Hi John! I'll try to address your "challenges"! Thanks for the feedback.johndmura wrote:I keep looking at Astro and I am sure that not only is the caption wrong, so is the picture. An exposure long enough to capture those stars would have left "star trails" I have seen pictographs like your images on a rafting trip down the San Juan River in Utah and they are located along the San Juan River not anywhere near Canyonlands. park! I would rather see old photos than having my "chain pulled" by sophist pundits who think they are clever.
1. Star Trails - this is a common question and I'm glad you asked it! Taking these images at night is not easy. It helps a lot to be using a Canon 5D MkII with a full frame sensor and quite good onboard noise reduction. These kinds of night shots need to be taken with ISO at least 1600 and up. This image was taken with ISO 3200. If you have a fairly recent DSLR go outside some night, set the iso to 3200, point it at the sky and see what it looks like...you'll see a LOT but it'll be noisy and not satisfactory. It's a credit to the Canon full frame sensor and noise routines that it can perform at such high sensitivity and get noise into a manageable range so now at least we have an extraordinarily sensitive sensor that can gather light like no consumer camera prior. When the sensor is on for 30-60 seconds at extreme high sensitivities it builds up enough heat to impart a thermal "signal" upon itself in the form of "noise". The onboard noise reduction is most helpful because it takes a blank shot for the same duration after you're done with the original and subtracts that signal from your original. This cannot be accomplished on your computer at home but must be completed in the field.
Next - consider the aperture and the focal length of the lenses used....the wider the lens the longer time you have before you start to see tracking. If you were zoomed way in with a 300mm lens at the sky it moves rather rapidly across your field of view. However if you are using a 15mm fisheye/f2.8 spherical (as was used for this shot) you can expose for quite some time (on the order of 60 seconds) before tracking becomes an issue. You are indeed "fighting" tracking/star trails to attempt shots like these and it is star trailing/tracking that largely bounds your exposure time! Fact is all my shots have some level of star trails they're just manageable and negligible at the settings used. This shot has very little (although a bit angling upper left to lower right) because I used the fisheye which encompasses a full 180 degree field of view! Most of my night shots are not taken with the 15mm fisheye because I prefer the 24mm/f1.4 which is an even faster lens. f2.8 is really a limit I believe for this kind of photography. Note with the 24mm lens I usually can only expose for 30-40 seconds before trails become an issue and they still have more star tracking than in this Ghost Panel image.
It's a further tribute to the Canon full-frame sensor that you can "paint" the foreground rock to your artistic satisfaction with the ISO at 3200 and still generate a nice clean rock image that is not noisy. The point is modern technology is enabling new regions of photographic expression.
So although I'm sure that's unsatisfactory I hope it begins to address the doubts that you expressed about star trails. Actually an astute challenge and I thank you for it.
2. Regarding the location of the alleged "Ghost Panel" actually being located on the San Juan river... Man oh man do I love the San Juan river! Like you I am now disappointed in myself, the Utah Museum of Natural History, the University of Utah, Canyonlands National Park and many many rock art lovers and archaeologists throughout the world that we would all be duped so easily into believing that the most spectacular and famous panel of rock art in North America is actually in Horseshoe Canyon when you have now confirmed and exposed (to my utter humiliation) that it can be found along the San Juan river!
John - Thanks for generating the provocative and useful conversation and challenges. This image is as presented with no punditry or sophistry and I hurt a little that you even suspected it!
Bret
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so we must be missing most of what goes on in our lovely Milky Way. No wonder we do not understand very much about anything. The EYES have it, but we do not have the eyes.
