Saturn was shot with a C11 Edge and Barlow working at f/29 at 8,100 mm of focal length with a Canon T2i (550D) in 640 x 480 Movie Crop mode at 60 frames per second at ISO 6,400 at 1/60 second exposure. About 7,200 frames were shot in 2 minutes of video. The best 1,000 were stacked in RegiStax.

640 x 480 Movie Crop Mode is a special video recording mode that was introduced with the Canon T2i (550D). It is also available on the Canon 60D and 60Da. It records a 640 x 480 pixel rectangle in the center of the sensor at 1:1 pixel resolution. Movie crop mode allows you to shoot at 60 frames per second.

When we use just the central 640 x 480 pixel rectangle inside of the larger full 5184 x 3456 pixel size of the sensor, we are utilizing the full resolution of that 640 x 480 pixel area. The detail in the final image is exactly the same as when it was shot. This is exactly what we need for high-resolution planetary imaging.

Movie Crop Mode is a special video mode that is accessed through a sub-menu on the LCD on the back of the camera when the camera's main control dial on the top of the camera is set to video mode.

The following table compares the differences between 640 x 480 Movie Crop Mode in the Canon T2i (550D), 60D, and 60Da and 5x Live View capture with with software.

Not all DSLR cameras offer 640 x 480 Movie Crop Mode. But it's not a big deal if your camera doesn't have this mode - we can still access 1:1 pixel resolution for high-resolution planetary work by recording Live View at 5x magnification.

For high-resolution planetary imaging, with whatever method and software you use, make sure you are recording at 1:1 pixel resolution or as close to it as possible. Normal full frame high-definition 1080p and 720p video, and 640 x 480 standard-definition video, are not close to 1:1.

No Computer Needed

One of the very nice features of using Movie Crop Mode is that you don't need a computer with you at the telescope to record the video like you do for recording Live View.

The video for Movie Crop Mode is recorded directly onto the memory card in your camera.

The only things you need to worry about are having a memory card that is large enough to store the amount of data that you will record and fast enough to keep up with the tremendous data rate that the camera can produce.

Most DSLRs use H.264 compression when they record video. This is a very good and efficient compression method, so files are not gigantic. A 2 minute MOV video of Jupiter is only about 215,000 kilobytes. MOV is the file format that is used to record movies. The file size will vary a bit depending on the subject matter and how much detail is in it. But if you are going to shoot a lot of video, having extra cards is a good idea. They are relatively inexpensive these days.

Also note that you need a reasonably fast card to record video. Canon recommends a class 6 speed card. Since so many cameras as shooting video these days, large fast cards are not that expensive or hard to find.

It is also a good idea to have an extra battery on hand if you are going to shoot a lot of video.

Not having to lug a computer with you to a remote location can be nice because you also have to power the computer. Newer laptops use less power, so you may be able to get away with using one for a couple of hours without 120-volt or mains power, but batteries last less time in the cold. Older laptops usually don't have great battery life to start with, and can be slow in writing files if you are recording Live View. This can drop your framing rate a lot, which is a significant consideration in high-resolution planetary photography.

For focusing, you don't really need a computer at the telescope either. The computer is not giving you any more resolution for the image display than what you are getting on the LCD on the back of the camera. Since you can magnify the image, it is fairly easy to focus with the LCD on the back of the camera. The only inconvenience is that sometimes if you are using the camera on a refractor or SCT, the screen may be pointing down towards the ground, making it harder to see. Newer cameras, such as the Canon T3i (600D), T4i (650D), 60D, 60Da and Nikon D5000 and D5100 have LCD screens on the back of the camera that will tilt and swivel to different viewing positions, making their use much easier.

MOV Files

Most modern DSLRs that shoot video record the data in a MOV file format. This is a QuickTime movie format that uses H.264 compression.

Quicktime formats are Apple / Mac based, so sometimes they don't play well with PC-based software. For example, RegiStax AviStack and AutoStakkert! will not open a MOV file.

If you shoot with Movie Crop Mode or high-definition video in the camera and record a MOV file, you will have to convert it to an AVI file format that these planetary imaging programs can work with. We will cover this in-depth in Chapter 5 Section 2.