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Astrophotography:

 Astrophotography for Beginners focused on film photography
by Bert Katzung

http://www.astronomy-images.com/Articles/Astrophotography_for_beginners.htm

"How to" Solar Camera (pinhole camera) 6 month exposure

http://inatarius.wordpress.com/2009/07/01/solargraph-building-guide/ 

Digital Photography Tutorials and How To's

Cambridge in Colour
http://www.cambridgeincolour.com

NOTE: This article is excerpted from a  copyrighted manuscript (Astronomy for Beginners) before CCD cameras became the standard for astrophotography. It is therefore focused on film photography with only a few mentions of CCD. However, the reader should note that current digital cameras, even the point & shoot variety, can also be used for some types of astrophotography and with very little change in procedure. Certain other chapters in the original manuscript may be cited in the text below but are not yet available on this website. All rights are reserved and reproduction without explicit permission is prohibited.

Astrophotography Techniques & Targets

There are many different ways of capturing images in a permanent and reproducible form. For images of astronomical objects, traditional film cameras and charge-coupled device (CCD) cameras are the most practical methods at present. CCD cameras designed specifically for astrophotography can be expensive ($900 and up—way up!), require the use of a computer, and have a significant learning curve. In this article, we'll mention them only briefly (see the box below: CCD astrophotography).

Astrophotography with Film

Almost any through-the-lens reflex camera can be used for film astrophotography. Furthermore, the most interesting method for astrophotography through a telescope requires removing the camera lens. Thus, a 35 mm reflex camera with a removable lens is by far the most practical and popular astro camera. It doesn't have to be the latest and greatest electronic Nikon or Canon, however. In fact, the older mechanical models are better for our purposes than the fully electronic marvels that are being produced now. Almost any brand (Canon, Leica, Minolta, Nikon, Olympus, Pentax, Yashica, etc) will do, but it must have a time or bulb exposure shutter setting for long exposures. (Most removable-lens 35mm reflex cameras have such shutter settings.) You will need a few special accessories for attaching the camera to your telescope when you take photos through the scope. If you happen to have a medium format reflex camera (one that uses 120 or 220 roll film) you can use that and get superb results — many advanced astrophotographers use medium format. Unfortunately, the number of suitable astro films available in 120 format is very small.

The Big picture Many amateur astronomers are drawn to capture images of the night sky through their telescope and camera. Astrophotography, also referred to as astro-imaging (for you savvy folks), is both an art and a science. What you see in an astrophoto is real. However, it will not look the same as when looking through a telescope visually. Given some practice and patience, you can take beautiful celestial images not unlike the ones displayed in posters and magazines. Astrophotography has progressed greatly over the last few years, especially with the rise of digital camera technology. While astrophotography is both challenging and rewarding, modern low-cost equipment brings this exciting hobby within reach for any enthusiastic amateur astronomer.

The Simple Approach You can start snapping photos with nothing more than a "point and shoot" digital camera, such as a Canon PowerShot or Nikon CoolPix. With a modest telescope, it's possible to start taking impressive photos of the solar system objects which include the Sun (with a solar filter), Moon, Jupiter and Saturn. We'll briefly cover some simple ways you can start taking astrophotos with any camera setup you might have. Shoot the Moon Any telescope and camera setup will allow you to take quality astro-images of the Moon. Because the Moon is so bright, it does not require a long exposure and can be imaged without the use of an equatorial mount equipped with a tracking motor. The exposure is only a small fraction of a second, almost the same as a daytime photo. All you're basically doing is holding the camera in front of the telescope's eyepiece to snap a shot of the Moon.

The telescope and tripod are setup as they normally would be for visual use. If you are using a "point and shoot" digital camera, you can easily couple it to the telescope's eyepiece using the Orion SteadyPix Deluxe Camera Mount. Star Trails Star trails are a fun kind of time lapse photography that can be performed under any decent dark sky. Using a SLR (Single Lens Reflex) camera and an ordinary camera tripod, you can point the camera at the sky and open the shutter for several minutes. As long as the camera does not move during the exposure, you will capture the apparent movement of the stars in the sky during the exposure. Pointing the camera near the celestial pole will reveal steep concentric arcs. The further away from the pole you point the camera, the straighter the arcs become. Piggyback Photography - Make your Telescope and Mount Hold your Camera Beginners in astro-imaging can start taking quality wide field photos by "piggybacking" a camera to their telescope and mount. You will need a telescope equipped with a equatorial mount (EQ) which has a motor to compensate for the apparent movement of the sky (which of course, is really just Earth's rotation), and an SLR or DSLR (film or digital single lens reflex) camera capable of manual shutter control.

