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I need help removing gradient

Victor Boesen

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Victor Boesen

Victor Boesen

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I am currently editing a photo from last night, and because of the sky not getting totally dark and the moon, there is some serious gradients. I can't seem to remove them, and I don't have photoshop, so I can't download gradient exterminator. What do you do? Could flats correct for such a bad gradient?

I would also really like some tips for taking flats, because when look at my flats they're not flat!

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DaveS

DaveS

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Flats won't deal with gradients.

I use AstroArt 5, it's now at 6. The gradient removal tool is very effective though you may need several passes.

Best not to try AP with a near full moon, even when it is dark.

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DaveS

DaveS

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DSS is OK (But only OK) for stacking, but neither it, nor LR are any use for post.

Have a look at AA6, it'll do your capture, guiding, stacking, and first pass (At least) post. Including pretty good gradient removal.

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SonnyE

SonnyE

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7 minutes ago, DaveS said:

DSS is OK (But only OK) for stacking, but neither it, nor LR are any use for post.

Have a look at AA6, it'll do your capture, guiding, stacking, and first pass (At least) post. Including pretty good gradient removal.

Is that Astroart, Dave? http://www.msb-astroart.com/

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happy-kat

happy-kat

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Posted

As a test you could take the stacked image and open it in the free trial of StarTools. You'll need to load the autosaved FITS file from DSS. You could use this blog to get you a quick first pass test in StarTools and whilst you cannot save the trial you could do a screen grab.

StarTools has a very powerful wipe tool.

link to blog

 

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Victor Boesen

Victor Boesen

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1 hour ago, DaveS said:

DSS is OK (But only OK) for stacking, but neither it, nor LR are any use for post.

Have a look at AA6, it'll do your capture, guiding, stacking, and first pass (At least) post. Including pretty good gradient removal.

I will have a look at it! Thank you very much for your help

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Victor Boesen

Victor Boesen

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42 minutes ago, happy-kat said:

As a test you could take the stacked image and open it in the free trial of StarTools. You'll need to load the autosaved FITS file from DSS. You could use this blog to get you a quick first pass test in StarTools and whilst you cannot save the trial you could do a screen grab.

StarTools has a very powerful wipe tool.

link to blog

 

I have looked at startools before so I'll give it a go!

thank you for your help!

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  • 5 months later...
Stub Mandrel

Stub Mandrel

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19 minutes ago, happy-kat said:

Eek I can't get them to show in PSPx7, x9 and 2018 on W10 64bit

At least it isn't just me...

3 minutes ago, jjosefsen said:

There is also a free 30 day trial of Astro Pixel Processor you could try

Not sure I want to dive into any other routes just yet. I bought PSP because I find it much nicer to use than PS.

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wimvb

wimvb

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On 2017-07-09 at 19:35, Victor Boesen said:

I am currently editing a photo from last night, and because of the sky not getting totally dark and the moon, there is some serious gradients. I can't seem to remove them, and I don't have photoshop, so I can't download gradient exterminator. What do you do? Could flats correct for such a bad gradient?

I would also really like some tips for taking flats, because when look at my flats they're not flat!

DBE in PixInsight is my "weapon of choice".

As for flats, I use a led panel from IKEA

http://www.ikea.com/dk/da/catalog/products/40332210/

I just point my scope at zenith, stop tracking and put the panel on top, with a few layers of white sheet inbetween to dim the light. Then I let Ekos/Kstars determine the best exposure time for my flats. (It targets an average ADU count of 25 000 on a scale from 0 to 65 000.) I take 15 - 20 exposures per filter.

The panel is a bit heavy, and probably best not to use it on a scope smaller than about 5".

Btw, flats shouldn't be flat. They should have the same vignetting as your light frames, such that when you use the master flat to calibrate the light frames, the vignetting will divide out.

Here's one of my flats (Red filter). On the left the flat as is, on the right stretched with STF in PixInsight. (This exaggerates the vignetting)

flats.thumb.png.1555f55a214ae458d0f85f0bc83b0ce3.png

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Stub Mandrel

Stub Mandrel

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1 hour ago, ollypenrice said:

Indeed flats certainly shouldn't be flat. If they were you wouldn't need them. The less flat they are the more you need them...

Olly

I have a really odd flat p[roblem - they are causing noise :-(

Intestingly my 58mm flats are flat when stretched so have stopped using them!

My 130P-DS ones are fairly flat but do show vignetting.

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