Planetary Imaging using K3CCD - capture

Firstly, a few things about planetary imaging

• The resolution you achieve in planetary imaging is dependant on the aperture of the scope you use - the more aperture, the better the resolution.
• The image scale (i.e., how large the image is) depends on focal length - on my webcam planets page, there is a series of 4 shots of Jupiter shot using a 5" Maksutov Cassegrain telescope 1500mm focal length and a 4x barlow giving an overall focal length of 6m - at 6m using a standard webcam, this is the size an image will be regardless of the aperture of the scope.
• Planetary imaging is entirely dependant on seeing and transparency - you will only get good results on a really clear, still cool night after air currents have settled down.
• The same techniques can be used for lunar imaging - this is a good place to start as you can get good results without a barlow... and the target's larger.
• It's impossible to give settings that will work with every scope as f ratios/ apertures/ focal lengths and conditions will vary. I'll attempt to give you figures and directions that should get you started - you will have to experiment though.

right then, down to business...

It might sound silly, but before you can get the focus right, you need to make sure that the target is going to be on the webcam's chip.

To do this, you should make sure your scope is well polar aligned so that the scope tracks well and centre the target in a high powered eyepiece - at least 200x magnification.

Swap the eyepiece for the webcam (don't use a barlow yet), make sure the webcam is connected by it's usb cable ONLY. If using an SC modded webcam disconnect the parallel cable if connected. If it has a long exposure mode switch, make sure it is switched to normal mode.

In K3CCD, click 'Video Capture' and 'Video Source'. This will give you (in the case of Windows XP and the WDM driver) this window.

Other drivers and versions of windows will have different windows to this, but the controls will essentially be the same.

In this window, make sure that the 'full auto' box is unchecked. Set saturation and brightness to 50% and gamma to 0%

Click on the 'Camera Controls' tab and you will see the following.

Leave the White Balance on 'auto', set the shutter speed to 1/25th (initially) and leave the gain high (70% will be fine)

Click 'Apply' and close the window.

Click 'Video Capture' and 'Video Format'. This gives you the below window.

Set the resolution to 640x480 and click 'OK'

Focus slowly - the focal point is normally a little further in than an eyepiece. If you are focussing manually, between small adjustments, step back from the scope and allow the image to settle. This may take some time. With the above settings, the image should be overexposed and bright white - focus until the edge of the disk is sharp and has no halo. Carefully centre the image.

If you are using a barlow, put it in the focusser and put the camera into it. Refocus.

NOTE: some planets come with natural focussing aids - in the case of Jupiter, if there is a moon in the field of view, focus until the moon is as small a point as possible - in the case of saturn, focus until a sharp triangle appears between the rings and the disc.

Now you will need to adjust the gain/ shutter speed and brightness until detail in the disk is resolved.

Try adjusting the gain to around 10% or 20% and then increase the shutter speed (in the Video Source, Camera Control window, 2nd picture) until the planet dims and the light meter shows a maximum value of around 100 to 150. You may need to carefully adjust the focus until detail is visible.

This should give you something like this (light meter is shown on the left).

Right - now we're ready to record an avi. You can try setting the frame rate to either 10 frames per second or perhaps even 15, though the camera may start to compress frames and detail may be lost.

On the toolbar is a button that looks like click this to start recording. Your PC/ laptop may not be able to record and refresh the view at the same time, so K3CCD may seem to freeze - don't worry. Allow the system to record the image for a few minutes (at closest approach and high resolution it's possible for Jupiter's rotation to be noticeable after 40 secs, but normally it's OK for 2 mins). This will create a large file - at 15fps, the file will be over 1Gb after a few minutes. To stop the recording, hit the 'esc' (escape) key.

That's it, now you'll need to register and stack the frames. I'll do a tutorial for this soon...

Please contact me if you have any questions or alternatively join UKAstroImaging where plenty of people will be able to help you out. I always try and answer emails as quickly as possible, but I do get quite a few.