Posted on August 9, 2020
As soon as I announced that I’d purchased the just-announced Sony a7SIII, people started asking why I wanted a 12 megapixel camera when I already have a 61 megapixel Sony a7RIV (two, actually). When I hear these questions, I realize the myth that megapixels are a measure of image quality is still alive. The truth is, megapixels are a reflection of image size, not image quality. In fact, for any given technology, the fewer the megapixels, the better the image quality.
Without getting too deep into the weeds of noise and clarity in a digital image, it’s safe to say the the more efficient a sensor is at capturing light, and the less heat the sensor generates, the better it will perform in these areas. How do you make a sensor more efficient? Well, you start with bigger photosites to catch more light. And how to keep the sensor cool? Give your photosites more room to breathe. But how do you make your photosites both bigger and farther apart without increasing the size of the sensor? It doesn’t take a rocket scientist to conclude that reducing the number of photosites is the only way to achieve both of these objectives.
So why do the manufacturers keep giving us more photosites? (My last rhetorical question, I promise.) Well first, advances in technology make it possible to cram more photosites onto a fixed-size sensor without compromising image quality (and in fact, often while still improving image quality). But more important that is the sad, simple truth that megapixels sell cameras.
Don’t get me wrong, I think megapixel count is great and am all for as many megapixels as I can have—as long as they don’t come at the expense of image quality. The more megapixels you have, the more you can crop, and the larger you can print. While cropping is a nice safety net, goal should be to get the composition right at capture. And before chasing more megapixels, you should ask yourself how large you need to print, and how many megapixels you need to do it. Whenever this question comes up, I think about an image that I have printed 24×36 and hanging in my home. It’s an extreme close-up of a raindrop festooned dogwood flower, with Bridalveil Fall in the background. I can stand six inches from this 24×36 print and not feel like it’s missing any detail, from its delicate spider web filaments to the small dust particles suspended in the raindrops. All this was captured as a jpeg on my first DSLR, a 6 megapixel Canon 10D.
So given all this, you may be wondering why my primary camera is a 61 megapixel Sony a7RIV, with a second a7RIV as my backup. Well, like I said, all things equal, more megapixels are better than fewer megapixels, and for the vast majority of the natural light landscapes, on a tripod, that I photograph, my a7RIV bodies give me cleaner, higher resolution images than I ever dreamed possible. The dynamic range is the best I’ve ever seen, and my high ISO images are as good as any primary body I’ve ever owned. They’re so good, in fact, that last year I set aside my dedicated night camera, my 12 megapixel Sony a7SII, in favor of the a7RIV. I was getting such good results after dark with the a7RIV, I figured I could sacrifice a little low light performance to lighten my bag.
And for the most part I was satisfied—I’ve now used it enough at night to know the a7RIV is hands down the best night camera I’ve used that’s that not an a7S (original, or a7SII). But photographing Comet NEOWISE last month in Yosemite, I started to wonder if I might have been too quick to jettison the a7SII. My images were clean enough, but if I could get even less noise…
If you follow me regularly you know that I’m a one-click shooter—if I can’t get an image with one click, I don’t shoot it. That doesn’t mean I think it’s wrong to composite night images, but that approach doesn’t give me satisfaction, and I don’t like the artificial look of images that have clearly been blended. The analogy I like to use is the difference between applying a little make-up (dodging/burning and noise reduction in Photoshop), and submitting to cosmetic surgery (blending multiple exposures captured at different times, or with completely different focus and exposure settings). (There’s also a third option that’s more of a Frankenstein solution that involves assembling images from two different scenes, that I don’t even consider real photography.) My one-click approach means I have to live with more noise in my night images, but anyone viewing them knows that that truly is what my camera saw.
So anyway… For my Grand Canyon trip a couple of weeks ago, I decided to dust off the a7SII and give it a shot at Comet NEOWISE. My plan was to concentrate on the park’s east vistas to get away from the lights of Grand Canyon Village. Desert View was closed, but all the other vistas—west to east: Grandview, Moran, Lipan, and Navajo Points—were open for business. So during the day, while chased lightning out on the east end, at each stop I made a point of firing up my astronomy apps to figure out where the comet would be after dark.
