Talking about digital black and white photography you probably first think about image processing, because every tool offers at least one option to convert a color image to black and white.
Back in the days of analog photography a descision has to made to capture either in color or in black white. This was easy if you owned 2 camera bodies which could be be loaded with different films. And sometimes you rolled back a slide film at image number 12 to insert a roll of black and white film.
Today we can decide during image processing if an image looks better in color or in black and white, you can try it out and even go back to the original image.
I did a short video on this:
The biggest advantage on modern cameras is the viewfinder or the camera display. Almost every camera of a list of picture styles or effects including at least one option for black and white which alter the viewfinder display.
Here i can switch between different monochrome options and more important i can judge the effect in teh viewfinder or the camera display.
This even works with most of the smartphones like with my iPhone Xs. E
This makes it more easy to judge if a b/w effect works on this image.
And back to color
Capturing your images in JPEG format the decision for black and white is final. Choosing raw for your images, which is my advice, then all color informations are kept in the raw file.
Depending on your image processing tool even raw files are displayed in black and white. This is due to the camera profiles built by different manufacturers.
Lightroom Classic and Luminar 4 are some of those tools.
The raw files are displayed with the camera profile applied to the image. But you can choose a different profil, like landscape or neutral to go back to the color image and process it normally.
On the iPhone this can be done with the app “Photos” with HEIC format and even with the regular JPEG format. Just apply another filter and go back to the original color image.
Changeing the display or the viewfinder is a tremendous ease for black and white photogrpahy. and capturing in raw format the descision is not final. Just take care to swtich the picture style if you plan to shoot video clips.