Tag Archives: Orion Nebula

Orion Nebula M42

The Orion Nebula must be one of the greatest objects in the night sky. At about 1,344 light years away it’s not close but it is visible to the naked eye as a fuzzy patch in the middle of Orion’s sword.

This nebula is difficult to photograph because of the large dynamic range in the image. The Trapezium is a group of bright stars that illuminate the nebula and the difference in brightness between these stars in the centre and the fainter clouds on the outside makes it hard to image and process the nebula in all its glory.

This image was taken at Rabbiter’s Hut in the Adelaide Hills on a dark night and processed from 5 light frames and 2 dark frames of 5 minutes each. I used the Orion ED80 (500mm focal length) and Canon 600D (modified). The Skywatcher EQ6-R was tracking on its own without any guiding but I do make an effort to get the polar alignment as accurate as practically possible.

Processing was normal with DSS and Lightroom 4.

Orion Nebula M42

Orion Nebula M42

Canon EOS 600D IR filter Replacement Results

A couple of weekends ago, late on a Sunday afternoon I decided that the time was right to open up my 600D. I suppose I was in a hurry and couldn’t wait any longer. The clear glass replacement filter has just been sitting there and I was already prepared with all my tools and silicon, etc.

So I did it.



Opening the camera up was pretty easy. I used the following websites to guide me along:




A large number of very small and delicate connectors have to be disconnected.




Eventually the CCD assembly can be removed.


This is the complete filter and imaging chip assembly, before I took it apart (and almost broke it…)


The piezoelectric element is removed here..


And here I was too impatient and broke the IR cut filter. The crack line can be seen from top left to bottom right. I should have ready the instructions in more detail! Take it from me, don’t be in a hurry when you do this. Fortunately there was no damage to the imager chip and after I cleaned all the filter glass fragments off the CCD surface I could start the assembly process again.

The clearglass filter replaced both the IR cut filter and the piezoelectric filter element. I have now modified the camera to a full spectrum camera.


Pieces of the IR cut filter. This is not the way to do it!


Inside of camera, looking at the back of the shutter.


Putting it all together was reasonably easy. The most difficult part was to get the imaging assembly in the correct position to allow the auto focus to work properly.  I will have to make some more adjustments to get the auto focus to be more accurate. It can wait as I mostly use manual focus for astrophotography anyway.

A big sigh of relief when the camera fires up and still works !



A weekend later and I was testing the camera under an almost dark sky. Nothing spectacular but just confirming that it all works as it should.

Orion Nebula (M42 / M43)

Picture saved with settings embedded.


Large Magelanic Cloud (LMC)


Coalsack with the Southern Cross and two pointers


And, the evening would not have been complete without a image of Carina.


DIY Autoguider for Long Exposure Astrophotography (Part 4)

I tried the upgraded autoguiding tracker again on Wednesday and the results improved quite a bit. I used a 250mm lens to image the LMC. The following is a photo of the PDH graph showing the tracking error. The error is a small fraction of pixel. It has improved a lot since the previous test where the typical tracking error was ±3 pixels.


The resulting images of the LMC are not great due to the light polution but the tracking is starting to show promise.This is a single image (no darks or flats) taken at 60mm, f/2.8, 120 seconds and ISO 800 showing some round stars. Some cropping, levels and stretching was done with Lightroom 4.

IMG_6253 bright-1

This is the setup I used:



I used a Canon 18-55mm lens for the guide webcam. Tracking accuracy will improve a lot if I increase the focal length for the guiding, maybe use a 18-135mm. The zoom works well on the guide camera to find a suitable guide star.

The advantage of this mount is that it can take a bit of weight. I tried to mount an Orion EON 80mm on and it did not complain too much. Maybe I will need to modify a bracket to make sure the camera mount ball head cant slip with the 80mm scope. I will try that next.

