RIP: George MacDonald Fraser, 1925-2008

http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/01/03/db0304.xml

Cheap Man's Observatory

While I live in a rural part of our county, and the skies are startling crisp at the Zenith, I am located near an intersection that features a safety light, store light, and neighbors on each side of my property. Up to this point, much of the glare from these sources has been avoided by setting the telescope up in the shadow of my storage building. But light is still slipping into some of my photos as a gradient and if I take one step the wrong direction I lose my dark adaptation. Since a permanent Observatory housing for my telescope is not feasible at the moment, I wanted to try a low cost solution to block out a lot of the stray light.

My plan is this: find something to act as 10 foot poles that would extend from each corner of my building. Between my building and these poles, I will hang tarpoleun to act as a temporary wall. This will hopefully block out extraneous light while having the advantage of being quick to assemble and disassemble as necessary.

Project Materials:

3 8x10 tarps (I could only find 10 mil thickness, colored gray on one side and Brown on another)

2 PVC 10 foot long pipes

2 cinder blocks

1 roll of duct tape

1 box of eye hooks

Project Materials Needed Later:

1 roll of twine

2 cans of matte black spray paint

4 camping tent stakes

First, I measured up the PVC 8 feet and screwed in two eye hooks at a 90 degree angle from each other. Next, on each corner of my building, I measured up the same height and screwed in an eye hook on each side. Now I can use the reinforced eye holes in each tarp to hang my temporary walls.

Now I only needed to secure the poles and I should be set. To do this, I liberally applied duct tape to the base of each pole and a cinder block. In hindsight, not the best idea I never had.

The PVC turned out to be too weak to really hold each tarp, so I had to break out the twine and tent stakes to string up some guide wires opposite the directions of tension created by each tarp.

This created my enclosure and after each session I could unhook the tarps and be done with it. Now to test it!

Once settled in after sundown, I noticed a significant reduction in glare. Two problems were obvious though. First, the caution light at the intersection was just high enough to slip over the edge and create some glare on the top foot off the glossy tarp. To fix this, I took some matte black spray paint and coated areas that were affected. Problem solved (mostly anyway). Second, because the tarp was not as thick as I would like, my neighbors safety light created a soft glow of against one side. Another application of spray paint should fix that!

In the end, I achieve the desired effect of greatly reducing the effect of my neighbors' lights. Is it the best solution? Definitely not. Is it much cheaper than a dedicated Observatory? Absolutely. Will my dog rip it down when my back is turned? Almost certainly.

Book Review: Digital SLR Astrophotography

Book review: Digital SLR Astrophotography
ISBN number: 9780521700818
Price: $45 US
Author: Michael A. Covington
Publisher: Cambridge University Press

Astrophotography has always involved a skill set requiring precision, patience, and a lot of trial and error. The learning curve has been steep, to say the least, but with the advent of Digital photography a larger and larger number of amateurs face this learning curve. Unfortunately, Digital photography also demands a different set of skills not documented before. With the exception of the few books that have tackled the subject in one way or another, amateur astronomy using DSLRs still lacks one good all-around, comprehensive introductory text for beginners. A few books have concentrated on the processing aspects of Digital imaging, and a few older books have updated sections on film photography with mention of Digital cameras, but Covington's work here is one of the first to approach DSLR astrophotography as its primary focus. Digital SLR Astrophotography does a good job of introducing the interested amateur to the subject while providing enough information to allow a beginner to advance in the hobby.

Astrophotography's 217 pages are divided into 14 chapters. In the first part of the book, Basics, Covington spends four chapters discussing DSLR options, technical issues unique to this format, problems associated with using electronic sensors in the cameras, and a few simple projects to introduce the reader to some immediate success using the camera. Throughout this section Covington mostly refers to Canon or Nikon cameras, which are the two main brands currently on the market, but he pays little attention to other options aside from a brief mention. His treatment of software is similar, however, he does mention freeware options which any beginner is well advised to try before investing in an expensive processing package. Most examples used in the book refer to Adobe Photoshop or MaxDSLR.

In part two, Cameras, lenses, and telescopes, Covington uses a chapters to explain how to couple the camera to the telescope and how different configurations how different effects on the final image, modifying the light path with focal reducers (Meade or Celestron), the pros and cons of using camera lenses piggybacking to a telescope, issues and solutions to focusing Digital cameras, the necessity of tracking the sky and how to go about it, keeping power to the camera and finally, different types of Digital sensors in the cameras and their response to various wavelengths with and without filters. Throughout this part of the book Covington references Meade and Celestron products but with one or two exceptions, ignores what has come to be the third major supplier of telescope products, Orion Telescopes. Covington does a good job of providing illustrations that clarify some of the technical issues he discusses in the text. These are generally excellent, and go a long way towards clarifying the various lenses and focusing options. Covington also does a good job for presenting the reader with the various choices and amateur astronomer has to make, including guiding options and focusing aides. Unfortunately, in the case of the latter, Covington mentions that it is easy to create a Hartmann mask but fails to deal instructions, instead referring the reader to his earlier book Astrophotography for the Amateur.

