October has brought clear skies and some fine celestial sights. Here’s a potpourri of what was up from home.
We’ve enjoyed some lovely early autumn weather here in southern Alberta, providing great opportunities to see and shoot a series of astronomical events.
On October 5, Venus and Mars appeared a fraction of a degree apart in the dawn twilight. Venus is the brightest object, just above dimmer but red Mars. This was one of the closest planet conjunctions of 2017. Mars will appear much brighter in July and August 2018 when it makes its closest approach to Earth since 2003.
Satellites: The Space Station
The Space Station made a series of ideal evening passes in early October, flying right overhead from my site at latitude 51° N. I captured it in a series of stacked still images, so it appears as a dashed line across the sky. In reality it looks like a very bright star, outshining any other natural star. Here, it appears to fly toward the rising Moon.
Often appearing brighter than even the ISS, Iridium satellite flares can blaze brighter than even Venus at its best. One did so here, above, in another time-lapse of a pair of Iridium satellites that traveled in parallel and flared at almost the same time. But the orientation of the reflective antennas that create these flares must have been better on the left Iridium as it really shot up in brilliance for a few seconds.
Little in the sky beats a fine aurora display and we’ve had several of late, despite the Sun being spotless and nearing a low ebb in its activity. The above shot is a composite stack of 200 images, showing the stars circling the celestial pole above the main auroral arc, and taken on Friday the 13th.
This frame, from some 1300 I shot this night, October 13, captures the main auroral arc and a diffuse patch of green above that pulsed on and off.
You can see the time-lapse here in my short music video on Vimeo.
Friday the 13th Aurora from Alan Dyer on Vimeo.
It’s in 4K if your monitor and computer are capable. It nicely shows the development of the aurora this night, from a quiescent arc, through a brief sub-storm outburst, then into pulsing and flickering patches. Enjoy!
What all these scenes have in common is that they were all shot from home, in my backyard. It is wonderful to live in a rural area and to be able to step outside and see these sites easily by just looking up!
I put two new fast 14mm lenses to the test: the Sigma 14mm f/1.8 Art vs. the Rokinon 14mm f/2.4 SP.
Much to the delight of nightscape and astrophotographers everywhere we have a great selection of new and fast wide-angle lenses to pick from.
Introduced in 2017 are two fast ultra-wide 14mm lenses, from Sigma and from Rokinon/Samyang. Both are rectilinear, not fish-eye, lenses.
I tested the Nikon version of the Sigma 14mm f/1.8 Art lens vs. the Canon version of the Rokinon 14mm f/2.4 SP. I used a Nikon D750 and Canon 6D MkII camera.
I also tested the new faster Rokinon SP against the older and still available Rokinon 14mm f/2.8, long a popular lens among nightscape photographers.
The Sigma 14mm is a fully automatic lens with auto focus. It is the latest in their highly regarded Art series of premium lenses. I have their 20mm and 24mm Art lenses and love them.
The Rokinon 14mm SP (also sold under the Samyang brand) is a manual focus lens, but with an AE chip so that it communicates with the camera. Adjusting the aperture is done on the camera, not by turning a manual aperture ring, as is the case with many of Rokinon’s lower cost series of manual lenses. The lens aperture is then recorded in each image’s EXIF metadata, an aid to later processing. It is part of Rokinon’s premium “Special Performance” SP series which includes an 85mm f/1.2 lens.
All units I tested were items purchased from stock, and were not supplied by manufacturers as samples for testing. I own these!
For those with no time to read the full review, here are the key points:
• The Sigma f/1.8 Art exhibits slightly more off-axis aberrations than the Rokinon 14mm SP, even at the same aperture. But aberrations are very well controlled.
• As its key selling point, the Sigma offers another full stop of aperture over the Rokinon SP (f/1.8 vs. f/2.4), making many types of images much more feasible, such as high-cadence aurora time-lapses and fixed-camera stills and time-lapses of a deeper, richer Milky Way.
• The Sigma also has lower levels of vignetting (darkening of the frame corners) than the Rokinon 14mm SP, even at the same apertures.
