Ngc3576

gregbradley · #1 27-01-2009, 11:12 AM

Here is an image I took over the weekend from my dark site.

After a super wild thunderstorm on Friday night I had 2 perfectly clear nights, if a bit windy on the first night. Seeing was good (7/10?).

This one was almost all night and is well placed after about 11-12pm for imaging.

TEC180mm with field flattener. FLI Microline 8300 at -35C (even though it was 22C ambient). Astronomik LRGB and Astrodon 5nm Ha filter (not S11 filter by mistake!!!).

HaLRGB 75 60 30 20 30 .

http://www.pbase.com/image/108558640

I think I will shoot some O111 on this one next trip as I'd like the gas loops to stand out more.

Greg.

bluescope · #2 27-01-2009, 01:28 PM

Don't know this object but the image looks a little bit flat .... needs something to give it more definition ... perhaps the O111 will help. Still a nice image though Greg.

gregbradley · #3 27-01-2009, 02:03 PM

Quote:

Originally Posted by bluescope

Don't know this object but the image looks a little bit flat .... needs something to give it more definition ... perhaps the O111 will help. Still a nice image though Greg.

I know what you mean Steve.

I just uploaded another version which has more contrast and is a bit richer. I think this one has more appeal.

What do you think? (same link).

Greg.

Peter Ward · #4 27-01-2009, 02:08 PM

Greg,

I can't quite place my thumb on it, but the image lacks the "snap" I'd expect from that mega-refractor of yours....ie needle like stars across the field.

You have caught the dust obscured and h-beta regions very well..the colour is great.

gregbradley · #5 27-01-2009, 02:37 PM

Quote:

Originally Posted by Peter Ward

Greg,

I can't quite place my thumb on it, but the image lacks the "snap" I'd expect from that mega-refractor of yours....ie needle like stars across the field.

You have caught the dust obscured and h-beta regions very well..the colour is great.

I agree Peter.

The Ha turned out fairly well:

http://www.pbase.com/image/108586625

I think 2 things, I need to sort out an adapter to use my FLI PDF focuser with it as focus is critical and a little hard to achieve perfectly manually. Plus I need to set up some auto control software like CCD Commander or AutoPilot and rig it to do autofocusing between LRGB to catch those little shifts of focus. Plus some O111. I think it will bring it up nicely.

Oh well next trip - on the list.

Greg.

atalas · #6 27-01-2009, 02:38 PM

Snap crackle Pop ! well you've actually done a very fine job with this one Greg!
It will be very interesting to see the 0III added but there is no doubt that this image still stands on It's own two feet ! well done.

bluescope · #7 27-01-2009, 03:15 PM

Quote:

Originally Posted by gregbradley

I know what you mean Steve.

I just uploaded another version which has more contrast and is a bit richer. I think this one has more appeal.

What do you think? (same link).

Greg.

Yep that's better .... will be interesting to see the added O111 version.

gregbradley · #8 27-01-2009, 03:45 PM

Quote:

Originally Posted by atalas

Snap crackle Pop ! well you've actually done a very fine job with this one Greg!
It will be very interesting to see the 0III added but there is no doubt that this image still stands on It's own two feet ! well done.

Thanks Louie. I think I will still work on this one and see if there are some tricks in Ireland's Photoshop Astronomy. I was thinking of one approach which is Wodaski's removing the stars and working them as a separate layer. Always thought that was hard to do but it might be the technique to get more control of the stars in these delicate neb with crowded stars scenes.

Greg.

Quote:

Originally Posted by bluescope

Yep that's better .... will be interesting to see the added O111 version.

Thanks Steve.

Greg.

Alchemy (Clive) · #9 27-01-2009, 04:30 PM

tried several times ..... link not responding

strongmanmike (Michael) · #10 27-01-2009, 05:42 PM

Well not sure which version I am looking at but the colour is just beautiful! I would say pretty well perfect?

The Ha only version you have posted while a great vista does look very processed, looks a bit like clay or plasticene and is burned out in the bright areas a tad.

