Two hours with the crab

[wimvb]

While waiting for the main target to get into view, and my "Astrofest" buddies to arrive, I collected subs on the crab nebula.

(click on the image to get to the full size version)

Gear as per my signature.

Capture details:

• Gain: 75, temperature: -30 C
• 30 x 30 s each of RGB
• 30 x 120 s Ha (astronomik 12 nm 1.25")
• 2 x 30 darks, 30 flats and 30 dark flats, no bias frames

Total ingegration time: 1 hr, 45 mins

The Ha master still has a lot of noise, which gives the image a slight reddish background. This is especially visible in the lower right corner, where amp glow is at its worst. While darks remove the glow, they don't remove the noise that comes with it. This target would need more data, but unfortunately it's disappearing behind a tall hedge.

[stepping beyond]

Wim , That's showing those skills . I really enjoy the look of the nebula and the detail you pulled . The stars are very nice, that's eye candy for sure ! Awesome 

[Sunshine]

I love the fact that it looks 3D, the surrounding star field looks 2D then the Crab looks as though you can fall into it, very nice image!

[northward]

Recently spotted this cloudy streak in the sky with my naked eye, prompted me to look it up.  Thanks for this, now I can see a closer view.

[MarsG76]

Nice work.. detail within the "cloud" and all... that's one object I haven't tried yet...

[Demonperformer]

Nice for such a short time. It really is amazing what these zwo cameras can achieve with such short subs.

[wimvb]

5 hours ago, stepping beyond said:

Wim , That's showing those skills . I really enjoy the look of the nebula and the detail you pulled . The stars are very nice, that's eye candy for sure ! Awesome 

 

3 hours ago, Sunshine said:

I love the fact that it looks 3D, the surrounding star field looks 2D then the Crab looks as though you can fall into it, very nice image!

 

2 hours ago, northward said:

Recently spotted this cloudy streak in the sky with my naked eye, prompted me to look it up.  Thanks for this, now I can see a closer view.

 

1 hour ago, MarsG76 said:

Nice work.. detail within the "cloud" and all... that's one object I haven't tried yet...

 

33 minutes ago, Demonperformer said:

Nice for such a short time. It really is amazing what these zwo cameras can achieve with such short subs.

Thanks guys. Glad you like it. I'll revisit this target next season, weather permitting. Hopefully also from a darker site.

[Sunshine]

6 hours ago, wimvb said:

The Ha master still has a lot of noise, which gives the image a slight reddish background.

Thank you Wim for granting permission to relieve some of the noise you mentioned and letting me repost here, i did a quick pass over it in Lightroom and i think the noise is relieved pretty well.

i also further deepened the darkness of space to an inkier black, and very slight luminosity adjustments on the Crab itself so it would pop just a tad more, and a slight crop, thank you for letting me have a go at your beautiful shot of the Crab!

its 3am here and i have no idea why im still up, evident i don't work tomorrow lol.

[MarsG76]

1 hour ago, Sunshine said:

Thank you Wim for granting permission to relieve some of the noise you mentioned and letting me repost here, i did a quick pass over it in Lightroom and i think the noise is relieved pretty well.

i also further deepened the darkness of space to an inkier black, and very slight luminosity adjustments on the Crab itself so it would pop just a tad more, and a slight crop, thank you for letting me have a go at your beautiful shot of the Crab!

its 3am here and i have no idea why im still up, evident i don't work tomorrow lol.

I find that there is always more data that can be eeeeked out of the stacked subs... that's why reprocessed images are usually an improvement.

[Sunshine]

Lightroom is a handy tool!

[gorann]

14 hours ago, Sunshine said:

Thank you Wim for granting permission to relieve some of the noise you mentioned and letting me repost here, i did a quick pass over it in Lightroom and i think the noise is relieved pretty well.

i also further deepened the darkness of space to an inkier black, and very slight luminosity adjustments on the Crab itself so it would pop just a tad more, and a slight crop, thank you for letting me have a go at your beautiful shot of the Crab!

its 3am here and i have no idea why im still up, evident i don't work tomorrow lol.

Sunshine,

I really liked Wim's processing of his data. Unfortunately, in your version you have completely cut out all data in the sky background. When I read off your image in Photoshop your background sky lightness is 0, on a scale from 0 - 255. That means that there is no longer any sky there, or any information about its structure, just blackness. The sky is never completely black (just have a look at it). It is full of all kind of light stuff like distant galaxies, faint stars, ISM and IFM (InterStellar Medium and Integrated Flux Nebulae). So whatever you do be very careful of cutting your black point. We usually try to keep our black point betwen 20 and 30 (Wim was actually in the low end around 16).

