Video test: primes vs kit zooms, same settings, GH2 at high ISO (5000)

Описание: A post on DPReview revealed a massive difference in video quality between a kit zoom and a prime lens at the same settings. The noise with the kit zoom was very high while the noise was very low with the prime. The setting were allegedly f/4 and f/4.6 (the poster originally thought both were at f/4 but the zoom could not do f/4 at that focal length) and ISO 1600. Some speculated a difference in T Stops would do it (but that would have made the video darker, not just noisier.) Others thought the ISO was floating, despite the insistence that the settings were manual. I subscribe to that theory.

So I put together this test with the GH2. I set the camera to manual mode with the highest quality video at 1080/24p. I set it on tripod and mounted the four lenses one at a time -- 14-140 mk1, 14-42 X PZ, Olympus 45 1.8, Pentax K 50 1.4. I set f/5.6 to avoid any variance, and I set 1/25 shutter and 5000 ISO.

The results make it obvious that the original poster did not actually have it in manual mode. I see essentially no quality difference between the four lenses at 5.6 ... the final scene is shot at f/1.4 and 400 ISO .... and THAT makes a massive difference in noise. DOF is so shallow, though, that the subject is only in focus in one small spot. Trade-offs ...

Also note that I graded the entire track the same way to pull even more noise out ... I raised brightness at least one stop and I compensated by changing contrast.

Note: I hold the copyright for the entire video and all content. The music is all royalty free.