Part three, Digital image processing, covers a topic that can be most confusing to new astrophotographers. Covington explains the difference between dark, bias, and flat frames well but consistently uses MaxDSLR for his examples. This obviously works well for readers already using that particular software package, but may not be as clear for beginners using some of the free software packages. Nevertheless, this section is a real strength of the book, and will definitely aid the beginner in understanding some of the complexity involved in serious DSLR astrophotography.

An appendix of about 10 pages briefly mentions WebCams and their use for planetary photography. The inclusion of this seems odd, and out of place, as if, after having read the entire book, a beginner decides DSLR photography is not for them and perhaps they would be interested in WebCams instead.

Overall, Covington has done a good job of providing an introduction to the topic that also presents the reader with some of the options they can face in the hobby as well as potential solutions to problems that will inevitably occur. As a primer the book is first rate. Covington's strengths are evident in his handling of some of the more confusing topics; he explains them well. The diagrams provided are clear and informative. However, a serious drawback of the book is that photographs (all black-and-white} are often unhelpful and in some cases confusing. Perhaps due to the black-and-white nature, this can be annoying and for a book that cost $45 may leave the reader feeling less than inspired. For example, when discussing the pros and cons of modifying an DSLR to be more sensitive to hydrogen alpha emissions, side-by-side photos are given to display the difference. Now, Covington's point is to show how well an unmodified camera can do, so some similarity is expected, but I have yet to detect any difference between the two photos. Secondly, for a book whose purpose is astrophotography, it is criminally bereft of any striking photos that typically inspire beginners into the hobby in the first place. Covington would have been well served by including even a small section of color plates illustrating some of the superior photos being taken with relatively inexpensive equipment by amateurs using DSLRs. Still, Digital SLR Astrophotography fills a much needed role as an introductory text on the subject.

The Great Orion Nebula

Last night I decided to take another stab at M42. After capturing my light frames, I started to change the battery and accidentally bumped the camera. There was no way for me to get back in exactly the same position. Discouraged, I only took a few dark frames since I did not think it would matter. This morning I processed them both with and without the darks. I also forgot to bring out my material to give my flat field frames. So not an optimal night, and I also have a sore throat this morning! Then I continue to be inexplicably drawn to this hobby, HA! Here is the result of both, the first without darks and the second with them.

Information for the photos:

8 inch Newtonian reflector mounted on an Atlas
unguided, approximately 11 frames at 15 second
approximately 40 frames at 30 seconds
unmodified rebel 6.8 megapixel version
baader 2 inch UV IR cut filter

Processed using deep sky stacker, pixinsight, and the gimp


Things to improve:

Get a coma corrector!
Get guiding to work!
Learn how the process image functions work better!
Be sure to accurately capture dark and flat frames!

December Full Moon

Here's a quick one. Full moon, December 2007.

Merry Christmas!

Here is a photo of my third attempt at Mars as well as a shot of the Moon. Hope everyone has a good Christmas!

finally a clear night!

Last night the sky finally cleared after weeks of cloudy weather and rain. With the closest approach of Mars upon us for the next 10 years, I wanted to try and grab some photos while I could. Using an off-the-shelf WebCam with my existing telescope and mount, I captured several short video clips and then used software to select the best frames and combine them into a single image. This is a new process for me so it took awhile to get everything working properly. This image is a composite of the images resulting from each of movies. The polar ice is clearly visible, as well as numerous albedo features. Mars is currently bright red and high in the sky by 10:00 p.m.



This image is a single frame of 30 seconds showing M42, commonly known as Orion Nebula. I snapped this with a DSLR at prime focus before putting everything up for the night. Later this winter I will be taking numerous photos of it so I wanted to get an idea of how well it filled the frame. This is one of the brightest nebulas in the night sky, and appears to hang in the middle of Orion's sword belt where a scabbard would be.



This image is a single frame of 4 1/2 minutes, unguided, showing the Flame Nebula in Orion's belt. Designated NGC 2024, it is much fainter than M42, appears next to Alnitak, the third star in the belt, which shines at magnitude 1.74 and lives 817 light-years away. The smudge in the upper right is a nebula, NGC 2023, surrounding a smaller bright star.



I could not resist snapping at least one image of the first quarter moon!