Speaking of pulling focus, I watched American Hustle the other night and couldn’t help but pay close attention to the focus since it’s something others kept bringing up in discussions about the movie across the web. In fact, the film’s focus puller, 1st AC Gregory Irwin, offered an explanation for the focus issues in one such discussion thread at Cinematography.com:

You’re right!  Much of the movie had focus issues.  The cinematographer insisted upon using old Canon K35 lenses for their 1970’s look, the time period that the movie takes place. Unfortunately, the K35’s have 1970’s technology as well.  Since AMERICAN HUSTLE was shot entirely on steadicam, the use of Preston FIZ remote focus units were necessary.  Since the K35 lenses have a compressed focus scale and are known for “loss of motion,” they could neither respond to the Preston transmitter commands nor return to a prescribed focus mark.  There wasn’t much chance for success in the focus department with these lenses.  About half way through the shoot and against the cinematographer’s wishes, the First AC insisted on switching the Canon K35 lenses for the Zeiss Hi Speed lenses which were made for cinematic use.  After the switch, the focus issues were eliminated and the integrity of a period look was mantained.

Without this knowledge, you might assume the focus issues were related to such a loose shooting style – constant camera movement on Steadicam without rehearsals. Irwin himself confirmed that’s how director David O’Russel likes to work, saying, “David does not rehearse, there are no marks and we haven’t a clue to what’s going to happen during a take till after we have shot it.”

But Irwin refutes that the style of shooting played any role in the sometimes buzzy focus:

It’s interesting to note that Geoff (“A” camera and Steadicam operator) and I are very accustom to no rehearsals or no blocking of a shot.  In fact, we kind of enjoy that challenge.  We had a tremendous success with David’s THE FIGHTER which was shot in the same fashion.  The movie is in frame and completely in focus.  The difference was that we did not use the Canon K35 lenses.  We shot with Zeiss Master Primes at a T1.3 and it looked fantastic!  Hoyte van Hoytema was the cinematographer on THE FIGHTER where as Linus Sangren was the cinematographer on AMERICAN HUSTLE.  His choice of employing the Canon K35s was fatal to our success when referring to the focus pulling challenges. Those lenses simply could not perform to the level we required.  Thankfully, after we changed lenses to the Zeiss High Speeds, our focus issues were put behind us.  I only wish we had made the change earlier in the shooting schedule.

Overall it’s an extremely interesting thread to read from a camera assistant’s perspective.