Tag: Canon EOS 6D

Milky Way on Kythira

To capture our home galaxy Milky Way properly was my dream for a very long time. A long time ago I started with Canon EOS 40D with Tokina 11-20 f2.8. Then I changed the rig to Olympus PEN-F with Zuiko 12-40 mm f2.8. A year later I upgraded to Zuiko 8 mm f1.8. Recently I purchased a second-hand full-frame camera Canon EOS 6D and I let it modified for astrophotography. All my previous attempts were based on a single photo strategy, following the 500 rule. Basically, you divide 500 by the focal length of your lens and you get maximal exposure time. Of course, you have to crank up the ISO, use as wide aperture as possible, and a tripod. Photos produced by the above-described methods lack the details or they are very noisy, depends how much you de-noise in post-processing.

However, there is another method, which requires a tracker, which is basically a motor with a gear, which makes a full revolution in one day. By other words, it compensates for the Earth’s rotation. This means, you are not limited by a single picture, but you can make as many pictures as the weather allows. Of course, you have to stack the pictures. Therefore the post-processing is a bit complicated, but the signal to noise ratio can be significantly improved. I purchased Baader Nano tracker for my trip to Fuerteventura, but I was struggling with the equipment (shutter release, polar alignment, and lens) and as soon I got familiar with the setup, the weather got really bad, so the outcome was not as expected.

I got a new opportunity to test this set up on Kythira, where the Milky Way was not spoiled by the light pollution, because in direction south, there was nothing else than the Mediterranean sea. The primary target was the Rho Ophiuchi cloud complex. I have to say that I managed to capture it really well:

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure80x25s, ISO 1600
Date2020-07-11

After collecting 80 photos of Rho Ophiuchi, I pointed the camera to the east side of the Milky Way and I tried to capture the brightest objects in the sky – Jupiter and Saturn (upper left corner). Can you see the dark cloud at the bottom left corner? This is NGC6726 Nebula and NGC 6723 Chandelier Cluster.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure40x23s, ISO 1600
Date2020-07-11

The next day I turned the camera 90 degrees and capture the Milky Way again. At the bottom, there is “a line” of red nebulas. From left to right: Cat’s Paw Nebula, Lobster Nebula, Lagoon and Trifid Nebulae, Omega Nebula, and Eagle Nebula. The brightest object at the top right is Jupiter, making some reflections.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure47x25s, ISO 1600
Date2020-07-12

Here is another stack of 40 pictures targeting the core of the Milky Way.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure40x25s, ISO 1600
Date2020-07-12

Later on, the Milky Way started to submerge into the Mediterranean Sea, so I changed the composition slightly, to capture the constellation Scutum. I also changed the post-processing technique and left bit of the green color. 

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure47x25s, ISO 1600
Date2020-07-12

I also took a different lens with me – Samyang 24 mm f1.4. This lens is theoretically very fast, but I experienced very ugly stars if it’s fully opened. The reasonable aperture starts at f2.4, but at f2.8 the sharpness is very good, except in one corner. Here is a stack of 55 pictures, 60 second each:

LensSamyang 24 mm f1.4 @ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure55x60s, ISO 1600
Date2020-07-17

Or here is another wide-angle picture, which is a stack of 60 samples, each 24 second long:

LensSamyang 24 mm f1.4 @ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure60x24s, ISO 1600
Date2020-07-13

The last picture I would like to post here is made by the smartphone Xiaomi Mi 10 Pro. The camera has a night mode, but for astrophotography, one would need something better. Google Pixels has a special feature for it. Moreover one can install a non-official port of the Goggle Camera App to third-party Android phones. So I purchased the holder for the phone, placed on a tripod, and pressed the shutter button. The camera collected photons for 3 minutes and made multiple shots and stacked them automatically. The result is, however, not impressive and I have to conclude that smartphones cannot replace the DSLR or mirrorless cameras. There is Milky Way visible in the picture, but it lacks details and stars are elongated. The conclusion: for my next expedition I still cannot leave the camera at home and take only the smartphone.


Chasing darkness on Fuerteventura

This year was a special year. The pandemic outbreak ruined my first attempt of darkness chasing on the Canary Islands in May. I didn’t give up and as soon the restrictions were released, I purchased plane tickets to Fuerteventura again. We rented a house via AirBnB on the south side of the island, in the middle of nowhere, where the light pollution supposed to be minimal (measured SQM 21.2).

The island lies on the 28th parallel, which makes the core of the Milky Way pretty up in the sky. And this was exactly my primary astrophotographic target. I packed recently astro-modified Canon 6D, nifty-fifty 50 mm f1.8 lens and headed south. The aim was to capture the Antares region together with the core of the Milky Way and in the end, I somehow managed.  However, the lens disappointed me a lot, because it suffers from comatic and chromatic aberrations, combined with astigmatism. The stars in the corners are not round, even if the lens is slowed down to f 3.5. I was trying nearly every evening to recapture the Milky Way, but I was fighting with the weather (it was very windy) and with the equipment (polar alignment, shutter release, drained batteries), but I somehow managed to generate at least one decent picture of the desired target. Lessons learned – I need a better 50 mm lens.

