I was thinking about buying a couple of filters for my Leica glass and I had one of those ah-ha moments.

I looked at the filter sizes for my gear and it struck me that someone in at Wetzlar was thinking when they speced out the gear. Most of it had a 46mm filter thread.

  • 15mm f/4.5 (Voigtländer, not Leica) – 58mm
  • 21mm f/3.4 – 46mm
  • 28mm f/2.0 – 46mm
  • 35mm f/1.4 – 46mm
  • 50mm f/1.4 – 46mm
  • 90mm f/2.0 – 55mm

I did the equivalent exercise for my Canon kit:

  • 16-35mm f/2.8 – 88mm
  • 24-105mm f/4.0 – 77mm
  • 35mm f/1.4 – 67mm (Sigma, not Canon which would be 72mm)
  • 50mm f/1.4 – 58mm
  • 85mm f/1.8 – 58mm
  • 100mm f/2.8 – 67mm (Macro)
  • 70-200mm f/2.8 – 77mm

There just seems to be more variation between the lenses for the Canon. Especially if you take out the third party lenses. Canon has actually regressed a bit. Their previous 17-35mm shared the filter size with the rest of the pro zooms: 77mm. Once things get too long, wide, or fast physics take over and you’re constrained a bit more than normal.

I know that Leica likes 39mm and 46mm a bunch until the physics get out of hand. Canon’s older kit seems to have liked 58mm and 77mm, but lately they’ve been all over the map.

This might be an interesting thing to do a much deeper dive to see how things vary between camera systems. Maybe with a cross-reference by release year.