Andromeda 2 panels mosaic, city backyard

[alexbb]

Andromeda rises again so it's her time. Last time I shot her, it was 2 years ago from under dark skies, with 2 Tair3s and 2 DSLRs. Now I shot from under the city skies with light pollution, but with an Esprit 80 and an ASI1600MMC.

For both panels I shot 60-70x120s each RGB and 90x120s through an IDAS LP D2. The amount of RGB was significant so I made a synthetic luminance which I combined with the real luminance as 2:3. The result lum had ~1.8px FWHM before deconvolution.

I've some issues around the gradient removal, I believe the colour in some areas is shifted towards red or blue.

I still need to acquire Ha for a panel, but the forecast is cloudy for a few days and I will leave on holiday next week.

Attached are also a full resolution crop and the image from 2 years ago, but reprocessed this year.

Now back to the comet processing.

Clear skies!

2016

 

Edit:

Last version, details in the last post

.

[Allinthehead]

Lovely image Alex. Very natural looking.

[MarsG76]

Excellent looking andromeda... great work.

 

[simmo39]

v nice image!

[Kev M]

Think this is a fantastic image, I would be delighted if I got one a tenth as good as this.

Very well done indeed.

[alexbb]

Many thanks to you all, I appreciate it!

41 minutes ago, Kev M said:

Think this is a fantastic image, I would be delighted if I got one a tenth as good as this.

Very well done indeed.

Kev, for the image at the bottom I only needed a dark sky, 2 old lenses and 2 DSLRs and it was shot in a bit less than 3h. You can do the same with a single lens and a DSLR in 5-6h. That's a single night in September/October. Just don't forget to refocus.

If I was to shoot the same with the current setup, but under dark skies... ? This is not possible anyway, as I have to go to work every next day so the terrace is the only option.

[Shibby]

Excellent rendition. Very nice, natural processing - love it.

[alexbb]

3 hours ago, Shibby said:

Excellent rendition. Very nice, natural processing - love it.

Thank you, Lewis!

One more Ha panel tonight and I believe I can switch after to the 130PDS to add more luminance data at a higher resolution.

[newbie alert]

Beautiful image, as a technical question does the whispy cloud part come from the luminance?

[swag72]

Great star colours and super detail..... really natural.processing.... ????????

[Selborne]

Absolutely stunning image,

I have been thinking of moving up from my Sony A7Rii to a Pro level astro camera, but I look at the number of shots you have to take, with four different colours / filters, wow.  That is a lot of work.  The picture below is no where near the quality of yours, but it was only 20 x 30s images at 800iso, no flats or darks, just stacked (Mean) in Photoshop, to be honest noise is not a problem with the A7Rii at 800 iso, the camera has not been modified and I do not use any filters, straight out of camera as RAW's, with 14/15 stops of dynamic range at 14 bit, it gives a great deal of 'fiddle room' as long as the histogram shows the exposure in the middle.

Is the real difference in the image due to using a mono camera with all the different colour exposures etc, or is it due to the much higher number of exposures ?, how many flats / darks do you use in the stack ? just a great image.

Would be very interested in your thoughts and comments,

thanks

Jamie

 

[alexbb]

On 17/08/2018 at 21:37, newbie alert said:

Beautiful image, as a technical question does the whispy cloud part come from the luminance?

Thank you, Derek! All the details are present both in the RGB data and the luminance data. In my case, the luminance is just a bit brighter than the RGB. As I had just 3h of luminance/panel, I extracted the synthetic luminance from the RGB too and combined it with the real luminance data. On short, no, the whispy cloud part doesn't come solely from the luminance.

On 17/08/2018 at 22:06, swag72 said:

Great star colours and super detail..... really natural.processing.... ????????

Thank you, Sara, much appreciated! I've 3 more hours of real luminance taken at a dark site and another few hours of Ha. Let's see if I can blend them all successfully.

On 18/08/2018 at 21:20, Selborne said:

Absolutely stunning image,

I have been thinking of moving up from my Sony A7Rii to a Pro level astro camera, but I look at the number of shots you have to take, with four different colours / filters, wow.  That is a lot of work.  The picture below is no where near the quality of yours, but it was only 20 x 30s images at 800iso, no flats or darks, just stacked (Mean) in Photoshop, to be honest noise is not a problem with the A7Rii at 800 iso, the camera has not been modified and I do not use any filters, straight out of camera as RAW's, with 14/15 stops of dynamic range at 14 bit, it gives a great deal of 'fiddle room' as long as the histogram shows the exposure in the middle.

Is the real difference in the image due to using a mono camera with all the different colour exposures etc, or is it due to the much higher number of exposures ?, how many flats / darks do you use in the stack ? just a great image.

Would be very interested in your thoughts and comments,

thanks

Jamie

Hello, Jamie and thanks!

I believe with a full frame sensor and a larger aperture you already have an advantage compared to many imaging setups. Your Esprit 100 gathers more than 50% more light than my Esprit 80. You also can fit the whole galaxy in a single frame so you can halve the time compared to what I need to do. When it's warm outside, cooling the sensor removes a lot of noise and that's a big benefit.

From my gut feeling, the cooled mono sensor is maybe 5 times more efficient than using a crop sensor DSLR on the same scope on a cool night. On a warm night, even more efficient. But that's a feeling only, I didn't spend time to really calculate.

All in all, since you can fit all the galaxy in a frame and have a larger aperture with bigger pixels which don't heat up so much, you might be able to get close to the same result I have in the same amount of time. That's if you have the same amount of light pollution I have.

A few other tips.

Go to a dark site. That helps a lot. Compared to a light polluted sky, you can get the same result in a 10th of the time.
Increase the sub exposure duration if you can.
Shoot the calibration frames too. I usually use ~50 frames for each flats/darks/bias.
Use a dedicated calibration/stacking program. For starting, DSS is just fine and it's free.

HTH,

Alex

[Selborne]

Hi Alex,

 

Thank you for the response and information,

As you say, I will retry the shot with longer frames perhaps 240s and aim to get as many shots as possible, plus get the darks/bias etc and then use Deep Sky Stacker to try to get a better image.  The detail in your shot is just incredible, it inspires me to try harder ? 

When we get another clear night I will try to get out into the countryside for darker skies as you suggest,

Speak soon

thanks

Jamie

 

[alexbb]

I traveled during the weekend to a dark site, close to a dam in the mountains, where I managed to acquire 55x120s + 38x120s of luminance. I used the AZ-EQ5 which didn't track that good so the data went mostly to the fainter areas.

I also managed to shoot the other Ha panel. The Ha went into the image as red, lighten mode.

Attached is also a screenshot of how 3 hours of luminance under dark skies compare to light polluted images worth of 6h of luminance + 12h of synthetic luminace extracted from RGB.

When I return from holidays, I think I will put the newton for another round of luminance to enhance the finer details. Though, the FWHM of the combined total luminance was ~1.8px.

Thanks for looking!

Alex