Blackmagic Forum

Has anyone notice the iris reading changes depending on focus distances with this lens?

I don’t have the same lens, but what I have observed when using my Sigma 12-24 f4 is that, iris reading always starts at 4.2 instead of 4, despite of focus and/or focal length.

This is how most macros work. As the close focus/magnification becomes greater the more stop you lose. Check out this Tokina, the stops are color coded to match the focus distance. At extreme magnification this f2.8 lens becomes an f8.

Good Luck

This does not happen with my Canon 5D, I set the aperture at f2.8 it stays at f2.8

Seems silly to relay the incorrect aperture but apparently that's a feature on Canon cameras. If you mash the focus all the way down to .3m does the 6K report f5.9? According to the manual that would be the correct reading.

Good Luck

The iris does not change on the Pocket 6k Pro so this make no sense.

Does the FF report f5.9 at .3m or something else? Maybe they’re all wrong.

Good Luck

No but iris changes higher when focus closer. I look at the iris slider and it remains stagnate, not moved, so I detach the lens while the camera is still on to check the aperture blades and they have closed.

Either its the camera or the Sigma MC-21 EF to L adapter. Has anyone got this problem with this lens on the 6KFF?

I've tested the Canon EFS 60mm f2.8 Macro and Canon EFS 35mm 2.8 Macro on the 6kFF and the iris on both these lenses also changes depending on focus distances but stays constant on other BMD cameras and Canon bodies so something is not right with the 6KFF with macro lenses with the L mount conversion. This may also have implication with the Pyxis at least with the L mount version using a L to EF adapter?