In this day of automatic everything, have you ever wondered why, perhaps surprisingly, the brightness of the image seen in the viewfinder is not controlled to be directly proportional to the brightness of the recorded image?
There certainly are pre-electronic historical reasons, but it is still a valuable feature. It allows the tracking/capture of an image independently of the chosen exposure/storage. This independence can be used to advantage.
This article reviews a technique to capture moving objects in low-light by under-exposure and then post-processing to recover the image - but without motion blur.
With it, you will be able to show some crisp keeper shots under difficult conditions from your new gear.
My D300s DSLR was a huge step up from my digital point-and-shoot in shutter lag, focus speed, frame rate, viewfinder . . . in every way shooting with my new camera was a joy. I could capture anything. I had good gear, it worked great, and life was good.
I chose an 18-200mm f/3.5-5.6 super-zoom (f/5.6 @ 200mm) because I don’t have the budget for an exotic zoom or a fixed focal-length professional lens - and heck, I was just getting my feet wet with digital after years shooting a film SLR.
Of course, being human, I soon started to expect even more.
Being a bird-watcher it didn’t take long to find tough shooting conditions. Birds hiding in shaded brush and jumping from branch-to-branch are pretty darn hard to capture cleanly.
Most consumer zooms shoot at f/5.6 when zoomed, so that fixes one leg of the exposure triangle. Next, choosing the highest clean ISO for my camera, I am faced with metered shutter speeds of 1/4 to 1/30 of a second in the woods - and lots of blurry bird pictures. Also, forget about hummingbirds in the golden light of dawn.
A note here, your camera may be newer than mine, and your woods brighter than mine. You may get the results you need by increasing the ISO farther than I can, so experiment. And yes, sometimes there is more than one way to accomplish a given goal, but there is a limit somewhere to every camera and lens combination.
The following under-exposure technique is used to accomplish my objective - images to help identify birds in the field - where sharp capture is more important than dynamic range or image noise.
Since 1/4-1/30 of a second shutter speed is just not going to capture a sharp image of a moving bird, the shutter speed must be forced upward. This will result in an under-exposed image - but one without blur.
To force the shutter speed, as you do for action shots, switch from “program” or “aperture priority” to “shutter priority” mode. Then, instead of selecting a shutter speed to give the right exposure, select one fast enough to freeze the motion. That will vary from 1/125 for some subjects to more than 1/1000 of a second for others - experiment.
Ignore the meter which can be showing 2, 3 or 4 stops underexposed at this point.
Here is where you see the advantage of not tying the viewfinder brightness to the exposure of the image.
The viewfinder is still usable for tracking, framing, focusing and shooting - all are unaffected. Be warned that chimping will show a nearly black captured image.
As a bonus, the faster shutter speed may allow the camera to shoot more frames-per-second, and that can help get the right pose to help identify a bird.
Use RAW mode and shoot away . . . and then take the camera back to your computer to develop what you have captured. Reset the shutter speed and any other settings before you forget.
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