DSLR Camera Settings for Astrophotography

Modern DSLR cameras are sophisticated and highly complex pieces of technology. They offer an almost bewildering array of settings and functions. Most are accessed either directly through buttons on the top or back of the camera, or through a series of software menus.

To simplify things for novice photographers, camera manufacturers offer a series of automatic modes that pretty much control everything on the camera. Various different shooting scenarios, such as special settings for sports photography, can be set on the main mode dial on the top of the camera. Unfortunately, there is no special setting for astrophotography!

Instead, we will almost exclusively use the Manual mode setting. This will give us complete control over all of the camera’s settings and functions. Most will only have to be set one, but some, such as the custom white balance setting will be used each time we shoot long-exposure deep-sky astrophotos.

It would be a good idea to spend some time with the camera and camera manual familiarising yourself with various different settings and menu items. The primary menus are available by pressing the Menu button. Each menu item’s settings are usually accessed by a sub-menu. Another series of settings are accessed in sub-menus under the Custom Functions Menu.

• Program Mode – Set to Manual.

• Autofocus – Turn off, or set to Manual.

• White Balance – Set a custom white balance on the sky background.

• Colour Space – use sRGB.

• Drive – Set to One Shot.

• ISO – Generally the ISO should be set to 1600 for long-exposure deep-sky astrophotos with older cameras. New generation 14-bit cameras should be set to ISO 400 or ISO 800.

• Canon Picture Styles and Nikon Picture Controls – Set to Standard or Neutral for Canon, and Standard or Vivid for Nikon.

• Contrast – Increase for faint deep-sky objects. Turn down for star clusters.

• Sharpening – For JPEGs it’s usually best to turn the sharpening down.

• Saturation – Adjust to taste by shooting a test image.

• Custom white balance fine tuning – Try adding some blue.

• Image Review – The camera will display the image after the shutter closes. Turn this off. You can turn it on to examine your test images by simply pressing the display button on the back of the camera. But having the image displayed after every shot will heat the camera up causing more thermal noise. It can also be very distracting to other people at a star party.

• Metering – Generally doesn’t matter, but you can try setting it to Spot if you are shooting the Moon or Sun (with proper filtration).

• Exposure Compensation – Set to Zero, no exposure compensation. This setting doesn’t really matter because you are not using autoexposure.

• Shutter Speed – Set to the correct exposure as determined by examining the histogram, which we will discuss in the next section. Up to 30 second exposures can be dialled in directly. For longer than 30 seconds, set to Bulb. On some cameras, Bulb may be a separate exposure mode setting, or it may be accessed on the shutter speed dial one click past the 30-second setting.

• Self Timer – If you don’t have a remote release, you can use the camera’s self-timer to trip the shutter so you don’t have to touch the camera, which will help reduce vibrations and possible star trailing.

  

• Mirror Lock-Up – For long exposures with a very solid mounting, it probably is not necessary to lock the mirror up before an exposure. For short exposures for high-resolution planetary or double-star work, it is a good idea to lock the mirror up before the exposure to reduce camera movement and vibration caused by mirror slap. Some cameras access this setting with a control on top of the camera and some through a custom setting in a menu. Some cameras like the 20Da require the shutter to be pressed once to lock the mirror up, and then be pressed again to actually open the shutter. Take care to learn exactly how your camera works for this feature, because you could press the shutter thinking you have opened it for a long exposure and go off to do something else, and then come back only to find that all you had done was lock the mirror up and that no exposure had been taken. Some cameras do not offer a mirror lockup at all, but they may move the mirror up out of the way as the first thing when using the self timer. Read the camera manual to learn how your particular model works.

• File Format: RAW vs JPEG – Most DSLR cameras come with the file format that images are stored in set to JPEG as the default. Today’s DSLR cameras also allow images to be saved in a proprietary “RAW” file format that offers the potential for higher quality images. Many cameras also allow JPEG and RAW file formats to be used at the same time, with the camera writing two files to the memory card after an image is taken.

  Beginner’s can shoot in JPEG file format. More advanced astrophotographers will want to use RAW file format.

• JPEG Compression Settings – DSLR Cameras also offer different JPEG compression settings, sometimes also called “quality” settings. Higher quality means less compression which results in a larger file size. To fit more images on a card, for normal daytime snapshot photography, some people shoot with a lower quality setting that compresses the JPEG files more. Of course, you lose more information when you use higher-compression JPEG settings. If you don’t want to go to the trouble of shooting with RAW files, set the JPEG compression to the highest quality setting (largest file size).

• RAW Compression – Some cameras offer an in-camera compression for their RAW file formats that is different than the compression used with JPEG files. It may be lossy or lossless. This RAW compression will be proprietary and you may only be able to access the file with the manufacturer’s software. In general, I would advise against using RAW compression. Memory storage is inexpensive enough to not have to use it.

• Native Optical Resolution – Many cameras offer different resolution settings. The camera’s native optical resolution outputs the same number of pixels that the image is taken with. This is the setting you want to use. For example, the Canon 1000D offers a native optical resolution of 3888 x 2592 pixels, but also offers lower, interpolated resolutions of 2816 x 1880 pixels and 1936 x 1288 pixels. You can always resize down to a smaller file size later in software, but if you do it in the camera to the original file, you throw away valuable data and you can never get it back.

• Built-in Flash – Turn off, because it won’t reach to infinity. It won’t even reach to the Moon.

• Red-Eye Reduction – Turn off.

• Long-Exposure Noise Reduction – If you are going to shoot just a couple of long-exposure frames, turn on in-camera long-exposure noise reduction. If you are going to shoot multiple frames for stacking and are shooting separate dark frames, then turn it off.

• High ISO Speed Noise Reduction – Like long-exposure noise reduction, if you are going to shoot just a couple of long-exposure frames at a high ISO, turn on High ISO Speed Noise Reduction. If you are going to shoot multiple frames for stacking and are shooting separate dark frames, then turn it off.