First, you need a camera. Nearly any digital camera will work. A SLR (single-lens reflex) give you more flexibility and lets you switch to faster lenses, but even a point-and-shoot will work if you have control over the aperture, shutter speed, and ISO speed. You might need the camera manual for this!

And you need a tripod. It’s just as important as the camera, since there’s no way to hold the camera steady for the relatively long exposures need to image aurorae. You don’t need a $300 tripod for this… a simple one will do. Even those little backpack-friendly Gorilla-Pods can work well.

A DSLR on a tripod (credit: Jerry Lodriguss)

Now here’s what to do when you’re graced with a good display of aurorae overhead…

• Put the camera on a tripod.

• Set the lens’ aperture to its fastest setting (if you have a DSLR, select a wide-field lens, not a telephoto); you want a setting of f/2.8, f/3.5, or f/4… even f/5.6 works well enough.

• Set the focal length to its widest setting if you have a zoom lens. If you have an 18mm-55mm zoom, for example, choose something closer to 18mm.

• Focus on infinity (it may help to pre-focus on a distant object when there’s still some light)

• Aim the camera to frame what you want to shoot: the aurorae.  Don’t just shoot the sky… make sure there’s something interesting in the foreground… trees, houses, mountains, whatever… it makes for a more dramatic image.

• Set the ISO to 1600 (or as high as your camera allows)

• Open the shutter for 10 seconds to 1 minute. Use a remote shutter release or the built-in timer to avoid shaking the camera. Any longer than 1 minute, and you may see some star trailing, and the aurora themselves may start to blur because of their apparent motion.

• Close the shutter (which will likely happen automatically, depending on your camera)

That’s it!

Now take a look at your image (don’t move the camera yet). Is the aurora bright enough? If not, set the shutter to open longer. If the aurora is too bright, set a shorter shutter time. Experiment will many shutter settings… digital images are free. You can always pick the best one later.

If you get a really good image, send it to me and I’ll share it with your fellow readers!!

Note: If you want to learn how to image all aspects of the night sky with a digital camera, why not learn from the best? Master astrophotographer Jerry Lodriguss shares all his secret with you, and you can learn more from him right here…

(Image at top of page credit: Jan Curtis)

Binoviewers are a packaged set of prisms that split in two the light path from your telescope and direct each beam to a separate eyepiece. There are two main types available. The less expensive is based on designs for lab microscopes. They tend to use smaller prisms which can vignette (cut off) light from some lower-power eyepieces, which are just the ones you want to use to get wide-field views of star fields. But these types are less expensive… you can get a set for $300 from Orion, Celestron, or Williams Optics. They work quite well at moderate magnification.

The more expensive binoviewers from Denkmeier use larger prisms and accommodate wide-field, low-power eyepieces, so they give crisper and more expansive views than less expensive optics. They also hold focus as you adjust the inter-pupillary distance. But they are heavier and much more expensive… at least $1000 to $1500 (not including eyepieces). Denks are a good choice if you have an excellent telescope, a solid mount, and a generous budget.

Of course, both types of binoviewers require two identical eyepieces, so this also adds to your expense.

Binoviewers attached to a small refractor telescope

What’s the drawback of binoviewers? Since they split the light into two beams, binoviewers reduce image brightness by at least a factor of two. The effect is to make an image of an 8-inch scope as bright as a single beam from a 6-inch scope, for example. But the effect is not as pronounced, because the brain more clearly perceives images from both eyes. So you hardly notice the loss in brightness unless you are observing right at the limit of your telescope.

Here’s another thing to consider. Binoviewers add another 4-5 inches of light path, so the focuser of a telescope needs enough travel to bring the image to a focus. This is usually not a problem with Schmidt Cassegrain scopes, which you focus by moving the primary mirror itself. But many refractors and nearly all Newtonians do not have enough travel in their focusers, unless you add a Barlow lens to bring the image to focus. And a Barlow lens at least doubles the magnification of each eyepiece, which means a smaller field of view.

So are binoviewers worth it?

Looking at the Moon and bright planets through a scope equipped with binoviewers is a stirring experience. The Moon takes on an almost “3D” appearance like you’re looking out of the window of a spaceship. The bands of Jupiter and rings of Saturn snap into view clearly. And looking with two eyes seems to reduce eye fatigue and the effects of distracting “floaters” that move in and out of view.

