Star Trails – Quick and Easy

Creating night-time images with star trails is the easiest and should be your first project when getting into astro photography.

Back in the day of film, you had to stomp down the diaphragm and use a shutter actuator to take one VERY long exposure. And if something happened during that long exposure (bird, plane, clouds, etc…) your photo was ruined. With digital, you can instead take LOTS of short exposures and digitally stitch them together, leaving out the ones that got ruined.

Setup your camera to take a series of short exposure photos, 10 seconds is good. For some tips on how to setup your camera, head over to my Astrophotography Cookbook page.

If you are starting out, or want to simply do this quickly, skip taking Bias, Dark and Flat photos. These are used to improve the final image processing and make more sense when you wish to do some deep sky stacking.

For this exercise I configured the intervalometer of the camera to take 10 second exposures with a 1 second pause between (i.e. the shutter is pressed every 11 seconds and each click is a 10 second exposure). I left the camera operating for a little more than one hour, with the result over 400 photos captured.

It’s important to review all the photos and note down the ones to exclude from the final image, things like camera movement because you knocked the tripod, a plane, clouds, etc. It’s possible that from the 438 photos taken, only the range 5 to 352 will be good to build the star trail image as clouds decided to roll into view on the 353rd photo.

The next step is to import the photos into Deep Sky Stacker. This is done by using the Open picture files… command. As I mentioned earlier, the dark, flat and bias can be skipped, these are not required. But if you have them, they will improve the quality of the final image. Don’t forget to select Check all before moving to the next step, and to uncheck any photos you want to exclude if you did a bulk import.

Once the photos are selected, go straight to Stack checked pictures… In the window that pops-up, hit the Stacking parameters… button and select the following:

  • Result – Standard Mode
  • Light – Maximum
  • Alignment – No Alignment

The remaining tabs can remain with the default setting. Hit OK and the program will now start processing all the photos. Note that DSS will still register each image even if you selected No Alignment. If you know how to prevent this waste of time, please tell me in the comment below.

The end result is something like the image below. Base on your the quality of your sky, the camera setting, color balance, etc… various level of work will be required to make it look nice, but you now have something to import into your photo editor and correct all that.

In my Post-processing section of the Astrophotography Cookbook, I provide some tips on how to correct for things like sky gradient.

Clear dark skies!

December 13 – Trying to catch the Geminids

About a week ago I crossed on my news feed that the Geminid meteor shower was peaking on the 13th and 14th and it should be a good year. At the same time I saw some pretty impressive photos of photographers catching spectacular fireballs as these tiny dust and grains of rock plunge into the atmosphere.

Braving the below freezing weather I setup the Canon 80D on a tripod in the back yard to see what I could catch. I read that the best time for the Geminids is 2am, I wasn’t going to stay up that late on a weeknight, so 10pm would have to do.

Wanting to capture as much of the sky as possible, the zoom lens is set to 17mm and wide open at F4. Note that I live in the city with considerable light pollution (I guess that’s what happens when electricity is cheap) which meant only the brightest meteors would be visible. Playing around with the settings I quickly concluded that at ISO1600 10-seconds of exposure would be the longest I should use to avoid having an over exposed sky. Normally it’s best to have the image intensity peak on the left half of the histogram. This can be quickly checked by viewing a captured image and selecting the Info option.

The camera operated for over an hour and managed to take 304 images before the memory card was full. The camera could have kept going much longer had I wiped the card clean before setting up as the battery still had over 25% charge.

Once the photos transferred on computer I reviewed all the images and identified those that had what appeared to be a meteor, plane or clouds such that I could do the necessary processing later on.

I know the chance of catching a spectacular fireball is slim, but it’s still interesting to review the images for any surprised and explore the various types of processing that can be done.

The easiest and quickest thing to do with all these images is a time-lapse movie. This is essentially a no-brainer. I used Canon Digital Photo Professional 4 to perform some color and brightness corrections on the photos prior to creating the movie. The benefit of this software is that you can save the “recipe” you used on one photo and apply it to all. I also did a batch processing to generate individual JPEG with 1080p of resolution to limit the quantity of GB of intermediate files required for this time-lapse movie.

The clouds that showed halfway through the sequence limited what I could do next with regards to “processing”. My next plan was for star trails!

I selected the longest stretch of images without clouds and then stacked them without alignment, using the ADD MAX operation in DSS. The result will be star trails as well as light trails from any passing plane. The image below is 122 individual 10 second exposures for just over 20 minutes total exposure time.

