Double-Double Cluster First Attempt

[NovaTJ]

Taken tonight between the clouds and high moisture content of the air. 30 image files, 10 darks, 5 flats and 5 bias files applied. Re-sized in CS4 and some sharpening. Double Cluster...not double-double...it's getting late...Greg

[troypiggo]

Well done! What objects are they?

[Adrena1in]

NGC 869 and NGC 884 Troy. Weirdly not a Messier object, which is strange since they're naked-eye objects.

Nice shot Greg, I was going to correct you when you called it the Double-Double-Cluster...were you thinking of Epsilon Lyrae, also known as the Double-Double?! What did you shoot it with though? Seems lacking in any colour. There are some beautiful coloured stars in there. Here's a link to the only shot I've taken of it close up so far. (http://img707.imageshack.us/img707/7913/doubleclustersmall.jpg).

Really must get my APO out and try again, with better tracking and more exposure time, while it's still around.

[NovaTJ]

What I was doing originally, was classifying it first as a double, then naming it what it's called as in nebula-orion. Then it occurred to me afterward that some smart person may constru it as the double-double, which it is not. You are right about the colors being lacking, and I will do more post processing on this later on tonight. Comments are appreciated...thanks.

Greg

[Celestron]

Looks good ! Looks like color is a little lost tho . You might increase saturation some or did you change to grayscale ?

[NovaTJ]

Thanks Ron, as I said, it was getting late and I was tired. Will do some more PP tonight and try to coax some color into it. Greg:)

[Nighthound]

Great work Greg.

I know I harp on preserving the low end of the histogram, but try this test to illustrate why I do.

Open your file above in Photoshop and bring up the histogram. You'll note that the black point is clipped indicated by the color peak being pegged all the way left.

Now grab the bottom corner handle on the histogram where the black point is pegged and slide it straight up along the left edge of the graph while watching the image. Look at all those faint stars appearing that are being flooded and diminished by black. Being dimmer stars they fall in the low end of the histogram as does much of the faintly illuminated dust/gases seen in nebula and galaxies. Those are subtleties that require some preservation in processing. It's always tempting to go dark in the background to provide "pop" or to diminish noise but this comes at a price of tossing valuable and hard-earned data.

I'm not trying to be overly critical and I hope you don't take it that way. I'd just like to see you get the most from your efforts and from what is clearly good data.

Really well done.

[NovaTJ]

Steve (Nighthound), I appreciate any help and would never take advice from someone as yourself wrongly. Now help me out some more please. I did as you said, but cannot find anyway of bringing up the histogram in the Autosave.tif file that Deepskystacker left me. I'm using CS4. I can do lots of adjustments for saturation and tone control, and have brought out many more stars in the process...just can't find a histogram.

Greg

Great work Greg.

I know I harp on preserving the low end of the histogram, but try this test to illustrate why I do.

Open your file above in Photoshop and bring up the histogram. You'll note that the black point is clipped indicated by the color peak being pegged all the way left.

Now grab the bottom corner handle on the histogram where the black point is pegged and slide it straight up along the left edge of the graph while watching the image. Look at all those faint stars appearing that are being flooded and diminished by black. Being dimmer stars they fall in the low end of the histogram as does much of the faintly illuminated dust/gases seen in nebula and galaxies. Those are subtleties that require some preservation in processing. It's always tempting to go dark in the background to provide "pop" or to diminish noise but this comes at a price of tossing valuable and hard-earned data.

I'm not trying to be overly critical and I hope you don't take it that way. I'd just like to see you get the most from your efforts and from what is clearly good data.

Really well done.

[NovaTJ]

Well I still havn't heard back from Nighthound, but here is another PP attempt using curves. Cropped off some of the coma too. This was taken with my C6 Newt on CG-5 Goto. Greg

[troypiggo]

In PS, Window->histogram ??

[Nighthound]

Greg, yes, Window>Histogram will bring it up. It's a good idea to keep it visible throughout any PS adjustments to monitor the color balance and black point.

I can't do much with the low rez JPEG but if look across the second image you'll see those faint stars that were flooded by the black:

YOUR ORIGINAL:
http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/tst2/DDouble.jpg

BLACK POINT ADJUSTMENT:
http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/tst2/DDoublelight.jpg

[NovaTJ]

Thanks guys, I'll have another go at it tonight.

[NovaTJ]

Ok, hey...I found the histogram. I stretched it out and increased saturation and did some other "guess work" and came out with this...I think I over-did the saturation, but I hope you all will let me know where to go from here.