I’ve acquired a set of Williams Optics binoviewers, and I was pleasantly surprised by the views of the Moon and big planets. I can look at Jupiter for long periods of time without fatigue and see much more detail with my 4″ refractor than with a single eyepiece. And the binoviewers have renewed my interest in the Moon. I’m even following along with the notes of my own course “Lunar Observing for Beginners”, just to make sure I can find everything!

I also get good images of globular clusters and bright planetary nebulae with the binoviewers, since they are usually compact enough to fit into a single low-power field of view. With my refractor and the 2x Barlow, the restricted field of view at low magnification doesn’t work well for rich star fields and nebulae. And in my Schmidt-Cassegrain, where no Barlow is needed, the long focal ratio still meant no good wide-field views. So for wide star fields, I switch a single low-power eyepiece, or use a pair of regular binoculars.

If you have a chance to peer through binoviewers at a star party or other astronomy gathering, then take the opportunity. If you have a good quality telescope of 4″ or larger aperture, perhaps no other accessory can add as much to your enjoyment to viewing the night sky.

Here is a shot from my Beginner’s series – The Summer Triangle, taken on a barn-door tracker. Click on the image or the link to see a higher-resolution version of the image and more technical data and object identificatons.

It shows one of the amazing kinds of pictures that you can take with incredibly simply equipment.

In this case, the shot was taken with Canon’s least expensive DSLR, the Digital Rebel XS (1000D) unmodified, and the kit 18-55mm EF-S f/3.5 – 5.6 zoom lens working at 18mm and f/3.5.

The exposure was just two and a half minutes at ISO 1600.

A fog filter was used on the lens to highlight the brightest stars.

The camera was mounted on a simple home-made barn-door tracker that was hand cranked.

Believe me, if I can make this tracker, anyone can!

In an extra little bit of luck, the image also recorded a satellite flaring as it went through the frame, something I didn’t even see because I had my head down turning the crank on the barn-door tracker and watching the second hand of the watch.

It’ll go something like this…

You’re out with your telescope on a pleasant summer evening, up late to get a preview of the nebulae and star clusters along Scorpius and Sagittarius. The sky is clear, the seeing steady, and you can stay up all night because you don’t have to work tomorrow.

Then, as you’re getting your best-ever view of M7, or M8, or the great Sagittarius star cloud, you notice something strange. The dim stars begin to fade. The images of the brights stars suddenly have ghostly white haloes. And finally, you can barely see anything at all.

The stars are gone.

You look at the sky. Have clouds rolled in? No. All clear.

Then, you take a peak at the lens of your telescope. A thick layer of water– dew– has condensed on your lens.

You don’t dare wipe the dew off the lens for fear of damaging the soft anti-reflection coatings. And with no other way to remove the coating of water, your idyllic observing session has come to an early end. All you can do is pack up and go home, with your ambitious observing plan left undone.

What happened?

Condensation. The temperature of your telescope’s lens fell below the so-called “dew point”. And just as when you take a bottle of cold beer out the fridge, a swarm of water molecules from the surrounding air condensed onto the glass like locusts on a field of wheat.

The front lens of refractors and Schmidt-Cassegrain telescopes are especially prone to dew. That’s because they point directly into the bitter cold of space and radiate their heat faster than surrounding objects. You’ll notice the same effect on a car’s windows early in the morning. The windshield, which points toward the cold sky all night, often has more a thicker coating of dew than the side windows.

When dew forms on the lens of your telescope, you can try to heat the lens to get it back above the dew point. If you have access to electricity, you can do the job with a gentle flow of warm air from a hair dryer. Repeat when necessary.

Or you can prevent the dew from forming in the first place with a specialized dew heater, a strip of resistive electrical wire which fits around the circumference of the lens to warm it up. These wires are often driven with a DC battery, which makes them ideal for remote locations.

You can also use a dew shield… a long extension of your telescope tube, which cuts down on the amount of cold sky your lens is exposed to. While not perfect, these shields can extend your session by a few hours. They’re not as effective as heaters, but they’re less expensive and need no electricity.

A dew-shield on the end of a Schmidt-Cassegrain telescope.  The length of the shield should be 1.5x the diameter of the objective lens.

