Variable focal length with electronic focus assist — shift focal length without moving the optical bench. Niche but invaluable for tight rigs and real-time adjustments.
When you need to work in the tightest spaces — an airplane cockpit, an elevator, a cramped interior — and simultaneously want to switch flexibly between wide-angle and medium telephoto without shifting the entire lens rail, the Dynalens lands on the equipment plan. It's a lens with electronically controlled variable focal length and integrated focus assistance, enabling classic zoom changes with significantly less physical space requirement.
The system works via controllable lens element groups that are electronically shifted — not mechanically like with classic zooms. The focus operates in parallel via autofocus or manually with live feedback. The big advantage: you pack less hardware into the same space. Instead of two or three prime lenses with lens changes, you can use one Dynalens with its continuous focal length range. This saves not only space but also time when changing focal length — crucial when the camera is rolling or you need to remain flexible in a live interview.
In practice, this means: the focus assistant sits next to the camera and adjusts the focal length electronically while you concentrate on framing. Modern Dynalens systems communicate via 3D LUT and autofocus tracking, especially with moving subjects. You lose minimal optical sharpness compared to high-end primes, but gain considerable setup flexibility.
However: Dynalens is not standard. You'll find them at specialized rental houses, mostly for documentary work or high-budget corporate assignments. The electronics make them temperature-sensitive, and a failure is expensive. For tight setups with live-action requirements, the research is always worthwhile — but factor in the technical support. With the right focus puller, the Dynalens becomes a real time-saver, especially when space is tighter than your daily budget.