It's basically impossible for even the most experienced instructor to get more than a rough sense of the quality of a player's mechanics with the naked eye. As a result, I always have a camera with me when I'm working with hitters or pitchers.
I am often asked to recommend a camera to buy, so I have put this piece together.
Importance of Shutter Priority Mode
The key to stopping the motion blur in a swing is the shutter speed, and many cameras have a shutter priority mode that lets you select the shutter speed and the camera will adjust everything else like the aperture accordingly. There is a trade-off between the shutter speed and the amount of light that is required. Basically, the faster the shutter speed, the more light that is required. When I am shooting at night under the lights, I generally use a 1/500 shutter because that lets me slow down the motion enough while still keeping the image acceptably bright. If I'm shooting with natural lighting during the day, I will increase the shutter speed to 1/1000, 1/2000, or more in order to maximize the sharpness of the image.
The problem with many cheaper (e.g. sub $250) and sometimes more expensive cameras is that they either do not offer shutter priority mode, do not offer shutter priority mode in video mode, or do not offer shutter priority mode in high speed video mode.
The problem with my Nikon P600 is that Nikon says that shutter priority mode is available in high speed video mode, but it actually isn't.
60P is Becoming the New Standard
While you can find higher frame rates on some cameras, 60P (60 Progressive) is becoming the new standard feature for most cameras with video capabilities, and that is a very good thing.
60P is just another word for 60 Frames Per Second (60FPS). The majority of the clips on this site were shot using a video camera that shoots 60 FPS, and 60 FPS is good enough for most analysis purposes. The difference is that I had to de-interlace the video that I shot with my HV-30, which is a slightly complicated task.
Now, with the new 60P cameras, there's no need to de-interlace the video to get 60 FPS video. Instead, the video is recorded to the card at 60 FPS, so all you have to do is open the clip and view it.
The only lingering difference between cameras is that some cameras will shoot 60P at full HD resolution (1920x1080 pixels) while others will only shoot 60P at a lower resolution (1280x720 pixels). While full HD (1080P) is better, the lower resolution HD (720P) is plenty good for most purposes. For instance, I have a Canon T3i that I sometimes use for shooting video and it only shoots at 720P, but that's not a big deal.
The only downside to 60P is that most cameras who use it do so using a CODEC called AVCHD/MTS, which is fairly hard to work with. You can often do on-camera analysis of clips, but working with the clips off of the camera can be complicated.
Here are the cameras that I currently have and my opinions of them.
Casio EX-FH25 & EX-FH100 (EBAY Only)
These are my go-to cameras for instruction.
These cameras, which are basically the same except for different-sized zoom lenses, will shoot 640x480 video at 120 FPS, which is plenty good for analysis work, including looking at the release of pitches (and you can always up the frame rate to 240 FPS if you need to).
Casio EX-FH25 Video
120 Frames Per Second
What's more, you can quickly and easily view the footage you just shot, at 120 FPS and frame by frame, on the camera itself while in the field. That is incredibly useful and, at least for me, well worth the extra $150.
This camera is my primary tool for use in lessons.
This camera is also nice because it saves its files to a normal memory card in AVI format, which makes it easy to export the clips to a laptop (via a USB cable or just by putting the memory card in your laptop) and review them using QuickTime.
I prefer this camera over the preceding, and less expensive, EX-FH20 (in fact I bought an EX-FH20 and returned it) because it will shoot 120 FPS at 640x480. The EX-FH20's lowest setting is 210 FPS at 480x360. 210 FPS sounds cool, but it's actually overkill for analysis purposes. I prefer the slightly larger image size and it's worth it to me to trade off a lower frame rate for a larger image size.
Canon ELPH 100 HS ($150)
My most basic and portable camera is a Canon PowerShot ELPH 100 HS (now the Canon PowerShot ELPH 110 HS). The nice thing about this camera is that it is affordable but still has the ability to shoot video at either 120 FPS or 240 FPS in the QuickTime MOV file format. It's fairly easy to view footage on the camera while in the field. The only down-side to this camera is that there is no shutter priority mode, which means you have to shoot in fairly good lighting conditions (e.g. outdoors in the middle of the day) to avoid motion blur.
Canon offers other cameras which offer 120 FPS mode.
Canon T3i ($600)
The Canon T3i, and the new Canon T4i, is a relatively expensive camera, but if you happen to have one, or are in the market for a digital SLR, you should know that the T3i/T4i has everything that you need to good and easy analyses; 60P video mode (60 Frames Per Second), shutter priority mode that can be used in the 60P video mode (there is a manual exposure control setting in movie mode), and an easy to use file format (QuickTime MOV). The T3i/T4i will only shoot 60P in the slightly smaller 720P resolution (and not full HD 1080P), but that isn't that big of a deal.
Canon HV-30 ($800)
This is the camera that I used to shoot my DVDs and to put together most of my flipbooks. This camera uses videotapes, which I like because they are a relatively cheap means of storage. This camera can also support a number of different telephoto and wide angle lenses, which makes it very versatile. The only thing about the camera is that, on the camera itself or via an HDMI connection, you can only view the footage at 30 Frames Per Second (FPS). To view the footage at 60 FPS, you have to import it into a non-linear editing program and de-interlace it. That isn't that hard once you learn how to do it, but it's definitely not a simple or quick process.
I have seen some 240FPS video off of an iPhone 6 that has impressed me, especially since it was taken indoors. The iPhone 6 will also shoot at 60FPS, which is good enough for much analysis work. I'm desperately hoping Apple will put this same camera on the iPod Touch and/or the iPad, but they haven't so far.