When shooting in video mode using Canon lenses on Canon bodies, when the aperture changes the blades may or may not make a sound. Newer lenses have gradual, silent aperture transitions. Older lenses only have the sudden and noisy transition.
The observations confirm that such a feature exists. But searching on the web I could not find any official or unofficial information about it.
Is there any materials (marketing, discussion, etc.) that acknowledge that some Canon lenses support smooth aperture transitions?
Is there a list of lenses that are known to support and not support smooth aperture transitions?
Some verbose extra background information, only if the above question is unclear.
In Canon's video recording mode, the aperture can change during filming. You can either manually dial in the aperture, or you can let the auto exposure algorithm run the show. Interestingly, the auto exposure uses large jumps, like from f/2.8 to f/5.6 to f/16 with nothing in between.
What I noticed is that different lenses behave differently when the camera requests it to change aperture. Some lenses will gradually change the aperture (you can look through the front of the lens to see the blades in motion) and make no sound. Other lenses will change the aperture abruptly and make a metallic flapping sound. This question only applies to video mode - because in photo shooting mode, all lenses will change the aperture abruptly when the depth-of-field button is pressed or when a photo is being taken.
So far I know these lenses support smooth aperture:
- Canon EF 100mm f/2.8 macro L IS USM
- Canon EF 16-35mm f/4.0 L IS USM
- Canon EF-M 11-22mm f/4.0-5.6 IS STM
- Canon EF-M 18-55mm f/3.5-5.6 IS STM
- Canon EF-M 22mm f/2.0 STM
And these lenses do not support smooth aperture:
- Canon EF 17-40mm f/4.0 L
- Canon EF 24-105mm f/4.0 L IS (Mark I)
- Canon EF 50mm f/1.4 USM
- Canon EF 85mm f/1.8 USM
- Canon EF 70-200mm f/4.0 L USM
- Canon EF 70-200mm f/4.0 L IS USM
These sources allude to something about smooth aperture without giving definitive details on what's going on:
I'm not sure to what extent the video mode smooth aperture feature depends on the camera body's model. Maybe old bodies never support smooth aperture even on good lenses. Maybe new bodies support smooth aperture on a wider selection of lenses.
I'm not interested in information about clickless hand-operated apertures. But I am interested if other non-Canon brands are supporting smooth electronic aperture transitions on their lenses, especially if they have official marketing materials.