Cheers

[Sunshine]

1 hour ago, gorann said:

I really liked Wim's processing of his data.

Oh i do love and appreciate honesty, working on AP photos is totally new to me and i should approach it differently than photos i deal with daily. Now that i look with my brain tweaked differently i see exactly what you say, my goal was never to better but erase some noise and, all of your eyes are accustomed to seeing AP and mine are not if that makes any sense. thanks!!

Also, it being a Jpeg greatly limits my ability to make far more discrete changes, i work with RAW files which allow a far more flexibility to isolate whats wanted and whats not.

And WIM, sorry i didn't mean to highjack your post.

[wimvb]

1 hour ago, Sunshine said:

And WIM, sorry i didn't mean to highjack your post.

No worries. It's discussions like this that help improve our skills, and makes us more aware of what's in the data we collect.

[wimvb]

8 hours ago, gorann said:

We usually try to keep our black point betwen 20 and 30 (Wim was actually in the low end around 16).

What can I say, I prefer dark skies. 

At first I thought the sky was still too bright. But the brightness of my laptop screen depends very much on viewing angle. At a better angle the image is quite a bit darker. Maybe almost too dark.

[Allinthehead]

Nice one Wim.

[wimvb]

A reprocess with a little more attention to detail: deconvolution and lhe applied to give the nebula more structure. Also a gentle dose of noise reduction at the end.

(click on image to see the full size version)

I noticed that I must have a bit of tilt somewhere, since the stars aren't uniform. But since imaging season will soon end up here, I'm going to have plenty of time to sort that out.

[wimvb]

4 minutes ago, Allinthehead said:

Nice one Wim.

Thanks. Glad you like it.

 

On 2018-03-20 at 13:12, Sunshine said:

Lightroom is a handy tool!

So is PixInsight.  Dynamic Background Extraction took care of the noise in the lower right corner. The trick wasn't to get rid of all the noise, but rather to keep the image plausible. Usually the best way is to reduce the noise, rather than to remove it.

[gorann]

On 3/20/2018 at 23:26, Sunshine said:

Oh i do love and appreciate honesty, working on AP photos is totally new to me and i should approach it differently than photos i deal with daily. Now that i look with my brain tweaked differently i see exactly what you say, my goal was never to better but erase some noise and, all of your eyes are accustomed to seeing AP and mine are not if that makes any sense. thanks!!

Also, it being a Jpeg greatly limits my ability to make far more discrete changes, i work with RAW files which allow a far more flexibility to isolate whats wanted and whats not.

And WIM, sorry i didn't mean to highjack your post.

Sorry if I sounded blunt - and I really hope I did not discourage you from astroprocessing. I do wonder if Adobe Lightroom is the right tool for processing astro images. It seems to be a rather blunt instrument and Adobe Photoshop is probably much better suited with more processing options. At least PS has become a favorite program for many of us, in addition to Pixinsight (PI). Unfortunatel PS and PI use quite different approaches and most of us usually focus at mastering just one of them.

[Sunshine]

3 hours ago, gorann said:

Sorry if I sounded blunt - and I really hope I did not discourage you from astroprocessing. I do wonder if Adobe Lightroom is the right tool for processing astro images.

Oh no my friend you needn’t worry about that, you weren’t blunt, or discouraging, in any way, you made all the right points!.

Adobe Lightroom is a RAW file developing program, and a brilliant one at that, but likely not as suited and as subtle as PS is with astro images, you are definitely right about that.

That being said, regarding the appearance of space and what looks and doesn’t look natural, you are right in pointing out that space is not the inky black we see in Star Wars movies, but what amount of noise is correct? I doubt there is a value for that!?

How much blacker would space look if we were to have a peek from 300km up? what I mean is, and please don’t hesitate to correct me, that noise in a photo one can never discern whether it’s is the result of thin nebulosity or light scattering through the atmosphere from a nearby city?

I have never taken an AP shot short of holding my phone to the eyepiece lol, yes it is sad I know, but I am inhaling every tip and article in preparation for my first attempt. My goal,  is to one day produce AP I can proudly print and display on my wall, I think at least for that purpose of display I may just opt for a darker sky.

It is how everyone perceives “space” to be, and the fact that noise, however natural it may be in a picture,does not reproduce nicely in a print. Thank you for your concern my friend! I so wish I had you as my neighbor to guide me through my first AP attempt!, which will likely resemble static on a television lol.

[gorann]

2 hours ago, Sunshine said:

Oh no my friend you needn’t worry about that, you weren’t blunt, or discouraging, in any way, you made all the right points!.