Knowing that at about an hour after sunset, NEOWISE would be the northwest sky just a few degrees west of the Big Dipper (which would be dropping and rotating closer to due north as the night wore on), I decided that Grandview Point would be the best place to get it above the canyon. After it rotated farther north, I liked the way NEOWISE aligned with the canyon from the more eastern vistas. On that first night I got about 45 minutes of clear enough skies before the clouds returned.
For this trip I’d brought two tripods so I could simultaneously shoot with both the a7SII and a7RIV. On the a7SII I mounted my Sony 20mm f/1.8 G lens; on the a7RIV was the Sony 24mm f/1.4 GM lens. For both cameras I had long exposure noise reduction turned on (because with the Sonys it does make a difference for exposures measured in seconds). LENR doubles the capture time, which gave me at least 30 seconds between each shot, making it really easy to switch back and forth between cameras.
Having both cameras set up side-by-side like this, I was reminded what a nighttime monster the a7SII is—even though the a7RIV had a slightly faster lens, I could see the dark scene much better with the a7SII. I wouldn’t know how much cleaner the a7SII files would be until looked at them on my computer, but what a joy that camera is to work with in the dark.
I went with relatively few compositions, but varied my exposures for each for more processing options later. To focus, I just picked a star in my viewfinder, magnified it to the maximum, and dialed my focus ring until the star became the smallest dot possible. And even though that’s usually enough to ensure a sharp image, each time I focused I verified sharpness by magnifying the captured image in my viewfinder and checking the detail in the canyon.
I was thrilled by how much light the 20% waxing crescent moon cast on the scene. While the moonlight wasn’t noticeable to my eye, and didn’t seem to wash out the stars at all, it did cast enough light to bring out more canyon detail in my images. The small meteor that scooted through the Big Dipper during this frame was a welcome bonus that surprised me when I reviewed the image later.
When I finally got back to the room and looked at my images from that night a little more closely, the a7SII images were noticeably cleaner, so much so that when I went back out to photograph the comet the next night, I didn’t even set up the a7RIV. Is the a7RIV bad for night photography? Absolutely not. In fact, to capture 61 megapixel, high ISO, long exposure images as clean as the a7RIV does feels like cheating. But given my one-shot paradigm, and the fact that 12 megapixels is more than enough resolution for pretty much any use I can think of (for me—you need to decide for yourself how much resolution you need), for dark sky night photography, my vote goes the a7SII’s cleaner files and ease of use.
Some of my fellow Sony Artisans got to preview the a7SIII, but since it’s primarily billed as a video camera and I don’t really do video (yet), I’ll have to wait until mine arrives at the end of September (fingers crossed). But the reports from my colleagues about the a7SIII’s high ISO performance have me salivating.
Posted on July 19, 2020
My dad would have turned 90 today. We lost him 16 years ago, but I have no doubt that he would still be going strong if Alzheimer’s hadn’t taken over. I have always been grateful for Dad’s love, gentle discipline, wisdom, advice, and laughs (especially the laughs), but it takes being a parent to fully appreciate our own parents’ love, and their influence on the adults we become.
Dad was a United Methodist minister who literally practiced what he preached. In 1965, when Martin Luther King issued a plea for clergy to join him on his voting rights march to Montgomery, Dad borrowed money and flew across the country to join Dr. King in Selma, Alabama (where he was on national TV getting arrested).
His was an inclusive, Jesus-centric theology that respected all religions and people: I remember him opening his pulpit to the local rabbi one Sunday morning, then reciprocating the following Saturday with a sermon of his own at the synagogue. Dad welcomed everyone into his churches, and became an outspoken advocate for LGBT rights (before the acronym made it into popular culture). He frequently provided odd-jobs around the church to people who were down on their luck, and I lost track of the number of homeless people, including families with young children, we housed while they tried to get back on their feet.
In addition to the values he instilled, so many of the things that define my personality are directly attributable to my dad’s influence. My positive spirit, sense of humor, and love for sports were absolutely modeled by Dad. And when asked how I became a photographer, the instant answer has always been that my dad was a serious amateur photographer whose 80-hour work week offered too little time to pursue his passion, so he made up for lost time on our summer family vacations. So frequent were the photo stops, I grew up believing that a camera was just a standard outdoor accessory.