• Both the Sigma Art and Rokinon SP lenses showed very sharp star images at the centre of the frame.
• Comparing the new premium Rokinon 14mm SP against the older Rokinon 14mm f/2.8 revealed that the new SP model has reduced off-axis aberrations and lower levels of vignetting than the lower-cost f/2.8 model. However, so it should for double the price or more of the original f/2.8 lens.
• The Rokinon 14mm SP is a great choice for deep-sky imaging where optical quality is paramount. The Sigma 14mm Art’s extra speed will be superb for time-lapse imaging where the f/1.8 aperture provides more freedom to use shorter shutter speeds or lower ISO settings.
•Though exhibiting the lowest image quality of the three lenses, the original Rokinon 14mm f/2.8 remains a superb value, at its typical price of $350 to $500. For nightscapers on a budget, it’s an excellent choice.
For all these tests I placed the camera and lens on a tracking mount, the Sky-Watcher Star Adventurer Mini shown below. This allowed the camera to follow the sky, preventing any star trailing. Any distortions you see are due to the lens, not sky motion.
As I stopped down the aperture, I lengthened the exposure time to compensate, so all images were equally well exposed.
In developing the Raw files in Adobe Camera Raw, I applied a standard level of Contrast (25) and Clarity (50) boost, and a modest colour correction to neutralize the background sky colour. I also applied a standard level of noise reduction and sharpening.
However, I did not apply any lens corrections that, if applied, would reduce lateral chromatic aberrations and compensate for lens vignetting.
So what you see here is what the lens produced out of the camera, with no corrections. Keep in mind that the vignetting you see can be largely compensated for in Raw development, with the provisos noted below. But I wanted to show how much vignetting each lens exhibited.
Stars are the severest test of any lens. Not test charts, not day shots of city skylines. Stars.
The first concern with any fast lens is how sharp the stars are not only in the centre of the frame, but also across the frame to the corners. Every lens design requires manufacturers to make compromises on what lens aberrations they are going to suppress at the expense of other lens characteristics. You can never have it all!
However, for astrophotography we do look for stars to be as pinpoint as possible to the corners, with little coma and astigmatism splaying stars into seagull and comet shapes. Stars should also not become rainbow-coloured blobs from lateral chromatic aberration.
SIGMA 14mm ART
These images show 200% blowups of the two upper corners of the Sigma 14mm Art lens, each at five apertures, from wide open at f/1.8, then stopped down at 1/3rd stop increments to f/2.8. As you would expect, performance improves as you stop down the lens, though some astigmatism and coma are still present at f/2.8.
But even wide open at f/1.8, off-axis aberrations are very well controlled and minimal. You have to zoom up this much to see them.
There was no detectable lateral chromatic aberration.
Aberrations were also equal at each corner, showing good lens centering and tight assembly tolerances.
ROKINON 14mm SP
Similarly, these images show 200% blow-ups of the upper corners of the Rokinon SP, at its three widest apertures: f/2.4, f/2.8 and f/3.2.
Star images look tighter and less aberrated in the Rokinon, even when compared at the same apertures.
But images look better on the left side of the frame than on the right, indicating a slight lens de-centering or variation in lens position or figuring, a flaw noted by other users in testing Rokinon lenses. The difference is not great and takes pixel-peeping to see. Nevertheless, it is there, and may vary from unit to unit. This should not be the case with any “premium” lens.
SIGMA vs. ROKINON
This image shows both lenses in one frame, at the same apertures, for a more direct comparison. The Rokinon SP is better, but of course, doesn’t go to f/1.8 as does the Sigma.
We don’t want good performance at the corners if it means sacrificing sharp images at the centre of the frame, where other aberrations such as spherical aberration can take their toll and blur images.
These images compare the two lenses in 200% blow-ups of an area in the Cygnus Milky Way that includes the Coathanger star cluster. Both lenses look equally as sharp.
SIGMA 14mm ART
Even when wide open at f/1.8 the Sigma Art shows very sharp star images, with little improvement when stopped down. Excellent!
