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NGC7635 - Bubble - First Exposure...

RichieJarvis

By RichieJarvis
in Imaging - Deep Sky

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Tim

Tim

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It's not really clear here, and everywhere is sodden, we've had over an inch and a half of rain in the last 24 hours, so I'm not gonna bother.

In fact I am still processing the few pics from last saturday under similar conditions, to see whether its worth making the effort on murky nights in future.

Hope you get a good stack though!

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RichieJarvis

RichieJarvis

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Incidentally - do u know much about Ha shooting? I've just got an Astronomiks Ha filter, and wondering if I need to shoot 5 minute subs with that on 2x2 binning?

Was thinking of doing L (60mins), Ha (20min, 2x2), G (10min, 2x2), B (10min, 2x2) - do you reckons that will be enough colour data?

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RichieJarvis

RichieJarvis

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Well - its been a reasonably long and clear night....

Here is the result - I am very pleased with it myself - anyone got any comments?

2008-09-02-NGC7635-Small.jpg

Date: 2008-09-02

Object: NGC7635 - Bubble Nebula

Scope: F5 GS 153mm Newtonian

Camera: SXV-H9

Guide Scope: Williams Optics ZS66

Guide Camera: SX Guidehead

Exposure (L): 20 x300 seconds

Exposure (Ha): 20 x 120 seconds

Exposure (G): 10 x 120 seconds

Exposure (:clouds2:: 10 x 120 seconds

Cheers,

Richie

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RobH

RobH

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Very good image Richie :clouds2:

It looks like, as often happens, the stars are larger in the blue subs than the rest, giving rise to the blue haloes. Maybe try reducing star size a little on the blue channel. This should tighten the starfield a bit.

Also, I see that you used the same exposure time for your Ha filter as you used for blue and green.

Try upping the exposure for your Ha as there really isn't a lot of light coming in through the NB filter as compared to the broadband ones. Try 300-400 seconds for Ha and you'll get a lot more detail in the reds and also a better match with your blue and green filters.

You can also blend this with your luminance data....there's a lot of Ha detail in this object.

Cheers

Rob

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RichieJarvis

RichieJarvis

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Thanks Rob...

I'll give that a try with the blue layer. I did double the number of Ha subs - you reckon double the individual exposure time as well?

When you speak of blending in the Ha data with the Luminance - how is that achieved? Do you have or know of a tutorial for that, or is it just a case of combining the Luminance and Ha in MaximDL, and then using that?

Cheers,

Richie

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RobH

RobH

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Hello Richie,

You can very simply blend your Ha and luminance layers in Photoshop by using one layer as a luminance layer at around 50% opacity.

You simply convert your first layer to RGB colour (IMAGE/MODE/RGB) and then add the second layer (Ha or whatever) by making sure that the layer you wish to add is the active one, then clicking on this in the layers pallete while holding down shift.

Keep holding SHIFT and drag it across into the other image (luminance in this case)

Set your blend mode to luminance and adjust the opacity until you have the effect you require.

Then flatten the layers and convert back to greyscale.

The same approach works for adding Ha data to a red channel, which can be a nice way to blend Ha with RGB data.

I use Maxim for my image acquisition, but use photoshop to build up the RGB image.

With any narrowband data, get as many subs, and as long exposures as you can. You're dealing with a much lower signal so the better you can get your overall signal to noise ratio, the better the result.

Cheers

Rob

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RichieJarvis

RichieJarvis

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Cool - thanks for the hints Rob... I've just been playing with it - first pass went well, and I got a nice image - but only in the centre of the image :)

When I looked at the edges, the stars didn't line up between layers, and it got progressively worse from the centre to the edge.

I'll give it another try once I get back from Herstmonceux - or I may even try it AT Herstmonceux, and get Tommi and Nik's opinion on it (he owes me beer + favours atm :clouds2: )

Stupid me though - I shoulda saved it so you could see the result... The bubble itself was alot sharper though, so I definately think this is the way to go :)

Thanks to everyone for the help, praise and advice on this - enjoy!

Cheers,

Richie

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