Piggyback astrophotography is a great way to start taking deep sky astrophotos without an elaborate setup. Instead of photographing through the telescope, you're placing the camera on top of the telescope. The camera telephoto lens is being used completely independent of the telescope. The point of placing the camera on top of the telescope is really just to take advantage of the heavy-duty equatorial mount which offers stable tracking. Many telescopes, such as Orion refractors and reflectors have tube rings with a camera attachment bolt on the top, ready for your SLR/DSLR camera. Some EQ mounts offer a 1/4"-20 adapter to fit directly to the top of the mount, allowing you to bypass the telescope and use the EQ mount directly. The camera telephoto lens has significantly less power than the telescope, which makes it far easier to track accurately; any errors or drift in tracking will not show up as much with a small camera lens. This is one of the reasons why piggyback photography can easily achieve good results. Milky Way panoramas, comets, meteor showers, and night landscape silhouettes are just a few of many fun things you can try with piggyback astrophotography.

The exposure time can be anywhere from a few seconds to several minutes. The shorter the f-stop on the camera lens, the shorter the exposure can be. But with any type of photography the required exposure ranges greatly. Bracket your exposures by starting with an educated guess, say 3 minutes, then experiment with shorter and longer exposures to determine what exposure time works best for your purpose. It is helpful to record your settings in a photo log. Solar System Imaging While the Moon can be photographed through just about any telescope and camera, the planets need more magnification because their apparent size is so much smaller. The full Moon is half a degree in the sky (about half the size of your pinky at arms length), while the largest planet in our Solar System, Jupiter, is about 2.5% the size of the Moon as seen from Earth. Telescopes with a long focal length and focal ratio work well when imaging the planets. The planets are bright, but because they require so much magnification to see well, the image will appear much darker, just like using a high power eyepiece.

It's a common practice to use a 2x or 3x (or higher) barlow lens to further boost the power on the planets to photograph them. But like visual astronomy, too much power will significantly degrade the quality of your image. You will need an equatorial (EQ) mount equipped with a motor drive that compensates for the rotation of the Earth. It's also possible to use a simple altitude-azimuth mount with tracking ability, like some computerized "Go-to" systems such as the Orion StarSeeker 80mm GoTo Refractor Telescope or the Orion StarSeeker 130mm GoTo Reflector Telescope. Exposure times will vary greatly, but is usually anywhere from a fraction of a second, to 1-3 seconds. Stack Your Images One of the biggest breakthroughs in digital image processing for astrophotography has been the method of stacking and combining the images to yield extraordinary detail of the Moon and planets. The same method is used for deep sky astrophotos as well. One high power digital image of Jupiter may not look impressive.

However, by taking 50, 100 or even 500 fast exposure images of Jupiter, computer software (such as MaxIm DL, MaxIm DL Essentials included with Orion StarShoot cameras, or Registax ) will sum all the good detail, and remove the bad detail. The bad detail which stacking eliminates includes camera noise and lapses of time when the image may have been blurry due to atmospheric turbulence. The powerful effectiveness of digitally stacking several images allows ordinary digital cameras and web cameras to achieve amazing results of the Moon and planets. Modified webcams and planetary imagers, such as the Orion StarShoot Solar System Color Imager III, work very well for capturing Solar System objects. Deep Space Imaging The "deepest" form of astro-imaging is of faint, deep space objects. These objects consist of nebulae, galaxies, and star clusters. Compared to solar system objects, deep space objects are extremely faint and require special CCD or digital SLR cameras. Many of these objects, especially galaxies, are invisible to the unaided eye and require a large telescope to see visually.