Here is the latest version of the Arduino sketch:  Stepper Motor sketch (pdf download)


Canon EOS 350D IR filter replacement

In the past I have used my Canon EOS 600D for astrophotography. The noise performance on this camera is quite good and I am very happy with its performance (for now). In the future somewhere I will probably upgrade to a 6D. The performace of the 600D (and 6D) is limited by the infra red (IR) cut filter that is installed in front of the CCD. This blocks the infra red light, that is invisible, from reaching the CCD and recording a very red looking image.

A large proportion of the light coming from deep space objects such as galaxies and nebulae is in the infra red part of the light spectrum and is therefore lost when you take a photo with a normal DSLR camera.

This project aimed to remove the IR cut filter from my old Canon 350D and replace it with a special filter that transmits the H-Alpha and S-II light. I used a Baader ACF2 filter that I purchased on-line from Astro Shop.

There are a lot of websites with detail, step-by-step procedures for doing the filter replacement. I used the following website by David Campbell. It was very good and I did not have any serious problem with any of the steps.

Another website describing the process for the 350D is Life Pixel ,

I need to make the point that you should not attemp this if you are not very comfortable with taking apart your DSLR and using a soldering iron on the delicate circuit boards and a sharp knife / glue / silicon on the optical components of the camera. One slip and you could be trashing the camera as nobody will repair it for you.Typically you will be doing this modification if this is your second or third camera that is not used regularly anymore. Mine was sitting on the shelf so a disaster during the modification process would not have been a problem. I found the most difficult part the reconnection of the delicate ribbon cables.

I was quite successful and the 350D is alive and well and taking great photos with a lot of colour detail coming out of the Orion nebula and Carina nebulae.  I will post photos of these once I have finished processing them.

Here are a few photos of the modification process.



Opening up the camera


Removing circuits boards and disconnecting the ribbon cables


The back of the CCD is now visible


Taking the CCD assembly off the camera


This is the shutter from the inside


The surface of the CCD chip visible through the IR cut filter



Removing the IR cut filter from the CCD assembly. It is glued in place with a silicon type glue and has to be cut out with a sharp knife.



The new Baader ACF2 filter is now glued in place with silicon sealer applied with a thin syringe and needle. In my case the needle was very thin and it look a lot of pressure to get the silicon out. A slightly larger needle would have been better.


New filter fitted back on the CCD assembly


CCD assembly back on the camera body


A few quick photos to check if it is still working ….

IMG_3395 (800 x 533)

IMG_3388 (800 x 533)

I tested the camera with an image of the Orion nebula.  The photo was taken with 6 light frames of 30 seconds each, f/2.8, ISO-800. Lens was a Canon Macro EFS 60mm lens and the mount was an iOptron SkyTracker on a Meade tripod.   I had four dark frames and stacked with DSS, processed with PS CS2 and Lightroom. Light conditions was not very good, lots of cloud around and light polution (as always…). Still need to sort out the light gradient on the image.

I used a trial version of Backyard EOS to help me with the focussing of the 350D. This camera does not have a live view function and it makes it quite difficult to achieve sharp focus.

Picture saved with settings applied.


During one of my recent trips to the Flinders I took a few photos of Orion. Orion is one of my favourite summer constellations. Normally Orion is visible during the early evening in Summer months. Well, its winter here at the moment and I had to get up at 3am to take my photos of Orion. I had to wait until 3am because the moon only set at 2am and I needed some sleep.

In this image the Great Nebula in Orion (M42) is at the top right. The Horsehead Nebula is just visible at the bottom centre to the right of the bright Zeta Orionis. The three bright stars in a row is also known as Orion’s belt and the large nebula is located in Orion’s sword.

Orion 3x3min 1200

This image is made up of 3 x 3 minute exposures with 3 dark frames. I used an iOptron SkyTracker to keep my Canon 600D with a Canon EFS 18-135mm on target. I used 135mm. 540 seconds in total, f/5.6 at ISO-3200. Processing as usual with DSS, CS2 and LR4.