Just 1 hour of 2 min subs on the Rosette Nebula

[StuartT]

23 minutes ago, Stuart1971 said:

I think the gap between OSC and mono has definitely gotten smaller, gone are the days where people can say that mono is better, it may still slightly have the edge, but OSC CMOS is for sure catching up, you say longer imaging times for mono, but with modern CMOS MONO cameras these are far quicker than older CCD mono cameras, so what was a long job to get a good mono image with CCD, is now much much quicker…and easily doable to get a good image in one session, with three filters to get through…even here in the UK…

Like you, I have the 2600 sensor camera, and find it very good, now I have the hang of the gain and offset settings, as this was all new to me coming from a world of CCD, but I would consider the mono version too, when funds allow….😮👍🏼

 

Thank you Stuart. I'm relatively new to all this, so never knew the CCD days.

I use an offset of 50 and a gain of 105 (just after the sudden drop in read noise. Generally I cool to -15°C.

Typically I do 35 sec exposures (as I've not gotten to grips with guiding yet and that is the longest my mount can manage and still get round stars). What exposure length do you use?

[powerlord]

On 28/02/2022 at 10:59, StuartT said:

Ok, I’ve not tried that (I just use all the default settings in APP as I don’t understand what it’s doing anyway! 🤣)

so could you assign the Ha and O III to blue and yellow to get something like a Hubble image?

Luke has some good videos on how to do it in Siril and PI. And tbh you could then apply that to APP easy enough or any other tool.

https://www.youtube.com/c/lukomatico

Here's one I did of Rosette that way (shot with asi533 OSC and L-extreme):

 

 

[powerlord]

duplicate - deleted

 

Edited March 1, 2022 by powerlord

[Stuart1971]

2 hours ago, StuartT said:

Thank you Stuart. I'm relatively new to all this, so never knew the CCD days.

I use an offset of 50 and a gain of 105 (just after the sudden drop in read noise. Generally I cool to -15°C.

Typically I do 35 sec exposures (as I've not gotten to grips with guiding yet and that is the longest my mount can manage and still get round stars). What exposure length do you use?

I have the QHY version of the camera and use the high gain mode, gain 56 and offset 30, which is equivalent to your ASI on 100 gain, and was using 5 min subs, but found it was too much, so dropped to 2 mins and that is what i used for the rosette at the start of this thread, and that is with the L-Extreme narrowband filter too, so will be sticking with 2 min subs on that,  and with broadband, will probably drop to 1 min or lower depending on brightness of the object, I have bortle 5-6 skies..👍🏼

[StuartT]

2 hours ago, powerlord said:

Luke has some good videos on how to do it in Siril and PI. And tbh you could then apply that to APP easy enough or any other tool.

https://www.youtube.com/c/lukomatico

Here's one I did of Rosette that way (shot with asi533 OSC and L-extreme):

 

 

Lovely image! How much integration time is this?

(I think you have a bit of coma there. Do you have a field flattener?)

[powerlord]

that's about 3 hours on my ancient Helios 200p. I don't have a field flattener, nor was it particularly well collimated at the time tbh (you're very kind to say it is 'a bit of coma' - it's a punctuation rave on there - but I'm not much of a pixel peeper and still thought it looked good)

It was really just to show the SHO type look you can get with bicolour L-extreme images.

basic process in a nutshell:

- seperate out channels, throw away blue. lets call the remaining ones RED and GREEN.

- make a synthetic new green out of say 60% red, 40% green (we'll call this NEWBLUE)

Now you can do SHO kinda thing by merging with mapping:

L = RED

S = RED

H = BLUE

0 = GREEN

You can then  play with the blues and reds to move the lower or higher luminance of each to a slightly different colour - in PI you'd do that with curves. In affinity photo you'd do it with a combination of masking, blurring and selective colour hue changing.

 

Here's a link to @Luke Newboulds tutorial using Siril - which is free so available for anyone to try.

stu

Edited March 1, 2022 by powerlord

[powerlord]

4 hours ago, Stuart1971 said:

I think the gap between OSC and mono has definitely gotten smaller, gone are the days where people can say that mono is better, it may still slightly have the edge, but OSC CMOS is for sure catching up, you say longer imaging times for mono, but with modern CMOS MONO cameras these are far quicker than older CCD mono cameras, so what was a long job to get a good mono image with CCD, is now much much quicker…and easily doable to get a good image in one session, with three filters to get through…even here in the UK…

Like you, I have the 2600 sensor camera, and find it very good, now I have the hang of the gain and offset settings, as this was all new to me coming from a world of CCD, but I would consider the mono version too, when funds allow….😮👍🏼

 

I agree, the only thing to remember is, there's no such thing as a free lunch.

my asi1600 is 12mp. My asi533 is 9mp, but heck lets just pretend it was 12mp..

when I shoot mono, every single one of those 12m pixels is capturing L, R,G, B. Or S H O depending on how I'm shooting. I get a resultant sub where every single one of those 12m pixels is a 'real' colour pixel.

With the (imaginary 12mp for easy comparison) asi533 I have a 4 colour RGGB bayer mask. So I'm only capturing 3mp of R, 6mp of G, 3mp of B. Actually with an L-extreme you can pretty much forget about the B as it's usually trashed since it's just a noisy version of G. So I get 3mp of R and 6mp of G - which the camera/bayer mask interpolates up to be a 12mp colour image.

i.e. once debayered, it appears that I have the same 12mp colour image I get when I composite my asi1600 subs into an LRGB or SHO image, in fact, the majority of the data for each pixel is 'made up'.

