I would like to present the astrophotography set up I used for the recent pictures of Jupiter I took during the Jupiter Opposition of August 2009. I found this set up to work quite well, allowing me to take quickly, and in a repeatable manner high resolution pictures (when the seeing allows it!).
This set up will work on any Telescope having enough in-focus travel, which is the case for Schmidt Cassegrain and Maksutov Cassegrain Telescopes.
Telescope and accessories
First, the Telescope: Orion Maksutov Cassegrain 7″ – on an Orion Atlas Mount attached to a Pier.
I am very happy with this telescope. The scope has to be placed outside 2h before observing to cool down, but otherwise the scope is very easy to set up, keep extremely well its collimation, and has a quite a good optical quality. I noticed also that once the tube reaches thermic equilibrium, the scope is less affected by Turbulence (most of the time) than my larger aperture telescope (SCT 9.25″) when the seeing is average or below average (3-4/10 on ALPO scale) – which is unfortunately the case most of the time at my location (San Bruno, CA).
Here are the accessories / cameras I use for this set up:
- 1 – Telrad unit, with Dew heater: the Telrad is very convenient to align the Telescope and/or point to bright objects. There is no need for a conventional Finder when doing planetary observation with a go-to scope! Note the Telrad gets foggy very quickly – the Dew heater is a must as soon as the temperature drops below the dew point. The dew heater was ordered at Agena AstroProducts
- 2 – Focusing knob: It is probably not as good as an electronic focuser, but it is cheap and does reasonably well the job. The focusing knob was ordered at ScopeStuff
- 3 – Orion Filter Wheel: a must to take RGB pictures, especially with a planet like Jupiter, having a very fast rotation. RGB pictures have to be taken within 3 to 4 minutes maximum with this Telescope, otherwise the effect of rotation is noticeable when integrating RGB channels.
- 4 – Flip Mirror: with this it is extremely convenient to center planets especially with a planetary Camera having usually quite small sensor sizes. The flip mirror was ordered at Orion.
- 5 – Imaging Source Camera DKF 21AU04.AS: this is a great B&W camera with a sensitive and high resolution chip. Maximum frame capture is 60 fps! The chip sensor is very small (1/4″) but it does not matter for high resolution planetary astrophotography. However the camera cannot really be used to capture large lunar landscapes, and the Flip mirror helps saving time to center the planet in the sensor field of view.
- 6 – NetBook Asus 2G Ram/160G Disk : even though the camera capture frames at high rate, since the resolution is 640×480 on 8 bits – the size of the AVI files for a 30-40sec movie is still small (compared to my Orion Solar System Imager Camera where the Asus had trouble handling the frame download rate). The Netbook is built like a Tank which is great on the field – and has a long battery life (+6 hours).
Being new to B&W CCD astrophotography, I found the following benefits for planetary photography compared to Color CMOS sensor such as the Orion Solar system imager III:
- b&w camera are usually more sensitive, minimizing the exposition time (even with RGB filters, compared to CMOS color cameras)
- taking exposures in each channel allow an optimal focus for R/G/B – quite useful especially when captured objects are low on the horizon, with extra color dispersion caused by the athmosphere
- There is no bayer matrix in front of the sensor – for the same sensor pixel resolution, black and white sensor with RGB capture will produce more detailed images
- No bayer matrix and IR filter in front of the sensor gives complete control / more options when choosing which combination of filters to use
On the cons side, taking RGB pictures takes extra captures that have to be done in limited time (at least for Jupiter) and some extra processing time, but this is far out weighted by the benefits…
In terms of AVI/ picture processing I use the following software:
- Registax V5 for making composite images for each RGB channel.
- Max DSLR for aligning and combining RGB channels
- Occasionally, Astra Image 3.0SI for their great deconvolution utility
- PaintShop pro photo X2 for final processing: image rotation, cropping, histogram adjustment, and color adustments. PaintShop pro does the job and is less expensive than PhotoShop.