Apple’s latest dynamic duo–iPhone 4 and iMovie–makes shooting and editing videos easier than you’d guess, and our expert guide to the process will remove any lingering doubts you might have.

If you think the idea of editing video on a cell phone is crazy, you probably haven’t tried it yet. When you pair an iPhone 4 with the $4.99 iMovie app, almost anyone can capture footage, assemble the best bits, and share the finished results in minutes–all from the palm of their hand. But we understand that even the phrase “video editing” scares off many of you. So we’ve put together a guide to quickly making great videos that’ll help both newcomers and old pros get the most out of this powerful combo of hardware and the software.

Frame Shots for TV

Last year’s video-enabled iPhone 3GS brought with it a new phenomenon: the vertically lensed movie (or what many have dubbed “tallscreen”). While they get the job done, vertical movies (shot by holding the iPhone in portrait orientation) aren’t very TV-friendly, so if you plan to eventually present your creations that way, do yourself a favor now and remember to hold your iPhone 4 in landscape orientation while shooting to keep your video properly horizontal. This is particularly important now that the rear camera is working in the wider 16:9 aspect ratio inherent with 720p HD video–you’ll get results that completely fill the frame of your HDTV, rather than displaying a thin vertical image with mostly black at the sides.

Let There Be Light

More than a simple camera flash, the LED light on the back of the device can also act as a lamp that lights your movies. Just tap the lightning bolt icon in the upper left corner to toggle between Auto (where the light comes on only when necessary), Off, or On. We recommend using it sparingly, however–and not just because it’ll drain your battery faster. In many settings with at least a little bit of light, a grainy video is often preferable to a gaudy blast of LED light…complete with your subjects having glowing retinas right out of Village of the Damned.

See the Whole Widescreen Frame

720p HD video is wider than the iPhone 4 can display, so by default, the screen is actually showing you a cropped version of what you’re shooting. To see the whole widescreen view, open the Camera app, switch to movie mode, and double-tap in the center of the screen. Now you’ll see a wider image with black bars filling the rest of the frame–this is the full image area you’re actually recording.

While you’re at it, don’t forget to tap on your key subject to focus the camera on what’s important. In our tests, the iPhone 4 does quite a nice job of keeping things in focus when the subject is moving. But in general, the closer the subject, the more you’ll need to tap to focus.

Include Yourself in the Fun

The best part of a handset with two cameras is that the front-facing camera is always just a tap away. Using the front camera, not only can you see exactly what the device is capturing, but you can also include yourself in the fun. The results won’t be in HD (the front camera only records 640×480, similar to the 3GS’s camera). In a pinch, it’s better than nothing, and the resulting video can also be added to iMovie projects. Such footage will have those black bars on the sides, and we cover dealing with those next…

NEXT: Editing, Sharing, and importing iPhone 3GS videos with iMovie>>

Don’t Forget Those iPhone 3GS Videos

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If you upgraded to the iPhone 4 from the 3GS, any Camera Roll videos from your last phone came along for the ride when you set up the new handset in iTunes. The good news is that videos shot with the 3GS will import into iMovie just fine, and you can even mix and match them with new video shot on the iPhone 4–3GS videos will be automatically “pillarboxed” with black at the sides to fill out the wider 16:9 aspect ratio of the 720p HD frame. If you’re editing a Mobile iMovie project comprised entirely of 3GS video, we recommend using the Medium (640×360) export option, which is the least likely to degrade your original footage. (The others will enlarge it.)

Editing Insights

When it’s time for the nitty-gritty work of editing, know that clips in Mobile iMovie can only be trimmed at the head or tail, and you can only insert a new clip before or after another one, rather than in the middle of an existing clip. There’s no splitting of clips, although you can awkwardly get the same end result by importing the same clip twice. On the first clip, trim the out point (“out points” are the ending points of an edit). On the second clip, trim the duplicate’s in point (or the starting point of the edit). It’s kludgey, but it’s the only way to get it done.

To quickly make adjustments with long clips, tap a clip to select it, then tap on the handle, hold and swipe it–right for in points or left for out points. The handle will then snap back to the center, ready for another swipe so you can find the edit point you’re looking for with less effort. Move the handle slower for finer control over your selection. For even faster editing within Mobile iMovie, keep your iPhone 4 videos short–maybe 30 seconds or less–and try to capture the action from a few different angles, which will make your edited project more interesting.

Respect Those Copyrights

Just because Apple is allowing you to use music from your iPod app in iMovie doesn’t mean that the copyright holder will be happy about it. You’re free to use commercial music in your iMovie projects for fun or to show off to loved ones, but be careful about posting movies containing such music on sites such as Facebook or YouTube. If a particular copyright holder doesn’t want you to use their work, YouTube’s Content ID service may flag it and have it removed. You’re better off sticking to Apple’s supplied Theme music or creating something of your own using Garage Band, syncing it to your iPhone 4, and using that for the soundtrack on your original movies.

Copy Movies to Your Computer…

iMovie for iPhone 4 is strictly limited to exporting at one of three sizes–Medium (360p), Large (540p), and HD (720p). These files (as well as any photos you’ve taken with the device) are available for importing into iPhoto or the desktop version of iMovie, but you can also copy them straight to your computer via the Image Capture application included with Mac OS X. Just open the app with your iPhone 4 docked, select the files you want to import. and either drag and drop them to the folder of your choice, or use the Import button.

Thanks to Apple’s $29 Camera Connection Kit, you can also copy movies straight onto your iPad and enjoy them on the larger screen. Plug the USB dock adapter into the iPad and use a standard dock cable to connect it to your iPhone 4, then select the files you want to import (or import them all) and watch the magic unfold on a bigger display.

…Or Share with the World

Thankfully, Apple has built additional sharing methods into iOS 4 via the Camera Roll, which includes emailing, MMS, or sending directly to MobileMe or YouTube. While these methods are fine for quick sharing with family or friends, one big disadvantage is that your beautiful 720p HD video will get reduced to a smaller file size when going this route, even if you’re using a Wi-Fi connection. (The same also applies when uploading via apps such as Dropbox–it’s an iOS 4 limitation.) If you want to share your work with the world in glorious HD, import it to your computer first and then upload it to the service of your choice.

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