Tracks from two planes are clearly visible over the arc motion of the stars. A third plane much higher and on a different flight path also crossed the image if you pay close attention.

The timelapse and the star trails are two quick and interesting results from the photo session, but that was not my initial plan. Next I created a “starless” version of my night sky to serve as a background. This was achieved by selecting 8 images 1 minute apart and stacking them using the SIGMA MEDIAN operation. DSS will compare the pixels of all 8 images and if it falls outside a defined sigma distribution, the pixel will be replaced with the median value. As the images are once again not registered or star-aligned, the foreground will remain fix while the stars will move. As the stars move between each image, they will fall outside the sigma distribution and will be replaced by the median value instead.

With my starless image completed, the next step is to use GIMP to blend together the individual meteor trails with the starless nigh sky image. I use a MASK to select just the meteor trail of each photo that I previously identified contained a meteor. Each photo was manually added as a layer to the starless background.

Picture saved with settings applied.

There’s a total of four faint meteor trails as well as one very bright but short lived meteor in the middle. That short bright one ended up being special. Most meteor trails appear only on one frame, but this one left a smoke/dust trail that lingered for a few frames (40 seconds) and can be seen drifting in the high-altitude winds. To best see this, I selected some photos, cropped, enhanced the individual frames and generated an animated GIF.

The last processing I did was select a large sequence of photos that had no clouds or planes but this time register them such that the stars would be aligned between each frame. I simply did an ADD AVERAGE to stack the 62 individual photos, creating the equivalent of a 10 minute exposure of the night sky.

Because the field of view is wide, and I wasn’t in a particularly dark sky area the resulting photo isn’t that interesting, not like some of the other ones of the Milky Way taken while camping away from cities. However I was able to crop the image down to an area that had multiple Open Star Clusters showing up. Swipe to see the photo with the Open Star Clusters identified by their Messier Catalog number.

Click here to enlarge the above photo.

There you have it, a camera outside on a tripod for 1 hour and plenty of interesting results.

May Lunar Eclipse (Yes a Super Moon)

I hope that some of you will be taking a few minutes this evening to head outside and glance up at the Moon. Not only is tonight a “Super Moon” but depending where you are, you may find the Moon taking on a red hue due to a lunar eclipse.

September 27th 2015 Lunar Eclipse

For tonight’s event, those around the Pacific rim are best located to see the lunar eclipse. On the east coast of North America you might spot the start of the eclipse as the Moon sets in the early morning.

Location of best viewing. Leah Tiscione / S&T; Source: USNO

Even if you are not in a favorable spot, take the time to look at the Moon. There’s this timeless element to it, knowing that it’s been there for millions of years and will continue to be there for many more.

It is also accessible to everyone, no matter how light polluted your sky happens to be.

The best way to see the Moon is with nothing else but your two eyes. Resist the urge to attempt a photo with your phone. That will only end in frustrations. All photographs of the Moon are heavily processed because it’s very hard for a camera to handle both the brightness of a full Moon and the black of the nuit sky, or the glowing halo shining through the thin clouds. And when you do get the brightness under control, all the subtle details of the Moon’s surface is lost. Your eyes are better equipped to handle the large range of brightness and the resolution to really enjoy the sight.

Two separate shots and 15 minutes of processing is required for this, yet your eyes can easily see the details in real time.

February’s Snow Moon

There’s been lots of attention over Mars this past week. I can’t really blame all the media coverage, the Mars 2020 Perseverance EDL to the Martian surface was really cool and a great feat for NASA. I enjoyed watching it live on the NASA YouTube feed. But this weekend let’s turn our attention to the Snow Moon; the only full moon in February.

The full moon will occur at 3:17am Saturday, so tomorrow evening will be the best time to catch it. There’s nothing particularly special about this full moon, not a Blue Moon (second Full Moon in the month) or “Super Moon”. The name Snow Moon comes from the Farmer’s Almanac as February is normally the month that receives the most snow in North America.

The great thing about full moons is that you don’t need to stay up all night and wait outside in the frigid cold to see it. At this time of year, in the Northern hemisphere, the Moon is visible for more that 12 hours a day.

If you’re tempted to photograph the Snow Moon, leave the mobile phone behind, it’ll just give poor results and you’ll end up frustrated with frozen fingers. Instead just enjoy the view, paying close attention to the various dark “seas” spanning the lunar surface.

