In the night from 23th to 24th August I have gone to Bohor to take some photos of Elephant’s trunk, but I had to end taking photos about at midnight because the object passed the meridian and I couldn’t track it anymore. I had to make quick decision which object to capture the rest of the night and I choose the dark nebulas B334, 336-7 in Aquila, near Altair. I had no internet and I hadn’t a clue how this nebula looks like. Some of dark nebulas are really breath-taking and impressive (who doesn’t know Horsehead). Well, mine isn’t so spectacular, but I am pretty satisfied with the result. The next day I have checked the google image search for this nebula and found nothing, which means that I am one of the first who decided to “burn” his CMOS sensor on this object for some hours After all, that counts as well …

Here you go:

Dark Nebulas B334, B336, B337 @ photo: Primož Cigler

Some technical data about the exposure, equipment and so on:

Object: B334
Date and Location: 23. 8. 2009, Oslica, Bohor
Exposition: 26 x 5min
Camera: Canon 350D, Baader mod., ISO 800, RAW
Optics: Orion Optics Europa 20cm f/4.5
Mount: Vixen GP-DX SS2K
Autoguiding: SW 80/400 with QHY5
Processed in: Iris, Ps

Object: M31 and M32 (Andromeda Galaxy)
Date and Location: 20. and 21. 8. 2009, Mali Orehek, Slovenia
Exposition: 2×1 mosaic: 30 x 5min and 36 x 5min
Camera: Canon 350D, Baader mod., ISO 800, RAW
Optics: Orion Optics Europa 20cm f/4.5
Mount: Vixen GP-DX SS2K
Autoguiding: SW 80/400 with QHY5
Processed in: Iris, Ps

M31 and M32 @ photo: Primož Cigler

I hope you like it, I am very satisfied with the result. More is coming soon…

“Hi,

My name is Mathew Oehler, and over the past several months I have become more interested in astrophotography, after having general photography as a hobby for about 6 years.

Last year a family friend was gracious enough to give me a 100mm Orion refractor telescope, and I have gotten excellent use out of it in viewing Saturn, Jupiter, and the Orion nebula among other things.  More recently I purchased a T-ring that enabled me to connect my Canon Rebel to the telescope, and was disappointed in its capability.  I would ideally like something designed to reach deeper, so I can get some clearer shots of nebulas and galaxies. I have heard that Schmidt-Cassegrain telescopes are designed for this purpose, but I’m having trouble finding good information amongst the sea of astrophotography information on the internet.  Are SC telescopes good for this, and will a standard one have an equatorial mount that I can put a motor onto?

Thank you in advance for any help you can provide me!”

The answer is not very simple (as always). The main reason why SCTs are so popular telescopes is their portability and compact size. They have a short optical tube because the light goes three times through it before it reaches the focus. The consequence is that they have long focal length comparing to diameter of the primary mirror which means slow optics (high f-ratio) – typically between f/8 and f/12. And here’s the catch! F-ratio is a king at photography because it tells you how many light the optics gathers per pixel. The lower f-ratio means more light, which means lower ISO setting (less noise) and shorter exposition to go deeper. This is the main reason why SCTs are not so good and popular among astrophotographers. In spite the fact they are compact, they have long focal length, small field of view (a lot of nebulas on the sky are larger than the diameter of the Moon) and require long exposition. Usually they come with mounts which are not capable to guide accurate enough to achieve pin-point stars at longer expositions (5min and more). All their characteristics suits for planetary and moon imaging, where longer focal lengths are needed and guiding is not so critical. On good mounts and with company of high detective CCD cameras they are good optical instruments for small planetary nebulas and galaxies, but I would highly dissuade this type of imaging the deep sky from beginners.

Mathew, I suppose that you have an achromatic telescope, because I have heard just good things about 100mm APO Orion refractor and it is good imaging instrument. I suggest you to start imaging at wide angle, since this is the easiest and the cheapest option. DSLR in combination with kit lens is good start point and your first object are star trails (if you don’t have a mount with tracking) or Milky Way (if you have the mount). It’s good to have in mind that you need to “build” your equipment from the ground, that means that first you need a good tripod, then mount and at the end the optics and camera. Note that good mount is astrophotographer’s best friend and it’s worth to buy a good one in the beginning, because you can put on whatever you want (just camera with kit lens or 16 inch RC). Later on you can buy a telephoto lens or APO middle-sized refractor which has many many objects in range (practically all the M catalogue and long list of NGC objects). If you are interested in little smaller objects you may find 8-10 inch f/4-f/6 high-quality Newton good instrument as well. At the end there are more exotic telescopes like SCTs, RCs which cost a fortune and need very expensive and good mounts (in range of 6000+ USD).

I hope I have answered to your question. You are welcome to leave a comment if I haven’t.

