We’ve embarked upon a new project to produce a comprehensive tutorial on deep-sky imaging with DSLR cameras.
This past week we launched a new KickStarter campaign to fund the production of a new multi-hour video course on how to capture deep-sky objects using entry-level telescope gear and DSLR cameras.
The emphasis in the course will be on techniques for taking and processing publication-quality images as simply and easily as possible.
The final video course will consist of several programs, including a video of one of our annual “Deep-Sky with Your DSLR” workshops presented locally here in Alberta. We’ve often had requests for a video version of those workshops, for those who cannot attend in person.
This is it! Here’s a short preview of some of the content.
We include the Workshop video, but we supplement it with much more: with video segments shot in the field by day and by night, showing how to setup and use gear, and shot in the studio showing how to process images.
While much of the content has been shot and edited, there’s more to do yet. Thus our KickStarter campaign to complete the funding and production. Backers of the project through KickStarter will get the final videos at a substantial discount off the final retail price.
All the details are on the project’s KickStarter page. Click through for the listing of course content, and options for funding levels. An FAQ page answers many of the common questions.
A week into the campaign and we’re just over 50% funded, but we have a way to go yet!
We hope you’ll consider backing our project, which we think will be unique on the market.
Following up on my earlier tests, I compare the new Canon 6D MkII camera to earlier Canon full-frame models in long, tracked exposures of the Milky Way.
A month ago I published tests of the new Canon 6D MkII camera for nightscape images, ones taken using a fixed tripod in which exposures usually have to be limited to no longer than 30 to 60 seconds, to prevent star trailing.
Despite these short exposures, we still like to extract details from the dark shadows of the scene, making nightscape images a severe test of any camera.
Here I test the 6D MkII for what, in many respects, is a less demanding task: shooting long exposures of deep-sky objects, the Milky Way in Cygnus in this case.
Why is this an easier task? The camera is now on a tracking mount (I used the new Sky-Watcher Star Adventurer Mini) which is polar aligned to follow the rotation of the sky. As such, exposures can now be many minutes long if needed. We can give the camera sensor as much signal as the darkness of the night sky allows. More signal equals less noise in the final images.
In addition, there are no contrasty, dark shadows where noise lurks. Indeed, the subjects of deep-sky images are often so low in contrast, as here, they require aggressive contrast boosting later in processing to make a dramatic image.
While that post-processing can bring out artifacts and camera flaws, as a rule I never see the great increase in noise, banding, and magenta casts I sometimes encounter when processing short-exposure nightscape scenes.
For this test, I shot the same region of sky with the same 35mm lens L-Series lens at f/2.2, using three cameras:
• Canon 6D MkII (2017)
• Canon 6D (2012)
• Canon 5D MkII (2008)
Note that the 5D MkII has been “filter-modified” to make its sensor more sensitive to the deep red wavelengths emitted by hydrogen gas, the main component of the nebulas along the Milky Way. You’ll see how it picks up the red North America Nebula much better than do the two off-the-shelf “stock” cameras. (Canon had their own factory-modified “a” models in years past: the 20Da and 60Da. Canon: How about a 6D MkIIa?)
I shot at four ISO speeds typical of deep-sky images: 800, 1600, 3200, and 6400.
Exposures were 4 minutes, 2 minutes, 1 minute, and 30 seconds, respectively, to produce equally exposed frames with a histogram shifted well to the right, as it should be for a good signal-to-noise ratio.
Noisy deep-sky images with DSLR cameras are usually the result of the photographer underexposing needlessly, often in the mistaken belief that doing so will reduce noise when, in fact, it does just the opposite.
The above set of three images compares each of the three cameras at those four ISO speeds. In all cases I have applied very little processing to the images: only a lens correction, some sharpening, a slight contrast and clarity increase, and a slight color correction to neutralize the background sky.
However, I did not apply any luminance noise reduction. So all the images are noisier than what they would be in a final processed image.
Even so, all look very good. And with similar performance.
