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[RCC] NGC 4565 Needle Galaxy

Russell Croman Astrophotography NoiseXTerminator Russell Croman Astrophotography BlurXTerminator Pleiades Astrophoto PixInsight Processing Request for feedback
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Illia Lukashchuk avatar
Illia Lukashchuk avatar
Hello
This is my first acceptable shot with skywatcher 130pds.

Image calibration:
40 darks, 20 flats (t-shirt and blue sky), 20 dark flats (used as biases)
Stacking: Siril with 2x drizzle
Image Processing:
All in PixInsight.
Crop stacking artefacts > SPCC > gradient correction> blurXterminator > noiseXterminator > Resample to make file less heavy > EZ soft stretch > GHS stretching to cut grey background and get more details > mask and playing with curves to increase saturation

Image:
https://www.astrobin.com/qxewjn/
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Brian Puhl avatar
Brian Puhl avatar
The only critique I have for you is to go easier on the curves/stretch.   You've gone too far and the background is clipped and it's also created hard edges on the galaxy / stars.   It doesn't feel natural.   Looking a bit closer at the image, I can tell you had flat issues… so I'd maybe go back to the drawing board on that one.

There's also a noticable amount of green throughout the image.
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Illia Lukashchuk avatar
Illia Lukashchuk avatar
Yeap, I have flat issues. There is some overcorrection or something. Tried different exposures for flats, but nothing helps. 
Thanks for your response.
Brian Puhl avatar
Brian Puhl avatar
Illia Lukashchuk:
Yeap, I have flat issues. There is some overcorrection or something. Tried different exposures for flats, but nothing helps. 
Thanks for your response.



Flats can be a pain on newts, there's always potential for light leak.    I made sure I always took them at night time using a flat panel (you can get a cheap tracing panel on amazon, they work great).   Also make sure your bias exposures are at least 0.2s long.   Taking the shortest exposure possible doesn't work well, and it will end up leaving your bias median too low.  This doesn't bode well for flats too as they can oversubtract from the light frame.    Hopefully if you can fix that, you won't feel the need to 'hide' the background like I'm guessing you did with this image.
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Andrew Ford avatar
Andrew Ford avatar
My honest impressions: 
The background looks very clean, perhaps too dark, but overall the image is decent. Colour calibration and noise/gradient control looks decent. Definitely wouldn't have made the background any darker than it currently is - you're right on the bleeding edge of clipping the blacks there. 

Subjective thoughts: 
Other than that, the image is just a bit boring - The image just doesn't "pop" much, the stars are just a bit "meh". It's too clinical. The main subject is (relatively) small in the frame and you could probaly have done at least a 30-50% crop and framed the needle galaxy differently. 

Don't get me wrong though, this is a perfectly passable image, just perhaps not attention-grabbing enough if your goal is fake internet points.
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Dave Rust avatar
Dave Rust avatar
Hmmm, I see no black clipping on a calibrated monitor. In fact, the Astrobin histogram shows the background is a bit high. Also, the gradient fall away from amorphous targets is gentle with no obvious final clipping. This is a nice image. On my monitor, it seems like needle would benefit from just a tad more contrast, but that's subjective. Nice job.
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