ROKINON 14mm SP
The same can be said for the Rokinon SP. It performs very well when wide open at f/2.4, with star images as sharp as when stopped down 2/3rds of an f-stop to f/3.2
SIGMA vs. ROKINON
This image shows both lenses in one frame, but with the Sigma wide open at f/1.8 and stopped down to f/2.8, vs. the Rokinon wide open at f/2.4 and stopped to f/2.8. All look superb.
The bane of wide-angle lenses is the light fall-off that is inevitable as lens focal lengths decrease. We’d like this vignetting to be minimal. While it can be corrected for later when developing the Raw files, doing so can raise the visibility of noise and discolouration, such as magenta casts. The less vignetting we have to deal with the better.
As with off-axis aberrations, vignetting decreases as lenses are stopped down. Images become more uniformly illuminated across the frame, with less of a “hot spot” in the centre.
SIGMA 14mm ART
This set compares the left edge of the frame in the Sigma SP at five apertures, from f/1.8 to f/2.8. You can see how the image gets brighter and more uniform as the lens is stopped down. (The inset image at upper right show what part of the frame I am zooming into.)
ROKINON 14mm SP
This similar set compares the frame’s left edge in the Rokinon SP at its three widest apertures, from f/2.4 to f/3.2. Again, vignetting improves but is still present at f/3.2.
SIGMA vs. ROKINON
This compares both lenses at similar apertures side by side for a direct comparison. The Sigma is better than the Rokinon with a much more uniform illumination across the frame.
In these two images, above, of the entire frame at their respectively widest apertures, I’d say the Sigma exhibits less vignetting than the Rokinon, even when wide open at f/1.8. The cost for this performance, other than in dollars, is that the Sigma is a large, heavy lens with a massive front lens element.
ROKINON 14mm f/2.4 SP vs. ROKINON 14mm f/2.8 Standard
Even the Rokinon 14mm SP, though a manual lens, carries a premium price, at $800 to $1000 U.S., depending on the lens mount.
For those looking for a low-cost, ultra-wide lens, the original Rokinon/Samyang 14mm f/2.8 (shown above) is still available and popular. It is a fully manual lens, though versions are available with a AE chip to communicate lens aperture information to the camera.
I happily used this f/2.8 lens for several years. Before I sold it earlier in 2017 (before I acquired the Sigma 14mm), I tested it against Rokinon’s premium SP version.
The older f/2.8 lens exhibited worse off-axis and on-axis aberrations and vignetting than the SP, even with the SP lens set to the same f/2.8 aperture. But image quality of the original lens is still very good, and the price is attractive, at half the price or less, than the 14mm SP Rokinon.
TWO 14mm ROKINONS: OFF-AXIS ABERRATIONS
Here, in closeups of the upper corners, I show the difference between the two Rokinons, the older standard lens on the left, and the new SP on the right.
The SP, as it should, shows lower aberrations and tighter star images, though with the improvement most marked on the left corner; not so much on the right corner. The original f/2.8 lens holds its own quite well.
TWO 14mm ROKINONS: ON-AXIS ABERRATIONS
At the centre of the frame, the difference is more apparent, with the SP lens exhibiting sharper star images than the old 14mm with its generally softer, larger star images. The latter likely has more spherical aberration.
TWO 14mm ROKINONS: VIGNETTING
The new SP lens clearly has the advantage here, with less vignetting and brighter corners even when wide open at f/2.4 than the older lens does at its widest aperture of f/2.8. This is another reason to go for the new SP if image quality is paramount
The new Sigma 14mm Art lens is costly, at $1600 U.S., though with a price commensurate with its focal length and aperture. Other premium lenses in this focal length range, either prime or zoom, from Nikon and Canon sell for much more, and have only an f/2.8 maximum aperture. So in that sense, the Sigma Art is a bargain.
The new Rokinon 14mm SP sells for $800 to $1000, still a premium price for a manual focus lens. But its optical quality competes with the best.
The older Rokinon 14mm f/2.8 is a fantastic value at $350 to $500, depending on lens mount and AE chip. For anyone getting into nightscape and Milky Way photography, it is a great choice.