All frames were shot with Long Exposure Noise Reduction (LENR) on, for an automatic dark frame subtraction by the camera. I saw no artifacts from applying LENR vs. shots taken without it.
The 6D and 6D MkII perhaps show a little less noise than the old 5D MkII, as they should being newer cameras.
The 6D MkII also shows a little less pixelation on small stars, as it should being a 26 megapixel camera vs. 20 to 21 megapixels for the older cameras. However, you have to examine the images at pixel-peeping levels to see these differences. Nevertheless, having higher resolution without the penalty of higher noise is very welcome.
Above, I show images from the three cameras side by side at ISOs 1600, 3200, and 6400. It is tough to tell the difference in noise levels, the key characteristic for this type of astrophotography.
The new 6D MkII shows very similar levels of noise to the 6D, perhaps improving upon the older cameras a tad.
Because images are well-exposed (note the histogram at right), the 6D MkII is showing none of the flaws of its lower dynamic range reported elsewhere.
That’s the key. The 6D MkII needs a well-exposed image. Given that, it performs very well.
This version shows the same images but now with stacked frames and with a typical level of processing to make a more attractive and richer final image. Again, all look good, but with the modified camera showing richer nebulosity, as they do in deep-sky images.
The lead image at the very top is a final full-frame image with the Canon 6D MkII.
As such, based on my initial testing, I can recommend the Canon 6D MkII (and plan to use it myself) for deep-sky photography.
Indeed, I’ll likely have the camera filter-modified to replace my vintage yet faithful 5D MkII for most of my deep-sky shooting. The 6D MkII’s tilting LCD screen alone (a neck, back, and knee saver when attached to a telescope!) makes it a welcome upgrade from the earlier cameras.
The only drawback to the 6D MkII for deep-sky work is its limited dark frame buffer. As noted in my earlier review, it can shoot only three Raw files in rapid succession with Long Exposure Noise Reduction turned on. The 5D MkII can shoot five; the 6D can shoot four. (A 6D MkIIa should have this buffer increased to at least 4, if not 8 images.)
I make use of this undocumented feature all the time to ensure cleaner images in long deep-sky exposures, as it produces and subtracts dark frames with far greater accuracy than any taken later and applied in post-processing.
I hope you’ve found this report of interest.
With the 6D MkII so new, and between smoky skies and the interference of the Moon, I’ve had only one night under dark skies to perform these tests. But the results are promising.
For more tips on deep-sky imaging and processing see my pages on my website:
From southern latitudes the most amazing region of the sky shines overhead late on austral autumn nights.
There is no more spectacular part of the Milky Way than the regions around its galactic centre. Or at least in the direction of the galaxy’s core.
We can’t see the actual centre of the Galaxy, at least not with the cameras and telescopes at the disposal of amateur photographers such as myself.
It takes large observatory telescopes equipped with infrared cameras to see the stars orbiting the actual centre of the Milky Way. Doing so over many years reveals stars whipping around an invisible object with an estimated 4 million solar masses packed into the volume no larger than the solar system. It’s a black hole.
By comparison, looking in that direction with our eyes and everyday cameras, we see a mass of stars in glowing clouds intersected by lanes of dark interstellar dust.
The top image shows a wide view of the Milky Way toward the galactic centre, taking in most of Sagittarius and Scorpius and their incredible array of nebulas, star clusters and rivers of dark dust, all located in the dense spiral arms between us and the galactic core.
Zooming into that scene reveals a panoramic close-up of the Milky Way around the galactic centre, from the Eagle Nebula in Serpens, at left, to the Cat’s Paw Nebula in Scorpius, at right.
This is the richest hunting ground for stargazers looking for deep-sky wonders. It’s all here, with field after field of telescopic and binocular sights in an area of sky just a few binocular fields wide.
The actual galactic core area is just right of the centre of the frame, above the bright Sagittarius StarCloud.
Zooming in again shows just that region of sky in an even closer view. The contrast between the bright star fields at left and the dark intervening dust at right is striking even in binoculars – perhaps especially in binoculars.
