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My set up is relatively new and I'm dabbling with some things while I impatiently wait for the clouds to clear and the skies to get a bit darker. I took 10 x 120s images of M31 last weekend and I've stacked them and tried to run them through StarTools. I've attached a couple of screenshots to show what the FTS file looks like and then how it looks once I hit the AutoDev button.

When I compare the AutoDev outcome that I get to a YouTube tutorial it's nowhere near where I'd like it to be.  Is it simply because I only used lights and there are only 8 images that have been stacked?

 

M31-01.jpg

M31-02.jpg

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Autodev at the outset is intended to show up problems within the image. 

Crop (if necessary) followed by bin (again if required) then wipe, using which ever preset is appropriate, then a further autodev or dev and then the rest of the modules as required in the order shown in the video here: https://www.youtube.com/watch?v=IDY3ov2dQe4

Your data looks (although it's hard to tell from just the screen shots) as if you might well have some stuff there once the colour cast is removed.  

 

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Yes autodev is great to show how much to crop then if my data is thin I'll cancel them go crop then bin 50% then wipe then manual develop then colour as a first pass of what I've got.

There are preferred settings to follow for getting the best from DSS for then using in startools, I don't have the link to hand but basically don't select align rgb boxes.

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Thanks folks. It was clear last night so I now have (what should be) better data to work with. I have a .FTS file that is 24 x 120s stacked images and I'm hoping there's something worthwhile hidden away in there!

I'll try it as per that YouTube video and see how it goes........

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Posted (edited)

Well here's a screenshot of what I got from last night's data and it's fair to say that it aint good. It looks like someone has taken a sander to it! Any pointers on where I'm going wrong would be appreciated. The images were taken using........

SW Esprit 100ED, SW HEQ5 Mount, Flattener (which is brand new and the first time I've used it), Modified Canon 600D, 24x120s and ISO800.

I also have a decent .FTS file of M42 from last February so I'll run that through StarTools as well and see how it comes out.

M31StarTools.jpg

Edited by Mikey07

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Posted (edited)

This is the workflow I use for DSLR; for other cameras I adjust the Wipe params (e.g. Aggressiveness 83%, Drop-off Point 50%).  I don't think your result is caused by 'Canon banding' but if so, there are ways of fixing this.

STARTOOLS EXAMPLE WORKFLOW

Command

Action

Params

Notes (for DSLR imaging)

Open

Open the stacked image from DSS (ideally from fits format)

 

Use left option on opening - DSS actually does some white balancing which can't be disabled

Bin

Scales down pixels and noise and reduces subsequent processing time

50% (default)

50% converts each 2x2 pixels to 1 pixel

AutoDev

'Digitally develops' the image - stretches it to show faint signal and issues to be addressed

Drag RoI around target

Will probably look horrible but this shows you the worst of the image that the processing will fix

Crop

Discards unwanted border around target (and stacking artefacts)

Drag area to be left

Best to eliminate worst of gradients, vignetting, etc around the edges

Wipe

Removes light pollution, gradients, vignetting and colour casts

Drop off point 0%

Say Yes to Temporary AutoDev as well and maybe a few pixels of dark anomaly filter

Dev

'Digitally develops' the image - stretches and applies curves

Re-do global stretch

Use "Home in" or manual % to stretch until best compromise achieved (detail vs. noise)

(Decon)

Compensates for atmospheric distortion (e.g. tightens stars)

2 pixels

Optional - set Mask manually first using Clear, Auto, Stars, Do, Shrinkx2, Invert, Keep

(Sharp)

Sharpens the image using wavelets

 

Optional

(Contrast)

Increases local contrast

 

Clear mask from Decon beforehand (Mask, Clear, Inverse, Keep)

(HDR)

Optimises dynamic range - replaces manual curve manipulation

Choose algorithm

Optional - apply algorithm to suit the target - e.g. Tame, Reveal, Optimize, etc

(Life)

Brings back life into an image by remodelling uniform light diffraction

Moderate

Optional - not sure how natural this action is - may border on artistic licence!

Colour

Adjusts the colours of the image (e.g. compensates for modded DSLR)

Fill mask if not already

Can adjust to suit - presets for scientifically accurate or artistic (latter can seem more natural!)

Filter

Modifies features in the image on the basis of their colour

e.g. Ha

Can boost nebulae

Track

Switch off tracking in top menu to reduce noise and finish image

10 pixels?

Initial example screen makes it look as though everything will end up fuzzy, but it is selective

Save

Save resulting image to storage

Need to put type e.g. TIF

Not supported in trial version

Key commands are in bold

   

N.B. Can re-do the AutoDev (or manual Digital Dev) any time before tracking is switched off and it reapplies the other changes made

Edited by prusling
Corrections
  • Like 1

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Thanks for that. I'll try that on my M42 image before trying M31 again.