And if anyone have a question related to astrophotography just contact me. I’ll try my best to solve your problem …

Last week we had some clear skies out here and on Thursday I decided to go to the near hill named Bohor to caputre the Rho Ophiuchi region, which is a large cloud of colorful nebulas, a part of Milky Way. June is the only month when this region is accessible to photograph from our latitude because it comes the highest on the night sky – about 20 degrees. Se we had clear skies, warm weather, no moon – perfect astrophotography conditions. I packed my mount Vixen GP-DX with SkySensor 2000 PC to the case with all the accessories and went to the Bohor to take some shots. I arrived there 2 hours before the astronomic night, prepared everything, aligned the mount, focused my modified Canon 350D with Canon 70-200 f/4.0 IS L lens and waited for the night. I started shooting at 23.45 LT. After first two shots I saw that everything works OK and went into the car, watching a movie for two hours. When  the film finished I was planning to take some darks and then to go home but when I checked the destination folder for images on my laptop I immediately noticed that something had gone wrong – THERE WERE JUST 6 PICTURES!!! OMG, I was awake till 4 a. m., getting just 6 frames. There was noting else to do, I had about half and hour till the dawn so I packed up the mount and everything and went home.

Nevertheless, on Sunday I decided give it a try and I processed the image. Honestly, I suspected to be worse, but it’s far from that I was planning to do. So here you have, Rho Ophiuchi nebula, not so perfect:

Rho Ophiuchi region @ 6 x 5min, ISO 800, RAW. Author: Primož Cigler

I hope that next time I will show something more attractive. And which are yours most common troubles you are dealing with?

Thanks for reading!

I managed to make a new cable for QHY5 so now it works with SkySensor autoguiding port. With that I decreased the number of cables from laptop to my mount from 5 to 3. Now I need only USB connection between PC and Camera, Bulb shutter release cable and USB connection with QHY5, which is great. I am planning to buy a new CCD for astrophotography so after that I will need only 2 cables. No more mess around the scope, finally!

So, I have just processed the image, the result is shown below:

Spiral Galaxy M51 @ 26 x 5min, ISO 800, RAW

I have also taken a shot of my equipment, at the “working” state

My Astrophotography Equipment

M86 with neighbours

I am very satisfied with the result because I have spent some nights outside recently without any useful pictures, because autoguiding wasnt’ working properly. I had to change some settings and now works again.

Yesterday I calibrated system again and did this shot of NGC2403 galaxy in Camelopardalis:

Galaxy NGC2403, taken with Orion Optics Europe f/4.5 on Vixen GP-DX SS2K @ Photo Credits: Primož Cigler

It’s composition of 26 exposures, each of 5min on ISO800 with Baader modified Canon 350D and IDAS LPS P2 filter. The mount was Vixen GP-DX with SkySensor 2000PC and the telescope Orion Optics Europe 8″ f/4.5. I processed image with Iris, Photoshop and Lightroom. It’s not my the best image of this object, but I am satisfied with a result because it’s a proof that everything is OK with the mount.

My Astrophotography tutorial will be continued as soon as I find more time.

Clear Skies!

The Newtonians, for example, are very handy and good instruments for astrophotography, though they need to be collimated very precisely and often. On the other hand ED and APO refractors are better, but they are much more expensive. The SCTs are compact and provides longer focal lengths but they are rarely well-made.
So the question is what telescope to choose for deep-sky astrophotography with DSLR camera?

There are several different answers, depending on our object to be captured. Let’s start with the largest: wide-field images of the sky. If you are planning to capture the wide-field images of the night sky you don’t need the telescope but the lens. This is because telescopes are optical instruments with longer focal lengths and that means smaller field of view (FOV) whereas the lenses has a really wide range of focal lengths, from 4mm up to 1200mm and more. The most common target in this range of objects is the Milky Way. This kind of astrophotography is especially appropriate for beginners because the auto-guiding is not necessary and most of the cameras already comes with “kit” lenses which have wide field of view.
One of my images of Milky Way in Cygnus taken with 50mm lens:

Mosaic of Milky Way taken with 50mm lens

Next step are large deep-sky objects. For this objects I recommend the middle-sized APO and ED refractors (80-120mm) or telephoto-lenses. If we have a good mount we still don’t need auto-guiding at this focal length but in most cases it’s better to use it if possible. The most common objects in this range are constellations, detailed locations of Milky Way, large nebula complexes (Orion) and bright comets. The next picture represents Comet Holmes as it was seen 8th January, 2008, taken with Canon EF 70-200 f/4.0 lens:

Comet Holmes with Canon EF 70-200 f/4.0 at 200 mm

Next are middle-sized deep-sky objects. The best focal lengths for them are from 1000 mm to 2000 mm. Newton telescopes and larger refractors has the most appropriate specifications for imaging this type of objects. The auto-guiding is really necessary here because just the best mounts can slew accurate enough to assure the pin-point stars at these magnifications. In this range we find almost all the object from Messier’s catalogue and the brightest NGCs. One of my pictures taken with Orion Optics Europa 8″ f/4.5 are Pleiades.

