Fri, 14. September 2012
Astro-Speaker Watch - August 2012
Humayun Qureshi: “Delivering Aesthetically Pleasing DSLR Images”.
I began this “Speaker Watch” series because I felt that some of the things our guest speakers were telling us were far too important to be completely lost - despite the obvious risk posed by condensing a talk down to a few paragraphs. This is particularly true in the case of Humayun Qureshi, who shared his best images with us at the August Forum and provided many tips for the Society's growing army of astro-imagers. Reducing all of his tips into a single article is not easy.
Humayun's talk was called “Delivering Aesthetically Pleasing DSLR Images”. He described himself as both a “technical person” and a “creative person.” I think he should also have added “very patient person” because he does not appear to be a man who churns out astro-images in large quantities. Rather, he concentrates on planning a stunning image and takes as much time as he deems necessary in order to achieve just that.
Whereas perhaps many of us might just “point and shoot” and worry about the details later, Humayun will be spending a great deal of time, prior to even going outside with his equipment, first selecting the initial target, then determining how best to frame, compose and orient the contents of the image and deciding how many exposures he will need to achieve a great image. He will then spend many long hours exposing the images – often over a period of many nights spread across many months – and then spend many more hours patiently stacking, cropping and processing his images to bring out the best contrast and colour.
Some of Humayun's best tips? Image no more than one object per night. Image only high in the sky, where the atmosphere is thinnest and light pollution is minimised. Apply the “Rule of Thirds:” which means the focal points in any composition should fall on the horizontal and/or vertical “lines of thirds,” because our minds seem to pick up on thirds, making the image more pleasing.
The colder the better – camera noise doubles for every six degree temperature rise. Do test exposures. Use the histogrammes provided on DSLR camera images. Use a focal reducer. Know the absolute limitations of your ISO settings, which can vary between cameras and can improve with technology. Always do dark frames before, during and after the main images and then combine them. Take 16-25 flat frames (at the lowest ISO) – e.g. an image of a white wall or a lightbox - and combine them to enable the subtraction of dirt and dust residue in the camera.
If you use Photoshop CS4, use the “Vibrance” command. When taking landscape images, do so only around dawn or dusk, during the “Golden Hour.” To get diffraction spikes – use black cotton (or light fishing line) fixed with blue tack.
Two years ago, Humayun embarked on a new long-term challenge, that of photographing a mosaic of sixteen adjacent sky images and stitching them into one large composition. He's well into it and he showed us the results in progress: an astonishingly detailed wide field image of the Rho Ophiuchi region.
Humayun uses the following free software: Iris ; Canon EOS Utility and Canon DPP; Deep Sky Stacker.
He uses the following purchased software: Photoshop ($1,168 for CS6); Starry Night Pro Plus ($250.00); and Pixinsight (171 Euros); Diffraction Limited Maxim DL ($199-$665); Skysurvey.org ($2.99 app)
Humayun's is a member of the Canberra Astronomical Society and his best images are available in his Google+ Image Gallery: https://plus.google.com/photos/105538468557560833220/albums/5776462316403951729
AT THE MACARTUR ASTRONOMY FORUM:
This month: Cosmologist, Professor Geraint Lewis.
October: Astronomer, Dr. Simon O'Toole.
This article was written for publication in the September Edition of "Prime Focus" magazine - the journal of Macarthur Astronomical Society.
in Astro Forum: MAS
at
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