file to see what the data is like showing any anomalies such as stacking artifacts ,dust motes ,light gradients ,
2/bin data reducing resoloution info here
3/crop any artefacts from stacking multiple images /basically overlapping pixels around edge of image this effects wipe module info here
4/Now wipe module will rid data of gradients like light pollution
5/Auto dev Again this will restretch data info here
once these initial steps are done then work through modules left to right until you get to colour after that you dont need to use Superstr module (Startools 1.7} but once finished you do need to turn tracking off so after that Denoise can be done to smooth the image once thats done save file as a Jpg ,get those initial steps working other modules can be done later on once you get your head around the basic steps , take time to read guys user notes viewforum.php?f=12 very informative ,no such thing as a stupid question unsure just ask ,always try for the best data you can get and remember to take calibration frames such as flats ,bias and darks unless you dither between frames then darks not needed ,try for at least 4hrs of data the more data the better and makes processing easier to learn as you will have more signal to noise ,less noise the better , hope this helps .
A quick go of your data gave me this
m42.jpg (223.83 KiB) Viewed 599 times
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Re: Newbie trying to figure out StarTools,

Post by hixx »

you do not need the different exposure lengths at all to capture M42. As Ivo pointed out it will just create trouble. A set of different exposure length stacks will create multiple stacks with more noise each rather than 1 single stack with optimum noise and dynamics. Also it's hard to master such a dataset as there's more options to spoil it. You´ll get much more mileage using a simply but perfectly created dataset. Some hints:

1) check for the optimum ISO setting for your camera (on the homepage)
2) Use a total integration times of at least 3-4 hours (with f/5 optics) - either 240 x 1min or 60x 4 min etc. (I use 1 min subs @ f5/ISO1600). If your camera has an optimal ISO of 800, you`d do 2 min subs @f5 etc)
3) Do some 10% more subs than you need and discard the worst 10% subs when stacking
4) Keep your sensor and filters absolutely clean - whatever sits at the end of your imaging train will give you the nasty blobs which spoil your data
5) Create flats by all means! - If you dont like to create these in the field, use a rainy boring sunday to do 'vignetting only' flats at home at least. These will give you a much better Wipe result.
6) Use Dark Flats with the same Iso/Exposure time than flats.
7) The noise of your calibration frames will ADD to the image, so the less noise your Calib masters have, the better the end result. For Flats and Dark Flats I´d suggest to take at least 30, better 60 if shot at low ISO (100). If shot at normal ISO, take 100. For Darks @ sub-ISO take as many as you can (some when preparing the scope, some when dismantling)

The long integration time without overexposing will give you extra headroom at the low dynamics end - it is the key to a clean and useable dataset. Sorry, it is just photon counts that really matters and the ONLY factor to really increase this count is time.

Then just do a regular simple stack as described in the DSS settings in the tutorial section, stick to the basic ST workflow (drawing on download page) and you'll get stunning results even with mostly preset settings. Of course you can stick to DSS or other simple tools but these will not pull the most out of your data

clear skies
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