What are Gate B and Gate T? How long exposure?

Both door B and door T are shutter positions required for long exposure. The specific differences are as follows: door B: Press the shutter button and the shutter will open; release the shutter button and the shutter will close.

Otherwise, you will keep pressing the shutter button. Even if you ignore the camera shake, your hands will still be sore if you keep pressing it for a long time. Press the shutter button on the shutter line to lock the shutter. Then wait two or three minutes for a short time and half an hour for a long time to see the brightness of the ambient light. So it is necessary to take more photos. When you feel that the exposure is almost complete, you can unlock the shutter button and the exposure is complete.

Operation mode:

Set the camera to full manual mode, that is, M gear; Set the shutter to the lowest until the shutter value becomes a "light bulb", which means that the "B door" has been opened.

Fix the camera with a tripod. Then turn the camera to gate B. Some cameras have a separate B-door mode in the mode dial, and some cameras adjust the shutter speed to B-door after 30 seconds in M-file. Use a smaller aperture after adjusting to door B. At this time, it is best to use cable release to operate the camera shutter.

When shooting, press the shutter and the camera will start to expose until the shutter button is released.