North American Nebula Region on Friday Night

[BitsyLon]

Hello everyone,

I went out Friday night with the intent of setting up my C8 with an f/3.3fr to try and do some DSLR imaging with that set up. Turned out after SEVERAL different stacks of adapters/tubes, etc. that the only way i could get focus was to strip off the micro-focuser, and install the adapter ring that came with the FR (with no extensions)...... That of course would not allow for the use of any filters.

I Switched the DSI Pro over to the C8 (with the f/3.3 still installed, and imaged through the ED80mm with the XTi @prime.

Friday night was an absolutely terrible night for imaging - but I figured that I'd at least get to do some testing using the C8 @f/3.3 for guiding. I also wanted to get an idea of the FOV I would get with the ED80, so slewed over to the North American Nebula.

Not only did I have the moon to content with - the atmosphere was like imaging from the bottom of a fish bowl LoL.

Hutech 1a XTi @prime on Orion ED80mm. 40X3min. @ISO1600. Auto-guided with Meade DSI Pro on Celestron C8 with PHD, EQMOD/DIR on Orion Atlas EQG Mount. Stacked in Iris with Darks/bias/flats - further processing in PSCS2.


http://i106.photobucket.com/albums/m273/bitsylon/My%20Astronomy%20Images/namirisgrad3szd2.jpg

I had to do a few gradient subtractions in Iris, along with Wavelet filtering. I can't even REMEMBER the sequence I went through in PS - Noel's actions played a big roll LoL ....

C's & C's always welcomed and appreciated.

Lon

[Radar]

Wow! Nice image Lon. You've captured the filaments nicely.

Can you tell me what exactly is a gradient extraction and wavelet filtering? Is Iris specifically for digital?

Ray

[BitsyLon]

Hiya Ray,

Thanx for the comments :)

Gradient can best be explained by clicking on the second link below ;)

The first link is to Iris's home page (there are tons of tutorials towards the bottom of the home page.

http://astrosurf.com/buil/us/iris/iris.htm

http://astrosurf.com/buil/iris/tutorial4/doc14_us.htm

A wavelet filter helps remove unwanted noise in the background of an image. Iris has a LOT of command features, and basically you draw a square in a "dark" section of the image, right click, and Iris will give you the Sigma of that area. You can do this several times at different parts of the image (making sure you click on "dark sky" to get a good average.

An image with lots of data (basically exposure time) will "usually" give you a low sigma. Of course transparancy conditions can cause problems also.

Any way - once you have that number, you apply a wavelet filter using a number that is greater than the sigma number (trial and error here) .... Iris will take that data and smooth out the background. The Ideal situation is to get a "sigman" below "10" ..... this could take several iterations of the filter depending on the noise level to start with.

In answer to your second question - Yes - Iris is a digital processing program ... It's free ... and really to be honest NOT very user friendly! Once you learn the sequence and "tricks" - then it is arguably the best stacking and pre-processing program out there for astro-imaging. It can get you very close to a finished product that can then be pulled into a program like Photoshop for final touches.

I have put together a little "Quickie Tutorial" in pdf format if you are interested.

Cheers,

Lon

[Radar]

Cheers Lon,

I'll check those things out.


I have put together a little "Quickie Tutorial" in pdf format if you are interested.


Yes I am interested. I am putting together a bunch of reviews and tutorials for the hoempage of this website. Contributors are credited of course. So if you don't mind me using it for public view then that would be great.

Ray