But I think his influence on my photography goes deeper than that. More than simply modeling camera use, Dad instilled in me his appreciation of nature’s beauty, and his longing for its soothing qualities. I realize now, because I see it in myself, that it’s not simply photography that dad loved, he was motivated by an insatiable desire to record and share the people and places he loved.
On a minister’s budget, our family summer vacations were, without exception, camping trips—always tent-camping, though in the later years we splurged on a used, very basic tent trailer (no kitchen, bathroom, or any of the other luxuries available in today’s tent trailers). These vacations usually took advantage of the mountain scenery within a few hours of our California home (we were just as close to the ocean, but our vacations were always in the mountains), but every few years we (Dad, Mom, my two brothers, and I) hit the road for a longer camping trip. Especially memorable were the full month we camped all the way across the United States and back, and a multi-week camping adventure into and around the Canadian Rockies.
Of our more frequently visited destinations, Yosemite was the clear favorite. Marveling at the Firefall from Camp Curry and Glacier Point, waiting in lawn chairs with hundreds of fellow tourists at the Yosemite garbage dump for the bears to arrive for their evening meal (really), rising in the dark for a fishing expedition to Tuolumne Meadows, family hikes up the Mist Trail to Vernal and Nevada Falls, are just a few of the memories that I realize in hindsight formed the bedrock of my Yosemite connection.
My favorite Dad photography story happened when I was about ten. It involves an electrical storm atop Sentinel Dome, and his desire to photograph a lightning bolt, a desire so great that it trumped common sense. As his ignorant but trusting assistant, to keep his camera dry I stretched high to extend an umbrella above Dad’s head. (In his defense, as Californians, the novelty of lightning obscured a full comprehension of its dangers.) We didn’t get the lightning, and more importantly, it didn’t get us. But that’s not the end of the story.
After risking our lives on Sentinel Dome, the family ended up at Glacier Point, just down the road. Dad had returned to tourist mode as we browsed the shop at Glacier Point Lodge, no doubt seeking souvenirs that would fit our meager budget. But when a vivid rainbow appeared out of nowhere to arc across the face of Half Dome, Dad was ready with his camera still draped around his neck. Watching Dad’s excitement, better than any souvenir, this felt as if God was giving him a much deserved, “I got your back.”
I love you, Dad.
About this image
I’ve written recently about my love of astronomy that dates back to when I was 10 years old. While my memory isn’t complete, I do know that not long after I expressed an interest in something astronomical (which could have been as simple as asking a question at dinner), my dad presented me with a used telescope gifted to him by a Kiwanis friend who was a serious amateur astronomer. I have no knowledge of the specifics, but I know my dad well enough to know that my simple query was enough to prod him to ask his astronomer friend for guidance that might fuel my interest, which no doubt led to the gift of this mothballed telescope that became the catalyst for my relationship with the night sky.
Of course photographing celestial objects requires some cooperation from Mother Nature. But one of the things photographer friends seem to resent me for is my good photography luck: the clouds that part just as the moon rises, the snowstorm that arrives just as a workshop starts (that’s good if you’re a photographer), the rainbow that appears out of nowhere.
My brother Jay and I take many photo trips together, and he seems blessed with similar luck. On our photo trips, sometimes we talk about Dad, and sometimes we don’t, but he’s always with us. Often it feels to Jay and I that Dad is watching over us, pulling whatever strings he can to deliver something special.
In the last ten days, Jay and I have made two trips to Yosemite to photograph Comet NEOWISE. On the first trip we were surprised by how visible NEOWISE was to the naked eye, as if its brightness had been cranked up a couple of magnitudes for our visit to Glacier Point. And Venus’s proximity to Half Dome was another an unexpected gift.
On our trip to Yosemite last Thursday afternoon, I had one eye on the road and another eye on the clouds obscuring the entire Sierra range. Would we be shut out entirely? I needn’t have worried. When we pulled into the trailhead parking area the clouds had started to clear, and by the time we’d finished the one-mile hike out to Taft Point, they had all but vanished.
