IC-410, IC-417 and part of IC-405

[Rodd]

I played it safe with this image taken with the FSQ 106 with .6x reducer and ASI 1600 with 3um Astrodon filters.  The  saturation level is uncharacteristically low, and I was expecting a bit brighter in regions removed from the main nebulae.  Based on the original Ha mono image, I expected a more robust field og filaments and structures in the background.

The one thing about this image that confounds me is the location of the noise.  The red channel was the noisiest, even though it contained 123 5min subs--over 10 hours of SII (30 subs being taken during the full Moon).  The blue channel (OIII) only has 26 5min subs--and I expected more trouble associated with this imbalance.  I had to work fairly hard to tame the noise.  I wasn't 100% successful, but it holds up fairly well to full resolution viewing.  

Ha: 51 5min

OIII: 26 5min

SII: 123 5 min

 

 

 

[wimvb]

Dusty, I like that. And good framing with the various objects in the same image.

[Rodd]

8 minutes ago, wimvb said:

Dusty, I like that. And good framing with the various objects in the same image.

Thanks Wim.  I really don't hate anything about it--which is a bit unusual I guess.  I don't think it rings the bell, though......almost.  The tadpoles are decent, but there is overexposure in the fly--with 5min narrowband subs?  Seems odd.  I think I edited the image since you first saw it--tiny histogram curve.  Its hard to know which version is the best (slight differences only)-but I am a perfectionist so I spend hours flicking from one to the other trying to decide.  Maybe 26 OIII subs are not enough.  I think I will capture a few more hours of OIII if I get a clear night.  

Rodd

[Rodd]

A bit more star control....that's it.  The only revision (probably)?

[vlaiv]

7 minutes ago, Rodd said:

A bit more star control....that's it.  The only revision (probably)?

Oh noooo

I better not mention artifact in the image then ...

Can't help it, but it is your fault Rodd, always aiming for the best

There should not be in the image:

It is probably due to hot pixels (100% saturation) in darks which in calibration subtract from lights to 0.

If you dither, your dither step is not enough to spread pixels sufficiently - also check the sigma settings - these 0 values are not being removed. Couple that with noise control and you get bunch of dark spots that are not supposed to be there ...

 

[Rodd]

6 minutes ago, vlaiv said:

t is probably due to hot pixels (100% saturation) in darks which in calibration subtract from lights to 0.

I don't think so--these spots cover dozens of pixels--Not sure what they are--I think they have to do with me trying the starless technique with an ill fitting star mask.  These are the result.  Oh well--I know I had to reprocess it.  

Rodd

[Rodd]

1 hour ago, wimvb said:

Dusty, I like that. And good framing with the various objects in the same image.

 

1 hour ago, vlaiv said:

It is probably due to hot pixels (100% saturation) in darks which in calibration subtract from lights to 0.

Just as I suspected--darn that BW anyway?!  My own fault for not checking the star coverage--it IS a dangerous technique to try and do quickly.  Anyway--I went back to the spot where the train left the rails.  What would I do without you Vlad.  I should get you a monocle for Christmas--a 100x monocle!  That will enable your penchant for PP.

Rodd

 

[adamphillips]

that's a great image. man that fsq 106 with a .6 reducer is a nice setup.

[Rodd]

13 minutes ago, adamphillips said:

that's a great image. man that fsq 106 with a .6 reducer is a nice setup.

Thanks Adam.  I still need to move the camera 1mm further away from the back of the reducer.

Rodd 

[Rodd]

 

I reprocessed the image using deconvolution in the linear state to squeeze as much fine scale detail out of IC-410 as possible.  

 

 

 

[Allinthehead]

Very nice Rodd.

[gorann]

Looks really nice with or without monocle Rodd!

[Rodd]

46 minutes ago, Allinthehead said:

Very nice Rodd.

Thanks Richard.

[Rodd]

44 minutes ago, gorann said:

Looks really nice with or without monocle Rodd!

Thanks Goran.  I don't understand why things dim down when the 3 channels are combined.  The ha mono has nebula extensions everywhere--but when the channels are combined I really had to work to keep them visible.

Rodd

[vlaiv]

2 minutes ago, Rodd said:

Thanks Goran.  I don't understand why things dim down when the 3 channels are combined.  The ha mono has nebula extensions everywhere--but when the channels are combined I really had to work to keep them visible.

Rodd

I think it has something to do with this graph:

Perception of brightness changes based on color used to represent intensity - colors on the right all have the same intensity, but our brain sees them being same level of brightness as shades of gray on the left.

If you have 100% intensity and assign gray to that intensity it will be white - brightness will be full. But take that 100% intensity and assign it to red color (100% red in this case) - it will only have 54% perceived brightness compared to gray (white) version. Blue version will be even dimmer - at 44% bright for same 100% intensity.