Technical details:

LensCanon EF 50 mm f1.8
F-stop2.8
Focal length50 mm
MountBaader NanoTracker
CameraCanon EOS 6D Astro modified
Exposure14x20s, ISO 1600
Date2020-07-22

I also packed 150mm Newtonian, together with my new mount Rainbow Astro RS135. This mount is simply excellent and very portable. I still have Avalon M-Zero, but it is significantly heavier, therefore if I travel with Avalon, I have to order a second suitcase and to travel with two suitcases is not that convenient. Rainbow Astro occupies only half of my luggage, so there was a space for some T-shirts. I must say, that the Avalon is a better mount for tracking and there is no need to do a meridian flip, but the portability is for me more important. The primary target was the Lobster nebula, but I managed to capture some DSOs around Antares and in the core of the Milky Way (Lagoon, Trifid, M4, M6, M7, M24, IC4304)

The conclusion: the weather was much better than in La Palma last year. Every night was cloudless, but it was windy. Fortunately not every day, so in the end, it was a quite successful trip.


Samyang 24 mm f 1.4 review

I have been searching for a wide lens for my recently astro-modified, second hand Canon 6D. This means the lens should be suitable for a full-frame sensor 36 x 24 mm. The requirements on lenses are very tough for astrophotography because you photograph the stars – pinpoint sources of the light. The design/manufacturing flaws of the lenses are revealed on every astrophoto and optical aberrations spoil the good shot. Astrophotography of the Milky Way needs a lot of effort. Specifically, you have to travel to reach the dark sky and if you do so, you want to make nice pictures. In my opinion, the lens is the most important piece of equipment for astrophotography, because nowadays you can buy second hand Canon 6D, which is still very good and relatively inexpensive.

All the lenses are very sharp and aberration-free in the center of the picture, but the more you go off the axis, the aberrations start to pop up. There are many kinds of optical aberrations. Very nice article about the most common aberrations is on Lonely Speck.

Last year I purchased Samyang 14 mm f2.8, which is a great lens for the money, but the corners are not perfect and the stars are strongly deformed in every corner. I assumed that almost twice more expensive Samyang 24 mm f1.4 will perform much better and I also assumed that it’s easier to make a 24 mm lens compared to 14 mm. Moreover, f1.4 is a brilliant convincing argument. On the other hand, Samyang 24 mm doesn’t communicate with the camera, which means no EXIF of aperture and manual focus. This makes the lens a one-trick pony, suitable mainly for astrophotography and not that practical for regular photography.

Before I take this lens to the dark site, I decided to test it from my light-polluted home. The equipment: Canon 6Da, Baader Nanotracker, and of course, Samyang 24 mm f1.4. The main aim was to find the best aperture/sharpness ratio. Most of the lenses get sharper if slowed down. So I kept the exposure time 20 s, ISO 800, and was systematically changing the aperture from 1.4 to 2.8.

Here are the results of uncropped and uncorrected (no flats, no bias, no darks, and no noise reduction) pictures:

F1.4

F2.0

F2.4

F2.8

And the winner is…. obviously, the largest aperture (the smallest F number) collects the most of the light, but it vignettes strongly and honestly, the stars are ugly even in the center – this is totally unusable for serious astrophotography. The situation is not much improved by slowing the lens down to F2.0. At F2.4 the situation is significantly improved but at F2.8 the star roundness is acceptable almost everywhere, except the left corners.

Let’s have a look to the upper left corner – there the stars are the worst.

F1.4

F2.0

F2.4

F2.8

Conclusions

Samyang 24 mm F1.4 should be slowed down to at least to F2.4, to offer decent quality of the stars on a full-frame sensor. At F2.8 the quality is even slightly better, but at the top-left corners are the stars still elongated by astigmatic aberration. I expected better star quality, but in the end it’s not so dramatic, because the right side is not perfect, but acceptable. At least I know which side of the camera I should turn towards the ground if making a portrait picture of the Milky Way.


Chasing darkness in Greece – Karpathos

Like every summer, I packed the telescope, mount, camera and many accessories and flew to Greece. This time we went to Karpathos, the island not spoiled by massive tourism and light pollution. Long story short, the skies were amazing, but every single night, except one, was extremely windy. It was a torture – to see millions of stars and not be able to photograph them. There is no surprise that Karpathos is beloved by windsurfers and kite surfers. In the end I captured only the Iris Nebula and the Double Cluster. I talked to locals and they told me that the wind should stop at the end of September, so probably I picked the wrong time.

On the other hand I was able to do a wide angle astrophotography of the Milky Way. SQM reached 21.5, galactic core was so bright and I think the photos of the Milky Way are quite decent. This time I changed the setup and purchased Canon EOS 6D, which is one of the best cameras for this purpose. Moreover, there are many second hand 6Ds, because mirrorless mania arrived. 6D combined with Samyang 14 mm f2.8 offers excellent performance for this purpose.