Focus issues...me, equipment, or paranoia?

Started 6 months ago | Discussions thread
doonie Senior Member • Posts: 1,462
Re: Focus issues...me, equipment, or paranoia?

Cakeshoppe wrote:

If there are focus issues here, they are being masked by atmospheric haze. The distortions in the rock surface in your puffin picture are a dead giveaway for heat haze. Heat haze is most often caused by significant differences between ground and air temperature, so rocky surfaces that soak up the heat are especially prone.In your puffin image, you have probably 100 feet of hot stone between you and the puffin radiating heat into your FOV. Your Tern and Gull images both appear to be at closer range, and with vegetation tempering some of that heat. Unfortunately, there's not much you can do for heat haze, aside from waiting for conditions to improve (a breeze to pick up, a period of cloud cover, waiting until evening). If possible, getting closer to your subject puts less air between you and your subject, minimizing distortion.

Stopping down to f/8 will also give you a little help. With that kind of pixel density, I'd treat your shutter speeds the way that you would for a crop camera (multiply your shutter speed by 1.5 when using the 1/f rule), but you're probably alright around 1/1250 to 1/2000.

+1 Heat haze is a shot killer ! When i reviewed these on my LCD I couldn't believe how soft they were. I was sure I had nailed the focus. And my D500 and Sigma S were on a Gitzo tripod with full Wimberly. Turns out it was heat haze and it's not something you can always see with the naked eye. There was rocks and sand between me and the bear.

As far as the OP goes, trying to come to any conclusion from that Puffin shot taken from too great a distance is futile. And the label tests are also inconclusive because of what the OP admits to being less than ideal conditions. If you're trying to conduct a test for sharpness and you are admitting that your setup is windblown and wobbly, what's the point ?

Every lens, especially long lenses, contain a learning curve. No matter what your level of expertise. Keep shooting, keep practicing, results will get better.

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