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My old astronomy project:
My first digital camera setup (2006)


EQ4 mount and Canon 350D

  1. Camera and lenses
  2. EQ4 Mount
  3. EQ4 mount minimized
  4. Controlling the mount with a guide camera
  5. A test on Andromeda galaxy
  6. Image calibration
  7. An overview of the constituent blocks

1: Camera and lenses

This is something that I wrote 2006, maybe something still of interest to catch up.

How to build a cheap computerized astrograph? An easy and cheap astronomy photography equipment can easily be built by standard components and software available for free download.

Here is my idea and how I have done it.

EQ4 mount and Canon 350D

For those of you who have not yet bought a digital camera:
The new Canon 40D (and 450D, 500D, 550D and 5D Mark II) solves several problems compared to their predecessors.

  1. Live-view, directly on the camera display to see when the focus is correct. Even better, you can also see on the screen of your computer corresponding picture via USB connection to the camera.
  2. The focus motor can be controlled remotely, you can then use the EOS lens with motorized focus and thus do not have complicated manual or expensive external motor solutions.
  3. The camera's ampglow from the readout circuits are basically completely eliminated and the camera's noise slightly lower than its predecessors.
  4. The exposure time can be set from the computer for more than 30 seconds and an interval meters are built in pc software, you do not have to use other external programs thereby.
  5. ADC, Analog digital converter is now 14-bit compared with predecessors 12-bit. The digital range has thus been increased from 4000 to 16000, almost as a professional camera. What is lacking now is that there will be a version like the previously 20Da (no IR filter), and with full frame sensor, but not impossible that it appears from the Canon, or what do you think? But already now the best option in this price level, are the Canon 1100D, about 300 Euro
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2: EQ4 Mount

  1. Star-tracker or guide camera, Philips Toucam 840 web camera
  2. Hand control to RA axis
  3. Strengthening of the assembly, M10 threaded rod with lock wing nut, very effective!
  4. 12 volt battery pack, in future replaced by a bigger lead battery, can also be used as a counterweight
  5. Canon EOS 350D
  6. Serial to camera interface, home made
  7. Polar axis telescope
  8. USB HUB and a 3 meter USB cable
EQ4 Mount
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3: EQ4 Mount, minimized

EQ4 mount minimized

When only doing astronomy photography and not visual it is not as necessary that the tripod is high. The lower part of the mount can replaced with a Biltema trestle, 6 Euro !

Very stable, withstand 1.5 ton! Weight about 2 kilogram.

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4: Controlling the mount with a guide camera

K3CCD control panel

The window in K3CCDTools (this is the free version) above.

A star are locked and the driving deviation is registered in RA and Dec axis. Lens focal length to guide camera should at the same pixel size of both cameras be the double focal length as main telescope. If your application supports sub-pixel it can be of shorter focal length. Web cameras have an exposure time of 1/5 seconds or less, there is high demands on the lens opening, quality can, however, be lower when you only make use of the central areas.

How to control the EQ4 mount isn't solved yet

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5: A test on Andromeda galaxy

Andromeda galaxy raw

First Light, the Andromeda galaxy, one of 35 raw images photographed from my balcony. Thinner clouds illuminated by highways trail lighting. Exposure 1 minute lens 135mm aperture 2.8, ISO 800. Angle 9x6 degrees. Results: Well you see it, in any case it is a galaxy. The next step is to fix a darker place!

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6: Image calibration

Andromeda galaxy calibrated

Image calibration:

  1. Subtracted remove bias and dark, and divided by the flat
  2. Registered and stacked the individual images
  3. Sky remove by a mask

As you can see, the result is quite impressive for being taken from a balcony near the city, right?

Image Processing done with IRIS

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7: An overview of the constituent blocks

Sorry, drawings only in Swedish, but not difficult to understand.

Connection with a camera with no liveview

This is the setup for older cameras without live-view, Canon 350D, Canon 400D.

Connection with a camera with liveview

This is the setup for newer cameras with live-view, Canon 40D, Canon 5D Mark II.

Today replaced with a more modern construction, computer controlled EQ6 mount.

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