The last type of object, accessible to amateur astrophotographers, are smaller deep-sky object. They are mostly galaxies and planetary nebulas. Because they are small, we need long focal length to capture the details inside them. The SCTs and other catadioptric telescopes are the most appropriate for these objects.

So, now you know which objects are in the range of your equipment. I hope that you enjoyed reading.

Let’s go back to the topic. The camera is important piece of equipment since it’s capturing the light. Not all the cameras preforms the same but there are some common setting that it’s good to setup before we go out under the stars.

The very first thing is the photography mode of the camera. Here we have just one choice – M (Manual) mode because of one simple reason: DSLRs are not meant to be astrophotography cameras but daylight cameras. So the longest exposition that automatic modes enables us it’s 30s. But that’s far not enough for deep-sky astrophotography. We need longer exposures and the M mode has a “bulb mode”. That means that the exposition is as long as the shutter is pressed on a camera. Of course, we cannot hold the button on a camera for 5 minutes so the wire trigger is necessary.

We select M mode

The second thing is mirror lockup. Almost all the DSLRs enables lockup function. Mirror lockup means that the mirror in the camera, which reflects light to the viewfinder, locks up some seconds before the start of exposition. And why is that so important? Because if you are using telescope with long focal length, then every single tiny movement is noticeable on a picture. And when the mirror “jumps up” it shakes the system and bright stars get tails and that’s what we obiously don’t want to have on the pictures. So the mirror lockup function triggers the mirror some seconds before the start of exposition so the system can settle down before the exposition is started.

Enable the mirror lockup function

Next important thing is ISO speed. This one is still a hot topic among astrophotographers since some claims that lower ISO is better and others who prefers higher ISO settings. Anyway, two years ago I have made a test on Youth Astronomy Camp which revealed that Rebel XT preforms the best at ISO 800.

Selecting the ISO 800

For additional processing it’s the best that we use uncompressed data so the RAW mode is the right decision. If you prefer having JPGs also, then you can select RAW + JPG.

RAW (uncompressed) format

Another not so important thing is LCD brightness. I strongly recommend to set this as low as possible because in the night our eyes are adapted to the dark and if you want to check for example the sharpness of the images on LCD with the full brightness then you’ll get blind for some minutes.

The last but not the least function is information LCD illumination. This function enables you to see the settings specified in the dark. Just press the button.

Info LCD illumination

Thank you for reading. So far we have chosen the object and specified all the camera settings.

When we are deciding which object we will be capturing we can help ourselves with different astronomy software. They display imaginary sky and we can take a walk into nigh sky, choosing the objects, checking the rising, setting, magnitude, distance, … All this parameters are important when we are selecting the target for astrophotography.

There is a lot of different programs available on the web for astronomy. Some are free and others are paid. There are some of them:

• Starry Night
• Hallo Northern Sky
• Cartes du Ciel
• SkyMap
• Stellarium

In this tutorial I will be using Starry Night. It is paid but it offers endless of useful options like FOV and has  really a huge database of objects.

First of all we have to know what type of object is appropriate for our astrophotography setup. The predispositions for deep-sky astrophotography are:

• Telescope of telephoto lens
• Mount for tracking that tracks very accurate (under 2″ of error) or has option of auto-guiding
• DSLR or CCS camera with remote control of exposition

In Starry Night we put the parameters in the the section Equipment:

Then we select FOV of our telescope and camera. The program displays us the rectangle that out astrophotography setup “sees”.

So, what’s next? We have to choose the target that we are going to capture. Here are some basic directives:

• Make sure that object is in the field of view at least 3 hours in the total darkness. It has to be at least 15-20° above the horizon all the time of the capturing. Make sure that you have specified your date/time and location accurately!
• Make sure that object roughly fits to the field of your telescope’s view. The rectangle that we have specified before helps us at this step. Make sure that it is not too small – it doesn’t make any sense if you are photographing a very small planetary nebula at 600mm of focal length.
• Make sure that it is not too dim. Almost all the objects from Messier catalogue are OK, and all the bright objects from NGC makes good target as well. If the object is dimmer than 10th magnitude then bigger telescope then 8″ is recommended.
• If you don’t have GoTo or it’s unreliable then make sure that you are able to find the object in the night sky. Help yourself with bright stars, print the carts out.
• If you are using german equatorial mount then make sure that object doesn’t pass the meridian during the planned time of capturing.

Some good objects to start with: M45 (Pleiades), M42 (Orion Nebula), M44 (Beehive Cluster), M27 (Dumbbell Nebula), NGC7000 (North American Nebula), M31 (Andromeda). They are all bright and easy to find even with binoculars.

And here we are. We have the object.

Next time we will take a look at the conditions in the athmosphere that affects to the astrophotography – the weather, seeing, transparency and more.