I’ve been experimenting with a motorized 2.8-12mm turret camera. It seems like when the camera is zoomed out it has much less depth of focus than a comparable 2.8mm fixed camera. Is this typical for vari-focal lens?
Depth of focus on vari-focal lens
- Thread starter rdagger
- Start date
It would depend on the quality of the optics used in the camera I would say.
I have a few 2.8-12mm and the turret is quiet good I did find when zoomed out near objects would blur a bit and clear beyond the near object but there so easy to set up the shot that you need to record the old ones with the small adjustment stick were painfull to get right easy 30min playing focus in focus out
Depth-of-field (DoF) depends on the lens aperture. The more the aperture the shorter the DoF (but better light sensitivity). In case of fixed lenses you can see the aperture (F-number) in spec. Using all parameters you can calculate and simulate the DoF. In case of ZOOM lens the spec shows maximum aperture. Real aperture with different focus differs. But entrance pupil of motorized ZOOM lens is bigger, in the most positions such lens has bigger aperture and shorter DoF than usual fixed lenses.
Also ZOOM lenses are frequently tested with long focal length (narrow angles). But the longer the lens focal length - the shorter the DoF. The same ZOOM lens with short focal lens set will have much longer DOF. It is optical law.
You can play with the focus distance. The nearer the focus point – the shorter the DOF.
Also ZOOM lenses are frequently tested with long focal length (narrow angles). But the longer the lens focal length - the shorter the DoF. The same ZOOM lens with short focal lens set will have much longer DOF. It is optical law.
You can play with the focus distance. The nearer the focus point – the shorter the DOF.
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