Posts Made By: dan kowall

Thanks, guys!
A couple of comments:
Greg---12 hours is a lot, but I was shooting unbinned and I needed to go that long to get a decent S/N.
Eric said "If you can do this from your light-polluted back yard, there's hope for us in similar situations!"---I was lucky in that I was able to get most of this data during a good imaging spell. As a matter of fact, I didn't have to do any gradient removal on this image. That's always a relief.
In response to an observation on another group, I stretched my data a little more on this image.
You can see the result here:
http://www.photonhunter.com/nebulae/IC5146,Wide,str,lrg.html
It shows more of the nebulosity. I'll probably update the page to show this version. It looks better to me.

dan

Excellent!

dan kowall

I used to do what Phil said, but if you dither your subexposures you don't have to do any cleanup at all!
It's great for us lazy guys.

dan

Looks good, Tom.
Keep it up.

dan kowall

As everyone has noted: great star colors, Jim.

dan kowall

That is a fine piece of work, Jim.
It's got star color, detail, and the delicate outer nebulosity.
That qualifies as a home run in my book.

dan

Excellent detail, Joe, and the color looks pretty good, too.

dan

Hi Brian,
I believe the DSI is an 8 bit camera (?) so your dynamic range is going to be a bit limited. You might be able to show everything by careful processing, i.e., when stretching your image, stretch the low end more than the high end. If not, there are a couple of ways to go then.
--If you can fit M31 into your field of view, then you could take two sets of exposures, one so that the core isn't overexposed and one longer set to show the arms. The best parts of one set can then be layered onto the best parts of the other set using Photoshop or some similar software.
--If M31 is bigger than your field of view, then make a mosaic. If you're just exposing the arms, you won't have to worry about core burnout. If you don't have Photoshop or Registar there are still programs out there that can stitch images together. I believe a lot of digital cameras come with software that can do this, though many people aren't aware of that.
I've attached a test image of the start of an M31 mosaic where the core exposures were something like three times as long as the arm exposure.

Later edit:
(Ooops! I meant to say that the arm exposures were three times longer than the core exposures.)

Rob Mackie said:
Comments and criticism most welcome. I'm still trying to figure out CCD imaging and appreciate people telling me where I'm going wrong.

Hi Rob,
I've found that all of the basic advice that I got that seemed counterintuitive to me turned out to be true.
Spend most of your money on the mount? Spend time learning Photoshop? I had initial doubts, but, after all, this was coming from people who had been doing this for awhile. Lo and behold, it turned out to be good advice.
There was another piece of advice that I got that did make sense to me: master making a greyscale image before moving to color. That advice turned out to be truer that I thought.
If I were you, Rob, I would first concentrate on honing your talents on luminance and Ha images. I would ditch the LPS filter and learn how to remove gradients, for instance. I know the temptation to jump right into color is strong, but learning the basics while wrestling with color is almost impossible.

dan kowall

Hi Louie,
Your detail looks good, but it looks a little too green on my monitor. Decreasing the green color balance in Photoshop brought out the blues and reds for me.
Do you have pictures of your Coonabarabran site? I'd be interested in seeing it.

dan