[Rodd]

33 minutes ago, vlaiv said:

I think it has something to do with this graph:

Makes sense for reflected light--like paintings--but how about emitted light?  Maybe it works the same.  It would explain things.  But I think that something is lost in the channel combination process beyond the brightness interpretation effect.  This is supported by the fact that after you combine the 3 channels, lets say RGB, then extract the R--it will look different than the R used for combination.  The emissions are spread throughout the channels it seems (somewhat).

Rodd

[vlaiv]

40 minutes ago, Rodd said:

Makes sense for reflected light--like paintings--but how about emitted light?  Maybe it works the same.  It would explain things.  But I think that something is lost in the channel combination process beyond the brightness interpretation effect.  This is supported by the fact that after you combine the 3 channels, lets say RGB, then extract the R--it will look different than the R used for combination.  The emissions are spread throughout the channels it seems (somewhat).

Rodd

Works the same for both - emitted and reflected light - same sort of light reaches the eye regardless of the source if spectral distribution is the same.

As for RGB composition - depends how you compose. If you take R, G and B and do straight forward channel assignment and then "extract" R back to mono - it will be exactly the same as original R channel, provided you have not done any manipulation on composed image. Other types of composition that perhaps do channel mixing can alter R channel if extraction is asymmetric to composition. For all linear transforms in channel combination you can do reverse transform and you should get same R if you use reverse transform for extraction. This is how switching between color models works (and it's even non linear in some cases like sRGB having gamma of 2.2, but there is inverse transform there as well).

[Rodd]

14 hours ago, wimvb said:

Dusty, I like that.

 

13 hours ago, vlaiv said:

Oh noooo

 

2 hours ago, Allinthehead said:

Very nice Rodd.

 

10 hours ago, adamphillips said:

that's a great image.

 

2 hours ago, gorann said:

Looks really nice with or without monocle Rodd!

OK--here is a cool demonstration.  I noticed red mottles in the red channel.  I inspected all the channels and saw that these mottles were actually caused by a blue deficiency (only 26 subs)--the blue channel had these same mottles except they were black.  So, I extracted a luminance from the finished image (the lum channel did not have the mottles), then I extracted the blue channel to which I applied a generous amount of ACDNR-then convolution.  Then I reinserted the blue channel and then I reinserted the extracted lum.  Like magic.  The crop is a zoom of the spider with the mottless.  Full resolution viewing of the full image will reveal a mottles spider!  EDIT--enlarged first crop for easier veiwing

[Rodd]

6 minutes ago, vlaiv said:

Works the same for both

Not so sure--because the various colors on paper, or paint, or whatever, will absorb different amounts of light.  With emitted light--there is no absorption

Rodd

[Rodd]

 

Final image--applied a little exponential transform to the outer reaches to lift them slightly--twas getting too dark.  

 

 

[vlaiv]

7 minutes ago, Rodd said:

Not so sure--because the various colors on paper, or paint, or whatever, will absorb different amounts of light.  With emitted light--there is no absorption

Rodd

Any light source has certain spectral distribution - how much light of each wavelength it contains.

If you have certain spectral distribution - it does not matter if it came from emission, or there were illuminant with different spectral distribution and material with certain "color" that has reflection distribution such that when illuminant's spectrum and reflection distribution are multiplied - they give off same spectral distribution as original source.

For example, let's have single source that emits 50 photons per second in Ha, and 16 photons per second in OIII.

Let's have a different source of light that emits 100 photons per second in Ha and 100 photons per second in OIII and paper that reflects 50% of light in Ha wavelength and 16% of light in OIII wavelength.

In both cases your eye will detect 50 photons/s in Ha and 16 photons/s in OIII - color will be the same and you will not be able to tell the difference as only thing that counts is number of photons per wavelength.

[Rodd]

8 minutes ago, vlaiv said:

they give off same spectral distribution as original source.

Only a perfectly reflecting body--which does not exist.  that is why the army uses the colors and materials it does--That is why a mirror can be used to reflect light and boil water--but not a red piece of paper

Rodd

(how about my demonstration!)

[Rodd]

This what I like about this camera and set up--you get 2 images at once.  This crop makes a decent image.

[ollypenrice]

12 hours ago, Rodd said:

 

I reprocessed the image using deconvolution in the linear state to squeeze as much fine scale detail out of IC-410 as possible.  

 

 

 

Beware of flattening the blues.

I like the image very much but can't comment on the processing in PI since I use it only sparingly.

Thought for the day: the Tadpoles are eleven lightyears long...

Olly

[Rodd]

18 minutes ago, ollypenrice said:

Beware of flattening the blues.

The blues were trouble.  Not much there to begin with.  Are they flattened?  I don't think from the deconvolution.  I did have to boost the bsaturation of the blue a bit--but then again all channels were pretty pale  from the outset.  maybe the blues got flattened when I eliminated the mottles--but that was an equitable exchange.  the mottles were unacceptable.  

Rodd

PS  the 2 stars in the lower tadpole are visible as individual points--which I find remarkable seeing that its a widefield image.  Our solar system would fit nicely between them!(along with alpha centauri!