You can get dew heaters and dew shields at most astronomy and telescope shops. Or you can make your own dew shield out of sheets of thick plastic. Just make sure the inside is painted flat black to cut down on reflection of stray light into your scope.

To learn more observing tips, check out the course Basic Astronomy with a Telescope, recommended by the legendary Sir Patrick Moore himself.

Based on technology developed for military surveillance and laser-based weaponry, IS binos are amazing high-tech wonders.

Inside the body of the binoculars, piezoelectric motion sensors detect the pitch and yaw motion caused by shaking, over-caffeinated arms. The sensors feed into a microprocessor that initiates image stabilization by controlling a vari-angle prism – a pair of glass plates joined by flexible bellows. The space between the plates is filled with a silicon-based oil to maximize image deflection to correct for the unwanted motion.

* * * * * Highly Recommended * * * * *

Tired of just reading about the stars? Stargazing for Beginners takes you on an easy-to-follow tour of the stars and main constellations.  No telescope required!  Click here to learn more…

* * * * * * * * * *

A pair of Canon 10×42 image-stabilized binoculars

The motion sensors work in daylight or total darkness and operate at any orientation, so there are no restrictions on where the binoculars can be pointed… up, down, sideways, anywhere.
You switch on the IS feature by pressing a button.  When you do, the image doesn’t “freeze”, but rather wanders slowly enough for your eye to follow. If your arms shift a little, you’ll still see motion, but it’s much slower and steadier than without the IS feature.  The IS still works when you sweep across a field of view, although there is a slight hesitation.  It takes a few seconds for the IS to kick in, and perhaps 10-15 seconds for the IS to really get ahold of the motion of your slightly shaking arms.

One drawback: these devices are battery hogs. You can burn through a pair of alkalines in 5 minutes on a cold night. With rechargeables, you might get 2 hours, or longer with warmer temperatures.  Of course, you can turn off the IS feature when you’re not using it.

Nikon, Canon, and Fujinon, among others, offer some type of image stabilization. Canon models seem to have the widest following among amateur astronomers.

IS binoculars are priced at a serious premium.  In North America, a pair of Canon 10×30′s go for about $400-$500.  A pair of Canon 10×42′s (which are waterproof) go for $1200-$1300, and the 15×50 go for about $1000-$1200.  The more expensive binoculars give you a brighter view of the stars, but they are heavier… about 2-3 lbs, which is hard to hold for a extended period.

Are IS binoculars worth the extra cost?

In a 2006 review of Canon’s 10×42 IS binoculars, Gary Seronik said “These are simply the finest binoculars I have ever used for astronomy”.

I agree.

After investing in a more modest pair of 12×36 Canon’s, I’ve found them extremely useful for quick tours of the night sky.  If you can afford a pair IS binoculars, and if you enjoy quick, convenient, wide-angle views of the night sky, I recommend you pick up a pair.  They’re not a “must-have”, but they’re an “awfully-nice-to-have”.

This idea’s been around for a long time, no doubt.  But I first thought of it when hearing about tourists and artists observing Michaelangelo’s paintings on the ceiling of the Sistine Chapel.  Instead of craning their necks for hours, the art lovers looked at a reflection of the ceiling from mirrors held at waist level.  It’s far more comfortable, and even an inexpensive mirror does a fine job giving a true image of priceless art.

The same idea works for stars.  If you want to spare your neck, get a small mirror (say at least 12 inches square), hold it face-up towards the sky, and let the star light reflect into your eyes while holding your neck at a comfortable angle. Or if you really like comfort, hold the mirror on your lap as you sit in a comfortable chair.  It’s a little strange at first, since the image you see is flipped left-to-right, but you’ll get the hang of it after a little practice.  It sounds obvious, but you won’t find many people trying this at a star party.

Some have adapted this idea for binoculars.  Here’s a home-made version of a mirror-binocular combination…

A binocular mount with a mirror to capture the sky in reflection.  Great for preventing neck strain.  Here’s a link to help you build your own.

I’ve used a commercial version of this mount a couple of times, and it works well.  Even a low-cost mirror doesn’t seem to impart much distortion to the image from binoculars.  If your neck pain gets in the way of stargazing, try out a mirror… you’ll enjoy the sky more if you do.