Now my asi533 isn't 12mp, its 9mp. But the difference is still visible enough in lack of resolution on the same targets to see this affect isn't just a lack of 3mp - its the nature of an OSC. In reality something between 25% -50% of the resolution/detail from the same size mono camera.

You could maybe argue that IF that OSC was 12x3 = 36 mp AND had an RGB only bayer mask, that they'd be the same... though of course since the pixels woul;d be a 3rd of the size it wouldn't be the same at all.

Anyhoo - as I say - no such thing as a free lunch. I love shooting with the asi533 - I can get amazing results in a very short integration time, but the results I get with my asi1600 blows it away because of the above really. Horse for courses.

stu

[Anne S]

53 minutes ago, powerlord said:

I agree, the only thing to remember is, there's no such thing as a free lunch.

my asi1600 is 12mp. My asi533 is 9mp, but heck lets just pretend it was 12mp..

when I shoot mono, every single one of those 12m pixels is capturing L, R,G, B. Or S H O depending on how I'm shooting. I get a resultant sub where every single one of those 12m pixels is a 'real' colour pixel.

With the (imaginary 12mp for easy comparison) asi533 I have a 4 colour RGGB bayer mask. So I'm only capturing 3mp of R, 6mp of G, 3mp of B. Actually with an L-extreme you can pretty much forget about the B as it's usually trashed since it's just a noisy version of G. So I get 3mp of R and 6mp of G - which the camera/bayer mask interpolates up to be a 12mp colour image.

i.e. once debayered, it appears that I have the same 12mp colour image I get when I composite my asi1600 subs into an LRGB or SHO image, in fact, the majority of the data for each pixel is 'made up'.

Now my asi533 isn't 12mp, its 9mp. But the difference is still visible enough in lack of resolution on the same targets to see this affect isn't just a lack of 3mp - its the nature of an OSC. In reality something between 25% -50% of the resolution/detail from the same size mono camera.

You could maybe argue that IF that OSC was 12x3 = 36 mp AND had an RGB only bayer mask, that they'd be the same... though of course since the pixels woul;d be a 3rd of the size it wouldn't be the same at all.

Anyhoo - as I say - no such thing as a free lunch. I love shooting with the asi533 - I can get amazing results in a very short integration time, but the results I get with my asi1600 blows it away because of the above really. Horse for courses.

stu

That's why I use the ASI533 for starparties, I may only get an hour or two. At home I can resume images after several weeks if necessary with my permanently mounted mono setup.

I love the field of view I get with my 533, 60mm refractor with focal reducer bringing me to 288mm. Over 2 degrees field of view. You don't need as much resolution for wide field. I can get all the California Nebula  in at once.

Edited March 1, 2022 by Anne S

[powerlord]

yeh, you pretty much don't even have to stack - one 5 min sub gets you M42, or IC434, etc. It really is amazing.

[StuartT]

4 hours ago, powerlord said:

that's about 3 hours on my ancient Helios 200p. I don't have a field flattener, nor was it particularly well collimated at the time tbh (you're very kind to say it is 'a bit of coma' - it's a punctuation rave on there - but I'm not much of a pixel peeper and still thought it looked good)

It was really just to show the SHO type look you can get with bicolour L-extreme images.

basic process in a nutshell:

- seperate out channels, throw away blue. lets call the remaining ones RED and GREEN.

- make a synthetic new green out of say 60% red, 40% green (we'll call this NEWBLUE)

Now you can do SHO kinda thing by merging with mapping:

L = RED

S = RED

H = BLUE

0 = GREEN

You can then  play with the blues and reds to move the lower or higher luminance of each to a slightly different colour - in PI you'd do that with curves. In affinity photo you'd do it with a combination of masking, blurring and selective colour hue changing.

 

Here's a link to @Luke Newboulds tutorial using Siril - which is free so available for anyone to try.

stu

Thanks Stu. I'm going to see if I can do this in Photoshop (as I don't have PI)

Can I just double check that it is NEWBLUE that you assign to H (rather than what you have written)? Or have I misunderstood?

How do I create the L, S, H and O channels in Photoshop? I think that only has R, G and B channels in a colour image

(and you forgot to link to the tutorial). 

 

Edited March 1, 2022 by StuartT

[powerlord]

oh yeh sorry NEWBLUE. But watch Luke's tutorial - it's Siril - Siril is free. Once you go through it there, you can then reproduce it in PS, etc (though dunno how you blend two channels in PS as I'm an Affinity Photo guy)

 

ah I see I forgot to link to the tutorial! here it is:

 

 

 

[StuartT]

4 hours ago, powerlord said:

oh yeh sorry NEWBLUE. But watch Luke's tutorial - it's Siril - Siril is free. Once you go through it there, you can then reproduce it in PS, etc (though dunno how you blend two channels in PS as I'm an Affinity Photo guy)

 

ah I see I forgot to link to the tutorial! here it is:

 

 

 

Oh that's good. I use Siril for stacking and postprocessing too! Thanks

Edited March 2, 2022 by StuartT