What's the difference between turning on hdr or not?

Whether HDR is turned on or not, the imaging effect is still different. Some cameras will have two photos of the original film and HDR imaging after using HDR.

HDR function can be simply understood as improving the parts that are too bright or too dark, and correcting the situation that the bright parts are too explosive and the dark parts are unclear in the environment with huge variance of light and dark.

HDR is a common technique in photography. The abbreviation of Range means "high dynamic range". HDR technology can overcome the shortcomings of limited dynamic range of most camera sensors, and control the tone of the picture within the range that can be recognized by human beings. It can superimpose multiple photos with different exposures into a delicate image.

The role of HDR.

After turning on HDR to reduce exposure, the camera will use the built-in image processor to calculate and add light to places other than the highlight level, so that the light and shadow of the whole photo will return to normal. But because the dark bits are prominent at the back, the noise will be more obvious.

Some cameras don't require people to choose a higher sensitivity, but they will instruct the metering system to automatically reduce the exposure value to increase the details of high light bits, and then highlight the dark bits during image processing. In addition, some models will not specify the selection of high sensitivity value, nor will it affect metering, but simply highlight the dark position of the photo.