Astronomy in the Inland Northwest

ASTROCON'S Worldclass Astrophotographers
Jack Newton - Deep Sky Imaging

Thursday - July 15, 1999

Jack Newton is an amateur astronomer from Victoria, BC, Canada. The quality of his images and his books on astrophotography have made him one of the most well-known amateur astronomers in the world.

Jack has recently built a new home on Vancouver Island, north of Victoria. In it, he has incorporated features like a integrated telescope dome, a fully equipped computer room, and the ability to remote control his telescopes from the living room. He has even managed to create a nice place to live! And being a good Canadian, he also runs a $100 per night Astronomy Bed and Breakfast in Florida to escape those cold Canadian winters. Jack referred to his new home as a “finished telescope with sleeping quarters attached.”

Jack’s current astronomical endeavor is CCD imaging from his home. And the fruits of his current labors can be found in his new book, Splendors of the Universe : A Practical Guide to Photographing the Night Sky, co-authored with Canadian author Terrence Dickinson.

Jack feels that CCD imaging has opened up new vistas for the home astronomer, by giving him an enormously powerful tool that allows him to use a small telescope to take observatory quality astrophotos. The CCD image can even be used by an amateur to duplicate the famous Hubble Deep Field, and Jack has done exactly that.

The three-color CCD imaging technique allows photographers to take color photos of deep-sky objects that reproduce the correct color balance that the human eye would see of it were sensitive enough. Color film, because it is not sensitive enough to the Doubly Ionized Oxygen Line that is common in astronomical objects, is unable to make this color rendition accurately.

Jack uses the Meade Pictor CCD chip for his imaging projects, and feels that this product is both cheaper and does just as good a job as other CCD cameras.

On Friday, July 16, Jack made a second presentation, showing many of his recent CCD images, including the Horse Head Nebula I Orion, Halley’s Comet and the Milky Way, Centaurus A, Comet Hale-Bopp, M31, and the Pleides.

David Malin - The Invisible Universe

Friday, July 16, 1999

Australian Astrophotographer David Malin was introduced by J. Kelley Beatty from Sky and Telescope Magazine.

David began by saying that his talk could have one of two titles: Things to See and Do in the Dark, or The Invisible Universe. He felt the first was too provocative, so he settled on the latter.

Most of the universe is either invisible to the human eye, or is obscured by local phenomena. In fact, 90 percent of the universe is completely undetectable.

David started imaging this invisible universe when he took a job to run the Anglo-Australian Telescope at Siding Springs Observatory in Australia in the mid-1970’s. This telescope is located at 30-degrees south latitude, 500 KM or 300 miles north of Sydney, and is built on the edge of a volcanic caldera in New South Wales. New South Wales is one of the darkest areas on the face of the earth, with no artificial lights close enough to be detectable. Only 10 percent of the world’s population lives in the Southern Hemisphere, and the skies at the observatory site are even darker than at sites in Chile and Hawaii. Even the darkest places in the US now have some reflection from city lights. The dark skies make Siding Springs ideal for astronomical imaging. Even so, the natural night sky shines from airglow, even in the darkest places. The night sky literally glows in the lines of nitrogen and hydrogen.

Photography was first introduced into astronomy in the 1880’s. Before that, astronomers relied on the memory of observers and the drawings they could make from personal observations at the telescope. The impact of the first astrophotos came not from the accuracy of their renditions of known objects like the Orion Nebula, but because they were able to record stars and features never seen before by visual observers. Photography was thus recognized as a tool for astronomers that would allow them to record and study things that could not be seen.

The Siding Springs Observatory uses special Kodak emulsions for photography. These plates are becoming more difficult to obtain since Kodak is finding less and less profit in manufacturing them for a shrinking, and highly specialized, astronomy market. When these plates are hypersensitized by soaking them in hydrogen gas and then bakeing them at low temperatures to evaporate any water trapped in the emulsion, there is an increase in sensitivity of 53 percent. The plates are black and white, and must be filtered to create color photographs. In order to create color pictures, separate red, blue and green images are taken, and then recombined in the photo lab. The night sky determines the final length of the exposures.