The visual impression is of looking into dark canyons of space plunging off bright plateaus of stars.
In fact, it is just the opposite. The dark areas are created by dust much closer to us, hiding more distant stars. It is where the stars are most abundant, in the dust-free starclouds, that we see farthest into the galaxy.
In the image above the galactic centre is at right, just above the small diffuse red nebula. In that direction, some 28,000 light years away, lurks the Milky Way’s monster black hole.
To conclude my tour of the galactic centre, I back out all the way to see the entire sky and the Milky Way stretching from horizon to horizon, with the galactic centre nearly overhead in this view from 3 a.m. earlier this week.
Only from a latitude of about 30° South can you get this impressive view, what I consider one of the top “bucket-list” sights the sky has to offer.
The sky of December contains an amazing array of bright stars and deep-sky delights.
At this time of year we peer out toward the edge of our Galaxy, in the direction opposite to what we see in July and August. Even though we are looking away from the centre of our Galaxy, the Milky Way at this time of year contains a stunning collection of sights – for the naked eye, binoculars or a telescope.
I can’t list them all here, but most are in the lead image above! The image is a mosaic of the northern winter Milky Way, including the brilliant stars and constellations in and around Orion the Hunter.
The Milky Way extends from Perseus in the north at top, to Canis Major in the south at bottom. Throughout the scene are dark lanes and dust clouds, such as the Taurus Dark Clouds at upper right.
The Milky Way is dotted with numerous red “hydrogen-alpha” regions of emission nebulosity, such as the bright Rosette Nebula at lower left and the California Nebula at upper right. The curving arc of Barnard’s Loop surrounds the east side of Orion. Orion is below centre, with Sirius, the night sky’s brightest star, at lower left.
The constellation of Taurus is at upper right and Gemini at upper left. Auriga is at top and Perseus at upper right.
There’s an unusually bright area in Taurus just right of centre in the mosaic which I thought might be an image processing artifact. No. It’s the Gegenschein – a glow of sunlight reflected off comet dust directly opposite the Sun.
Two highlights of this sky that are great regions for binoculars are the Hyades cluster in Taurus ….
…and the Belt and Sword of Orion.
The Hyades – the face of Taurus – is one of the nearest and therefore largest open star clusters.
Orion the Hunter, who battles Taurus in the sky, contains the famous Orion Nebula, here overexposed in order to bring out the much fainter nebulosity in the region.
The magenta and blue arcs in the image below are photographic targets, but the bright Orion Nebula in Orion’s Sword is easy in binoculars, shining below the trio of his Belt Stars.
For us in the northern hemisphere, Orion and company are winter sights. But for those down under, in the southern hemisphere, this is the summer sky. So pardon the northern chauvinism in the title!
Either way, on a dark, moonless night, get out and explore the sky around Orion.
I shot the segments for the main mosaic at top on a very clear night on December 5, 2015 from the Quailway Cottage at Portal, Arizona. This is a mosaic of 8 segments, in two columns of 4 rows, with generous overlap. Each segment was made of 4 x 2.5-minute exposures stacked with mean combine stack mode to reduce noise, plus 2 x 2.5-minute exposures taken through the Kenko Softon filter layered in with Lighten belnd mode to add the star glows. Each segment was shot at f/2.8 with the original 35mm Canon L-series lens and the filter-modified (by Hutech) Canon 5D MkII at ISO 1600, riding on the iOptron Sky-Tracker. All stacking and stitching in Photoshop CC 2015. The soft diffusion filter helps bring out the star colors in this area of sky rich in brilliant giant stars.
Last night I shot into the autumn Milky Way at the Heart Nebula.
I’m currently just finishing off a month of testing the new Nikon D810a camera, a special high-end DSLR aimed specifically at astrophotographers.
I’ll post a more thorough set of test shots and comparisons in a future blog, but for now here are some shots from the last couple of nights.
Above is the setup I used to shoot the image below, shot in the act of taking the image below!
