How to take better photos with a DSLR THE MOON
Capture high-quality images of the Moon with a DSLR camera and up-close detail using prime focus photography
The great thing about the Moon is that it’s bright enough for you to take a decent image of it using a smartphone and a telescope – just hold your phone’s camera lens up to the telescope’s eyepiece and use the afocal method (see page 2).
You can, however, take the quality of your lunar images up another level if you use a DSLR or MILC camera. You’ll capture more detail and less noise, while a longer focal length lens also allows you to increase the size of the Moon in your photos.
The great thing about these cameras is that they can also be WWHG GLUHFWO\ LQWR \RXU WHOHVFRSH V focuser – taking the place of the eyepiece – so that the telescope essentially becomes the camera lens. This allows you to employ a technique called ‘prime focus photography’, which can deliver shots that are much more close up.
To practise this technique you will need two accessories: a T-ring and D 7 DGDSWRU WKH 7 UHIHUV WR D VSHFL F type of thread, developed in 1957 by the Japanese optics company Taisei Kogaku, later known as Tamron). The 7 ULQJ LV EUDQG VSHFL F DQG PRXQWV on the DSLR. The T-adaptor screws into the T-ring and has a nosepiece to slot into the telescope’s focuser.
Any scope can give great results with a DSLR, even a small 2.5-inch UHIUDFWRU RU D LQFK UH HFWRU 7KH longer your scope’s focal length is, the closer up your images will be, though. This is why scopes like Schmidt- and MaksutovCassegrains are popular with top lunar photographers: they have long focal lengths, are well suited to close-up imaging of the Moon and, compared to a high-quality refractor, you get a much larger aperture for your money.
There is another way of getting close-up detail in images and that’s
by using a Barlow lens. Slot it in to a telescope’s focuser before the DSLR camera and it’ll increase the focal length of your system, giving you LQFUHDVHG PDJQL FDWLRQ LPDJHV – typically by two or three times.
Your telescope’s mount needs to be rock solid and stable, and the ability to track the Moon with a motor drive RU D *R 7R PRXQW LV D GH QLWH advantage. Don’t forget to set your mount to track at the lunar rate, not at the rate the stars move across the sky. If you’re using a Go-To mount, make sure that it’s set up properly.
Moon shots
2QFH VHW XS WKH UVW VWHS WR capturing lunar close-ups is to work out the best time to capture your target (see the box on the right for apps to help you to do this). To reveal the intricate, rugged surface of the Moon’s crust it’s best to take your shots with your target lit from an extreme angle, which happens when the terminator (the line between the light and dark areas of the Moon) is close by. A very turbulent atmosphere, known to astronomers as bad ‘seeing’, can also blur and distort your view of the Moon – like the heat haze rising from a road on a warm day. You can tell when the seeing’s good as the stars won’t be twinkling much. That’s when you’ll capture the best lunar images.
You can’t control these seeing conditions high up, but you can cut down on air turbulence lower to the ground. Leave your scope to cool down outside for about an hour before you start imaging and this will reduce wobbling in your images as there’s less heat rising from your instrument. For similar reasons don’t take images from indoors looking out of a window or doorway. Heat from the house will cause the view to shimmer wildly.
Try an ISO setting of 200 to 400 DW UVW WKRXJK \RX PD\ ZDQW WR progressively increase the sensitivity. Bracketing you shots (see page 5) works particularly well with lunar imaging. It’s a good way to deal with the often big differences in brightness with lunar features, so take multiple images with a wide range of exposures and ISOs. Taking lots of frames will also help you capture those moments of best seeing when the atmosphere is still. There’s an even better way of dealing with the unwanted effects of poor seeing, which you may want to move onto as your astro imaging skills progress. Turn the page to discover more.