M106 revisit

[Rodd]

I was never satisfied with this image.  I achieved great detail in the disc, but upon close inspection it was easily seen to be artifact laden--quite poor processing really.  A perfect example of pushing it too far. I think I have managed to make the image stronger.  The details are not quite as sharp and defined, but the details that are there, are not artifacts dressed up to be details.  HaLRGB composition TOA 130 no reducer ASI 1600 Ha 45 5min, L 84 2min, R 101 2 min, G54 2min, B 109 2min

The old image is not as bad as I thought--I guess the forum doesn't zoom in as far as I did when I inspected it.  I still think the new image is better though--On Astrobin the old image looks very posturized at full resolution

 

New Image

 

 

 

 

Old Image

[wimvb]

I'm looking at them on my mobile phone, but, Imo, you improved what already was a good image. There's definitely more detail in the new version.

[Rodd]

5 hours ago, wimvb said:

I'm looking at them on my mobile phone, but, Imo, you improved what already was a good image. There's definitely more detail in the new version.

Thanks Wim.  I guess I get hung up on full resolution viewing--especially on Astrobin.  I find that truly good images look excellent at full resolution, where as most of mine break down--all to some degree, and most in serious fashion.  I think the full resolution mode there is more zoomed than this forum's full resolution mode.  Anyway--not sure why but the details in the disc of M106 are somewhat blurry and smooth-even without any noise control.  Maybe its just the nature of M106, because focus was good, and the image is less noisy than many of my other ones using LRGB.  I guess I have to revisit this one.  It was one of the first images I did using the ASI 1600.  But, not too bad for  5" of aperture I guess.

Rodd

[wimvb]

1 hour ago, Rodd said:

But, not too bad for  5" of aperture I guess

Excellent for 5", I would say.

 

[Rodd]

34 minutes ago, wimvb said:

Excellent for 5", I would say.

 

Can't wait to hit it with the C11Edge.  I do hope to make a switch at some point.  However, there is a strong friction like force that works against changing out a scope (or camera for that matter).  I think the force is directly proportional to the amount of clear nights one has available.  What a hobby.

Rodd

[wimvb]

2 hours ago, Rodd said:

I think the force is directly proportional to the amount of clear nights one has available. 

Do you have clear nights? Wow, what's that like? ?

The larger aperture in combination with the smaller pixel scale should really get you the details you want. If the weather plays nice. But the edge is a slower scope, and you'll probably need longer exposures.

[Rodd]

1 hour ago, wimvb said:

he larger aperture in combination with the smaller pixel scale should really get you the details you want. If the weather plays nice. But the edge is a slower scope, and you'll probably need longer exposures.

I was thinking that the STT 8300 would be better on the C11--It has the self guiding filter wheel (like an OAG).  I couldn't guide with the guidescope I use for the refractors with the ASI 1600.  The good thing about the Edge is with the 0.7x reducer it if F7 which is faster than the TOA 130 unreduced (F7.7).

Rodd

[tomato]

Nice work, I think your new image is better, but would be very happy with either of them!

[Rodd]

38 minutes ago, tomato said:

Nice work, I think your new image is better, but would be very happy with either of them!

Thanks tomato.  

Rodd

[wornish]

Definitely better, but the original was very good as well.

Clear nights - they are just folk lore around here.

[Rodd]

1 hour ago, wornish said:

Definitely better, but the original was very good as well.

Clear nights - they are just folk lore around here.

Thank you--and tell me about it--presently it is raining at a rate of 2-3 inches per hour.  Flood warnings, roads closed.  I guess tonight's out, huh?

Rodd

[Petergoodhew]

A huge improvement Rodd - far less noise.  I love the framing - all of those distant galaxies peeping through the background. 

[Rodd]

2 hours ago, Petergoodhew said:

A huge improvement Rodd - far less noise.  I love the framing - all of those distant galaxies peeping through the background. 

Thanks Peter.  I was surprised at the detail present in the  dust lanes of the side on spiral in lower right--kind of M104ish.  I am starting to get a hankering for a longer focal length.  Now, if I ever get more than 3 hours of clear sky a week, I just might make the switch.

Rodd

[MartinB]

Both are terrific, especially the critical Ha details in the disc.  You have captured the jets beautifully

[Rodd]

2 hours ago, MartinB said:

Both are terrific, especially the critical Ha details in the disc.  You have captured the jets beautifully

Thanks Martin.  It still amazes me how our scopes, especially small refractors, are capable of revealing tiny but sharp details.  It kind of reminds me of the poem written on a grain of rice.  

Rodd

[gorann]

Both are good but the new one is also great! Lovely detail and bonus galaxies all around.

PS. You know I have a hang up on stars. What is going on with the big one? Stars spikes and chromatic aberration i a Japanese Ortho-Apochromat Triplet? Have not seen anything like it in my Chinese budget refractors?, at least not in the Esprit 150. Maybe someone knows what may cause it. No serious problem though since only that very bright star is affected and It would take a minute to remove the spikes in PS using curves and layers.

[ollypenrice]

I'm not persuaded that a good 5 inch apo is easy to beat with larger reflectors until they get to be very large. I feel there's nothing to choose between what I was doing in a 14 inch a few years ago and what I'm doing now in a TEC140. Let's see what you find, Rodd.

I think your second one is an improvement, certainly. A small thing but the colour balance seems to be off around the perimmeter of the image.

