Question: I see that a lot of new digital SLRs (single-lens reflex cameras) have high definition video recording. I already have a high definition camcorder. Why would I want my digital SLR to record high definition video?

Dexter Lawrence, Miami, Fla.

Answer: Besides the convenience of having a single device to handle your still photograph and video recording duties, there are some technical benefits as well. There is also a huge drawback that has only recently been overcome.

Digital SLRs have large image sensors that provide much better video quality than the small sensors found in consumer camcorders. The images look deep and rich, and the difference in low light performance is dramatic.

You also can use interchangeable lenses to get the same visual effects as a professional filmmaker, like shallow depth of field. The small sensors on consumer camcorders make depth of field control difficult, but it is easy with an SLR.

Up until now the drawback to digital SLR video has been focusing. Most digital SLRs cannot autofocus when recording video, so you must focus manually with the LCD (liquid crystal display) screen. This is extremely awkward to do while the camera is running, unless you are very skilled and using a tripod.

I have found two standout digital SLRs that tackle the autofocus issue and make video recording a much better proposition.

One is the extremely impressive K-7 from Pentax, recently announced at a price of $1,299 (body only.) Besides its compact size, weather-sealed magnesium alloy body, fast shooting, better image stabilization and dust removal, and many other improvements, the completely new K-7 records high definition 720p video at 30 frames per second (fps).

The K-7 does not continually autofocus but you can press a focus button while recording to bring things into focus. The K-7 can be used with any Pentax lens ever made but works best with the latest lenses with silent autofocus. This is a great digital SLR and though it cannot focus continually like a camcorder, with a little practice with the focus button it can definitely get the video job done.

The second exciting new entry is the Panasonic DMC-GH1, a "Micro Four Thirds" camera. Micro Four Thirds is a new variant of the Four Thirds system developed by Olympus, Panasonic and other partners. The DMC-GH1 is not an SLR because it has an electronic viewfinder, but its performance and form factor tend to get it grouped in the same category.

The DMC-GH1 features 1080p AVCHD recording at 24 fps. I have not tested one as of yet but by all accounts the video quality is simply spectacular and a huge leap over anything ever before seen in a consumer camcorder. The DMC-GH1 comes with a 14-140mm zoom lens that can autofocus continually and silently, just like a regular camcorder, and the viewfinder can be used while recording. The DMC-GH1 is unique in the sense that it is equally at home as a camera or a camcorder.

The downside to the Panasonic is lens selection. Currently the only lens that supports the continual video autofocus is the kit lens. Future lenses that support continual autofocus are likely to be introduced by both Panasonic and Olympus, but for now only the 14-140mm kit lens makes the DMC-GH1 equally capable as a camcorder as it is as a camera.