In astronomy, images are not just pictures, they are also data. Image enhancing techniques can reveal new data in the final color images, and the combining of the images also reveals hidden data.

Color film does not reveal the true color of astronomical objects, due to the specifications of color film emulsions. However, filtered tri-color photographs,. similar to CCD tri-color imaging, will reveal the true colors as they would be seen by the human eye. Photos of M42, the Horsehead Nebula, Rho Ophiuchi, the Pleides, and the Rosette Nebula illustrated the photographic techniques and astronomical principles David talked about.

In his career as an astrophotographer, David Malin has created some of the most exquisite astrophotography in the universe. Photography records the forms and colors of nature as they are. Like Ansel Adams in his great photographs of Yosemite Park, Malin tries to capture the natural wonders of the sky as they exist. Many human beliefs are formed as a method of explaining the nature of the world around us. Scientific investigation can then refine and replace our original theories. The images he chooses for illustration or exhibition are chosen both for their artistic merit as well as their scientific value. CCD images are a great way to study astronomical objects, but for high-resolution, wide field images that will “knock your socks off,” photography is essential. It is difficult for us to understand how people observed the deep sky before photography.

John Herschel, in the period 1840-70, was a greater observer than his father, Sir William Herschel. He was the first serious observer of the southern skies, from Sough Africa, before 1839. He was especially skilled in making drawings at the eyepiece of the objects he observed. But drawing, being subjective, is not a good way to record astronomical objects.

The first astronomical photograph was made in 1883 when Commons photographed the Orion Nebula. His photograph was the first that demonstrated the power of this new technology to detect stars not seen by the human eye.

Today, color photography is an important way to bring out interesting detail not otherwise easily seen in an astronomical photograph. Normal black and white film is not properly formulated for astrophotographic purposes. Instead, special high contrast emulsions are used to bring out faint detail in dim objects. And because these emulsions are slow, it is necessary to hypersensitize to remove water and oxygen from the emulsion, to increase sensitivity. Hypersensitizing can increase the sensitivity to faint light by a factor of 30.

David Malin uses two special processes to make his high quality astrophotos. The first is Unsharp Masking, and is a technique used to extract otherwise unseen detail from high-contrast exposures. If not properly masked during printing, pictures from unprocessed negatives will appear overexposed. Unsharp Masking is a way to do detail dodging on a photographic image during the printing process. The unsharp masking technique is now also available in image processing computer software like Photoshop.

Photographic Amplification is a contact processing technique using diffuse light during printing of a negative. Multiple photographs of the same object will have a dissimilar distribution of photographic grains. Combining these multiple images during printing will improve the resolution and contrast of the final print.

For three color astrophotography, three filtered images of an object are needed to be combined to make a color print. These three original images are taken of the same object through red, blue, and green filters, and registered and printed three times on color print paper to make the final print. It is also possible to use unsharp masking and photographic amplification on each of the three color images while making the final print, as long as the correct color balance is maintained. These techniques will add extra contrast and impact to the final print. Tri-color imaging plus unsharp masking produces the most interesting astrophotos, photos with high contract and crisp color.

Negatives can be manipulated during the printing process, even from the same negative, to bring out various details held within the negative. The final print depends both on the scientific use and the artistic judgment of the photographer. Very deep images, processed correctly, can reveal a wealth of otherwise unseen detail in an image.

The eye is effective at transmitting information to the brain. But the human eye and brain is a very complex system, and it is subject to subjective as well as objective interpretations of data. For this reason, the techniques used in processing to create a final image must be included in the description of that image to make an astrophoto scientifically useful.

View David Malin’s images on his own web page, http://www.aao.gov.au/images.html

Ed Flaspoehler
Vice-President, AAAA