Ivana's amazingly detailed image of Mars from her back garden
As winter approaches, so do opportunities to image the planets in their prime. For planets of the outer solar system, time around their respective oppositions is a chance to catch them at their seemingly biggest and brightest. Whether you are a seasoned deep space photographer or just starting out, planetary astrophotography can be fun and incredibly satisfying when it all goes well, so here is a very simple guide to making the most of this planetary season!
Planets take up an incredibly tiny portion of the sky, so to be able to capture detail, you will want as much aperture and focal length as you can realistically get. However, if you don’t have the space or the cash for large instruments, a simple 5” Maksutov-Cassegrain like Skywatcher’s universally beloved Skymax 127, or a 6” Schmidt-Cassegrain like Celestron’s Nexstar, could get you started off right. Planetary imaging requires no equatorial tracking, so the mount can be Alt-Az, and there’s no need for guiding, or calculating for correct backfocus as there’s no need for a flat field. All you want are good conditions – which is sometimes a tall order!
A planetary camera is best suited for the job because of their small sensors, fast framerates, and good sensitivity. DSLRs unfortunately don’t have the bandwidth for this type of imaging – not that they won’t produce results, but it won’t be the best the telescope can give. Similarly with dedicated deep space cameras, as they often don’t have the framerate and small enough regions of interest. Framerate is important for planetary imaging to beat the effects of seeing and atmospheric turbulence, as well as to allow for as much data to be captured in order to stack and reveal the detail. Some come with an already built-in UV/IR cut filter and some don’t, so if yours is the latter, you will need to add one to the imaging train.
A Barlow lens is a useful addition for those great nights of good seeing, when you can increase your reach to capture a bit more detail. The magnification will depend on your particular setup. TeleVue Powermates are a popular and more expensive option, which offer a bit more brightness, and are parfocal, making it easier to slot anywhere into the imaging train.
Another helpful addition to the imaging train for times when planets haven’t risen above around 30 degrees, is an atmospheric dispersion corrector, or an ADC. They can lessen the effects of atmosphere and correct the blue and orange fringe caused by diffraction.
When it comes to capture software, the most popular and often used ones are SharpCap and Firecapture. Both will allow to use a tight region of interest necessary for bringing framerate up, sharpening tools, and even track the object if it drifts across the sensor.
For stacking and processing, the best software to start with, if anything due to the sheer amount of tutorials and guidance available online, are Autostakkert and Registax. Autostakkert will analyse and stack best frames from the capture, while Registax splits the stacked image into six layers for targeted wavelet sharpening and denoise. It can also correct color balance, and fix some stubborn RGB misalignment.
The easiest target to start with are Jupiter and Saturn, which are bright and have clear features. Wider views and higher exposure may reveal some moons, which can either be captured together with the planet or layered afterwards. Sky and Telescope offers a handy tool for following moons around both of the planets, as well as planning transits and shadow transits. Among many handy tools, there is also a very handy tool to help plan for when the Great Red Spot will be visible on the surface of Jupiter.
For a more detailed dive into particulars of the equipment, setup, and process, I have assembled a few YouTube videos showing all the details of how I create planetary images:
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