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Tip of the Month

Using high ISO and Live View
for focusing in dim light

March-April 2010

mottled owl

On our last day in the field in Costa Rica we did a night walk for macro subjects, and while doing so we spotted a mottled owl perched about 30 yards off in the jungle. It was a misty night and our headlamps and flashlights' beams were muted by the moisture or steam floating in the air. I ran back for my 500mm and when I returned the bird was still there.

Unfortunately, in the excitement of trying to get a shot I wasn't thinking as clearly as I should have. We goofed up with the flashlight, thinking we had the beam zoomed tightly when it wasn't, and the lights we had on the bird were barely enough to discern the bird.

I was using my 500mm and a Mark IV camera, and try as I might I couldn't get the lens to focus in the dim light on the bird. A couple of times I came close, but each image was blurred. One of our participants had a bit more luck focusing in the dim light and got a shot, but I couldn't.

In desperation I tried going to Live View, hoping that my steamed up glasses wouldn't be an issue when I was looking at the LCD monitor rather than through my eyepiece. But that worked even worse, and I saw virtually nothing through the monitor. Evemtually the bird flew off into the blackness of the jungle, and I returned to my room, frustrated by my ineptitude.

Later, I came up with a solution that I thought might work. Had I raised the Mark IV's ISO to its highest ISO I may have had enough sensitivity to the light to see the owl. Certainly, had I also dropped my shutter speed down to 1 second or longer, the LCD monitor would have picked up the image. Then, using Live View, I could have focused and fired and, checking the resulting image with the zoom loupe, I could have fine-tuned the focus and tried again.

When I returned home, I tried this experiment, using the same light that I shone upon the owl. Changing the ISO to a higher ISO did increase the view-ability of the LCD monitor, but it didn't brighten incrementally brighter as I continued to raise the ISO. The monitor, and the picture, got brighter, but it never got really bright, even when I changed the shutter speed and lowered it to 30 seconds.

Nonetheless, in low light situations the Mark IV's high ISO and Live View may give you enough light for focusing. In this way, the camera can function like a night vision scope, giving you a chance to focus. You can then tweak the focus, or at least confirm whether or not you are in focus, by reviewing the shot and, if necessary, using the zoom button to increase the magnification of the image on the monitor. You could also use the zoom button for the LiveView image, and tweak from there, too. After achieving focus, you can then drop the ISO to a less noisy ISO, raise the shutter speed to one where ambient light won't play a role, and fire away.

I must admit that I was a bit disappointed that my full theory -- using LiveView, a very high ISO, and very long shutter speeds, would combine to create a very bright image on the monitor. There was a shift in brightness when I switched to a low ISO to a very high, but it was as if the monitor went from a 'normal' mode to a 'sensitive or abnormal' mode, and was not incremental. I think Canon, and other manufacturers, should think of doing so, and in doing so allow photographers to really focus in low light -- if they follow the above technique.

At any rate, I do have a new tool in my kit, and next time, I'll get that mottled owl.


Previous Tips, July 2009 onward

Art Print Scams for Hungry Photographers
Hungry Vultures ruin vehicles in the Everglades

Use a Short Lens for Depth of Field

Get Professional Help!

Mini-Molar Bag
Access America Trip Insurance
Bogen Base for Macro Work

Archived Tips of the Month
prior to July 2009
Most of my original Tips of the Month for the last several
years are available through this link. The 'look' is from my
original web site, although if I ever have enough time I might redo these pages to match the new web site But that's not a high priority.