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MattJenko

North America and Pelican Nebula

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Here is my first real multi session effort with my new widefield rig. It has a massive field of view so can fit all this in. This is my first attempt at processing something this large. It is a much bigger challenge than my smaller field of view images in the past. Feedback more than welcome please.

TS60ED, AzEQ6, ASI1600MM cooled. 

Lum : 135 x 300s.

Red: 160 x 30secs, Green: 65 x 30secs, Blue: 110 x 30secs. All processed in PixInsight.

550c20abf1d4173038574f9afa361de5.1824x0_

Enjoy,

Matt

Edited by MattJenko
nebula name (thanks daz)
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Wonderful image with great colours and so much to look at. Well done.

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Looks a great image Matt - why the short subs though? Unless these are unguided?

Also (and forgive the pedantic in me), it is the North America Nebula, not AmericaN. It is not owned by North America, it just looks like landmass. Hence the name.. :)

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Thanks daz (changed title).

Short subs as I didn't want to saturate the stars to keep the colour, and camera is so clean that I could still get the nebula in as well with lots of subs. Also, the camera is not 16bit, so more frames are required to really get the dyanmic range, and while I went for it on the Lum (was about 50% saturation at unity gain in 5 mins), I found that 30 secs gives pleasing star colours for RGB as most stars are not saturated and it alls me to get lots and lots of subs. Takes ages to process though!

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blown away mate, outstanding Matt. bet you carnt count all them stars :icon_biggrin: i count a google plex and 45 if ya like to check them. :happy6: thanks charl.

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Hi Matt

That is an impressive field of view !....I like the processing of the image, the details and particularly the stars ! 

Could you expand a bit more on your reason for short duration subs eg is it because of your camera ?

Alan  

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Thanks All,

Alan - yes, I did a test image before this one of the coathanger and found that 30 seconds gives a very nice level of saturation for each RGB sub where the majority of the stars are not saturated. This means when I combine them together, there is some colour, as opposed to all channels being 1 and a white star. The camera is a cooled CMOS and doesn't have full 16 bit capability like most of the CCDs available, so you need more exposures to get to that kind of level of differentiaion. An example is if you only have a value of 12 and 13, there is no detail to be had between them. However, if you have 25 subs with the value 12 and 48 with the value 13, the average is between the 2 with some decent precision. What is needed is lots of values, ie lots of subs in my case. Luckily with 30 second exposures, you can get lots of subs relatively easily so the combination of a clean sensor, meaning the noise doesn't drown out short subs and short subs equals the ability to get good non saturated dynamic range with lots of short subs.

Combining short subs with a 3"/pixel resolution at 260mm FL, makes for a very forgiving setup, which is ideal for me :) 

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1 hour ago, MattJenko said:

Alan - yes, I did a test image before this one of the coathanger and found that 30 seconds gives a very nice level of saturation for each RGB sub where the majority of the stars are not saturated. This means when I combine them together, there is some colour, as opposed to all channels being 1 and a white star. The camera is a cooled CMOS and doesn't have full 16 bit capability like most of the CCDs available, so you need more exposures to get to that kind of level of differentiaion. An example is if you only have a value of 12 and 13, there is no detail to be had between them. However, if you have 25 subs with the value 12 and 48 with the value 13, the average is between the 2 with some decent precision. What is needed is lots of values, ie lots of subs in my case. Luckily with 30 second exposures, you can get lots of subs relatively easily so the combination of a clean sensor, meaning the noise doesn't drown out short subs and short subs equals the ability to get good non saturated dynamic range with lots of short subs.

 Matt that is interesting.

I was basically wondering if I should experiment with my camera with this approach. However, with my camera, I rarely find that I get saturated stars at my normal RGB  exposure (600s). I do however, quite often get stars between 200 and 255 bit maps levels within PS (0 to 255) when I have stretched them along with the main image, in this case they are very difficult to colour. My current approach is to process the starfield separately,  so I will stretch them so that the values are below 200. I suppose what I could do, is take a few short duration subs and use this for the star field and use the longer subs for the main image, but I guess this would be unnecessary provided that the 600s subs star brightness values can always be constrained to be below the 200 bit map level. What are your thoughts ?

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That's worked well. I might be tempted to push the local contrasts in LHE, maybe?

Olly

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That is a fantastic example of the North America and Pelican Nebulae - and great to see it taken with the new ASI1600MM

I'm thinking about getting one of these and look forward to the short exposure capabilities as I won't be losing entire 15 minute subs anymore :-)

Funnily enough I had visited your website yesterday (before seeing this post) as I was googling "Star Adventurer" looking for tips on that mount 

I'll have another look at your photos now for inspiration to buy that ASI :-)

David

 

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Great image. The past week or so, several dso images have been posted here taken with this camera. Good to see that cmos is stepping out of the planetary arena.

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On 8/13/2016 at 17:44, ollypenrice said:

That's worked well. I might be tempted to push the local contrasts in LHE, maybe?

Olly

Thanks Olly. Surprisingly for me, I was a little restrained with this process. Some of the usual workflows I use didn't really work with this size of image, one of the tricky things with PixInsight and the way mask are generated

. I have tried again and been more forthright in the LHE process and also been a lot more careful in my masks, especially on the Lum combination to try and minimize the ringing artifacts I got in the first. Getting there I think. At least the issues remaining are down to me not the equipment, although I have noticed my Blue flats haven't quite corrected the vlignetting from the 1.25" filters in the bottom left corner.

293c85959d6f8922e123236da2390bff.1824x0_

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On 8/14/2016 at 09:41, David_L said:

That is a fantastic example of the North America and Pelican Nebulae - and great to see it taken with the new ASI1600MM

I'm thinking about getting one of these and look forward to the short exposure capabilities as I won't be losing entire 15 minute subs anymore :-)

Funnily enough I had visited your website yesterday (before seeing this post) as I was googling "Star Adventurer" looking for tips on that mount 

I'll have another look at your photos now for inspiration to buy that ASI :-)

David

 

Thanks! One of my main goals with this new setup was to use the Star Adventurer, as this rig (in theory) should be pretty forgiving of unguided tracking with the pixel scale and short sub capability.

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42 minutes ago, MattJenko said:

Thanks! One of my main goals with this new setup was to use the Star Adventurer, as this rig (in theory) should be pretty forgiving of unguided tracking with the pixel scale and short sub capability.

I bought the ASI1600MM :-) I was thinking that about the star adventurer too - should be interesting!

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