Production Clips: Selecting lenses

When the time comes to choose a lens for your broadcast or pro video camera, it can be tempting to look for a “magic bullet”: one piece of glass that does everything you need and nothing you don’t, all at the right price.
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When the time comes to choose a lens for your broadcast or pro video camera, it can be tempting to look for a “magic bullet”: one piece of glass that does everything you need and nothing you don’t, all at the right price.

However, reality is rarely so streamlined — with the increasing sophistication of lenses comes a constantly widening range of choices and decisions. Fortunately, if you do a little advance research, lens selection can be an accurate and efficient process that will have a positive impact on the entire production chain.

First, determine your budget. If you only have a certain amount of dollars to spend on your new lens, or it’s slated for an under-$10,000 camera, the field of appropriate choices will narrow immediately. The good news is that the dramatic increase in quality and features in pro video lenses has created new options for buyers on a tight budget.

Next ask yourself what the lens will be used for: Will it be for broadcast news, sports, documentaries or something else entirely? Assuming quality and specifications are the first concern, start by examining your HD needs. If you’re currently shooting in SD but expect to be using an HD camera in the near future, then HD lenses (which are also fully compatible with SD cameras) should receive serious consideration.

An important decision for SD shooters is whether or not to get a switchable lens capable of shooting in both the 16:9 and 4:3 aspect ratios. If you’re in the 4:3 world and 16:9 is on the horizon, a switchable lens provides a flexible solution for a switchable camera.

The issue of switchable lenses is a complex one, and contacting a lens manufacturer can go a long way towards simplifying it. All told, there are three categories of portable lenses to choose from — standard focal length, telephoto focal length and wide-angle focal length. It’s a cliché, but “wide” and “economical” usually don’t appear in the same sentence. Widening a lens while keeping image quality high is a more costly process, but for situations like interviews or documentaries, wide angle is often essential. Going super wide in a 2/3” camera, such as a 4.5mm spec, isn’t possible in pro video, but if the pro video 6.5mm spec works for you, then the latter may be a good compromise.

If a standard lens, say 16X telephoto with an 8mm (16x8) wide angle isn’t enough and more telephoto is your priority, portable zooms can come in sizes ranging from 21x7.8 all the way to 40x14. Again, what’s right depends totally on the application – sports and newsgathering will probably require more telephoto power, while studio newsroom use calls for less. In broadcast grade, the 2X extender is standard on all lenses, but in pro video it becomes an option worth some thought. If you’re only going to need more telephoto once in a while, a front-mounted teleconverter for an additional 1.5X focal length increase is a less expensive option, but it also adds weight.

Sometimes a lightweight telephoto isn’t telephoto enough, so bigger zoom lenses must be considered. These could range from 40X portable (not hand-holdable), all the way up to the box-style 86X lens.

By going through the above checklist and thinking about budget, specifications, HD and SD, switchability, and telephoto and wide angle issues, the lens selection process can become much simpler. Once you narrow the field from a possible 15 or more lenses down to a more manageable two or three, you’ll find the right lens on your camera.

Gordon Tubbs is assistant director for Canon Broadcast and Communications.