Contrast and Focus

Two Saturdays ago, I had the opportunity to pull over at a small pond on the Snake River at Marsing, Idaho. I had noticed there often was a Great Blue Heron there, and I wanted to try photographing it. I spent maybe half an hour there photographing it fishing. Then I went on up in the Owyhees, after stopping at the White House for a burger. I could have fun with that name, like “I’ve eaten at the White House several times,” but suffice to say, the White House in Marsing is a small drive-through with indoor and outdoor seating as well. They have good burgers and great shakes.

Anyway, from there I went up in the Owyhees and found a spot that in the intervening three years I’d forgotten how to get to. Having found it again, I made sure I grabbed a GPS position. I also shot two panoramas of the site, one at 80mm and the other at 200mm, intending to use them to verify locations and angles before I return next time. This is where I plan to try a night shoot on July 4 as from that location I can see from beyond the far east side of Boise, Idaho, and all the way west to Ontario, Oregon. I’d gone there several times for astrophotography and this time I want to set up and do a panorama while the various cities in view do their Fourth of July fireworks. I’m hoping they’ll be visible enough and more importantly discernible enough to have a panorama with long exposures for capturing multiple fireworks at each location. That’s the plan, anyway. We’ll see if it comes out as I visualize it. They never seem to, but I keep trying!

When I got home and examined my pictures of the Great Blue Heron, I was disappointed. As far as I was concerned, every image was too blurry to be worthwhile. I determined to return to the pond Sunday and try again, this time with the intent of getting the images nice and sharp.

Sunday, I spent over an hour at the pond and I had a bonus: not only was the Great Blue Heron there, but so was a Great White Egret. I knew the heron frequented the pond and I’d seen an egret there once in a while, so I was really pleased with that bonus opportunity.

For this session, my ISO was locked to 100, initially a coincidence but left alone when noticed, thus eliminating that as a variable. I elected to bracket every shot and I was shooting RAW for maximum post production capability if needed. I was using 200mm f/6 – f/8, which is the upper end of that particular zoom lens. I wanted the focus at a specific point, so I was using spot focusing and spot metering. With these parameters, I felt that I should get at least some good shots, nice, sharp, and clear.

Long story short, I discovered that in this particular situation, “t’aint necessarily so!” I was using the Program mode, and focusing on, well, focusing. Through the viewfinder I would swear I was getting good focus, yet when I examined the photos at home full size, out of about 189 images, only 8 or so were suitable for sharing. And those weren’t necessarily as sharp as I’d wanted. Also, especially with the egret, the whites of the bird were often blown (over-exposed), leaving those areas with no detail at all. No doubt that was partially due to the clear noon skies.

Struggling to understand what happened, when I showed them to my wife, her comment made things immediately understandable. Looking at the images, she said there was “very little contrast.”

Most, if not all, digital cameras focus by identifying areas of contrast and bringing those into sharp focus. In virtually every shot of the Great Blue Heron and Great White Egret, I had focused on their breast or wing…with spot focusing there is precious little contrast in those areas. In the case of the egret, being completely, brilliantly white, there was NO contrast. Ergo, my camera wasn’t able to autofocus the way I needed it to.

Compounding the problem, I couldn’t use a trick of focusing elsewhere where there was good contrast at the same distance then taking the shot of the bird because the bird was moving around. That meant the distance to which I needed to focus was constantly changing. There were times when the bird would stand still, but I never knew from moment to moment how long it would remain there.

So, why didn’t I switch to manual focus? At the time I didn’t fully realize the issue I was facing. In addition, when I checked the first few images in the LCD on the back of the camera they looked good, even zoomed in somewhat. Yes, I know better than to rely on the LCD, but I clearly wasn’t thinking. More to the point, though, I wasn’t confident in my ability to quickly manually focus nice and sharp, better than the camera’s autofocus, on such short notice. I’ve not practiced manually focusing my lenses on anything other than still subjects or subjects I can pre-set the focus for. Also, at the range I was shooting, my depth of field was shallower than I realized.

Despite the pictures, I learned from them.

I enjoy photographing birds because they are extremely challenging, pushing my skills and knowledge. But, man, they can sure be frustrating!

Naturally, I’m going back out soon to try again. I want to try focus trapping and see if that helps. I want to try using full scene focusing and metering and see how that makes a difference. I might push my ISO up, say around 400, and see if a higher shutter speed than the typical 1/350 or so I was using would make any difference. Maybe 1/1000 or thereabouts?

It’s nice having a spot where I know there’ll be a Great Blue Heron most of the time and a Great White Egret every so often. They make great experimental subjects and I can get in reasonably close.

The problem will be when I get back out in the Owyhees and start trying to use the 400mm on soaring hawks and turkey vultures. They move faster than a fishing heron or egret.


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