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Monday, August 6, 2018

Blue Grosbeak at Lake Hodges

I found a loudly singing Blue Grosbeak perched out on the top of a laurel sumac at Lake Hodges recently. He gave me a chance to adjust my aperture and see how the Auto-ISO responded. I gradually made my way a bit closer, starting at about 50 feet away and working to perhaps 35 feet. But the size difference in the following shots is due to how tightly I cropped each exposure, not how close I was.

Blue Grosbeak
Canon EOS 7D Mark II, Canon EF 100-400mm f/4.5-5.6 IS USM. 1/2000s f/10 @ 400mm ISO 1250
The bird was close enough to me, and the hill across the lake far enough away that f/10 didn't really make the hillside more in focus as I thought it might. And ISO 1250 is not grainy on this camera, so photo quality was not affected by high ISO.

Blue Grosbeak
Blue Grosbeak. Lake Hodges, California. July 4, 2018.
1/2000s f/7.1 @ 400mm ISO 640
The difference between the first two photos is one full stop. f/7.1 to f/8 is 1/3 stop. f/8 to /9 is another 1/3 stop. f/9 to f/10 is a final 1/3 stop. A full stop is twice as bright (or 1/2). And the ISO dropping from 1250 to 640 is a corresponding full stop.

Smaller in frame crop:

Blue Grosbeak
1/2000s f/7.1 @ 400mm ISO 640
Then I moved sideways and dropped down a bit to put blue sky behind the bird. I increased the exposure compensation one full stop because the bird was fairly dark against bright background. In order not to increase the ISO, I opened the aperture wide to f/5.6 (+2/3 of a stop brighter than f/7.1). Thus, Auto-ISO chose 500.

Blue Grosbeak
1/2000s f/5.6 @ 400mm + 1 stop EC ISO 500
I was disappointed at the number of shots that were out-of-focus, however. The shutter speed was more than fast enough for hand-holding, especially with image stabilization. Perhaps there was some heat shimmer in the air? It was only 8:40 am, though. More experimentation is in order.

Good photos were obtained full open (f/5.6), which is a happy discovery. This same lens on my old camera produced many more in-focus shots stepped down to f/7.1.

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