Like the proverbial elephant that can’t be fully seen up close, El Capitan is so massive that from Yosemite Valley it looks completely different depending on where you view it from. One of the things I like most about Taft Point is its elevated, more distant view that offers a more complete perspective of the world’s largest granite monolith. So as I waited for the darkness to reveal the comet, I took some time to drink in the view and appreciate El Capitan.
About 30 minutes after sunset I started getting serious about locating Comet NEOWISE. I knew this shoot would pose some problems I hadn’t had to deal with for the Glacier Point NEOWISE shoot a week earlier. First, the comet was more faint, but I didn’t know how much: would we still be able to see it without aid, or would it only appear in our images? And second, there would be no moon to illuminate El Capitan and Yosemite Valley.
Again, there was no need to worry because things always seem to work out for me (thanks, Dad). NEOWISE, though noticeably fainter, was still clearly visible. Not only that, it had developed a magnificent ion tail (the faint spike above the fanned out primary tail). And the extra darkness? The several stops of exposure it forced me to add, while introducing a fair amount of noise, only made the comet stand out more against the dark sky.
As with the Glacier Point shoot, I worked two bodies. I quickly found that a vertical composition with my new Sony 20mm f/1.8 G lens was wide enough to include all of El Capitan, Comet NEOWISE, and the Big Dipper. Pretty cool. By the time the night was over, I’d used every one of the five lenses I packed.
Jay and I stayed until about 11 p.m., then made the walk back in the moonless darkness, most grateful for bright flashlights and perfectly spaced reflectors mounted on trees lining the trail. After a four hour drive, I finally made it to bed at about 4:30 a.m. and managed to sleep for five hours, visions of comets dancing in my head.
Such a spectacular night. Thanks, Dad.
Click an image for a closer look, and to view a slide show.
Posted on July 12, 2020
When I was ten, my best friend Rob and I spent most of our daylight hours preparing for our spy careers—crafting and exchanging coded messages, surreptitiously monitoring classmates, and identifying “secret passages” that would allow us to navigate our neighborhood without being observed. But after dark our attention turned skyward. That’s when we’d set up my telescope (a castoff generously gifted by an astronomer friend of my dad) on Rob’s front lawn to scan the heavens in the hope that we might discover something: a supernova, comet, black hole, UFO—it didn’t really matter.
Our celestial discoveries, while not Earth-changing, were personally significant. Through that telescope we saw Jupiter’s moons, Saturn’s rings, and the changing phases of Venus. We also learned to appreciate the vastness of the universe with the insight that, despite their immense size, stars never appeared larger than a pinpoint, no matter how much magnification we threw at them.
To better understand what we saw, Rob and I turned to astronomy books. Pictures of planets, galaxies, and nebula amazed us, but we were particularly drawn to the comets: Arend-Roland, Ikeya–Seki, and of course the patriarch of comets, Halley’s Comet (which wouldn’t return until 1986, an impossible wait that might as well have been infinity). With their brilliant comas and sweeping tails, it was difficult to imagine that anything that beautiful could be real. When the opportunity came to do a project to enter in our school’s Science Fair, comets were an easy choice. And while we didn’t set the world on fire with our project presentation, Rob and I were awarded a yellow ribbon, good enough to land us a spot in the San Joaquin County Fair.
The next milestone in my comet obsession occurred a few years later, after my family had moved to Berkeley and baseball had taken over my life. One chilly winter morning my dad woke me and urged me outside to view what I now know was Comet Bennett. Mesmerized, my smoldering comet fascination flamed instantly, expanding to include all things celestial, and stayed with me through high school (when I wasn’t playing baseball).
I can trace my decision to enter college with an astronomy major all the way back to my early interest in the night sky in general, and comets in particular. I stuck with the astronomy major for several semesters, until the (unavoidable) quantification of magnificent concepts sapped the joy from me.
Though I went on to pursue other interests, my affinity for astronomy hadn’t been dashed, and comets in particular remained special. Of course with affection comes disappointment: In 1973 Comet Kohoutek broke my heart, a failure that somewhat prepared me for Halley’s anticlimax in 1986. By the time Halley’s arrived, word had come down that it was poorly positioned for its typical display (“the worst viewing conditions in 2,000 years”), that it would be barely visible this time around (but just wait until 2061!). Nevertheless, venturing far from the city lights one moonless January night, I found great pleasure locating (with much effort) Halley’s faint smudge in Aquarius.