With such a huge range in price, what should you buy?
A 14mm is a superb lens for nightscape shooting – for sky-filling auroras, for panoramas along the Milky Way, or of the entire sky. But the lens needs to be fast. All three lenses on offer here satisfy that requirement.
SIGMA 14mm f/1.8 ART
If you want sheer speed, this is the lens. It offers a full stop gain over the already fast Rokinon f/2.5, allowing exposures to be half the length, or shooting at half the ISO speed for less noise.
Its fast speed comes into its own for rapid cadence aurora time-lapses, to freeze auroral motion as much as possible in exposures as short as 1 to 2 seconds at a high ISO. The fast speed might also make real-time movies of the aurora possible on cameras sensitive and noiseless enough to allow video shooting at ISO 25,000 and higher, such as the Sony a7s models.
The Sigma’s fast speed also allows grabbing rich images of the Milky Way in exposures short enough to avoid star trailing, either in still images or in time-lapses of the Milky Way in motion.
While the Sigma does exhibit some edge aberrations, they are very well controlled (much less than I see with some 24mm and 35mm lenses I have) and are a reasonable tradeoff for the speed and low level of vignetting, which results in less noisy corners.
Photographers obsess over corner aberrations when, for fixed-camera nightscape shooting, a low level of vignetting is probably more critical. Correcting excessive vignetting introduces noise, while the corner aberrations may well be masked by star trailing. Only in tracked images do corner aberrations become more visible, as in the test images here.
I’d suggest the Sigma is the best choice for nightscape and time-lapse shooting, with its speed allowing for kinds of shots not possible otherwise.
The Sigma also appears to be the best coated of all the lenses, as you can see in the reflections in the lenses in the opening image, and below. However, I did not test the lenses for flares and ghosting.
As a footnote, none of the lenses allow front-mounted filters, and none have filter drawers.
ROKINON 14mm f/2.4 SP
For less money you get excellent optical quality, though with perhaps some worrisome variation in how well the lens elements are figured or assembled, as evidenced by the inconsistent level of aberration from corner to corner.
Nevertheless, stars are tight on- and off-axis, and vignetting is quite low, for corners that will be less noisy when the shadows are recovered in processing.
I’d suggest the Rokinon SP is a great choice if tracked deep-sky images are your prime interest, where off-axis performance is most visible. However, the SP’s inconsistent aberrations from corner to corner are evidence of lower manufacturing tolerances than Sigma’s, so your unit may not perform like mine.
For nightscape work, the SP’s f/2.4 aperture might seem a minor gain over Rokinon’s lower-cost f/2.8 lens. But it is 1/3 of an f-stop. That means, for example, untracked Milky Way exposures could be 30 seconds instead of 40 seconds, short enough to avoid obvious star trailing. At night, every fraction of an f-stop gain is welcome and significant.
ROKINON 14mm f/2.8 Standard
You might never see the difference in quality between this lens and its premium SP brother in images intended for time-lapse movies, even at 4K resolution.
But those intending to do long-exposure deep-sky imaging, as these test images are, will want the sharpest stars possible across the frame. In which case, consider the 14mm SP.
But if price is a prime consideration, the original f/2.8 Rokinon is a fine choice. You’ll need to apply a fair amount of lens correction in processing, but the lens exists in the Camera Raw/Lightroom database, so correction is just a click away.
That was a lengthy report, I know! But there’s no point in providing recommendations without the evidence to back them up.
All images, other than the opening “beauty shot,” can be clicked/tapped on to download a full-resolution original JPG for closer inspection.
As I’ve just received the Sigma Art lens I’ve not had a chance to shoot any “real” nightscape images with it yet, just these test shots. But for a real life deep-sky image of the Milky Way shot with the Rokinon SP, see this image from Australia. https://flic.kr/p/SSQm7G
I hope you found the test of value in helping you choose a lens.
“No ocean of water in the world can vie with its gorgeous sunsets; no solitude can equal the loneliness of a night-shadowed prairie.” – William Butler, 1873
In the 1870s, just before the coming of the railway and European settlement, English adventurer William Butler trekked the Canadian prairies, knowing what he called “The Great Lone Land” was soon to disappear as a remote and unsettled territory.