However, unlike visual astronomy, photographing a faint object is possible with a smaller telescope. Telescopes with a short or "fast" focal ratio (just like a camera f-stop) are favorable for deep space imaging. It is critical to have a high-quality EQ mount with a motor drive that will track very accurately. Instead of opening the shutter for a few seconds or less, deep space objects usually require several minutes of exposure to capture the light needed. A CCD camera replaces the eyepiece and plugs directly into the telescope's eyepiece holder. An SLR or DSLR can also replace the eyepiece, but they require a T-ring (specific to the make and model of your camera) and a universal T-adapter. This method of attaching the camera directly to the telescope without an eyepiece is known as prime focus astrophotography. This is the most effective way to capture deep space objects because you utilize the telescope's full light-collecting capability. Focal reducers, also called telecompressors, are available for some telescopes.

These increase the field of view and decrease the focal ratio to provide a brighter image. One of the biggest challenges of deep space astro-imaging is tracking. The telescope must move seamlessly with the apparent motion of the sky. Any drift or tracking error will create an oblong star in your image, or worse. All EQ mounts, even very expensive ones, don't track perfectly enough to produce a perfectly pinpoint star (also read about "polar alignment" in our Learning Center). When taking a long time-lapse exposure, the tracking will need to be corrected during the length of that exposure. This is known as guiding. Guiding involves monitoring a star through a separate guide scope and making tracking corrections as needed to prevent the star from drifting. This can be done visually with a crosshair (reticle) eyepiece, or with the use of a CCD autoguider. An autoguider is simply another camera that takes pictures of the star and sends corrections to your EQ mount. The guidescope is typically mounted on top of, or beside, the main imaging telescope.

Most guide scopes are small, high-powered refractors because they don't add much weight to the setup and do offer the image detail needed to see the star drift. CCD Cameras The ultimate camera for any type of astrophotography is the CCD camera. While CCDs are most commonly used for deep space imaging, they can also be used for solar system imaging. But you really take full advantage of a CCD when you go deep! The high sensitivity of a CCD camera allows you to take excellent images of distant galaxies and nebulas. High quality CCD cameras are equipped with a thermo-electric cooler which reduces much of the inherent noise from the camera. In general, CCD cameras have a higher cost compared to digital SLRs and also require the use of a laptop computer. But recently, more low-cost and high quality CCD cameras have become available, such as the StarShoot Pro V2 Deep Space Imaging Camera. Digital SLR (DSLR) Cameras DSLR cameras are favored for their versatility because they work well for deep sky astrophotography and can still be used as an ordinary daytime camera. DSLRs offer a large imaging sensor usually about 60% of the size of a traditional 35mm camera (some newer models are offering a full 35mm format). DSLRs do not require using a laptop computer, but using an external computer is still beneficial to better control the camera.

DSLRs have impressive capabilities, but they are also effected by noise and do not have the cooling capability of CCD cameras. As a result, longer exposures deliver more noise in the image. Give It a Shot! Becoming proficient in astrophotography is a challenging avenue, but it's also very rewarding. You can share your images with friends, family, and with the online community. As you continue to take better pictures, you may find that you were "bitten by the bug" and acquire more astro-imaging equipment. The sky is truly the limit for astrophotography. Here is a helpful book to consider which discusses astrophotography further: •The New CCD Astronomy by Ron Wodaski, Multimedia Madness Inc, Cloudcroft, NM, USA5

Cambridge in Colour
http://www.cambridgeincolour.com
PO Box 1719, 325 N Maple Drive, Beverly Hills, California 90210    

Here at this site you will find many tutorials and explanations on How To's for equipment set-up and lessons on editing and tools to use to make things a little simpler in the digital software world. Let me suggest a few lessons and tutorials to start with. These contain numerous interactive pages on all topics in photography, and use a unique visual approach that focuses on concept over procedure. They're therefore helpful regardless of your specific type of camera equipment. Start with these or if you are a seasoned photographer check out techniques table of contents.

Camera Lenses: Focal Length & Aperture
Camera Exposure: Aperture, ISO & Shutter Speed
Understanding Depth of Field
Understanding Histograms: Tones & Contrast

Otherwise you can also find more advanced topics by browsing the photography tutorials.