Adobe Lightroom is a RAW file developing program, and a brilliant one at that, but likely not as suited and as subtle as PS is with astro images, you are definitely right about that.

That being said, regarding the appearance of space and what looks and doesn’t look natural, you are right in pointing out that space is not the inky black we see in Star Wars movies, but what amount of noise is correct? I doubt there is a value for that!?

How much blacker would space look if we were to have a peek from 300km up? what I mean is, and please don’t hesitate to correct me, that noise in a photo one can never discern whether it’s is the result of thin nebulosity or light scattering through the atmosphere from a nearby city?

I have never taken an AP shot short of holding my phone to the eyepiece lol, yes it is sad I know, but I am inhaling every tip and article in preparation for my first attempt. My goal,  is to one day produce AP I can proudly print and display on my wall, I think at least for that purpose of display I may just opt for a darker sky.

It is how everyone perceives “space” to be, and the fact that noise, however natural it may be in a picture,does not reproduce nicely in a print. Thank you for your concern my friend! I so wish I had you as my neighbor to guide me through my first AP attempt!, which will likely resemble static on a television lol.

Noise is what we are fighting all the time. The best receipt against it is to collect a lot of data (as we call it) = many and/or long exposures. Some will not settle for less than 10 or more hours of total exposure time (collected by maybe 50 - 100 exposures) - all to get the signal to noise ratio down. Then there are numerous noise reducing routines (I have four as filters or actions in my PS). If you colect a lot of data you will finally find structure in what initially may have looked as noise, or drowned in noise. Have a look at this image:

https://www.astrobin.com/279188/

Cheers

Göran

[Sunshine]

40 minutes ago, gorann said:

Noise is what we are fighting all the time.

Is this image yours? because first of all it is stunning! and from what i see it took a monumental effort spanning several days totalling 47hrs of exposure?? am i reading that tech card correctly? that is just dumbfounding! i can't ever imagine having that much time to dedicate to a single shot. Having said that, the result is something to look at! and you said something very important in your post along the lines of "structure being perceived as noise" this is blatantly evident in that photo.

I am guessing that if the photo would have been a much shorter exposure, all that structure visible around the galaxies could easily have been seen as noise because it would not look like well defined structure but more like noise instead correct?. 

I would like to pick your brain if i may regarding my LX200, i am not totally ignorant about what equipment works  best and what doesn't when it comes to AP, i realize that a decent triplet frac on a good equatorial mount is a good start for deep space AP, yes a fast newtonian also. Having said that, do i have any hope of capturing any decent deep space images with an 8" F10 LX200?? it is slow and i would definitely need a wedge no? i realize long exposure are a must and a fork mounted scope is not ideal at all, but is it doable somehow?.

 

[wimvb]

7 hours ago, Sunshine said:

but is it doable somehow?

Doable, possibly. But I wouldn't consider it practical. I think that this instrument unnecessarily complicates matters. Besides that, you should also consider the field of view you get with a 2 m long focal length. Unless you will use it on galaxies and planetary nebulae, you will find it a very tight crop for any dso.

You should try it on an online fov calculator, to see what you can expect on various dso's

[gorann]

7 hours ago, Sunshine said:

Is this image yours? because first of all it is stunning! and from what i see it took a monumental effort spanning several days totalling 47hrs of exposure?? am i reading that tech card correctly? that is just dumbfounding! i can't ever imagine having that much time to dedicate to a single shot. Having said that, the result is something to look at! and you said something very important in your post along the lines of "structure being perceived as noise" this is blatantly evident in that photo.

I am guessing that if the photo would have been a much shorter exposure, all that structure visible around the galaxies could easily have been seen as noise because it would not look like well defined structure but more like noise instead correct?. 

I would like to pick your brain if i may regarding my LX200, i am not totally ignorant about what equipment works  best and what doesn't when it comes to AP, i realize that a decent triplet frac on a good equatorial mount is a good start for deep space AP, yes a fast newtonian also. Having said that, do i have any hope of capturing any decent deep space images with an 8" F10 LX200?? it is slow and i would definitely need a wedge no? i realize long exposure are a must and a fork mounted scope is not ideal at all, but is it doable somehow?.

 

Unfortunately, it is not mine - done by another SGL member - Paddy Gilliland. I have not had that kind of stamina yet. I usually stay below 10 hours. But like most of us I stick to one target each night. You find his and my and Wim's and many others images on Astrobin.com.

[Sunshine]

Thanks, i think ill pass on unnecessary hardship, i was aware of its limitations but thought i would ask in case there were viable solutions, there's a decent frac in my near future anyway so i might as well wait.