After many years with no naked-eye comets of note, 1996 arrived with the promise of two great comets. While cautiously optimistic, Kohoutek’s scars prevented me from getting sucked in by the media frenzy. So imagine my excitement when, in early 1996, Comet Hyakutake briefly approached the brightness of Saturn, with a tail stretching more than twenty degrees (forty times the apparent width of a full moon). But as beautiful as it was, Hyakutake proved to be a mere warm-up for Comet Hale-Bopp, which became visible to the naked eye in mid-1996 and remained visible until December 1997—an unprecedented eighteen months. By spring of 1997 Hale-Bopp had become brighter than Sirius (the brightest star in the sky), its tail approaching 50 degrees. I was in comet heaven.
Things quieted considerably comet-wise after Hale-Bopp. Then, in 2007, Comet McNaught caught everyone off-guard, intensifying unexpectedly to briefly outshine Sirius, trailing a thirty-five degree, fan-shaped tail. But because of its proximity to the sun, Comet McNaught had a very small window of visibility in the Northern Hemisphere and was easily lost in the bright twilight—it didn’t become anywhere near the media event Hale-Bopp did. I only learned about it on the last day it would be easily visible in the Northern Hemisphere. With little time to prepare, I grabbed my camera and headed to the foothills east of Sacramento, where I managed to capture a few faint images and barely pick the comet out of the twilight with my unaided eyes. McNaught saved its best show for the Southern Hemisphere, where it became one of the most beautiful comets ever to grace our skies (google Comet McNaught and you’ll see what I mean).
After several years of comet crickets, in 2013 we were promised two spectacular comets, PanSTARRS and ISON. A fortuitous convergence of circumstances allowed me to photograph PanSTARRS from the summit of Haleakala on Maui—just 3 degrees from a setting crescent moon, it was invisible to my eye, but beautiful to my camera. Comet ISON on the other hand, heralded as the most promising comet since Hale-Bopp, pulled an Icarus and and disintegrated after flying too close to the sun.
Since 2013 Earth has been in a naked-eye comet slump. Every once in a while one will tease us, then fizzle. In fact, 2020 has already seen two promising comets flop: Comets Atlas and Swan. So when Comet NEOWISE was discovered in March of this year, no one got too excited. But by June I started hearing rumblings that NEOWISE might just sneak into the the naked-eye realm. Then we all held our breath while it passed behind the sun on July 2.
Shortly after NEOWISE’s perihelion, astronomers confirmed that it had survived, and images started popping up online. The first reports were that NEOWISE was around magnitude 2 (about as bright as Polaris, the North Star) and showing up nicely in binoculars and photos. Unfortunately, NEOWISE was so close to the horizon that it was washed-out to the naked eye by the pre-sunrise twilight glow.
Based on my experience with PanSTARRS, a comet I’d captured wonderfully when I couldn’t see it in the twilight glow, I started making plans to photograph Comet NEOWISE. But I needed to find a vantage point with a good view of the northeast horizon, not real easy in Sacramento, where we’re in the shadow of the Sierra just east of town. After doing a little plotting, I decided my best bet would be to break my stay-away-from-Yosemite-in-summer vow and try it from Glacier Point. Glacier Point is elevated enough to offer a pretty clear view of the northeast horizon, and from there Half Dome and the comet would align well enough to easily include both in my frame.
While Yosemite is currently under COVID restrictions that require reservations (sold out weeks in advance) to enter, I have a CUA (Commercial Use Authorization that allows me to guide photo workshops) that gives me access to the park if I follow certain guidelines. So, after checking with my NPS Yosemite CUA contact to make sure all my permit boxes were checked, my brother Jay and I drove to the park on Thursday afternoon, got a room just outside the park, and went to bed early.
