Thanks for the compliments! I too had some issues with DSS at first and wasted a lot of really good nights of data by not really knowing what I was trying to accomplish (not taking darks or flats), but I have gotten better at it as I progressed. I have only been imaging through the scope since September and can try to outline the things I have learned in the time since then.
1. Spend a lot to time over at cloudy nights going through the "Beginning and Intermediate Imaging" and "DSLR and digital camera astro imaging and processing" forums.
2. Spend that $2k on a mount (I have an Atlas and love it).
3. Find a teacher or student to get you Photoshop (I'm a teacher and pulled the trigger during a pricing screw up so I landed CS5.5 for $45!)
4. Search for online tutorials (like this one -Enterprise Astronomy & Photography | Videos)
5. Learn EQmod (an open source mount control suite which allow you to sync a planetarium program to your scope and replaces the hand control).
6. Pick up a guide scope.
I do not have a permanent set up, so each time I want to image, I have to lug the mount, scope, and camera out of the garage. Here is an outline of a typical night:
At dusk:
-Bring mount to driveway and roughly align with north (if I can see it, I'll roughly align with Polaris)
-Level tripod - I use the bubble level on my iPhone placed on my accessories try. Once I am close, I shim the short leg with paint stirs.
-Balance scope
-Connect scope to net book
-Open Eqmod
-Open Carts du Ciel
-Open PhD Guiding software
-Go through the polar alignment technique outlined here (
You Tube
|
src="https://www.youtube.com/embed/FZgPZnC7zKc?controls=1" allowfullscreen>
|
) and here
-Using Carts du Ciel, I choose some bright stars/planets to slew to in order for eqmod to build an accurate model of the night sky and to align my finder and guide scope with my main imaging scope.
-Concurrently with the above step, I will hone my focus on a bright star by powering up my K-x (in debug mode in order to disable dark frame subtraction) (which basically lives connected (prime focally) to my scope), clicking on live view, then moving the scope to center my target in the view finder, then zooming up to 10x then fine tuning the location of my target, then adjusting focus so that the stars are as small as possible and I get good spike (only with reflectors). - I think my English teachers would give me heck for that last step, but hopefully you get the just
-Choose my imaging target in Carts du Ciel, but I don't go right to it just yet. I pick three stars that form a triangle that encompasses my target, and have Cart du Ciel slew to each, center the scope, sync, repeat for all three, just so that the computer has the best possible model of the sky.
-Slew to my target.
-Within the PhD guiding software, calibrate the mount (the software sends signals to the mount and reads how the image in the guide camera responds) - this takes about 15 minutes.
-While PhD is calibrating itself to my mount, I set up a folder that is named after my target and the temperature (Ex M51 45degs). Within that folder, I create 4 sub-folders - lights, darks, bias, and flats.
-I open PK tether and set up my shooting and saving settings. I have it name my files after my target, the ISO and the exposure length (ex: M51iso800-300s001).
-Once my mount and guide scope are synced, I take one exposure with my settings just to see if my focus is good and I don't have too much light pollution.
-If everything looks hunky-dory, I let PK tether rip and go inside while I am taking my lights.
-Fast Forward a couple of hours, I lug the whole set up in and disconnect everything but my camera from the netbook.
-I cover the scope with the cap, set up PK tether to dump the next batch for files I'm about to take into the folder I labeled "darks."
-Let PK tether rip (now taking pictures of the back of my lens cap in my dark garage) making sure that the temp has not changed much (+/-3 or 4 degrees max) at the same iso and shutter speed.
-The next day at dusk I replace the batteries, stretch a white t-shirt over the opening in my scope and take a (20-30) of flat frames with the scope pointed at about 90deg away from the sun (I hope this goes without saying, but DO NOT POINT YOUR SCOPE AT THE SUN WITHOUT A SOLAR FILTER - you will damage your camera). These basically allows DSS to account for vignetting and sensor dust. These have to be at the same iso, but at a shutter speed long enough to push the histogram about a third to a half way out from the left edge (usually well under a second if the sun is still above the horizon). These will be saved in the "Flats" folder.
- I then take a bunch(10-20) of bias frames (same iso, but the shortest shutter speed possible). These get saved in the "Bias" folder.
-If you have not rotated your camera, or done anything that my have removed or added dust to your camera since your last imaging session, you can reuse these flats and bias frames - that's what I do and have not have had a problem. When I used flats that I took with a different t-adapter, I get some weird vignetting.
Now on to processing:
-open DSS
-Click on add light frames
-Select all of the files in the "lights" folder
-Click on add dark frames
-Select all of the files in the "darks" folder
-Click on add flat frames
-Select all of the files in the "flats" folder
-Click on add Bias/dark flats frames
-Select all of the files in the "Bias" folder
-Click on "check all" on the left hand side
-Click on "register checked pictures"
-This will open a dialogue box
-The only thing I change on this is what % of light frames do I want to stack - I use 80%, but if all of your frames look good, adjust accordingly.
-I then click on the advanced tab, then adjust the slider so that DSS detects somewhere in the ball park of 50 or so stars. Use your judgement.
-I then click on the stacking parameters tab and will adjust the result tab to mosaic.
-I then click on the lights tab and select median kappa-sigma clipping (I don't know why I choose this one, but the DSS guide explains the difference.
-I click "Ok"
-I click "Ok"
-I surf over to cloudynights.com, or pentaxforums.com while my image stacks.
-When it is done, I will adjust the color sliders (usually only the middle triangle of each color) so that they overlap, and click the linked settings check box to move the colored histogram over to the steep part of the curve (more to the left side of the steep part than the right side).
-I will then click on the saturation tab and set it to about 15-17.
-I then click apply settings and let it do its magic.
-*This is not your final image, just a jumping of point* I usually aim for an image with a very bright back ground.
-I will now click "save picture to file" and save it to the same folder that my 4 sub folders are in with a descriptive name.
-I then open this file in Photoshop and adjust curves, levels, saturation, and contrast. I find numerous small swings are better than one or two big swings for any particular attribute. I recently purchased Noel Carboni's AstroActions which offers a number of useful astronomy related Photoshop actions.
-When I am happy, or feel like I am beginning to do more harm than good with a picture, I will save it as a JPEG, and a new TIF file, being sure that I can still access my original file as it came out of DSS.
I hope this helps and if anyone needs clarification on any of the steps, please let me know, I would be happy to help!
Mike
|
