Saturday, January 21, 2017

More Stars WIth the 500mm Lens!

A post or two ago I promised some more astronomy shots with the "new to me" 500mm F/4 telephoto lens. It is a fun lens to use - a full order-of-magnitude increase in scale over a normal camera lens it opens up a whole new world for imaging, and its unrivaled sharpness transfers to astronomy as well.

In my first post showing off the lens, I showed first results of the North American and the Rosette Nebulae. Both of these red-glowing clouds of hydrogen are excited to fluorescence by nearby hot stars, whose ultraviolet light cause the gas to glow much like the glow of a fluorescent light. This time of the year (recall these were taken the end of November!), it is possible to shoot the Summer Milky Way objects as it sets, as well as the Winter Milky Way as it rises, and these clouds of gas are large enough and bright enough to capture well, so more included here today. First up at left is NGC 2174, its popular name being the "Monkey Head" Nebula! I like to display my images with North up, sort of how it would look in the sky as it transited the meridian. The "Monkey Head" is more easily seen with South displayed upwards to see the outline of a monkey. Try it and you will see! While the nebula is very large and faint, I actually discovered this visually through my 11" Newtonian telescope at a star party while sweeping along the Gemini/Orion border. This is a stack of 5 exposures totaling about 12 minutes of exposure with the 500mm lens, with a pretty moderate crop.

The next object to show off is one of my
favorite areas - the belt area of Orion! The 3 main belt stars are the brilliant stars stretching diagonally across the image at left. The reason I like it are the little reflection nebulae scattered among the bright stars. While there is an ionized hydrogen cloud off the frame at lower left, the blue nebula at upper center is IC 426, a reflection nebula - here, the blue light of the bright stars are reflecting off the dust and gas making up the nebula. A careful examination will reveal LOTS of nebulosity through the field of both kinds - both reflection and ionized clouds, as well as a few others that are dark clouds that show up in silhouette against the others. This is nearly the full frame of the 6D with about 22 minutes of stacked exposures with the 500mm lens.

I've been a fan of IC 426 for a long while - it was one of my first objects photographed with my old venerable Canon 20Da camera and 11" Newtonian telescope. At left the nebula is shown in close-up cropped from 20 minutes worth of exposure with the 11" from January, 2006 - 10 years ago!

Finally often as I'm about to shut down for the night, I take a single exposure of a new object just to see how it will appear in the scope or lens in use. In this case, the only really clear night this lens was out on 28 November, I took a single frame of the Orion Nebula - 150 seconds-worth shown here. I rarely shoot the Orion Nebula, one of the more spectacular objects in the sky because it varies so much in brightness and is difficult to show such extremes in brightness well. Anyway, as soon as the image read out I could see something "weird"! Even though I was tracking the stars, there were streaks in the image! Of course, I'd seen them before and knew immediately what it was - geostationary satellites! Orbiting the earth 22,000 miles above the equator they orbit every 24 hours, so appear stationary in the sky, and if one was broadcasting a TV signal, your antenna dish wouldn't need to track it - ingenious, no? But as a result, from Tucson's latitude while tracking the stars, they will trail through the Orion Nebula. Here 4 satellites showed up in the 2.5 minute exposure... Just the other day, the Astronomy Picture of the Day showed a movie clip showing several hours worth of satellites "sailing" through the field...

Finally, I'll close with one more astro shot. While not taken with the 500mm, it was taken with a slight telephoto 80mm lens from Whitewater Draw 2 weeks ago. Watching the dance of the planets in the western sky, for many weeks I've been watching the orange-ish planet Mars as it approaches the brilliant Venus. But I also knew a secret - there was a 3rd planet between them! The most distant planet Neptune appeared between them... Since all the planets orbit more or less in the same orbital plane, just knowing that the planet was between them, I didn't have to know where it was - I could look it up later, and sure enough, just did this evening. Just shoot it with the appropriate lens to get both Mars and Venus and you'll get Neptune too! It was easily seen in this stack of a couple 30 second exposures tracking on the stars with the little Vixen Polarie tracker. One of our astronomy club members makes a planetary report every meeting, and Erich had noted the alignment, stating that the brightest planet (Venus) and dimmest (Neptune) was over 100,000 times different in brightness! You might have to click the image to even be able to see it!

As the cogs of the solar system continue to grind on, Neptune is, of course, no longer between them. I believe that Venus passed Neptune last weekend, and is now headed towards superior conjunction behind the sun on 1 March, 2017.

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