The alarm went off at 2:45 the next morning, and by 2:55 we were on the road to Glacier Point. After narrowly averting one self-inflicted catastrophe (in the absolute darkness, I missed a turn I’ve been taking for more than 40 years), by 4:00 we were less than a mile from Glacier Point and approaching Washburn Point, the first view of Half Dome on Glacier Point Road. Unable to resist the urge to peek (but with no expectation of success), I quickly glanced in that direction and instantly saw through my windshield Comet NEOWISE hanging above Mt. Watkins, directly opposite Tenaya Canyon from Half Dome. I knew there’d be a chance NEOWISE would be naked-eye visible, but I never dreamed it would be this bright.
Everything after that is a blur (except my images, thankfully). Jay and I rushed out to the railed vista at the far end of Glacier Point and were thrilled to find it completely empty. We found Half Dome beautifully bookended by Comet NEOWISE on the left, and brilliant Venus on the right. I set up two tripods, one for my Sony a7RIV and 24-105 G lens, and one for my Sony a7RIII and Sony 100-400 GM lens. Shut out of all the locations I love to photograph by COVID-19, I hadn’t taken a serious picture since March, so I composed and focused carefully to avoid screwing something up. The image I share here is one of the first of the morning, taken with my a7RIV and 24-105.
By 4:30 or so (about 80 minutes before sunrise) the horizon was starting to brighten, but the comet stayed very prominent and photogenic until at about 4:50 (about an hour before sunrise). When we wrapped up at around 5:00, NEOWISE was nearly washed out to the unaided eye; while our cameras were still picking it up, we knew that the best part of the show was over.
It’s these experiences that so clearly define for me the reason I’m a photographer. Because I’ve always felt that photography, more than anything else, needs to make the photographer happy (however he or she defines happiness), many years ago I promised myself that I’d only photograph what I want to photograph, that I’d never take a picture just because I thought it would earn me money or acclaim. My own photographic happiness comes from nature because I grew up outdoors (okay, not literally, but outdoors is where my best memories have been made) and have always been drawn to the natural world—not merely its sights, but the natural processes and forces that, completely independent of human intervention and influence, shape our physical world.
I think that explains why, rather than settle for pretty scenes, I try to capture the interaction of dynamic natural processes with those scenes. The moon and stars, the northern lights, sunrise and sunset color, weather events like rainbows and lightning—all of these phenomena absolutely fascinate me, and the images I capture are just a small part of my relationship with them. I can’t imagine photographing something that doesn’t move me enough to understand it as thoroughly as I can, and enjoy learning about my subjects as much as I enjoy photographing them.
The converse of that need to know my subjects is a need to photograph those things that drive me to understand them. Most of the subjects that draw me are relatively easy to capture with basic preparation, some effort, and a little patience. But the relative rarity of a few phenomena make photographing them a challenge. This is especially true of certain astronomical events. I’m thinking specifically about the total solar eclipse that I finally managed to photograph in 2017, and the northern lights, which finally found my sensor last year. But comets have proven even more elusive, and while I’ve seen a few in my life, and even photographed a couple, I’ve never had what I’d label an “epic” comet experience that allowed me to combine a beautiful comet with a worthy foreground. Until this week. And I’m one happy dude.
Comets in General
I want to tell you how to photograph Comet NEOWISE, but first I’m going to impose my personal paradigm and explain comets.
A comet is a ball of ice and dust a few miles across (more or less), typically orbiting the sun in an eccentric elliptical orbit: Imagine a circle stretched way out of shape by grabbing one end and pulling–that’s what a comet’s orbit looks like. Looking down on the entire orbit, you’d see the sun tucked just inside one extreme end of the ellipse. (Actually, some comets’ orbits are parabolic, which means they pass by once and then move on to ultimately exit our solar system.)
The farther a comet is from the sun the slower it moves, so a comet spends the vast majority of its life in the frozen extremities of the solar system. Some periodic comets take thousands or millions of years to complete a single orbit; others complete their trip in just a few years.
