M51- Gonzostars version

[gonzostar]

Hello 

This image taken of M51 (heavily cropped) with some fuzzies.  This is only 12  hours of data, and the aim was also to get the faint stuff around the galaxy

Telescope - 102mm APO ES refractor on a AVX mount

Camera- Canon 450d unmoded iso800 with a Astronomik CLS filter. 

Duration 12hours   - 300s lights., Darks, flats and bias frames also taken

Guided with PHD2 and processed in PS

Of course improvement advice much appreciated  I have attatched a TIFF file if anyone fancies a challange. Lots of gradients etc ?

Autosave001.tif

Thanks for looking 

Dean

 

[Sunshine]

13 minutes ago, gonzostar said:

This is only 12  hours of data

Very nice, and "only" 12 hrs of data, sounds exhausting!

[gonzostar]

Thanks. 12 hours over the month was quite enough  Now that the Sagittarius Messier are around the corner.

[wimvb]

Nice catch, Dean. When did you collect the data for this image? Despite the long integration time, you still have a lot of noise in the background. Light pollution, probably.

There is a lot going on in the background of this image. It seems to me that your flats aren't doing what they're supposed to do, because you still have a fair amount of vignetting (upper side of the image, mainly). And at the left they seem to over correct. There is a round dust bunny on the left that is brighter than the background.

The horizontal banding is some kind of read pattern. Canon cameras can suffer from this.

The good thing is, that once these things are corrected, a few background galaxies become visible (also in your image). I'm working on your image now. Here's a quick result of the luminance data so far.

PixInsight:

• Crop
• DBE
• Noise reduction (TGVDenoise)
• Stretching

[MarsG76]

Awesome work.. love DSLR astro pix.

[tooth_dr]

Very nice Dean. It is difficult contending with the hot weather.

[wimvb]

1 minute ago, tooth_dr said:

Very nice Dean. It is difficult contending with the hot weather.

You mean: high noise imaging conditions? ?

[gonzostar]

I agree Wim alot going on. LP is a bigger issue now as the council have replaced the Na Streetlight with a LED one. So i guess the CLS is not so effective. I have a IDAS-D2 on order See that improve things. Hope the 70d hopefully isnt as noisy

Yep i put my hands up. I have replaced the flats for a couple of months now. Ooops.

Cheers

Dean

 

[gonzostar]

Yep High noise imaging conditions, look to last fow a while yet  Maybe i should reduce exposure time for the light frames

[tooth_dr]

1 minute ago, wimvb said:

You mean: high noise imaging conditions? ?

Yes Wim, the old 'HNIC' lol.  For 12 hours, this image doesn't really reflect my own experiences of imaging from a city centre using a CLS filter, purely down to temp and perhaps high cloud??

[gonzostar]

13 minutes ago, MarsG76 said:

Awesome work.. love DSLR astro pix.

They are trying to convince me to go down the Mono route  Lets see how the 70d does!

[wimvb]

4 minutes ago, gonzostar said:

Yep i put my hands up. I have replaced the flats for a couple of months now. Ooops.

Try stacking without the flats. Incorrect application of flats may actually make gradients worse.

[gonzostar]

Okay will give that ago. 

[wimvb]

2 minutes ago, gonzostar said:

They are trying to convince me to go down the Mono route

Absolutely: Go mono. This is slightly less sensitive to light pollution. At least, that's my experience. I have the ZWO RGB filterset and these have a slight "gap" between the Red and Green filters, exactly where the sodium/mercury emission lines are. As long as sodium and mercury lamps are the dominant source of light pollution, this little trick works.

But if you do colour imaging, the IDAS filter seems better than UHC. At least for traditional light pollution, it's less of a colour killer than UHC.

[wimvb]

7 minutes ago, tooth_dr said:

and perhaps high cloud??

Could be, because there are halos around the brightest stars.

[MarsG76]

7 minutes ago, gonzostar said:

They are trying to convince me to go down the Mono route  Lets see how the 70d does!

DSLRs, especially when modded, are very capable when used for imaging properly.. That said, I'm sure that mono would be a improvement, but exactly how much in the real world.. that's still what I'm to discover.

[gonzostar]

5 minutes ago, wimvb said:

Absolutely: Go mono. This is slightly less sensitive to light pollution. At least, that's my experience. I have the ZWO RGB filterset and these have a slight "gap" between the Red and Green filters, exactly where the sodium/mercury emission lines are. As long as sodium and mercury lamps are the dominant source of light pollution, this little trick works.

But if you do colour imaging, the IDAS filter seems better than UHC. At least for traditional light pollution, it's less of a colour killer than UHC.

Does that include LED lights? I agree with the high cloud comment. IDAS-D2 filter should be arriving this week, Hopefully will help

[wimvb]

1 hour ago, gonzostar said:

Maybe i should reduce exposure time for the light frames

I wouldn't necessarily do that. Instead increase the number of subs.

According to Jerry Lodriguss ( https://www.skyandtelescope.com/astronomy-blogs/astrophotography-benefits-dark-skies/ ) you need to increase total integration time by a factor of 2.5 for each magnitude you lose due to light pollution. And since you can't increase singel frame exposure time, you need to increase the number of light frames. Eg, if you have a total integration time of 2 hours at a 20.7 sky, you need 5 hours at 19.7, and 12.5 hours at 18.7.

1 hour ago, gonzostar said:

Does that include LED lights? I agree with the high cloud comment. IDAS-D2 filter should be arriving this week, Hopefully will help

LED lights have a broad spectrum; they emit light at many wavelengths. Sodium and Mercury lights have a very narrow spectrum; they emit light at only a few specific wavelengths. That's why sodium light looks orange, especially low pressure lamps. Because LED lights have such a broad spectrum, the effect is harder to eliminate. The new IDAS D2 filter, tries to minimise the effect:

https://www.firstlightoptics.com/light-pollution-reduction/idas-d2-light-pollution-suppression-filter.html (scroll down)

vs the P2 filter:

https://www.firstlightoptics.com/light-pollution-reduction/idas-p2-light-pollution-suppression-filter.html (mouse over the image)

[wimvb]

Here's my attempt.

• Removed the horizontal bands with CanonBandingReduction
• Flattened the background with DBE (Lots of large samples, so I really ironed out any detail in the background). One sample was placed too close to the star at the top, so it has a slightly darker patch to its left (Oops).
• Colour calibration using the Photometric process.
• Noise reduction on Chrominance only.
• Extracted Luminance (processed seperately; noise reduction, stretching and local contrast enhancement)
• Mark Shelley's colour preserving stretch
• SCNR on the red channel
• Colour saturation
• L*a*b combination

(click on image to get to large version)

[gonzostar]

Wow Wim thats fantastic. Its amazing that you can extract so much out  of this data.. I need lessons and lots of them ?

Ok will increase the number of subs 12hrs and just about make out the faint stull, 2.5 more subs then  The IDAS-D2 filter arrived today so hopefully will make improvemts Will have to find this canon banding removal tool

 

Thanks again

Dean

[wimvb]

3 hours ago, gonzostar said:

Will have to find this canon banding removal tool

It's part of PixInsight.

3 hours ago, gonzostar said:

Ok will increase the number of subs 12hrs and just about make out the faint stull, 2.5 more subs then 

Go for it!

[gonzostar]

2 hours ago, wimvb said:

It's part of PixInsight.

Go for it!

Will archive it and get some subs next year. M51 is onthe decline. Also want to try the summer objects in sagittarius once they clear the neighbours conservatory!