I'm an amateur astrophotographer. And when i say amateur, i mean it in the most literal sense of the word. When someone googles amateur astophotographer, a picture of me pops up with the definition. But i'm proud of my photos and want to share them. They aren't super great. No one is going to confuse them with professional photos, and no one is going to accuse me of stealing images from the Hubble, but they are mine. This blog is not so much a venue to show the photos, but more of a journal of the learning process involved.
In future posts, i will talk about my equipment. how i set it up, the mistakes i made, and the workarounds i have used. Subjects for a rainy day. This post will explain the process i used to capture and develop this image. Messier Object 74 is a face on spiral galaxy in the constellation Pisces. It's about 32 million light years from earth and consists of about 100 billion stars. Much smaller than the milky way which contains somewhere between 200-400 billion stars. M74 is listed as an intermediate target. I cannot make it out in the scope. But the camera sees things that i can't.
Last night, as my wife and granddaughter were watching "Spy Kids 4", i decided it would be a good time to take advantage of the clear skies and open the observatory. I call my observatory "Don's Doghouse". If you saw it, you would understand why. I set the scope to the index marks, and did a four star alignment. Two stars in the east, and two stars in the west. There are a couple nebula i would like to capture in Orion, but it is not yet high enough in the sky. So, i decided to target Messier 74 in the constellation Pisces. I did a 180 second test and saw the distinctive bit of fuzz on the exposure that usually signifies a galaxy. It took a few minutes (almost standing on my head) to get the autoguider locked on a nearby star and guiding the scope. The computer was set to acquire 50 photos at ISO1600. Each photo would be a 180 second exposure. That would yield two and a half hours of exposure time. The computer assumes control of the camera once i start the process, so i don't really have a lot in the process for the next few hours. i step out of the Doghouse once the process starts, and do not enter it again until the run is complete. The idea is to create as little vibration as possible. Although the tripod sits on a 4" thick concrete pad, i won't go near it. NO walking on it, no touching the sidewalls, nothing. Fine with me! Frees me up to wander the yard, sit in my lawn chair, take in the sky, get a cup of tea, harass the granddaughter.
After two and a half hours, i reenter the Doghouse, shot 5 darks, and 5 bias. I didn't bother with flats. I could shoot some today to throw in the mix. The camera is still attached to the scope. (usually is) But i'm not convinced that the flats add all that much to the final photo. If you don't understand what these are, don't worry. I'll explain them in another post. The 50 photos were loaded into a program called DeepSkyStacker. i went thru the photos one at a time and deselected any pic that showed evident sign of vibration, or alignment errors. Twenty five shots were rejected during this process. Then the dark and bias frames were loaded. DeepSkyStacker is pickier than i am, and can see defects in the photos that i cannot. It rejected twelve more of the photos leaving me with thirteen 180 second exposures. i saved the result as a TIFF file, loaded into Photoshop and did some minor editing.
I'm not great at Photoshop. i have a lot to learn. But i am capable of stretching the histogram to bring out the color, removing a nasty gradient from the background, and making the background stars a little smaller. I'm particularly proud of the star resizing trick. without it, the stars detract too much from the focal point of the photo.
So there you have it. I'm unhappy with the reject rate. I think there are some things i can do about it. i do NOT want to shorten the exposure times, though that would help. i would rather concentrate more on getting a better polar alignment. The Clear Sky Chart indicates a relatively good sky tonight after six PM. Good, gives me a chance to practice more. Maybe a nebula.....
comments and advice are GREATLY appreciate...
clear skies....
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