]]> http://www.oneminuteastronomer.com/1170/window-sky/feed/ 0 http://www.oneminuteastronomer.com/1133/great-astrophoto/ http://www.oneminuteastronomer.com/1133/great-astrophoto/#comments Fri, 11 Dec 2009 03:38:27 +0000 admin http://www.oneminuteastronomer.com/?p=1133 Read More]]> A special treat today for you… an exclusive interview with astrophotographer Jerry Lodriguss in which he shares with you the basics of taking a simple but quite lovely photo of the night sky with a digital camera.  No telescope required.

Jerry’s a world-renowned astrophotographer and a former professional sport photographer who was 3 times nominated for a Pulitzer Prize.  His astrophotos have been published in Sky and Telescope and NASA’s Astronomy Picture of the Day, and he’s published three books about astrophotography including The Beginner’s Guide to DSLR Astrophotography.

In this interview, Jerry tells you how to …

• Choose the right camera and equipment for taking a good astrophoto
• Select a skyscape appropriate for a simple digital astrophoto
• Choose the right camera settings, including aperture, focal length, and exposure time
• Focus your digital camera on a dark sky… perhaps the trickiest aspect of taking an astrophoto
• Enhance your image of the night sky with free processing software

The interview runs about 20 minutes, and you can listen to it and download it at the link below…

Once you listen to this interview, you’ll be able to capture your own images of the night sky… such as Orion rising over the trees above the eastern horizon, or Taurus and the Pleiades high in the dark winter sky.

Click here to play the full interview (or right-click and select “Save Link As” to save the audio file to your computer to play at your convenience…)

To be honest, E.D. is on the right track.  He’s using a large aperture scope to increase resolution of fine detail.  He’s using high magnification to increase the image size, yet he’s not using a too-high magnification to dim the image.  And he’s using a filter of the opposite color from the object he’s trying to find… in this case, the Great Red Spot.

What else can one do to get a better view of Jupiter, its colorful cloud bands, and Great Red Spot?

Here are a few more tips, some of which come right out of Basic Astronomy With a Telescope, an online astronomy course recommended by none other than Sir Patrick Moore, the grand patriarch of amateur astronomy.

* For us northern observers, Jupiter has been at a low altitude these last few years, which means we have to look through a lot of atmospheric murk.  Next year will be better, but for now do most of your observing when Jupiter is highest in the sky so you look through the least amount of atmosphere.

* Try not to observe Jupiter when its over a rooftop or a driveway, or anything else that’s slowly radiating daytime heat.  The turbulence and shimmering caused by the rising warm air will make the image into an ugly boiling blob.

* Use a simple eyepiece design to enhance contrast and color fidelity.  Plossls and Orthoscopics work well, as does the slightly more expensive Radian design by Televue.

* Refractors tend to have better contrast than reflectors.  But bigger telescope have better resolutions.  While it’s easy to find an 8-10″ or larger reflector, good luck getting your hands on an 8-10 refractor!   But when using a reflector like E. D., make sure the instrument is well collimated (see your user’s manual for how to do this).  Sometimes, just a slight turn of an alignment screw makes all the difference (of course, you have to know which screw to turn and which way to turn it).

* Look carefully… even at 240x, the Great Red Spot appears tiny.  It takes a little practice seeing such fine detail.

* Above all, be patient.  Sometimes you just have to wait for a patch of steady air to let you glimpse the maximum detail.  Some nights, you get just 10 seconds of good seeing at a time.  But it’s often worth the wait.

And here’s an advanced tip…

* If you have an 8-inch or larger scope, try an apodizing mask.  This is a type of filter or screen than fits over the top of the telescope.  It gradually decreases the amount of light reaching the edge of the objective lens or mirror.  This has the effect of improving contrast by reducing the amount of light from one feature that diffracts into another.

(Trust me, you do NOT want to see the mathematics required to prove this).

On planets and double stars, apodizing masks can work remarkably well.  I’ve not seen such masks for sale.  But here’s a link to help you make your own.

http://www.bpccs.com/lcas/Articles/apodizing_masks.htm

Do you have a question about observing the heavens, whether with your eye, binoculars, or telescope?  Send us an email at info@oneminuteastronomer.com.  And remember, there are no dumb questions, only dumb mistakes.