Although a wide variety of lenses can be adapted for use with Lumix DSLRs, most still photography lenses have subtle drawbacks that make them less suitable for video shooting, regardless of the quality of the images they can capture. In order to shoot consistent, production-quality footage, it's often desirable to mount a DSLR and lens on a rig that provides traditional movie camera features:


* Stabilization and control of camera movement
* Matte box shading of camera lens
* Direct, tactile control of lens aperture
* Follow focus control of lens focus


Lenses that adapt well to these requirements will possess a combination of subtle features that are often omitted from manufacturers' data sheets and overlooked in published reviews. While vintage lenses provide full manual controls, their compact, old-school design often makes them unsuitable for use on a rig. At the other extreme, modern trends in auto-focus lens design have eliminated a number of manual lens features that remain essential to videographers. In many cases, the most usable lenses for video come from early generations of auto-focus lenses that combined vintage manual controls with modern lens design.

Here's my list of features that make a lens video-friendly:


* Manual aperture ring
* Direct-coupled focus ring
* Proper focus ring rotation
* Non-rotating outer barrel (internal focus)
* Non-extending outer barrel (internal zoom/focus)
* Constant field of view
* Constant f-stop aperture
* Rotational zoom ring


While few lenses possess all the above features, a good video lens will make up for any deficiencies with solid performance in other aspects.

* Manual aperture ring

Lenses that lack a manual aperture ring are problematic for video.

Vintage manual-focus lenses all have manual aperture rings, and most can be set to an auto-iris mode for in-camera control of aperture in shutter-priority mode. Many auto-focus lenses have eliminated the manual aperture ring, relying entirely on camera controls to set aperture in manual mode. This includes all Lumix, Zuiko Digital, Canon EOS, and Nikon G-type auto-focus lenses, as well as most currently manufactured lenses by Tokina, Tamron, and Sigma.


* Direct-coupled focus ring

Lenses with an electronic focus ring are problematic for video.

While all auto-focus lenses can be manually focused, not all of them are truly manual. The focus rings on Lumix, Zuiko Digital, and many Sigma HSM lenses are not directly coupled to the lens' internal focusing mechanisms. As a result, their focus rings continue to rotate uselessly beyond max and min focus limits. Lenses like this cannot be used on rigs with follow focus attachments, since focus ring position is completely uncalibrated.


* Proper focus ring rotation

Lenses with contrary focus ring rotation are problematic for video.

When mounted on a rig with a follow focus attachment, the focus ring rotation of the lens will determine the rotation direction of the follow focus wheel. Regardless of which side of the lens the FF wheel is mounted on, it's important that focus-pulling direction be consistent among all lenses used on the rig.

With Lumix, Zuiko, EOS, and Sigma lenses, infinity focus is at the counter-clockwise end of focus ring rotation. With Nikon and Pentax lenses, infinity focus is at the clockwise end of focus ring rotation. Tokina, Tamron, and Samyang/Rokinon lenses are usually built with the appropriate focus ring rotation for each type of lens mount. Sigma lenses, however, always rotate in the Lumix direction, regardless of the lens mount. For follow focus use, I prefer lenses that rotate in the Nikon direction because it pulls focus closer as I rotate the FF wheel toward me.


* Non-extending outer barrel

Lenses with an extending outer barrel are problematic for video.

Most zoom lenses, both manual and auto-focus, are designed with outer lens barrels that extend when the lens is zoomed and/or focused. While the barrels on most vintage prime lenses do not rotate, they usually extend when focused. A lens whose length changes can be awkward to use on a rig with a matte box.


* Non-rotating outer barrel

Lenses with a rotating outer barrel are problematic for video.

Most vintage zoom lenses are built with the focus ring on the outer lens barrel. This causes any attached lens filter to rotate as the lens is focused, making these lenses unsuitable for use with polarizer and anamorphic attachments. Most modern auto-focus lenses use internal focusing mechanisms that avoid these issues.


* Constant field of view

Lenses that breathe noticeably while focusing are problematic for video.

The focal length of almost all lenses will change slightly as the lens is focused. This effect, known as "lens breathing", alters the framing of a shot when pulling focus, making the lens appear to zoom as well as shift focus. This can ruin a shot if it is noticeable enough to be distracting.


* Constant f-stop aperture

Lenses with variable f-stops are problematic for video.

On many zoom lenses, the actual aperture will vary when the lens is set at its widest f-stops. This will cause zooming at wide f-stops to visibly affect exposure settings, which can ruin a video clip.


* Rotational zoom ring

Lenses with push-pull zoom rings are problematic for video.

Virtually all modern zoom lenses use individual focus and zoom rings. Many vintage zoom lenses were designed with a combined zoom/focus ring which zooms by sliding along the length of the lens barrel. Lenses like this are usually impractical to use on rigs with follow focus attachments.


In the next post I've reviewed a list of video-friendly manual-focus lenses that I've found well-suited for use with Lumix DSLRs. In addition, you can find a list of auto-focus zoom lenses for Lumix DSLRs at the following link:

http://www.personal-view.com./talks/discussion/859/video-friendly-lenses-for-lumix-dslrs/p5