Saturday, March 26, 2011

Hard Stop for Hard Focus

A huge challenge in shooting wildlife telephoto video footage with dslr cameras is the difficulty in attaining precise focus. A number of factors work against you: super-thin Depth of Field, lenses designed for auto-focusing in still photography...NOT manual focusing, moving subjects (frequently), and vibration that always seems to sneak in.

In a previous blog I've described the Cinevate "Franken Medusa" rig that I built up from their basic "dslr core rig". This gave me the ultra-rigidity I needed to eliminate/reduce vibration, along with the carbon fibre Manfrotto 536 tripod/504HD video head which supports this rig. A major plus is the Durus follow focus:

This thing is built like a tank, yet is buttery smooth. Just the thing for heavy duty use in the field for wildlife video-making. It ain't cheap at $1254.98, but I wager it'll outlast many cameras it gets hooked up to!

One little item I ordered along with it is a very simple, but nifty, device -- their hard stop:

These are extremely simple to use. Just pop off the Durus follow focus' white plastic focus-marking ring (easy - it's held on by a magnet), then screw this hard stop on. Actually, I ordered two which comes in handy when you want to repeat near-to-far-to-near focusing over and over. Another big advantage to these hard stops is that you can keep an eye on your subject (through viewfinder, external monitor, or even just eyeballing) while you bring it into focus -- so long as your subject stays in place while doing so (ie. sitting/perching/eating etc.).

Here's a little video I made demonstrating the advantages of easily adjusted hard stops:

Wednesday, January 5, 2011

Glass vs Digital Zoom

This morning I was shooting a double video with my Cinevate FrankenMedusa rig. Up top I had a Canon 5D Mark 2 with a Canon 135mm mounted, and below a Canon 7D with a rather elaborate telephoto setup of a Canon 100-400mm zoom lens with two stacked Canon teleconverters: 2.0 and 1.4. Factoring in the 1.6 crop factor of the 7D and the equivalent focal length of all this glass on the 7D totals up to 1,792mm!

However.....when I was aligning the upper and lower cameras using a distant hydro tower as a reference target, I was a little startled to see that the 5D/135mm was showing a clearer image in the LCD when multiplied by 10x than the straight 7D LCD image at 1,792mm. Hmmmm. I shot some footage with both cameras and got the results here:

Telephoto Glass vs Digital Zoom from David Rilstone on Vimeo.

As I mention in this video, the heavy glass gives a much sharper image than the short 135mm glass getting jacked up by 600% in post.