The equipment I use for planetary imaging is reasonably modest and the main components were bought 2nd hand, but it does the job for me. The picture of the complete setup is shown below, and then I’ll describe each of the components. I’ll replace these pictures with more purpose-taken ones soon.
I use a GSO 12″ Newtonian as my planetary imaging scope. It has a focal ratio of f/5 and a 1500mm focal length. It is still fitted with the standard single-speed crayford focuser (with mods described below) and 9×50 erect-image finderscope.
It has a few modifications and additions such as:
- Motorised focuser using the Orion AccuFocus unit fitted to the right focus knob
- Peltier-cooling of the primary mirror (manually controlled at this stage)
- Temperature sensors measuring the mirror temperature and ambient temperature
- Bob’s Knobs for easier collimation
- Hole cut-out near the primary mirror for dew removal (using a hair dryer)
Mount and Rings
I use a standard SkyWatcher EQ6 as the mount to hold my 12″ Newtonian. The tube is approx 22kg and requires 25kg of counterweights to balance it on the mount. It’s probably a little over-weight for the mount, but as long as it’s balanced I find the EQ6 does a fine job on tracking the planets, which doesn’t require highly accurate pointing or tracking. I generally don’t use the SkyScan GOTO, I just manually slew to the planet using the hand controller and then just track.
It was frustratingly hard to find a solid dovetail bar and rings that would suit my 12″ Newtonian OTA. I ended up getting them custom made by Orion Optics in the UK, but of course that means it wasn’t cheap (shipping is a killer!). The rings work great though and I’m much more comfortable with them than the half-rings-half-straps I used for the first 8 or so months, especially when the scope is pointing straight up!
I use a DMK21AU04 from The Imaging Source as my planetary imaging camera. It’s a monochrome camera with 640×480 pixel resolution and is an excellent intermediate/advanced level imaging device, especially given its low cost. It can capture at up to 60 frames per second (fps) through a USB (or firewire) interface and has a 1/4″ Sony CCD with a pixel size of 5.6 microns, giving a good image scale for most applications.
I use an Atik 5-position Manual Filter Wheel with my monochrome DMK21AU04. It’s cheap and easy to use, but does require you to get up at each filter change. Atik also have motorised versions these days at quite a reasonable cost.
For maximum image scale, I use a 5x Powermate from Televue. With the filter wheel in place, it acts as an extension tube for the powermate, giving me a magnification of approximately 7x and a focal length of approximately 10 metres (10000mm). When the seeing is exceptional, I also use an additional extension tube to increase my focal length to around 14m.
I also have a Meade 2x barlow and a GSO 3x barlow for when I need a shorter focal length and wider field of view.
My current setup is really all I need for planetary imaging in the short-medium term, however the most likely update for me in the future will be a better imaging camera. As technology improves, the imaging devices keep getting more sensitive, with faster frame rates and less noise. The Lumenera SkyNyx 2-0M or the Pt Grey Research DragonFly Express are two examples of current potential upgrades from the DMK21AU04, however they are both significantly more expensive so you have to weigh up the costs vs the benefits.