NGC 1333 lum.....done?

[wimvb]

1 hour ago, don4l said:

I think that "Aperture at Resolution" is where this thread has been heading.  It sounds like it has the potential to save us all a lot of confusion.  Is there a way to express it in numbers?  If there isn't then we should invent one.

Light gathering efficiency of an imaging system (scope and camera) is proportional to (p/F)^2, where p is pixelsize, and F = fl/D (focal length / aperture). You can also write this as (r*D)^2, with r = pixelscale and D is aperture: Aperture at Resolution.

[ollypenrice]

2 hours ago, wimvb said:

Light gathering efficiency of an imaging system (scope and camera) is proportional to (p/F)^2, where p is pixelsize, and F = fl/D (focal length / aperture). You can also write this as (r*D)^2, with r = pixelscale and D is aperture: Aperture at Resolution.

It's rather late at night but that sounds promising. It would be even better if all pixels were equally efficient! Of one thing we can be sure: there are no arguments against aperture. There are practical arguments against extremely fast F ratios, though.

As a pragmatist rather than a theoretician my preference is to find an optical system and camera which give excellent results by whatever means and then put another one alongside it. At this point there can be no significant dissent: you image at double the speed. (I don't doubt that the hard line theoreticians will quibble on subtleties of S/N etc but they know and I know that the dual rig will be effectively twice as fast.)

Olly

[wimvb]

On 03/12/2018 at 00:11, ollypenrice said:

It would be even better if all pixels were equally efficient!

That would be nice. The quantities you're refering to are quantum efficiency (photons to electrons) and uniformity of gain (electrons to ADU). Strictly, one would also need to add atmospheric extinction: light loss due to atmospheric effects. An imaging rig will perform better on a high and dry mountain top, than in a damp valley.

On 03/12/2018 at 00:11, ollypenrice said:

my preference is to find an optical system and camera which give excellent results by whatever means and then put another one alongside it.

Or 40. That effort goes by the name dragonfly:

http://www.dunlap.utoronto.ca/instrumentation/dragonfly/

I think we've discussed that before. ?

Btw, the formula for light gathering efficiency (including atmospheric extinction) is in one of their publications.

[Rodd]

On ‎02‎/‎12‎/‎2018 at 15:50, vlaiv said:

As for comparing scopes

 

On ‎01‎/‎12‎/‎2018 at 18:18, wimvb said:

 

On ‎02‎/‎12‎/‎2018 at 12:50, ollypenrice said:

Hmmm

Well--more data.  304 Red

subs.  This stack now consists of 711 Subs.  Vlad, the stack certainly looks cleaner and it was much easier to process.

 

[ollypenrice]

You're winning!

Olly

[vlaiv]

8 hours ago, Rodd said:

Well--more data.  304 Red

subs.  This stack now consists of 711 Subs.  Vlad, the stack certainly looks cleaner and it was much easier to process.

Nice! Will you adding both green and blue to the stack?

Short while ago there was some discussion about color of the dust, most people process it as dirt-red kind of colour, and I wonder how much signal there is per channel. My view was that its more grey than red - like Moon dust. Having this many subs could certainly answer that question - if "dust" signal is present in all three channels equally then it should be grayish, and if red dominates - then it would be red in colour of course - but in that case you will probably find that stacking green and blue don't contribute much to lum stack.

Looking forward to your finds on this matter.

[Rodd]

2 hours ago, vlaiv said:

Nice! Will you adding both green and blue to the stack?

Short while ago there was some discussion about color of the dust, most people process it as dirt-red kind of colour, and I wonder how much signal there is per channel. My view was that its more grey than red - like Moon dust. Having this many subs could certainly answer that question - if "dust" signal is present in all three channels equally then it should be grayish, and if red dominates - then it would be red in colour of course - but in that case you will probably find that stacking green and blue don't contribute much to lum stack.

Looking forward to your finds on this matter.

Not sure I will add the G and B to this data--my goal is an LRGB image.  I just wanted to see what adding the red to the lum would do.  We'll see.  Maybe a really nice mono super luminance would be kind of interesting.  It would have to be spectacular though to make up for the lack of color.  Not sure its possible for the reasons you stated above.  Hmmm..not sure what the "right" answer is regarding the color of the dust.    Most images portray the dust as reddish. In my older images, I found it to be either clayey gray as you describe or psychedelic (bad flats).   But I never liked the gray depiction.  We will soon find out as I am going to collect green tonight.  My goal is 500 of each channel, but the best-laid plans as they say.  The problem is I keep forgetting that the dither takes about 20 sec and then there is a 15-sec dither settling delay (which is pretty short as settling delays go--one advantage of using larger guiding pixels than imaging pixels, it only takes a couple guiding pixel move to equal 4-5 pixels in the image).  I calculated how many I get in 1 hour and it's about 38...not the 60 one would expect.  So at the end of a long night, I am left scratching my head and asking why do I only have 304 subs in an 8 hour period. 

But I am becoming excited about this image....there is hope after all.   

Rodd

[gorann]

Great image Rodd! I assume you have seen the other thread revealing that there is a dwarf planet travelling through your image: