5 Reasons 40mm is the Best Focal Length for a Do-It-All Prime Lens

Do you own and use a beloved 35mm or 50mm lens? Popular photography personality Kai Wong thinks you should consider trying out the middle ground between the two. He made this 11-minute video about why he thinks 40mm is actually the best focal length you can carry if you want a do-it-all prime lens.

There’s a long-standing battle between 35mm and 50mm lenses for which deserves the top spot, but Kai believes that 40mm is actually the best focal length out there. It’s a nice middle ground between what is “kind of like a portrait lens” and something a little too wide.

Here’s a rundown of the 5 reasons given by Wong (watch the video for elaboration):

1. 40mm is the standard focal length in cinematography (the equivalent when compared to 28mm on Super 35 sensors)

2. The ergonomics are good. It’s lightweight and compact

3. It’s a wide 50mm lens. It’s not too tight for narrow spaces in street photography

4. It’s a tidy wide. It doesn’t show much of the environment, meaning you need to pay less attention to the background

5. It’s cheap. The lenses are affordable and really don’t break the bank.


Canon’s 40mm f/2.8 lens costs $200, and Yongnuo makes a $90 40mm f/2.8 for Nikon cameras.

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