If you do try taking a picture, grab a DSLR or compact camera with manual mode. Set the ISO around 200 and the focus to manual. Your shutter speed should be high, around 1/800s; a full moon is surprisingly bright. You’re get better results by slightly under-exposing your shot. If you have a tripod, use it, else try to steady yourself on something (railing, chair, car roof, etc..) Subtle movement can easily ruin the details in you photos.

Clear skies!

Mars and the Milky Way

Campgrounds are offer good occasions to observe the night sky; away from the city lights or industrial parks.  And with little more than a camera on a tripod, some fantastic pictures can be taken.

But there are two drawbacks:
1) Campers make campfires that create a haze near the ground.
2) Trailers and vehicles often have lights on that ruin the show.

Mars (left) and the Milky Way - Benoit Guertin

Mars (left) and the Milky Way – Benoit Guertin

In case you missed the Venus-Moon close encounter

Last Saturday evening, if you happened to look outside and had a clear view there is no way you could miss the Venus-Moon close encounter in the dark blue sky. But just in case it was cloudy, or you weren’t paying attention here it is.

Moon and Venus within 8 degrees on June 16, 2018

Moon and Venus within 8 degrees on June 16, 2018

For those curious on the camera setting, the above is cropped from a single frame at 33mm f/4.5 1/30sec and ISO800 with Canon 80D.

Moving up to 85mm gives you the image below, also at 1/30sec and ISO800.  Both images were hand-held from a bedroom window. Could a tripod have helped? Sure, but I figured I could do just fine , especially with image stabilization enabled on the lens.

Moon and Venus within 8 degrees on June 16, 2018

Moon and Venus within 8 degrees on June 16, 2018

To put a bit of perspective on the distance of these two heavenly bodies and their apparent size in the sky I’ve added a bit of information on the above image. While Venus may be nearly 4 times larger in diameter, it looks quite small next to the Moon in the sky.

Moon and Jupiter Through the Clouds

After yesterday’s photo with the smart phone, I decided to go for a more professional shot and grabbed the Canon 80D and capture once again the Moon and Jupiter through the clouds. However this time around took two exposures, and stitched the together.

Moon and Jupiter Through the Cloud - May 27, 2018

Moon and Jupiter Through the Cloud – May 27, 2018

The wide-angle was 24mm F4.0 1/10s ISO-1600. This was to pick up the clouds against a night sky as well as Jupiter. Then a close-up of the Moon, with a shorter exposure and lowered ISO to pick up details of the lunar surface (85mm F5.6 1/250s ISO-200).

Opened them both in GIMP and played with layers, masks and curves to get the desired image.  The close-up Moon photo was scaled down to match the 24mm wide-angle photo to avoid having gigantic moon.

 

Bright Jupiter

Sometimes all it takes is a little cloud layer to hide the background stars to really reveal how bright Jupiter is right now. The photo below was taken with my smartphone on May 26th, with Jupiter clearly visible next to the Moon.

Jupiter and the Moon shining through the cloud - May 26, 2018

Jupiter and the Moon shining through the cloud – May 26, 2018

Jupiter and Earth were at their closest (opposition) on May 8th, but the entire month of May is a good time to spot Jupiter as it’s up high in the sky most of the night. Once Venus sets in the early evening, Jupiter is the brightest “star” in the sky, a good 20 times brighter than the next brightest stars.

Up until May 28th, Jupiter and the Moon will be near each other in the night sky, making for good photo opportunity.

Moon and Venus on May 17th

Came home from my piano lesson (yes you can still learn a new instrument past 40) and the sight of a 2-day old Moon and Venus in the dusk sky was stunning. Unfortunately by the time I got home to grab the camera, the sky had darken quite a bit, so I lost my opportunity for some color in the photo.

Venus 6 degrees from the Moon (May 17, 2018) - Benoit Guertin

Venus 6 degrees from the Moon (May 17, 2018) – Benoit Guertin

While I did take more close-up photos, I find adding the rooftop in the foreground helps establish scale.

Notice the Earthshine, it was easily picked up to naked eye.

Canon 80D
85mm F/8
ISO3200 (1/15sec)

Constellations at the Zenith

We don’t often look “straight up”. Unless you are laying down, it’s not a comfortable viewing position. However there is lots to see and the Big Dipper (Ursa Major) is right overhead this time of year.

Setting up a camera with a 10 second exposure can capture quite a good deal of the sky, and you don’t have to worry too much about star trails. What stands out is the large variations in the colors of stars, from cooler deep reds, to hot bright blues.

Constellation Near Zenith 08May2018

Constellations right above in the May evening.

17mm f/4
Canon 80D (ISO 3200)
12 x 10sec (2 minutes)