The quote from his book is on a plaque at the site where I took the lead image, Sunset Point at Writing-on-Stone Provincial Park.
The night was near perfect, with the Milky Way standing out down to the southern horizon and the Sweetgrass Hills of Montana. Below, the Milk River winds through the sandstone rock formations sacred to the Blackfoot First Nations.
The next night (last night, July 26, as I write this) I was at another unique site in southern Alberta, Red Rock Coulee Natural Area. The sky presented one of Butler’s unmatched prairie sunsets.
This is “big sky” country, and this week is putting on a great show with a succession of clear and mild nights under a heat wave.
The waxing crescent Moon adds to the western sky and the sunsets. But it sets early enough to leave the sky dark for the Milky Way to shine to the south.
This was the Milky Way on Wednesday night, July 27, over Red Rock Coulee. Sagittarius and the centre of the Galaxy lie above the horizon. At right, Saturn shines amid the dark lanes of the Dark Horse in the Milky Way.
I’m just halfway through my week-long photo tour of several favourite sites in this Great Lone Land. Next, is Cypress Hills and the Reesor Ranch.
In a winter of cloud, the skies cleared for a magical night in the Alberta Badlands.
Two weeks ago, on February 28, I took advantage of a rare and pristine night to head to one of my favourite spots in Dinosaur Provincial Park, to shoot nightscapes of the winter sky over the Badlands.
A spate of warm weather had melted most of the snow, so the landscape doesn’t look too wintery. But the stars definitely belong to winter in the Northern Hemisphere.
The main image above shows the winter Milky Way arching across the sky from southeast (at left) to northwest (at right). The tower of light in the west is the Zodiacal Light, caused by sunlight reflecting off dust particles in the inner solar system. It is an interplanetary, not atmospheric, effect.
Above, this 360° version of the scene records the entire sky, with the winter Milky Way from horizon to horizon. With a little averted imagination you can also trace the Zodiacal Light from west (right) over to the eastern sky (left), where it brightens in the diffuse glow of the Gegenschein, where dust opposite the Sun in the outer solar system reflects light back to us.
A rectangular version of the panorama wraps the sky around from east (left), with Leo rising, to northeast (right), with the Big Dipper standing on its handle. I’ve added the labels in Photoshop of course.
Here, in a single-frame shot, Orion is at centre, Canis Major (with Sirius) is below left, and Taurus (with Aldebaran) is at upper right. The Milky Way runs down to the south. The clusters M35, M41, M46 and M47 are visible as diffuse spots, as is the Orion Nebula, M42, below Orion’s Belt.
This is certainly my best shot of the evening Zodiacal Light from my area in Alberta. It is obvious at this time of year on moonless nights, but requires a site with little urban skyglow to the west.
It is best visible in the evening from northern latitudes in late winter and spring.
Here, Venus is just setting above the badlands landscape. The Andromeda Galaxy is at right, the Pleiades at left. The Milky Way runs across the frame at top.
There is a common belief among nightscape photographers that the Milky Way can be seen only in summer. Not so.
What they mean is that the brightest part of the Milky Way, the galactic centre, is best seen in summer. But the Milky Way can be seen in all seasons, with the exception of spring when it is largely absent from the early evening sky, but rises late at night.
After a year of work, the new edition of my Nightscapes and Time-Lapse ebook is on the e-shelves at the Apple iBooks Store.
In the two years since I first published this ebook, the field of nightscape shooting has enjoyed many changes, to equipment, software and techniques. Not to mention I’ve learned a lot!
All those changes are reflected in this new and expanded edition. It is 100 pages bigger – 500 pages now – than the first edition. It contains:
• 60 step-by-step image processing tutorials, all with current late-2016 software
• a dozen galleries of comparison “before-and-after” images
• 40 HD videos of time-lapse examples
• reviews of current equipment
• reviews of software, some very new – like this week! – to use in place of Adobe
• information on Nikon and Pentax cameras, as well as Canons
• In addition, many images can be tapped on to zoom up. And most text can now be enlarged in a Scrolling View for use on small-screen devices.
