Making zoom smoother?

Discussion in 'Video' started by Gary Naka, Apr 11, 2019.

  1. One of my students was complaining about how jerky the zoom looked, on the school's Canon T7i and 18-135 lens.

    For video I can see that most zooms are just not up to the task of smooth zooming for video. The zoom ring on some are so stiff that I have to grip the zoom ring with my hand and use my arm to turn the zoom ring. How the heck do the lens manufacturers expect people to use the zoom for video? It seems practical only to zoom between video shoots, and only shoot video WITHOUT zooming.

    Anyone have any tricks to make zooming smoother, so the kids can zoom while shooting video?
     
  2. I think that when they were new, most zooms were pretty smooth. The problem is that zooms and other telephoto lenses sometimes were made with a sort of cosmoline-like white 'grease' (lithium, probably) that hardens over time, and especially if not used frequently.

    Naphtha or some other spirit will often thin the out with some working of the item. However, it's very easy to get too much spirit into the lens and then things you don't want will get into other areas of the lens.

    The best way is to take the lens apart and clean, BUT be warned that it is not easy to put zooms together again. Local craftsmen here won't tackle zooms.

    New quality lenses are the least frustrating way to go.
     
  3. Sorry, these are current production lenses that we are using.
    The Canon 18-135 is less than a year old, from purchase date. This one does not stick, so much as it is not smooth/easy to turn, plastic on plastic feel. They can't zoom the lens without moving/shaking the camera.
    The Sigma 17-50/2.8 is even newer, and the worst of the bunch. Plus a very short zoom throw, so very hard to accurately zoom the lens.

    I'm thinking back to how easy it was to zoom my father's super 8 camera.
    But that was an internal zoom, and smaller format, so smaller lens vs. the 18-135 and 17-50 which are extending zooms and larger lenses.

    The inability to zoom while shooting makes me think back to my father's 16mm film camera with 3 lenses on a turret.
     
  4. Gary Naka likes this.
  5. I currently shoot video using FF cameras (Sony) with standard lenses. It is nearly impossible to zoom smoothly in real time by hand. Not only is the zoom action rough, but handling on the lens causes it to move, and even a little movement is objectionable in the video. There are motorized zoom lenses, but very few to choose from, and they tend to be expensive, with limited reach. I have a Sony PZ 28-135/4, which is very nice to use, but not long enough for what I need. A sony 100-400/4.5-5.6 is nearly ideal as a closeup camera at balcony distance, equivalent to 600 mm in Super-35 mode.

    While not the cheapest solution, a focus/zoom geared motor is arguably the best, and can be adapted to any zoom lens using flexible gear strips on the zoom ring. The motor can apply a lot of torque, which can displace the lens. To avoid this, everything must be rigidly mounted - the motor on 15 or 19 mm rods, and the camera itself. I use RRS Arca-style QR throughout. It also helps to zoom no faster than necessary. That said, you can slam zoom between shots if you have a b-roll camera to cover the transitions. There is no lag, the controller operates 1:1, and is easily modulated

    I chose an Ikan mini single motor kit, with a wired controller. There are Bluetooth and WiFi setups, but wired is less expensive, less fussy, and can be powered with a 14v D-Tap battery. Non-wired units use internal batteries, which may not have enough charge to last through an afternoon. Setup is easy. Once connected, press and hold a button on the controller or motor, and the motor will automatically determine the rotation stops. You can also set arbitrary stops manually, so the zoom (or focus) will have a pre-defined range.

    I use this setup with other lenses too, including a 70-200/4 and 16-35/4, and for focus with Loxia manual lenses. It's easy to set up cinematic focus shifts.

    ikanPD Movie Remote Live 2 Compact Follow Focus Control Kit
     
    Last edited: May 22, 2019

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