As a comet approaches the sun, stuff starts happening. It accelerates in response to the sun’s increased gravitational pull (but just like the planets, the moon, or the hour hand on a clock, a comet will never move so fast that we’re able to visually discern its motion). And more significantly, increasing solar heat starts melting the comet’s frozen nucleus. Initially this just-released material expands to create a mini-atmosphere surrounding the nucleus; at this point the comet looks like a fuzzy ball when viewed from Earth. As the heat increases, some of the shedding material is set free and dragged away by the solar wind (charged particles) to form a tail that glows with reflected sunlight (a comet doesn’t emit its own light) and always points away from the sun. The composition and amount of material freed by the sun, combined with the comet’s proximity to Earth, determines the brilliance of the display we see. While a comet’s tail gives the impression to some that it’s visibly moving across the sky, a comet is actually about as stationary against the stellar background as the moon and planets—it will remain in one place relative to the stars all night, then appear in a slightly different place the next night.
With millions of comets in our Solar System, it would be natural to wonder why they’re not regular visitors to our night sky. Actually, they are, though most comets are so small, and/or have made so many passes by the sun, that their nucleus has been stripped of reflective material and they just don’t have enough material left to put on much of a show. And many comets don’t get close enough to the sun to be profoundly affected by its heat, or close enough to Earth to stand out.
Most of the periodic comets that are already well known to astronomers have lost so much of their material that they’re too faint to be seen without a telescope. One notable exception is Halley’s Comet, perhaps the most famous comet of all. Halley’s Comet returns every 75 years or so and usually puts on a memorable display. Unfortunately, Halley’s last visit, in 1986, was kind of a dud; not because it didn’t perform, but because it passed so far from Earth that we didn’t have a good view of its performance on that pass.
Comet NEOWISE in particular (and some tips for photographing it)
Comet NEOWISE is a periodic comet with an elliptical orbit that will send it back our way in about 6700+ years. On it’s current iteration, NEOWISE zipped by the sun on July 2 and is on its way back out to the nether reaches of our solar system. The good news is that NEOWISE survived the most dangerous part of its visit, its encounter with the sun. The bad news is that NEOWISE’s intrinsic brightness decreases as it moves away from the sun. But if all goes well, we’ll be able to see it without a telescope, camera, or binoculars for at least a few more weeks. And it doesn’t hurt that until perigee on July 22, NEOWISE is still moving closer to Earth.
Because a comet’s tail always points away from the sun, and NEOWISE is now moving away from the sun, it’s actually following its tail. If you track the comet’s position each night, you’ll see that it rises in the northeast sky before sunrise, which makes it a Northern Hemisphere object (the Southern Hemisphere has gotten the best 21st century comets, so it’s definitely our turn). Each morning NEOWISE will rise a little earlier, placing it farther from the advancing daylight than the prior day, so even if its intrinsic brightness is waning, it should stand out better because it’s in a darker part of the sky. And as a bonus, the moon is waning, so until the new moon on July 21, there will be no moonlight to compete with NEOWISE.
Until now, Comet NEOWISE has been an exclusively early morning object, but that’s about to change as it climbs a little higher each day. Starting tonight (July 12), you might be able to see it shortly after sunset near the northwest horizon, and each night thereafter it will be a little higher in the northwest sky. Your best chance to view Comet NEOWISE in the evening is to find an open view of the northwest sky, far from city lights.
Photographing Comet NEOWISE will require some night photography skill. Since the moon is waning, you won’t have the benefit of moonlight that I had when I photographed the comet in Yosemite on the morning of July 10, when the moon was about 75% full. This won’t be a huge problem if you just want to photograph NEOWISE against the stars, but if you want to include some landscape with it, your best bet may be to stick to silhouettes, or stack multiple exposures, one for the comet and one or more for the foreground.
To photograph it against the starry sky, I recommend a long telephoto to fill the frame as much as possible. If you want to include some landscape, go as wide as necessary, but don’t forget that the wider you go, the smaller the comet becomes. Whatever method you use to focus (even if you autofocus on the comet itself), I strongly recommend that you verify your focus each time you change your focal length. If you choose the multi-exposure blend approach, please, please, please, whatever you do, don’t blend a telephoto NEOWISE image with a wide angle image of the landscape (because I’ll know and will judge you for it).
Camera or not, I strongly encourage you to make an effort to see this rare and beautiful object, because you just don’t know when the next opportunity will arise—it could be next month, or it might not happen again in your lifetime.