I'm hanging to see the 16803 with the 7" APO but from what I've seen already, that refractor is an RC (and BRC) killer mate throw everything else...?..err?..my way? and just keep using that chunk'a see through glass my friend

Mike

gregbradley · #11 27-01-2009, 06:52 PM

Quote:

Originally Posted by strongmanmike

Well not sure which version I am looking at but the colour is just beautiful! I would say pretty well perfect?

The Ha only version you have posted while a great vista does look very processed, looks a bit like clay or plasticene and is burned out in the bright areas a tad.

I'm hanging to see the 16803 with the 7" APO but from what I've seen already, that refractor is an RC (and BRC) killer mate throw everything else...?..err?..my way? and just keep using that chunk'a see through glass my friend

Mike

Hi Mike,

Yes you are right the Ha is overcooked. I redid it. It really doesn't need any processing just levels and curves.

You are looking at a later version which I tweaked from comments on the thread and that version I am happy with. Bringing out the gas tendrils was my main target and I used some layers to do that.

I got the adapters today that are needed to attach the Apogee U16M to the TEC flattener so I can now use it. I'll use that next. Just have to work out what to image.

I agree, the TEC is outperforming the other scopes as good as they are.

Greg.

gregbradley · #12 27-01-2009, 06:54 PM

Quote:

Originally Posted by Alchemy

tried several times ..... link not responding

Hi Clive,

I just checked it and it is working for me.

Here is a fresh link;

http://www.pbase.com/gregbradley/image/108558640

Greg.

Hagar (Doug) · #13 27-01-2009, 07:16 PM

Nice image Greg, not an area I know but overall the image has come up very well. I would be very happy with this type of result.
Well done.

gregbradley · #14 27-01-2009, 07:45 PM

Quote:

Originally Posted by Hagar

Nice image Greg, not an area I know but overall the image has come up very well. I would be very happy with this type of result.
Well done.

Thanks Doug.

Greg.

marc4darkskies (Marcus) · #15 28-01-2009, 01:01 PM

I really like the colour you've achieved with this shot Greg!

IMO though, looking at the Ha only version, you could tease out some more detail and reduce the star sizes by blending in some more Ha into the Red channel and maybe layering in some Ha as lum.

In any case, a very pretty image.

How about a full res version?

Cheers, Marcus

gregbradley · #16 28-01-2009, 05:33 PM

Quote:

Originally Posted by marc4darkskies

I really like the colour you've achieved with this shot Greg!

IMO though, looking at the Ha only version, you could tease out some more detail and reduce the star sizes by blending in some more Ha into the Red channel and maybe layering in some Ha as lum.

In any case, a very pretty image.

How about a full res version?

Cheers, Marcus

Hi Marcus,

Thanks.

The image already has a few layers of Ha as red, as blue, as luminance.

I found that pushing the Ha luminance will shrink the stars as you say and I have done this to the point where it starts to degrade the stars. If you push it too hard you get smaller stars with larger dull halos. Do you have a way around this, like perhaps a combine of Ha and lum used as luminance in the LRGB combine? I haven't done that.

Greg.

marc4darkskies (Marcus) · #17 29-01-2009, 08:50 AM

Quote:

Originally Posted by gregbradley

Hi Marcus,

I found that pushing the Ha luminance will shrink the stars as you say and I have done this to the point where it starts to degrade the stars. If you push it too hard you get smaller stars with larger dull halos. Do you have a way around this, like perhaps a combine of Ha and lum used as luminance in the LRGB combine? I haven't done that.

Greg.

Well, I don't have the perfect Ha recipe either (yet) but I usually blend the Ha with the Red (red on top as lighten) before creating the RGB and I add a carefully pre-blended Lum/Ha layer as lum only in PS. Opacities & layer masks to taste of course.