Olly

[Filroden]

44 minutes ago, gorann said:

PS. You know I have a hang up on stars. What is going on with the big one? Stars spikes and chromatic aberration i a Japanese Ortho-Apochromat Triplet? Have not seen anything like it in my Chinese budget refractors?, at least not in the Esprit 150. Maybe someone knows what may cause it. No serious problem though since only that very bright star is affected and It would take a minute to remove the spikes in PS using curves and layers.

I think it's an artefact of the camera rather than the scope. I get the same on some bright stars with my ZWO 1600.

[Rodd]

1 hour ago, gorann said:

Both are good but the new one is also great! Lovely detail and bonus galaxies all around.

PS. You know I have a hang up on stars. What is going on with the big one? Stars spikes and chromatic aberration i a Japanese Ortho-Apochromat Triplet? Have not seen anything like it in my Chinese budget refractors?, at least not in the Esprit 150. Maybe someone knows what may cause it. No serious problem though since only that very bright star is affected and It would take a minute to remove the spikes in PS using curves and layers.

Here we go!  Seriously, I have no clue.  

Rodd

[gorann]

17 minutes ago, Filroden said:

I think it's an artefact of the camera rather than the scope. I get the same on some bright stars with my ZWO 1600.

Yes, you may be right. Two things pointing at the camera is the perfect aligning with the image, and that odd things happen in astrophotography. Good if it is not the expensive refractor.

[Rodd]

55 minutes ago, ollypenrice said:

I'm not persuaded that a good 5 inch apo is easy to beat with larger reflectors until they get to be very large. I feel there's nothing to choose between what I was doing in a 14 inch a few years ago and what I'm doing now in a TEC140. Let's see what you find, Rodd.

I think your second one is an improvement, certainly. A small thing but the colour balance seems to be off around the perimmeter of the image.

Olly

Thanks Olly--I think that color imbalance--which is reddish to me--has to do with the fact that I got lazy when adding the Ha to the red channel.  I did not subtract the red continuum emissions from the Ha stack--or "cleaned it" as is commonly said in PI vernacular.   I guess this is proof that it pays to be thorough!  

With respect to refractors and reflectors.  I will be surprised if I don't get more definition with the 11' Edge--Certainly the details will be larger--and if the conditions are good, the resolution should be greater.  But not that much I suppose.  The pixel scale here is .7ish (TOA 130 native and ASI 1600).  the pixel scale with the STT-8300 and C11EDge reduced by .7x will be .57--so not that different.  It will be interesting to see what differing the aperture alone will do (ignoring the differences in the optics for the moment).

Rodd

[Rodd]

19 minutes ago, gorann said:

odd things happen in astrophotography

No...really?

Rodd

[wimvb]

 

6 hours ago, gorann said:

You know I have a hang up on stars. What is going on with the big one? Stars spikes and chromatic aberration i a Japanese Ortho-Apochromat Triplet?

The artefacts are caused by diffraction from the microlenses on the sensor. That's also the reason they're so wide, unlike the spikes from a reflector.

[wimvb]

6 hours ago, ollypenrice said:

I'm not persuaded that a good 5 inch apo is easy to beat with larger reflectors until they get to be very large. I feel there's nothing to choose between what I was doing in a 14 inch a few years ago and what I'm doing now in a TEC140. Let's see what you find, Rodd.

I think your second one is an improvement, certainly. A small thing but the colour balance seems to be off around the perimmeter of the image.

Olly

How far can we stretch your argument, Olly? Or: what about a decent 6" ED (specifically the new Skywatcher 150ED Pro)?

Sorry for hijacking your thread, Rodd. ?

Btw, I thought the colour issue near the edges was a stacking artefact. Easiest to deal with this is to crop.

[ollypenrice]

5 hours ago, Rodd said:

 

With respect to refractors and reflectors.  I will be surprised if I don't get more definition with the 11' Edge--Certainly the details will be larger--

Rodd

This is precisely the point I made in a recent article in the UK magazine Astronomy Now. The details will be larger but will they be more - ahem -  detailed?  In comparing older data from a 14 inch ODK with recent data from a TEC140 I found no difference in details, at least most of the time, though the 14 inch image was larger because the pixel scale was finer. But let's see what you find, which may not be the same. I find that any high res imaging is seeing-dependent (no surprises there) so I only do luminance when I get a good FWHM value. When it's bad I shoot colour and when it's very bad I work with the Taks at 3.5"PP and sulk. The received wisdom is that the smaller aperture should work better in bad seeing. My gut feeling, based on memory rather than objective comparison, is rather the reverse - but I really don't know.

2 minutes ago, wimvb said:

How far can we stretch your argument, Olly? Or: what about a decent 6" ED (specifically the new Skywatcher 150ED Pro)?

Sorry for hijacking your thread, Rodd. ?

I don't think we can stretch it too far because it's perfectly obvious that there are very big reflectors out there which comfortably out-resolve anything anyone I know has acheived in 6 inch refractors. Once you get up to the really big stuff - top quality 20 inch scopes - it's game over for the 6 inch refractors. In part I suspect this is because of the light grasp obtaining sufficient signal for very hard processing as well as the inherent resolution of the system. (Just think of how hard you can software-sharpen the brightest parts of an image. Imagine having that signal strength much further out from the brightest parts.) This is conjecture. I haven't processed data from a good 20 inch imaging rig. But offer me a free Esprit 150 or any free 14 inch reflector in the world and I'll take the Esprit. An error, maybe, but that's what I'd do.

Olly