The previous 2014 edition garnered rave reviews, with readers calling it:
“Incredibly well put together and visually stunning.”
“Simply amazing! From hardware to software, it’s all covered. Alan Dyer got it right!”
and “It is a must-have resource for anyone doing nightscape and time-lapse photography.”
As with the first edition, I’ve designed the ebook to appeal to both amateur astronomers and landscape photographers by providing what I feel is the most comprehensive information available in any ebook on the hugely popular field of nightscape and time-lapse photography.
This isn’t a simple 50-page PDF pamphlet, as so many ebooks are. This is an extensive and detailed tutorial, with loads of interactive and multi-media content.
The size and media content of the ebook make it impossible to publish on Kindle/Amazon or Google Play/Android.
How to Photograph & Process Nightscapes and Time-Lapses is available worldwide exclusively through the Apple iBooks Store, for the iBooks app on Apple Macs, iPads and iPhones.
My free Amazing Sky Calendar for 2017 is now available for download! Plan your astronomical year!
Once again, I have prepared a free 12-month Calendar listing loads of celestial events, Moon phases, highlighted space events, and with small charts to show what’s happening in the sky for the coming year. Plus a set of my favourite images from 2016.
I’m pleased to announce that after a year in production, our video tutorial series, Nightscapes and Time-Lapses: From Field to Photoshop, is now available.
It’s been quite a project! Over the last few years I’ve presented annual astrophoto workshops in conjunction with our local telescope dealer All-Star Telescope to great success.
However, we always had requests for the workshops on video. Attempts to video the actual workshops never produced satisfactory results. So we spent a year shooting in the field and in the studio to produce a “purpose-built” series of programs.
They are available now as a set of three programs, totalling 4 hours of instruction, for purchase and download at Vimeo at
For those wanting “hard copies” we will also be selling the programs on mailed USB sticks. See All-Star Telescope for info and prices. The downloaded version can also be ordered from there.
This series deals with the basics of capturing, then processing nightscape still images and time-lapse movies of the night sky and landscapes lit by moonlight and starlight.
Here’s the content outline:
Program 1 – Choosing Equipment (1 Hour)
• Tips for Getting Started • Essential Gear • Choosing A Camera • Photo 101 – Exposure Triangle • Setting Exposure • Expose to the Right • Setting a Camera – File Types • Photo 101 – Noise Sources • Setting a Camera – Noise Reduction • Setting a Camera – Focusing • Setting a Camera – Other Menus • Choosing Lenses • Choosing an IntervalometerSummary and Tips
Program 2 – Shooting in the Field (1 hour)
• Climbing the Learning Curve • Twilights • Astronomy 101 – Conjunctions • Shooting Conjunctions • Moonrises • Shooting Auroras • Astronomy 101 – Auroras • Photo 101 – Composing • Moonlit Nightscapes • Astronomy 101 – Where is the Moon? • Choosing a Location • Shooting the Milky Way • Astronomy 101 – Where is the Milky Way? • Astronomy 101 – Daily Sky Motion • Tracking the Sky • Shooting Star Trails • Shooting Time-Lapses • Calculating Time-Lapses • A Pre-Flight Checklist • Summary and Tips
Program 3 – Processing Nightscapes and Time-Lapses (2 hours)
• Workflows • Using Adobe Bridge – Importing and Selecting • Photo 101 – File Formats • Using Adobe Lightroom – Importing and Selecting • Adobe Camera Raw – Essential Settings • Adobe Camera Raw – Developing Raw Images • Adobe Lightroom – Develop Module • Adobe Photoshop – Introduction • Photoshop – Setup • Photoshop – Smart Filters • Photoshop – Adjustment Layers • Photoshop – Masking • Photoshop – Processing Star Trails & Time-Lapses • Stacking Star Trails • Assembling Time-Lapse Movies • Archiving • Summary & Finale
If this first introductory series is successful we may produce follow-up programs on more advanced techniques.