The Nikon is at the focus of my much-loved TMB 92mm refractor, riding on the Astro-Physics Mach One mount. The mount is being “auto-guided” by the wonderful “just-press-one-button” SG-4 auto-guider from Santa Barbara Instruments. The scope is working at a fast f/4.4 with the help of a field flattener/reducer from Borg/AstroHutech.
I shot a set of 15 five-minute exposures at ISO 1600 and stacked, aligned and averaged them (using mean stack mode) in Photoshop. I explain the process in my workshops, but there’s also a Ten Steps page at my websitewith my deep-sky workflow outlined.
The main advantage of Nikon’s special “a” version of the D810 is its extended red sensitivity for a capturing just such objects in the Milky Way, nebulas which shine primarily in the deep red “H-alpha” wavelength emitted by hydrogen.
It works very well! And the D810a’s 36 megapixels really do resolve better detail, something you appreciate in wide-angle shots like this one, below, of the autumn Milky Way.
It’s taken with the equally superb 14-24mm f/2.8 Nikkor zoom lens. Normally, you would never use a zoom lens for such a demanding subject as stars, but the 14-24mm is stunning, matching or beating the performance of many “prime” lenses.
The D810a’s extended red end helps reveal the nebulas along the Milky Way. The Heart Nebula, captured in the close-up at top, is just left of centre here, left of the “W” forming Cassiopeia.
The Nikon D810a is a superb camera, with low noise, high-resolution, and features of value to astrophotographers. Kudos to Nikon for serving our market!
Here are both the heart and the soul of Cassiopeia the Queen.
Two days ago I posted an image of the Soul Nebula. Now, here is the matching Heart Nebula, in a mosaic of the glorious region of the Milky Way called the Heart and Soul Nebulas located in the constellation of Cassiopeia.
They are otherwise respectively called IC 1805 and IC 1848. Amid the swirls of nebulosity are numerous clusters of stars, such as NGC 1027 just above centre. The separate patch of nebulosity at upper right is NGC 896.
I shot the frames for this 3-segment mosaic over two nights, with one segment taken from the frames that made up the previous post. Plus I shot two others to span the region of the Milky Way that is about seven degrees long, a binocular field.
Each of the 3 segments is a stack of 12 frames, with each frame a 6-minute exposure. I used the filter-modified Canon 5D MkII and shot through the TMB 92mm apo refractor at f/4.4. All processing was in Photoshop, including the mosaic assembly.
In all, it’s the best image I’ve taken of this much-shot area of the sky. It really brings out the diversity in star colours, and sky colours, from the dusty orange-brown region at left, to the inky dark dustless region at far right.
The Soul Nebula glows from within the constellation of Cassiopeia the Queen.
I shot this image last night, capturing an object prosaically known as IC 1848, but more popularly called the Soul Nebula.
It is often depicted framed with a companion nebula just “off camera” here to the right, called the Heart Nebula. Thus they are the Heart and Soul. Both shine on the eastern side of Cassiopeia the Queen.
Here I’m framing just the Soul, taking in some of the faint nebulosity to the left of the main nebula, including a tiny object called IC 289, a star-like planetary nebula at upper left.
I like this image for its variety of subtle colours, not only the reds and magentas in the bright nebula, but also in the dark sky around it from dim dust adding faint yellows, browns and even a touch of green.
The Soul Nebula lies 6,500 light years away in the Perseus Arm, the next spiral arm out from ours in the Milky Way. On northern autumn nights this region of the sky and Milky Way lies high overhead.
For the technically minded:
The image is a stack of 20 six-minute exposures, taken with a filter-modified Canon 5D Mark II at ISO 800. I was shooting through one of my favourite telescopes for deep-sky photography, the TMB (Thomas M. Back-designed) 92mm apo refractor, working at a fast f/4.4 using a Borg 0.85x field flattener and focal reducer.
I used one of Noel Carboni’s “Astronomy Tools” Photoshop actions to add the “diffraction spikes” on the stars. They are artificial (refractors don’t produce spikes on stars) but they add a photogenic touch to a rich starfield.
I shot this from the backyard of my New Mexico winter home.