Why doesn't SLR digital camera have video recording function?

First of all, your question is not a problem now because Nikon's

D90

SLR camera

You already have the video recording function

Second, why didn't SLR cameras have video recording function in the past? There are two main reasons:

1, video recording, CCD or CMOS exposure for a long time will increase its undercurrent, and the result is that the photos taken in photo photography will follow.

noise

Increase, which is unacceptable for SLR cameras with visual quality as the first requirement.

2. SLR camera adopts TTL focusing system, and the light source of this focusing system comes from the camera.

Reflector plate

Reflect on the past. When shooting, the reflector must be raised to let the light shine directly on CCD or CMOS, so that the SLR camera loses its continuous focusing function, which is obviously not allowed in shooting.

Why the current D90 can realize the video recording function is obviously an improvement on the above two points. The first is that the improvement of CCD can effectively resist noise, and the second is that two focusing systems are adopted, one of which is specially used for focusing when shooting. So with this function.

Digital Single Lens Reflex Camera

In the initial people's concept, it is "specialized", and specialized things are usually "specialized" or "single" in function. After D90 added the camera function, aren't there still many people who are somewhat critical and negative?

For ordinary consumers, many functions are better than one less, but you have to pay for this function.