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Best Lenses for DSLR Video (Parfocus Lenses)

posted 5 Dec 2012, 09:42 by Ben Edwards   [ updated 7 Dec 2012, 09:55 ]
Years ago was taught how to focus when shooting video, I have come across many people who also use this method and it is generally accepted as THE way to focus.  You choose where you want to focus (for a person it is generally the eyes), you zoom in to maximum and you focus. Then you zoom out and frame the shot.  This is because as you zoom in the depth of field becomes shallower (smaller) and focusing becomes less forgiving.  This means if you are focused when zoomed in you will be focused through the hole zoom range.

All great, accept for DSLR (stills) lenses this does not work.  This is because for it to work the lenses must hold the focus throughout the whole zoom lenses and for most stills lenses this is not the case.  Lenses which maintain focus throughout the zoom range are called parfocul lenses.  Professional video lenses are parfocul. Most of these need to be set up through a process called back focusing to calibrate the parfocus.   Cameras such as the Sony Z1 are parfocus but rather than doing this mechanically/optically (and using back focus) cheat the system by having a servo motor in the lens that adjusts to focus as yo zoom.  If this is officially parfocus I don't know (or care much) but works.  Well works most of the time, The reason I know about the servo is that my Z1 went wrong and the servo had to be replaces (luckily it was under guarantee but this would be very expensive) so there is a downside the this phudo-parfocus, i.e. it can go wrong.

So that the background, the real question is which lenses are parfocus, I use canon so will concentrate of Canon fit lenses. 

It should be noted that unless all your work is on a tripod for all lenses (apart from wide angle) you need image stabilization (IS) so I will mark these bold.

It should also be noted that as well as parfocal the lenses should also be consent aperture (i.e not have a range like f/4-5/6) as this means that the exposure will change as you zoom, whit will make the video unusable).

Canon Brand Lenses

It should be noted that Canon does not officially state that any of there lenses are parfocus, however people have found that the following are.

Canon Parfocal (EF)

EF 17-35mm f/2.8L USM *
EF 16-35mm f/2.8L USM
EF 17-40mm f/4L USM
EF 20-35mm f/2.8L *
EF 24-70mm f/2.8L USM
EF 24-105 f/4L IS *
EF 28-70mm f/2.8L USM *
EF 28-80mm f/2.8-4L USM  *
EF 50-200mm f/3.5-4.5 USM *
EF 50-200mm f/3.5-4.5 *
EF 70-200mm f/2.8L USM
EF 70-200mm f/2.8L IS USM
EF 70-200mm f/4L USM
EF 70-200mm f/4L IS USM
EF 70-210mm f/4 *
EF 75-300mm f/4-5.6 IS USM
EF 75-300mm f/4-5.6 III USM
EF 75-300mm f/4-5.6 III
EF 75-300mm f/4-5.6 II USM *
EF 75-300mm f/4-5.6 II *
EF 75-300mm f/4-5.6 USM *
EF 75-300mm f/4-5.6 *
EF 80-200mm f/2.8L *
EF 90-300mm f/4.5-5.6 USM
EF 90-300mm f/4.5-5.6
EF 75-300mm f/4-5.6 IS USM
EF 75-300mm f/4-5.6 III USM
EF 75-300mm f/4-5.6 III
EF 90-300mm f/4.5-5.6 USM
EF 90-300mm f/4.5-5.6 
EF 100-300mm f/5.6L *
EF 100-300mm f/5.6 *

* = discontinued

EF-S (close to parfocal)

EF-S 17-55/2.8 IS USM
EF-S 18-135mm f/3.5-5.6 IS STM

No parfocal, or even close

EF 35-350mm F3.5-5.6 L USM
EF 100-400mm F4.5-5.6L IS USM


Sigma 17-50mm f/2.8 EX DC OS HSM FLD

Olympus (need EOS Adapter)

Olympus Zuiko 35-70 F3.6
Olympus Zuiko 35-70 F4

Olimpus Zuiko Zoom 75-150mm F/4


11-17 ??

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