Greg

[Nighthound]

Greg you definitely pulled the color out, much better.

Your black point is still severely clipped. This is how it looks on the histogram when I bring it up in PS:
http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/tst2/histo-2.jpg

All colors are pushed all the way left. When I use the eye dropper tool and sample your background there are areas of R=0, G=0 and B=0 with some single digit areas as well. If you shoot for 20-25 in the RGB readings you'll be assured of good balance and that you are getting the most from the data you collected. Also, by improving saturation in star color the false color created by the optics(CA) is also increased in the process giving most of the stars the strong blue/violet color associated with CA. I adjusted the black point and reduced saturation selectively on the false color and came up with this. It's not ideal since there are things I can't do or undo with a JPEG:
http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/tst2/cormpiling15x.jpg

Here's a close up side-by-side comparison of your original and my adjustment. Grant it my blacks looked a bit washed next to yours since yours is so dark but if you look close many more faint stars can be seen in the adjusted version. If you view my adjusted image independently it doesn't look so washed in the background, in fact there's about 80% black in there:
http://i3.photobucket.com/albums/y67/Nighthd/Astrophotography/test/tst2/sidebyside.jpg

You are light years ahead of me when I was starting out. The processing part takes some finesse but once you get your workflow down it'll go like clockwork.

[troypiggo]

Wow - look at all the colours coming out. This shot is developing in front of our eyes. Looking forward to where it's going.

[NovaTJ]

Me too Troy! Steve, so this evening using the Tif file, set the RGB's to around 25 and move the black point up (or down) to pull out more stars or luminosity.
You mentioned CA from my optics...what optics? The C6 is sending the data directly to the camera's sensor without any glass, being a Newtonian. Another question...Deepskystacker, I created a starmask. Where can that be utilized in Photoshop to help round out the stars?

This is becoming quite a tutorial and as an eager student, I look forward to my next class:) See you this afternoon! Greg

[Nighthound]

Me too Troy! Steve, so this evening using the Tif file, set the RGB's to around 25 and move the black point up (or down) to pull out more stars or luminosity.
You mentioned CA from my optics...what optics? The C6 is sending the data directly to the camera's sensor without any glass, being a Newtonian. Another question...Deepskystacker, I created a starmask. Where can that be utilized in Photoshop to help round out the stars?

This is becoming quite a tutorial and as an eager student, I look forward to my next class:) See you this afternoon! Greg

My apologies Greg, I was thinking of the Celestron 6 inch achro for some stupid reason. I really should have went to bed, it was after 2:30 am. :???:

Somewhere in your processing, most likely in your attempt to increase star color a CA-like effect was introduced. Your mention of the star mask leads me to think that maybe that played a role in creating the effect that I was wrongly referring to as optical false color. This could have ben introduced at any point and became more prominent as you went through your work flow.

I selected the stars by selecting a brighter one(using small magic wand) standing alone(not clusters) and then went to Select>Similar to grab many across the image(this wont grab the very faint ones).

• Then I went up to Select>Modify>Expand and set it to 2. Next I went up to Select>Modify>Feather and selected 2. These numbers will vary depending on the file resolution you are working with so play with them until you get it where it looks best.

• It's a good idea to Save this Selection and to do this on a duplicated layer so you can click on and off of the layer to see a broad comparison of your adjustments. By saving the selection you can load the selection again and again if you need to use it for other adjustments. This will also allow you to lower the layer opacity and effect in percentages if your adjustment is too over done. This is a nice tweaking method.

• I used the above selection to reduce the excessive blue/violet that was around many stars by adjusting down saturation in the "Blues" only.

If you can get your DSS mask imported into PS somehow you could try a slight gaussian blur to soften them some adding a subtle glow, but since your oblong star shapes are coma related(projecting out at the edges) and not tracking I don't know of a method to repair that. I don't use DSS nor have I ever created a star mask in a stacking program so I don't know if it can be exported for use in another editing program like PS.

One thing that has helped me is to work very carefully(sometimes slowly) through the PS phase of the process. Provided your stacked file is in good order, PS is where the magic happens and also can be where the damage happens. I keep multi layer PS files with various adjustments to make it easier to go back and find a point where something may have went wrong. At very least it's good to save "stage" TIF files that allow you to go back and reevaluate if something isn't right. The idea is to keep from having to go TOO far back and start again.

One other thing I do is always use Curves for stretching data. I never use levels, I find Curves much more manageable and effective.