I'm paying more attention to matching star sizes in the channels these days too and some reduction is sometimes necessary (unless the seeing and focus was consistent throughout the data gathering, which is quite rare for me - I image over days without an autofocusser). In any case adding Ha makes this even harder and typically I'm never quite happy with the stars in my Ha shots. Maybe someone can give ME a better recipe!

Oh yes, I also usually throw a pure Ha layer in the mix as well later in the process to enhance emission detail but preserving my good stars from earlier steps. This always means careful layer masking though.

Pretty sure this doesn't help you

Cheers, Marcus

richardo (Rich) · #18 29-01-2009, 08:58 AM

Hi Greg,
nice to see the big refractor out and showing what it can do.
I like the blend you have with come up with. Colours look very good.
Like the way the Bok globs are standing out.

I was sort of wondering about the sharpness on the stars.. maybe the seeing was a little soft on one of the nights, or during the night?

I think it comes down to, the larger the aperture, the more the seeing will affect things.
Although as you said, you had a thunder storm, you'd think that would have cleaned and settled the sky.

Other than that, nice view of this interesting area.

Look forward to more images with this scope combo.

All the best
Rich

gregbradley · #19 29-01-2009, 09:43 AM

Hi Marcus,

Well here's what I have been doing lately and sometimes it has worked wonderfully and other times not as well so consistency can be a problem.

I use CCDstack to get up to an LRGB combine and then save it as a RAW tiff.

I process the Ha in CCDstack and save it as a RAW tiff.

Now I open the LRGB in Photoshop and process it with multiple levels/curves
until it is bright and the histogram is bell shaped. Then do bits and pieces until I am happy with the LRGB.

Now I open the Ha and convert it to RGB mode from grayscale.

I then do levels/curves etc and bring it up to the point I like it.

I then create a new layer on the LRGB and copy the Ha to that layer and delete the green and blue channel. I set this layer usually to screen rather than lighten although sometimes lighten gives a better result. Opacity usually about 50% or less. Now I duplicate that Ha layer and set that to "saturation" and opacity to probably only 20%. This brings out the Ha colour and give control over the colour. This approach gives rich colours and no salmon hues.

I then create 2 more new layers and one is assigned to the blue channel and maybe only 10% and the other to luminosity and again to suit but not too much. This last step will shrink stars to more the Ha sized tiny stars but
I find if you go too hard you will get a dull halo around a bright core for stars and it doesn't look good.

Then I flatten the image and do a few final tweaks, noise reduction, sharpening etc.

You are probably better off doing deconvolution on your subs prior to combine to get the star sizes smaller rather than trying after the combine when your options are limited by the blue or red subs being larger and bleeding through.

When you say you work to match star sizes what tools do you use to accomplish that?

Greg.

gregbradley · #20 29-01-2009, 09:52 AM

Quote:

Originally Posted by richardo

Hi Greg,
nice to see the big refractor out and showing what it can do.
I like the blend you have with come up with. Colours look very good.
Like the way the Bok globs are standing out.

I was sort of wondering about the sharpness on the stars.. maybe the seeing was a little soft on one of the nights, or during the night?

I think it comes down to, the larger the aperture, the more the seeing will affect things.
Although as you said, you had a thunder storm, you'd think that would have cleaned and settled the sky.

Other than that, nice view of this interesting area.

Look forward to more images with this scope combo.

All the best
Rich

Hi Rich,

The thunderstorm was actually 2 nights before and you are right it did settle the sky somewhat although the seeing was still not great maybe 6/10 although I am not exactly sure how to measure the seeing. I use the amount of twinkle in the stars as a guide and that is probably not very scientific.

I have looked at other examples of this image and they also show stars as being quite prominent. So perhaps part of it is the part of the sky, perhaps slightly off seeing, focus may have not been perfect on some subs.

I can probably reprocess some of it with attention to reducing star sizes and get it tighter. I think I will do that and see what I can do.

Also adding some O111 may be beneficial.

Its a funny object, kind of nice but also seems to be not totally photogenic.
The colours in the right hand nebula are a bit dusty and not so nice.

Greg.