NAM Pelican one night stand.

[ollypenrice]

Given that half the night was with a first quarter moon, I think this shows the virtues of a dual imaging rig and monochrome. The first two hours saw both sides of the tandem on Ha (4x30 mins each) and, with the moon gone, they both did RGB for the rest of the night. 15 min subs.

I'm moving away from luminance on these widefield HaRGB projects because it is easier to keep the stars down without L. I think small stars are essential on widefields.

We have a father and son team here at the moment and I was pleased that, despite the unfavourable moon, we were able to pull this out in 4 hours.

Olly

[oldpink]

stunning Olly
how much time do you spend processing the data, must be a full time job

[lensman57]

That is pretty hot for a one night stand Olly. 

Regards,

A.G

[theo]

Thats a very nice image.

Just a little confused though by your mention of moving away from luminance for HaRGB wide field. You slapped my wrist a little a while back for using Ha as opposed to luminance for a wide field image of the Elephant Trunk Nebula (though I did apply Ha to the red as well to contain the pink effect)...one of the main reasons I did this was to control the stars as you mention above? I'm just interested in your thinking here.

Pete

[ollypenrice]

Thats a very nice image.

Just a little confused though by your mention of moving away from luminance for HaRGB wide field. You slapped my wrist a little a while back for using Ha as opposed to luminance for a wide field image of the Elephant Trunk Nebula (though I did apply Ha to the red as well to contain the pink effect)...one of the main reasons I did this was to control the stars as you mention above? I'm just interested in your thinking here.

Pete

 I'm not sure that I slap wrists!

When I talk about luminance I'm talking about real luminance, which is red and green and blue - the full visual spectrum, though not distinguished between colours. This is, for instance, what is passed by a Baader luminance filter. We need to distinguish between this use of luminance and the use of the term in Photoshop. In Ps the luminance layer is the name given to the layer (which can be anything at all) which the imager chooses to illuminate whatever is in the layer below. It does not have to be a real luminance layer. Lunar imagers, for instance, might use a red layer as luminance for an RGB because the red suffers less atmospheric interference.

So I'm increasingly drawn to using pure RGB and adding Ha to it, mostly in the red channel in blend mode lighten. I don't shoot a real luminance (full visual spectrum) layer at all. There is no colour difference between LRGB and RGB. They produce the same colour, though L will probably dilute the RGB colour, notably in the bright parts like the stellar cores.

Having shot my pure RGB image here I added the Ha to red in blend mode lighten - which means the Ha influenced the red only where it was brighter than the red. The Ha stars are not as bright as the red stars so the stars are not affected. This is good.

I did then apply a small amount of Ha as luminance. About 15% is as far as I ever go. I've always argued the case for doing it this way. I feel that the main Ha input should be into the red because that is what Ha is. Red. However, a small application of Ha as luminance pulls down the stars and adds detail. I then try to haul the colour back to where it was before the Ha-as-luminance application.

A real luminance layer brightens everything including the stars, which it brightens the most, if you are not careful. That's my thinking behind not usng one on certain images, mainly emission nebulae. Dark nebulae, galaxies and reflection nebulae thrive on real luminance.

Olly

[ollypenrice]

stunning Olly

how much time do you spend processing the data, must be a full time job

Pretty quick (and it shows close up.) About three hours.

Olly

[theo]

I'm not sure that I slap wrists!

When I talk about luminance I'm talking about real luminance, which is red and green and blue - the full visual spectrum, though not distinguished between colours. This is, for instance, what is passed by a Baader luminance filter. We need to distinguish between this use of luminance and the use of the term in Photoshop. In Ps the luminance layer is the name given to the layer (which can be anything at all) which the imager chooses to illuminate whatever is in the layer below. It does not have to be a real luminance layer. Lunar imagers, for instance, might use a red layer as luminance for an RGB because the red suffers less atmospheric interference.

So I'm increasingly drawn to using pure RGB and adding Ha to it, mostly in the red channel in blend mode lighten. I don't shoot a real luminance (full visual spectrum) layer at all. There is no colour difference between LRGB and RGB. They produce the same colour, though L will probably dilute the RGB colour, notably in the bright parts like the stellar cores.

Having shot my pure RGB image here I added the Ha to red in blend mode lighten - which means the Ha influenced the red only where it was brighter than the red. The Ha stars are not as bright as the red stars so the stars are not affected. This is good.

I did then apply a small amount of Ha as luminance. About 15% is as far as I ever go. I've always argued the case for doing it this way. I feel that the main Ha input should be into the red because that is what Ha is. Red. However, a small application of Ha as luminance pulls down the stars and adds detail. I then try to haul the colour back to where it was before the Ha-as-luminance application.

A real luminance layer brightens everything including the stars, which it brightens the most, if you are not careful. That's my thinking behind not usng one on certain images, mainly emission nebulae. Dark nebulae, galaxies and reflection nebulae thrive on real luminance.

Olly

Thanks for the explanation of your method here Olly...yes i was referring to true luminance as opposed to the PS terminology. What you describe pretty much mirrors the method I use/d apart from the percentage of Ha I apply as luminance. That's why I was a bit confused by your comment suggesting I should capture some luminance and then return to reprocess the image at some point.

Anyhow thanks for the reply.

Pete.

[ollypenrice]

Thanks for the explanation of your method here Olly...yes i was referring to true luminance as opposed to the PS terminology. What you describe pretty much mirrors the method I use/d apart from the percentage of Ha I apply as luminance. That's why I was a bit confused by your comment suggesting I should capture some luminance and then return to reprocess the image at some point.

Anyhow thanks for the reply.

Pete.

I feel you have to play this by eye. Sometimes you see a need for real lum, sometimes not. Pleiades yes (to get the faint background nebulosity), Double Cluster no (because it will just burn out the stellar cores and still find no faint stuff.)

Olly

[swag72]

Interesting and good timing. I've just decided to point the scope at this target tonight. It's nice and bright and the moon shouldn't kill it too much in Ha! Anyway, you've shown me clearly that in order to get your framing I'm going to have to do a 2x2 mosaic!! Damn!!!

Great pic Olly, Love the detail!

[Epicycle]

Lovely image as usual!

[ollypenrice]

Interesting and good timing. I've just decided to point the scope at this target tonight. It's nice and bright and the moon shouldn't kill it too much in Ha! Anyway, you've shown me clearly that in order to get your framing I'm going to have to do a 2x2 mosaic!! Damn!!!

Great pic Olly, Love the detail!

Mosaics? Oh yes, I remember those...   

But it never stops. I want to bring in the lower loop to this image so I'll be back to mosaics at some point. It won't be very soon though because Tom will be driving when the moon clears off and he has some insane project in hand.

Olly

[gingergeek]

Olly, remember it's a fine line between insane and genius