Nature Shooting Skills

                                     By Dan Richards and Peter Kolonia

1. Pan a moving subject.


Panning—following a moving subject by pivoting the camera while the shutter is open—has two big benefits for shooting wildlife. It captures the subject sharply, while streaking the background to show motion (as in the photo above). It can also help you keep your subject sharp when the lighting’s too dim for you to set faster, action-freezing shutter speeds. Panning typically requires the shutter to be open for 1/8 sec or longer, depending on subject speed. Whether you’re handholding or using a tripod (which can produce straight, parallel lines in the background streaks—a cool effect), start the pan before the shutter is open and keep moving until after it’s closed. Like most things in life, practice makes panning perfect.

2. Check the histogram.


The peaks and valleys of this graph represent the amount of exposure in tones from darkest (far left) to brightest (far right). It’s the edges you should worry about: If any of the graph spills over the left edge, you lose detail in deep shadows and usually get a dose of noise. Spill over on the right edge, and you wind up with blown-out highlights, such as a blank sky. If the graph spills over on the left, increase exposure; if it spills over on the right, decrease exposure. Sometimes you won’t be able to get both sides contained simultaneously. Landscape shooters may opt to let the shadows fall off rather than get blown-out highlights, but there are exceptions—backlit landscapes such as David Clapp’s on pages 58–59.

3. Track with a zoom.


You want to fill the frame with a bird in flight, so you rack your long zoom out to the longest focal length. But when you put your eye to the viewfinder, you’re met with an empty field of blue sky or green foliage. Where’s the bird? Rather than swing your lens every which way in an often futile hunt for a moving subject, try zoom tracking. Set your zoom to a wide enough focal length to easily pick up the bird in flight when you put your eye to the viewfinder. As soon as you do, follow focus on it (as with panning, use continuous autofocus), until you’re in synch with its speed and trajectory. Then begin to zoom in and fill the frame. Also like panning, it gets easier with practice.

4. Set hyperfocal distance.


The hyperfocal distance is the focus setting that will give you the greatest depth of field (DOF) that still includes infinity. If your lens has a DOF scale (a series of inscribed lines adjacent to the distance scale and labeled with f-numbers), setting it is easy: Switch the lens to manual focus and turn it so that the infinity distance mark lines up with the f-stop you’re using. If your lens has no DOF scale, you can eyeball it using DOF preview (provided your camera has it): Set your aperture and trigger DOF preview. Focus the lens manually to a near distance, and, while looking through the viewfinder, set the distance farther and farther until the most distant object comes just into focus. If the viewfinder image is too dark, cover the finder, cup your hands around the eyepiece, and wait for your eye to adjust.

5. Bracket exposures and other settings.


A common myth is that one perfect exposure exists for every landscape, floral study, or wildlife portrait. But by under- and overexposing a scene, you can come away with two (or more) interpretations, each different yet compelling in its own way. Bracketing exposure—simple, thanks to auto bracketing on most DSLRs—nets you a decent exposure, several variations, and the potential to blend different exposures into a single, superior version of a scene. For really killer images, go a step further, if time permits: Bracket white balance, focusing, crop, and camera orientation (horizontal and vertical).

DSLR Test: Canon EOS Rebel T1i

PopPhoto.com 

Reviews

Cameras

(click these links)

DSLR Test: Canon EOS R... The best entry-level DSLR.

By Philip Ryan Posted August 21, 2009

What’s Hot


Low noise at higher ISOs.
Nice 720p HD video recording.
Fast autofocus.

What’s Not


1080p HD video is choppy at 20 fps.
No built-in wireless flash control.
Doesn’t come with video-editing software.

Who’s This For?
First-time DSLR buyers who know something about photography and want a more powerful camera than the Rebel XS or XSi, or who want video capture in their DSLR.
So you know a thing or two about photography, or plan to learn, and want the best entry-level DSLR you can get? Then take a look at Canon’s new EOS Rebel T1i. We already knew that it’s the first Rebel to shoot high-definition video. But now that we’ve run it through our battery of tests in the Pop Photo Lab, we can give you a better reason to check it out: Performance. The Rebel T1i beat its direct competitors in most areas of our tests, particularly in controlling noise as the ISO rises. And it does this while giving you more megapixels (15.1MP) than any other sub-$1,000 DSLR. With a street price of $800, body only, or $900 with 18– 55mm f/3.5–5.6 EF-S IS lens, it’s also more expensive than its closest competitors. 

