M33

[alan4908]

Since M33 is quite rich in H alpha emissions I decided to go for a reasonably long exposure, I ended up with 15 hours with about half being Ha.  Unfortunately, I was somewhat dismayed to discover a variety of scattered light "rainbows"  (caused by nearby bright stars just out of the field of view), one of which went directly through the galaxy !  Anyway, after a bit of fiddling in PS, I managed to eliminate the majority of the effect.  The image is a Ha L and H blend.  As always, constructive comments and criticism are welcome.

Alan

LIGHTS: L:15, R:9; G:10;B: 12 x 600s; H: 15 x 1800s. DARKS:30, FLATS:40, BIAS:100. All at -20C.

[ChrisLX200]

That's a lovely colourful rendition Alan - should have called it the Pizza galaxy

ChrisH

[alan4908]

5 minutes ago, ChrisLX200 said:

That's a lovely colourful rendition Allen - should have called it the Pizza galaxy

ChrisH

Thanks Chris -  maybe  the hot pepperoni galaxy ?  

Alan

[Tommohawk]

Well you can only really see it this time of year, so definitely not quattro stagioni (sorry!)

Lovely image, whatever the flavour!

[ChrisLX200]

15 minutes ago, alan4908 said:

Thanks Chris -  maybe  the hot pepperoni galaxy ?  

Alan

Not sure about the Blueberries though!

ChrisH

[Tom OD]

Very colourful, that is a lovely pic. 

[alan4908]

41 minutes ago, Tom OD said:

Very colourful, that is a lovely pic. 

Thanks for the comment Tom.

 

Alan

[Barry-Wilson]

Lovely M33 Alan - finely done!

[ollypenrice]

Great stuff. When deciding how much Ha to shoot it's worth remembering that only the brightest parts will end up in the final picture. This means that you can ignore low signal noise and stretch the blazes out of the rest, noise reducing merrily as you do so. The faint Ha won't be going into the final image. You don't have to think of Ha as a standalone image when processing it. It can look horrible as a standalone but still combine sweetly with LRGB.

Olly

[alan4908]

1 hour ago, Barry-Wilson said:

Lovely M33 Alan - finely done!

Thanks Barry, much appreciated. 

Alan

 

25 minutes ago, ollypenrice said:

Great stuff. When deciding how much Ha to shoot it's worth remembering that only the brightest parts will end up in the final picture. This means that you can ignore low signal noise and stretch the blazes out of the rest, noise reducing merrily as you do so. The faint Ha won't be going into the final image. You don't have to think of Ha as a standalone image when processing it. It can look horrible as a standalone but still combine sweetly with LRGB.

Olly

Olly - thanks for the comment and advice .  I wasn't really sure about how much Ha to shoot and to be honest I think I may have slightly over done the amount. 

(FYI I decided to combine the Ha through a technique recommended by Adam Block in his cosmic canvas tutorial series, which as you say involves slightly black clipping the Ha before blending with the red channel to remove the low signal to noise component of the Ha).

Alan

[nucdoc]

Wow, that is a really nice image. Ha looks great, and I love all the small blue clusters

Mark

[ollypenrice]

11 hours ago, alan4908 said:

Thanks Barry, much appreciated. 

Alan

 

Olly - thanks for the comment and advice .  I wasn't really sure about how much Ha to shoot and to be honest I think I may have slightly over done the amount. 

(FYI I decided to combine the Ha through a technique recommended by Adam Block in his cosmic canvas tutorial series, which as you say involves slightly black clipping the Ha before blending with the red channel to remove the low signal to noise component of the Ha).

Alan

Is that added in blend mode screen?

Olly

[alan4908]

1 hour ago, ollypenrice said:

Is that added in blend mode screen?

Olly

Yes it is. For comparison, I also tried the alternative blending option lighten, but I did not like the result since it looked a little artificial. 

[astro mick]

Exerllent image,beautiful job.

Mick.

[ollypenrice]

1 hour ago, alan4908 said:

Yes it is. For comparison, I also tried the alternative blending option lighten, but I did not like the result since it looked a little artificial. 

Thanks. I haven't tried this yet, though I have an Adam Block video on the technique. I use Lighten but manipulate the black point and the curve while the Ha is in situ over the red. But if it's good enough for Mr Block... etc!

Olly

[alan4908]

1 hour ago, astro mick said:

 

Exerllent image,beautiful job.

Mick.

 

Thanks Mick.

1 hour ago, ollypenrice said:

Thanks. I haven't tried this yet, though I have an Adam Block video on the technique. I use Lighten but manipulate the black point and the curve while the Ha is in situ over the red. But if it's good enough for Mr Block... etc!

Olly

Indeed.

By the way, I also used Adam Block's technique (also described in his cosmic canvas video tutorial) for removing the horrendous scattered light I experienced whilst acquiring the image - it gives amazing results. 

Alan

[alan4908]

14 hours ago, nucdoc said:

Wow, that is a really nice image. Ha looks great, and I love all the small blue clusters

Mark

Thanks for the comment Mark - I spent a bit of time fiddling around with the selective colour option in photoshop (I was attempting to make my purple stars more blue).

Alan

[PatrickGilliland]

That is a nice M33 and that Ha was worth the effort.

Paddy

[alan4908]

1 hour ago, PatrickGilliland said:

That is a nice M33 and that Ha was worth the effort.

Paddy

Thanks for the encouragement Paddy.

Alan