Astronomy and DSLR Astrophotography Blog

Dark nebula is a nebula in the galaxy which absorbs the light from the background. There are two types of them in general – one can be seen because they block the light of the emission nebulas in the background. One of the most spectalular of them is Horsehead nebula in Orion. The others block the light which comes from the stars behind them and those are best seen where the density of the stars is the highest – in the Milky Way. Dark nebulas consist of cold materia in the space, which is not hot enough to transmit the light.

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

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I think it’s not right always showing just the best works you produce. Sometimes it’s also good to represent worse pictures to show the world you also have troubles with everything and to encourage those who are not so good at astrophotography yet. I had a disaster last Thursday, capturing the Rho Ophiuchi region.

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!

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So let’s continue with the tutorial. The last time we have chosen the object. Today we will take a look at some common camera settings for astrophotography. In this tutorial I will be using modified Canon Rebel XT (350D). Modified means that I have replaced original filter in front of CMOS sensor with replacement filter of Baader. I have listed some good guides how to do it here.

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.

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A lot of astrophotograpers decide to make a modification of their cameras. The reason is that filter in front of CMOS or CCS sensor blocks almost all the H-α part of spectrum due to balancing the colors for daylight photography. But this is not suitable for astrophotography because almost all the nebulas consist of the Hydrogen and this light is cutted off just some millimeters in front of the sensor. If we remove that filter then we get much better response of the red color.

Since the Canon Rebel is the most common camera used between enthusiastic astrophotographers I’ll try to suggest some good links of step-by-step tutorials which guide you thought the process.

1. Canon Digital Rebel (300D) Modification
   Good tutorial with sample images before and after modification. For Rebel (300D).
2. ash’s Modified Digital Rebel XT Page
   Very nice tutorial for modification of Rebel XT (350D). I have done modification of my Rebel XT with this guide and he survived the operation!
3. Canon Digital Rebel XSi (450D) Modification
   Good guide with pictures and everything well explained for Rebel XSi (450D).
4. Canon Digital Rebel (300D) Peltier Modification
   Guide how attach Peltier cooling element into Rebel. Works good for long-exposure astrophotography.
5. Another Digital Rebel XT (350D) Modification
   Just another Digital Rebel XT mod. Maybe someone finds it useful.

For the end I am presenting one of my images after the modification. The Veil Nebula, NGC 6992:

The Veil nebula (NGC 6992) @ Primož Cigler

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Canon’s low-priced range of Digital Single Lens Reflexive (DSLR) cameras are extremely popular between amateur astrophotographers. In this group we can find the following cameras as they appeared on the market:

• Canon Rebel (300D)
• Canon Rebel XT (350D)
• Canon Rebel XTi (400D)
• Canon Rebel XSi (450D)

The first Canon Rebel was published in 2003 and since then the astrophotography began also more popular and reachable to everyone.
There is a lot of reasons why Rebels are so popular. I’ll try to emphasise the most important:

1. PRICE
   Until the announcement of Canon Rebel there were no other cameras for the reasonably good price delivering all the specifications that are needed for astrophotography. There were only a few astronomy CCD cameras available for high prices. With the Rebel everything changed. It has all the main features needed for astrophotography and it is providing excellent picture quality for low amount of money.
2. SENSOR SIZE
   The Rebels’ sensors are the APS-C size (22.7 x 15.1mm) witch works pretty well for astrophotography because it covers a large area on the sky with any optical instrument.
3. PREVIEW ON LCD
   We are always able to check the focus, the object, field of view etc. on the LCD. It’s one of the most useful things and here DSLRs beats even much more expensive CCD cameras.
4. HIGH SENSITIVITY
   The ISO setting ranges from ISO100 to ISO1600 and more. The picture quality is still OK at high ISO settings and with combining we can get practically noiseless images.
5. PICTURE QUALITY
   Picture quality is just outstanding for this price. At high ISO setting and long exposures the pictures are still useful.
6. DAYLIGHT PHOTOGRAPHY
   The camera you use for astrophotography can still be used for daylight photography unless you modified it. That saves you a lot of money since you don’t need two cameras – one for astrophotography and another for daylight photography.
7. DIGITAL FORMAT
   It’s quite obvious that images from digital camera are in digital format, isn’t is ? Digital pictures are much more fond for post-processing then scanned film.
8. MODIFICATION
   With modifications we can get out even more from Rebels – if we remove the filter in front of the CMOS sensor the camera becomes much more sensitive for H-α part of spectrum and we are able to get more information with shorter exposures.
9. VIEWFINDER
   Viewfinder is extremely handy when we are positioning the camera to deep-sky object. It saves us a lot of time. With the CCDs we are forced to take multiple exposures just to specify the right location and angle of the camera and that’s really time-consuming.
10. CONNECTIVITY WITH PC
    All the Rebels can be remotely controlled with a PC. They comes with the most basic software but on the web you can find a software that turns your Canon Rebel to the fully remote camera!

Of course, there are not only advantages of DSLRs. They have many cons and their quality is not on the same level as CCDs but with some skills we can turn them for really good astrocameras.

Thanks for reading!

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The light pollution is becoming more and more annoying thing more or less all over the world. Astronomers are the ones who suffers due to that more than any others. The problem is that there are every year less locations for observing and photographing the untouched sky. Well, some manufactures of astronomy equipment decided to produce filters that suppress the light pollution.

On the beginning of summer 2008 I figured out that the situation from the point of light pollution from my backyard is so bad that I need the solution. On the web I found some filters that suppress the light pollution but no one good review of them.

