Archive for December, 2009

Mars : tweaking my planetary imaging set up – November 2009

Taken on 11/26/2009 between 3am and 5am at San Bruno, CA.  Seeing: 6/10 (Alpo scale) – Transparency: 3/6 -Wind < 5Mpmh

Here are new pictures of Mars, shot at the end of November 2009. At this time, the disc was about 9.5″of diameter. For such a small target I had to tweak my planetary imaging set up to get better results. On the other hand, Mars is at a fairly high altitude, making it easier to deal with turbulence. There were few chromatic distortions (usually there when objects are lower on the horizon – e.g. for Jupiter in the 2009 opposition at my latitude).

Telescope: Orion Maksutov Cassegrain 7″ on Atlas Mount

Camera: DMK Imaging Source B&W  with RGB Filters

Barlow: from Siebert optics – this is an excellent barlow that can be used for 1.5x, 2.5x or 3.5x power magnification. Even though the Maksutov is at f/d 15, a barlow is necessary to reach the maximum resolution. Given the space between the camera and the barlow due to the RGB filter wheel I estimate the “true” magnification I used this night to be over 2.5x, which brings the pixel resolution at less than 0.2″ by pixel with the DMK Camera.

Processing: Registax V5 (Frame combinations), Maxim DL5 (initial RBG alignment), Photoshop CS4 and Nik Sharpener Pro 3 for final image processing.

Mars – 11/26/2009 – 4.24AM – RGB composite (see green and red channel below)


Red channel : 4.24AM PST       Green channel: 4.18 am  PST


Two more pictures, taken respectively by 3.44AM and 3.53AM PST


Some notes about the planetary imaging set up:  I used the same Planetary set up as explained in this post, but in addition, I added a Meade Microfocuser to the configuration (Meade #1209 Zero Image-shift Microfocuser for Schmidt-Cassegrain).

I removed rhe flip mirror for increased rigidity and alignment of the camera body and filter wheel.

The space gained by  removing the flip mirror allows having a reasonable distance between the barlow and the camera body.

When removing the flip mirror, it becomes indispensable to use the Microfocuser because you can focus without moving the primary mirror. Which means Mars stays in the field of view instead of jumping around when you focus with the maksutov cassegrain focuser. Otherwise you need a flip mirror to re-center the planet after focus: the field of view of the DMK camera is very small and you easily move the planet “out of target” when focusing.

In addition, the electric microfocuser allows a fine grain focus very hard to achieve with the manual focuser at the back of the Maksutov Cassegrain OTA.  When doing planetary imaging  at high F/D  it is a must-have accessory…

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