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Posted (edited)

Here's what it did with the images. M42 was taken last February using my 8" reflector and M31 was last night with the SW 100ED Triplet. Clearly one is much better than the other!

The M31 image is much improved but there's still very little detail.

 

M31 andDarks.jpeg

M42 andDarks.jpeg

Edited by Mikey07

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When using wipe do use the mask tool on any dubious areas. See if there are any to remove from your image. Did you take flats?

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The key to processing is good Data , take time to get darks and flats  get the latter two and you’ll start to see a difference and more data the better .

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The better-calibrated the image (darks, flats, etc) the more you can stretch it to obtain fine detail; my crib sheet for calibration frames is below (any comments very welcome).  Darks are pretty well essential with a DSLR, especially at this time of the year; also it is best to turn off LiveView when imaging as that adds to the noise.  I also cover the optical viewfinder to avoid stray light entering.

I judge the exposure time and ISO according to the darkness of the skies and the camera.  I have a Canon 550d (precursor to your 600d) and use 1-minute subs with ISO800 in dark skies and the same exposure with ISO400 in light pollution at home.  This means that you can afford to discard poor images and use a sigma clipping algorithm when stacking to eliminate outlier pixels giving a cleaner image.

Lights

Darks

Flats

Dark Flats

Bias/Offset

When

 

Before/after or can use a dark library

Ideally every session; can be next day

Optional if using Bias

 Occasional

Number

The more the better

20+

25

20+

50++ (> Darks)

Format

RAW

RAW

RAW

RAW

RAW

Optical Setup

 

Capped

Exactly the same as lights

Capped

Capped

Temperature

 

As close to lights as poss

any

As close to flats as poss

any

ISO

400 (LP) or 800 (dark sky)

Same as lights

Same as lights

Same as lights

Same as lights

Exposure time

Can vary with tracking / guiding, I normally use 1 min when tracking but not guiding

Same as lights

AV mode until 50-70% histogram then set manually

Same as flats

Shortest e.g. 1/4000 sec

Lens F Stop

Widest / 1 click or more back

any

As used for lights

any

 n/a

Lens Focus

LiveView x 10 on a bright star / distant target

any

As used for lights

any

 n/a

Stacking algorithm

Kappa-Sigma if >15 frames otherwise Average

Median

Median

Median

Median

 

 

 

 

 

 

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Thanks everyone. That's this weekend's project sorted if skies are clear!

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On 19/08/2019 at 01:50, Mikey07 said:

Well here's a screenshot of what I got from last night's data and it's fair to say that it aint good. It looks like someone has taken a sander to it! Any pointers on where I'm going wrong would be appreciated. The images were taken using........

SW Esprit 100ED, SW HEQ5 Mount, Flattener (which is brand new and the first time I've used it), Modified Canon 600D, 24x120s and ISO800.

I also have a decent .FTS file of M42 from last February so I'll run that through StarTools as well and see how it comes out.

M31StarTools.jpg

AutoDev serves a dual purpose; first it is used to show any defects in your image, then it is used to perform your final global stretch after you have mitigated the issues you found earlier.

In the above image, we can see gradients, dust donuts and (rather severe) walking noise. Flats are the #1 way to improve your image (and processing enjoyment! 😀), with dithering between frames a close 2nd (this solves the walking noise issue). They are really not optional and they don't really cost anything, except some time.

Also don't forget you can (should) click and drag a Region of Interest for AutoDev to optimize for (by default the RoI is the entire image). In the case of the image above, a slice of M31, including its core would constitute a good dynamic range sample we'd be interested in.

There are also cases where AutoDev simply cannot lock onto celestial detail. These cases usually involve heavy noise and/or lots of "empty" background. The latter can be solved with an RoI. The former can be solved by increasing the "Ignore fine detail <" parameter, which makes AutoDev "blind" to small noise grain. If you cannot fix or work around the calibration/acquisition issues in your dataset and cannot obtain a good result with AutoDev, you can always resort to a manual Develop.

As bottletopburly already highlighted though, post-processing becomes infinitely easier and repeatable when you have "good" data. I'm putting "good" between quotes here, because it just means "properly calibrated". It doesn't have to be deep, gradient free or noise free, as long as it has been dithered and properly calibrated with - at least - flats.

Hope this helps!

  • Like 3

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There are 4 dust bunnies I'd have masked out when doing autodev and the aircraft line.

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I'm pretty sure I've got good data from last night's crack at the Witch's Broom. 90% of 186 x 30s Lights plus 40 each Bias, Flats and Darks all stacked in DSS.

AutoDev is much better but the finished article isn't! Will keep plugging away at it.

 

NGC6960AutoDev.jpg

NGC6960Finished.jpg

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This is much better, more through trial and error than anything else!

NGC6960FITS1.jpeg

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