More SensitivityWhat does the extra dough get you compared with the Nikon D5000 ($810, street, with 18–55mm f/3.5–5.6 DX VR lens) and Olympus E-620 ($700, street, with Zuiko 14–42mm f/3.5–5.6 lens)? Not only lower noise at higher ISOs, but more ISO options. When set to its expanded range, the Rebel T1i tops out at ISO 12,800—1 stop beyond the limit of the Nikon (ISO 6400) and 2 stops beyond that of the Olympus (ISO 3200). Of course, at their highest ISOs, all of these cameras become overly noisy. But the Rebel T1i maintained a Low or better noise rating in our test all the way up to ISO 3200. Since that’s the top standard ISO, as long as you don’t turn ISO expansion on, you’re golden. Given that the T1i shares the same sensor as the more costly EOS 50D, it should come as no surprise that it also topped its competitors in resolution. It rated extremely high (2380 lines) compared with their Very High scores under our new, more stringent, resolution criteria. Color accuracy was Excellent, with an average Delta E of 6.93.

More Speed

 In our version of speed trials—the autofocus test—the EOS Rebel T1i raced to the front of the pack. Its 9-point AF system locked on our target in a scant 0.32 seconds at the test’s brightest light level of EV 12, and it still took less than a second even when the lights dimmed to the near-moonlit darkness of EV –1. That’s a half-stop dimmer than the light level Canon says the AF system can handle. Indeed, in our test, the Rebel managed to zero in on the target in 1.18 sec at EV –2 (the least light we consider), while neither the Nikon nor the Olympus could focus at all in light that dim. Buttons, dials, and controls are designed to make the camera quick and easy to operate. We appreciated finding the ISO button just behind the shutter, letting you change sensitivity on the fly. To avoid confusion, Canon put the exposure compensation button on the camera back, which also makes it easier to use in combination with the lone command wheel. (We wish there were two command wheels to make manual shooting more convenient, but you almost never find that setup on an entry-level DSLR .) And, as on the Olympus E-620, Canon lets the menu control buttons double as access to frequently used functions, such as white balance, AF, drive mode, and Picture Styles (Canon lingo for JPEG profiles). 

More Features The Rebel T1i’s body construction is as solid as you can hope for in an entry-level DSLR . You won’t find the weather sealing that you’ll get with a pro body, but the grip and an area on the back for your thumb have a textured rubbery material that makes the camera comfortable to hold. The LCD packs 920,000 dots into a gorgeous 3-inch screen, for lots of extra detail that comes in handy during live view and video shooting. If only it could be flipped, tilted, and swiveled, like the smaller and lower-res monitors on the Nikon and Olympus. Then there’s video. The Rebel T1i can record at a pixel resolution of up to 1920x1080, the limit of the U.S. HD standard, though at that resolution the frame rate is a choppy 20 frames per second. But if you just turn down the resolution to 1280x720, you get 30 fps, which matches the frame rate of your HDTV—and isn’t that where you want to watch it? At that setting, we got video that knocked our socks off. As with all of the first generation of video-shooting DSLR s, you can’t autofocus continuously during video capture. However, if you press the asterisk button on the camera back, the Rebel will focus once—press it again to focus on something else. All that button-pushing is likely to make for shaky video if you’re not careful. But if you plan your shots, use a tripod (preferably on a fluid head), and capture short snippets of video, you’ll be amazed at the results—even when viewed unedited from the camera’s built-in mini-HDMI output. Live view shooting remains the same as on earlier models. You can choose from two types of AF: Contrast detection, though sluggish, maintains an uninterrupted view of your subject, while phase detection interrupts your view by closing the shutter, flipping down the mirror, focusing, then flipping the mirror up and opening the shutter—a clunky process. Still, live view can be useful for landscape, still-life, and macro work.

Bottom Line

The image quality the Rebel T1i offers with its 14-bit RAW capture, Digic 4 processing, and accurate 35-zone metering is astonishing given its price. Just a few years ago, you couldn’t hope to get talent like this for under $1,000. In all, an amazing first—or step-up—DSLR .  

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