Heart and Soul in Ha

[Gina]

Captured with ZWO ASI1600MM-Cool camera and Super Takumar 135mm lens at f2.5 this is the result of processing 198 60s Ha subs using Astrodon 3nm filter.  Camera set to a gain of 500 (50dB) and sensor temperature of -30°C.  Calibrated with bias, dark and flat frames using Batch Preprocessing (BPP script) in PixInsight and histogram stretched and slightly cropped in Photoshop then saved as PNG for upload here.

Other gear - EQ8 mount unguided.  Captured with APT.  SharpCap used for framing and focussing.

[brrttpaul]

I love it, that zwo sure is good

[Chris]

Excellent Gina, I know it's a lot of subs, but not long ago who would have thought 60 second subs would yield this kind of depth!

[Knight of Clear Skies]

Really good and nicely framed, don't usually see that much structure above the Heart, with very good detail in the shock fronts. That's deep too, the joys of imaging at f2.5. With the large field of view and sensitivity I think this setup could be great for showing some rarely seen large but faint objects. That's a real mix of technology you're using there - 50-year old lens with cutting-edge camera and ultra-narrow Ha filter.

[Gina]

Thank you everyone

Yes, I think it's incredible   A combination of the camera and wide aperture but I think it's the camera that has made the main contribution.  And yes, the 3nm Ha filter certainly helps.

[simmo39]

V nice image that.

[Yamez]

Fantastic image, lovely work. I must say I love images of the heart and soul nebula!

[Starlight 1]

1 hour ago, Gina said:

Calibrated with bias, dark and flat frames using Batch Preprocessing

Very nice Gina , When you do Darks it taking out Bias , so you removing them again ?

[wuthton]

Gina, awesome picture. Would you say that you have a slight lightness gradient running bottom to top? 

[DaveS]

That's pushing me towards hiting the "buy" button.

Just the processing giving me pause, as up to now I've just used bias frames. If I have to do darks and flats that increases the complexeties and time.

[PatrickGilliland]

That a very nice tidy and well processed image well done.  Paddy

[Gina]

Thank you everyone for you nice comments

2 hours ago, wuthton said:

Gina, awesome picture. Would you say that you have a slight lightness gradient running bottom to top? 

Yes, I think there is.  This is just a quick process - BPP is designed as a quick look to see if the data is worth processing properly and I think this shows that it is.   I expect to do further processing on the calibrated data for an improved result.  I have also captured OIII data but this has proved defective so I need to look into that and re-capture it with different parameters.

[Gina]

2 hours ago, Starlight 1 said:

Very nice Gina , When you do Darks it taking out Bias , so you removing them again ?

Thank you

I wondered about that but the tutorials seem to imply that you take darks and biases in BPP, plus flats and lights so I imagine PixInsight takes care of it all.  If both darks and biases aren't included the Diagnostic comes up with a warning.  I have the PI book which I'm gradually reading so maybe that will explain things when I get that far.  I'm very new to PI and learning all the time.  A steep learning curve but I think it will be well worth the effort

[Stub Mandrel]

3 hours ago, Knight of Clear Skies said:

That's a real mix of technology you're using there - 50-year old lens with cutting-edge camera and ultra-narrow Ha filter.

The photons are 7,500 years out of date :-)

[Starlight 1]

Gina,  don't quote me on this I believe it was Craig Starkey from the original PhD and other programs he created worked  this out . You subtracting twice so may be some programs are not up to date with new findings .

[Ouroboros]

Extremely nice image, Gina. It is particularly informative to see all the image parameters you used. Too few posters include these. 

I'm not familiar with this camera.  What is the thinking in favour of shortish 60s exposures?  Presumably to do with signal to noise. Yet the camera is cooled. 

[Mick J]

Nice to see this Gina, been watching it evolve over in the diy,  be nice to see it when you are happy with it and call it finished.  60s subs unguided, narrowband an all.

[Gina]

28 minutes ago, Ouroboros said:

Extremely nice image, Gina. It is particularly informative to see all the image parameters you used. Too few posters include these. 

I'm not familiar with this camera.  What is the thinking in favour of shortish 60s exposures?  Presumably to do with signal to noise. Yet the camera is cooled. 

Thank you Ultra low read noise is the main thing.  That allows for taking many short exposures which reduces thermal noise in comparison with the signal ie. improved signal to noise ratio.  Also the PE is said to be higher than most other cameras.

[toxic]

great image Gina 

 

[Ouroboros]

1 hour ago, Gina said:

Thank you Ultra low read noise is the main thing.  That allows for taking many short exposures which reduces thermal noise in comparison with the signal ie. improved signal to noise ratio.  Also the PE is said to be higher than most other cameras.

OK .... Just trying to take this in. I'm not sure I get it. Thermal noise is cumulative isn't it, assuming temperature remains constant?  So won't 5 x 60s exposures have the same amount of thermal noise as 1 x 5 minutes exposure? .... And the read noise, albeit low, will be 5 times less for the single, long exposure. Happy to be corrected. I've probably got hold of the wrong end of the stick. 

The only thing I can think is that dithering between  the 5 x 60s shots may help smooth out some thermal noise. 

[Gina]

The noise is random and accumulates as the square root of the number of subs whereas the signal is purely additive.  This is the maths of the matter.  The result is that the signal is all added up resulting in N times the single sub for N subs whereas the noise becomes √N.  When the final image is normalised by dividing by N the signal is 1 whereas the noise is reduced by √N to 1/√N. 

Putting numbers into this algebra :- if the number of subs N is 100 the signal accumulates to 100/100 whereas the noise becomes 10/100 (√100 = 10) thus the noise is reduced to a tenth of what it was in a single sub.  Hope that makes sense.

[Barry-Wilson]

Great widefield image Gina, you must be very pleased with this FOV.

[ollypenrice]

To quote the Nobel Laureate, The Times They Are 'A Changin'...

Your numbers are interesting. F2.8, nearly 200 subs, exposures of just a minute. Result convincing. I wandered over and had a word with a couple of mates, Brontosaurus, Pterodactyl and Triceratops. After a few beers we concluded that we dinosaurs may not be long for this world!

Olly

[gnomus]

46 minutes ago, ollypenrice said:

To quote the Nobel Laureate, The Times They Are 'A Changin'...

Your numbers are interesting. F2.8, nearly 200 subs, exposures of just a minute. Result convincing. I wandered over and had a word with a couple of mates, Brontosaurus, Pterodactyl and Triceratops. After a few beers we concluded that we dinosaurs may not be long for this world!

Olly

So does that make you a Mast(r)odon?

Mike Giggler

[gnomus]

Super image Gina.  I wonder if your corners suggest that you might have to stop the lens down just a little bit.