In the end I decided for IDAS LPS filter of Hutec. Because I was pretty sure I will be using just for astrophotography I decided for front-filter (look at this figure) which can be placed directly in the camera’s body so I can use it with lenses also and not just with the telescope. The version of filter is P2, that means that is the most suitable for astrophotography in prime focus.

The filter arrived on June and costed approximately 250 eur here in Europe, in USA it’s a bit cheaper. The first impression was something like: “250 eur for such a piece of glass?!??”. But after a first-light I changed my opinion. It is worth every single pennie! It works just the best for me, my backyard turned to the very good astrophotography place. It has no affect to sharpness of the image. I use it with my Canon 350D (Baader mod.) and also both sample pictures are captured with this equipment. The telescope was William Optics SuperAPO 80/480 with TeleVue reducer/flattener 0.8x. The picture without filter is out of focus because when I removed the filter I didn’t refocused. Anyway, it represents the affect of filter. Both pictures are captured at the same settings: f/4.8, ISO1600, 120s, RAW, WB(2850, -30), imported and exported with Lightroom.

The image without Hutech IDAS LPS filter

The image with Hutech IDAS LPS filter

It’s quite obvius what the filter does.

I have also measured the Mean of these two pictures. The median value for the picture without IDAS LPS is 118 whereas the median for picture with IDAS LPS filter is 52.

That’s all, hope that this article will help someone to decide what to buy or not to buy.

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I still remember my beginnings in astrophotography some years ago. I joined some astrophotography forums and admired the pictures some masters were taking. I didn’t have a telescope, a mount or any other equipment. I had just a Canon 3000N camera and kit lens.

Many of you would say that with this equipment astrophotograhy is just impossible. But this is not true! I have spent a lot of time capturing the moon with my very first telescope (60/700 Meade) and the star trails. The pictures was often useless but I have learned a lot for my progress.

I have been searching a lot to find the first picture of star trails I managed to take but I haven’t found it. So I can show you the one I have made 2 months ago:

Star trails @ Primož Cigler

For image like this you don’t need any special equipment. Almost every digital or analog camera for daylight photography is ok. Everything that is obligatory is a stable tripod where we attach the camera and remote control for expositions is useful too.

Analog cameras are more suitable for this type of astrophotography because they don’t have a digital noise. Exposition can last as long as we want and that don’t influence on image quality. We just set the length of exposition (usually between 30min and 3 hours), the field of camera (usually to the widest) and start the exposition. We generally use low ISO speed for capturing star trails – ISO100, ISO200, ISO400, rarely more. The length of exposition, ISO speed and aperture depend from the conditions, especially from light pollution. The more light pollution we have, lower ISO speed we should use and take shorter exposition.

If we use digital camera the process is little different. As I mentioned the digital cameras have a digital noise which grows as the length of exposure. To avoid this problem we take a set of continuous shots one after another where single show is long from 1 to 3 minutes. It’s important that between exposures in no more than 5 s of pause and that we don’t move the camera all the time during the exposures. At the end we also make a dark-frame (we cover the lens of the camera with a cap and make the “dark picture” just the same length and with the same settings as all the other pictures before), which we be needed after at processing.
If we done everything ok then processing is just the easiest part. We just download this software called Startrails and combine all the pictures. That’s all!

I hope that this article/post will help someone to start with astrophotography. Star trail can be really beautiful, just give them a chance!

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In this post we will take a look at one of the most important equipment for astrophotography – that’s camera.

Only 10 years ago we’d found astrophotography as pretty expensive. The reason is that the cameras for serious work costed a fortune! Anyway, it was Canon 300D which completely changed everything in 2003. Now it’s only 6 years from that and we all are using DSLRs for astrophotography. Let’s take a look at it:

Canon 300D was the first very good DSLR. It’s price wasn’t too high and the picture quality was great comparing to other cameras. Firstly became very popular for daylight photography but very soon some astrophotographers figured out that it’s possible to get very nice picture with it. The main advantages are that we can set the high ISO level without suffering too much noise, we can always check the focus on LCD screen, we get digital images which we can post-processed with the computer and many more.

But that wasn’t enough for some of astrophotographers. If we take long exposures (above 1 min) that means that the sensor is on all the time and the temperature increase. And when the temperature increase the noise becomes annoying on pictures. This problem can be solved with cooling and some astrophotographers started to modify their Rebels to improve the image quality.

It’s not only the temperature which makes 300D worse that it could be. There is also a filter in front of the CMOS sensor which blocks almost all the light in H-α part of spectrum. That’s the problem because almost all the nebulas in the space consists of this element and when we are capturing we loose almost all the light we want. It’s like looking at Andromeda’s galaxy with sunglasses.
This problem can be solved also. All we have to do is to remove the filter in front of CMOS and replace it with some other or clear-glass. The only way to do this is to disassembly our camera or let someone do that.
For example, the Hutech is the company that produces replacement filters, they can replace filter instead of you, and what is more, you can buy the modified camera at them.
However, Teleskop-Service offers the same in Europe.

On the end I’m presenting you one picture that was captured with “the king of DSLRs in astrophotography”, Canon Rebel/300D/Kiss.
It’s picture of Veil nebula which is located in Cygnus. The exposure was 12 times 5 minutes post-processed in Photoshop and Iris. The telescope was Takahashi FSQ-106 and mount Celestron CGE. I’m sure you like it!

Veil Nebula @ Marjan Žagar & Primož Cigler

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