I know I'm pouring out a lot here and it seems like a ton but as I mentioned in time you'll get down exactly what works for you and it'll be a snap. As you know there are many ways to skin this processing cat, especially in PS so I'm in no way suggesting my way is best. There are others out there with better methods and I've always got my ears open for better ways to do things.

[NovaTJ]

Working on the double cluster again...I would like to know how you can capture your screen shot in Photoshop. I just used my camera. Since it's early and I finally have a day off tomorrow, I'll be working on this till it's right.

Greg

[troypiggo]

That histogram is still clipped on the left hand side. Can you maybe post a link to the original file you get after stacking, before you edit it at all?

Re: screenshots - you can hit the printscreen button to copy a screenshot to your clipboard, then paste into a new file in PS. That's the simple answer. There's also a simple freeware utility called "Printkey 2000" you can google and download. It's so simple, even my dad can use it.

[NovaTJ]

Love to Troy! Now if I can just find a place to put it!

http://www.yourfilelink.com/get.php?fid=521038

[NovaTJ]

I like the screen capture program...thanks!

[NovaTJ]

Coming along?

[troypiggo]

I had a quick play. Note the histogram, how it's not clipped at the left hand end?

http://piggo.com/~troy/images/potn/dblcluster/TJP_PP.jpg

http://piggo.com/~troy/images/potn/dblcluster/TJP_PP_SS.jpg

[spit]

i think the last full size image probably looks the best without the over saturation- you took enough light frames, try restacking without the darks and see what you end up with- it seems when you stretch the image to bring out the dimmer stars, you start getting star bloat

[NovaTJ]

Thanks Troy...looking good and we have very similar histograms...now i'm going to bed. Greg

[troypiggo]

I just noticed why/how you're clipping the blacks. In your post #21 above, see how you've dragged the curve up the left hand side of the window? You need to leave the bottom corner of it at 0,0 and bend the curve like this:

http://piggo.com/~troy/images/potn/dblcluster/curve.jpg

[NovaTJ]

Yes, you are right in the above post #21 was an example of the screen capture program and the action depicted was not the final adjustment...just showing that I found the histogram and the tool needed to adjust the blackpoint. On your post, is that lower point on the line just somewhere to start, or did you grab that spot based on the histogram under the line? I'm relatively satisfied with what I've done so far...but in your opinion, what more do I need to do?

Greg

[troypiggo]

You've done very well on this. The only point I was making, and Nighthound is saying the same thing, is that your black point is clipped. You might need to do some reading on histograms, curves, and levels a little more. It looks like you clipped the blackpoint somewhere early in your editing, then by raising the line in your curves, you've shifted the whole histogram to the right but the data is still clipped. See how the left hand edge of your histogram is a dead straight vertical line? On mine, it's steep but does have a bit of a slope on it still. There is no clipped data on mine.

It would take too long for me to explain it here. Have a bit of a google and see if it all makes sense. Here's a starter:

http://www.photoshopessentials.com/photo-editing/photoshop-cs3-curves/

[DonR]

Hi NovaTJ,

Using the blackpoint dropper to set the blackpoint is generally not a good idea in this type of image, because it assures that the point you click with the dropper is set to 0 intensity in all three channels. This usually means that you will loose data during subsequent processing steps due to clipping. What Troy and Nighthound are saying is that rather than adjusting the blackest part of your image to 0 intensity you should leave it around 20 to 30 counts. This is not possible when you use the blackpoint dropper in Levels or Curves, so the blackpoint input level slider in the Levels tool is a better choice.

At the end of all processing steps you can use the Levels tool to ease up on the blackpoint and get it closer to 0 if you want, but in my opinion most deep sky astrophotos look more natural if you leave some space between the blackest parts of the sky and the absolute bottom of the histogram scale. If you do want to trim out this last bit of sky illumination, you should do it after all the other processing is complete.

Don

[ejicon]

Nicely done.

[NovaTJ]

Thanks Troy and DonR, you too Nighthound, your points are taken well. I do need to do more study before jumping in head first. Yes, I remember adjusting the blackpoint early and I want to say it may have been in Deepskystacker before Photoshop came into play. Sometimes I've seen Deepskystacker leave a dark image and sometimes a gray image. This may have been one of those gray times. I think I will go back to the stacking process and redo. Hopefully, since the weather is starting to clear and turn cold on the east coast, maybe I can add to the stack. I appreciate all the comments and praise. You all have a happy holiday.

Greg