I typically tend to not venture out with my camera when it’s that cold, but it has been known to happen from time to time. One thing I hadn’t experienced when I had been shooting in the cold, though, is random lens softness. So, this video from Steve Perry surprised me a little. He noticed that he was getting very soft images on his Nikon Z9 when shooting wildlife out in cold (single digit °F) temperatures.
And this isn’t just a Nikon issue, either. His wife was having the same problem with her Canon EOS R5. During further testing, he added a Sony body into the mix and that one, too, was soft. Very soft. He was getting the same results with them all regardless of whether it was a Nikon, Canon or Sony camera and lens combo. It turns out that it might actually be a heat issue.
You may not have experienced this issue yourself if you’ve not been shooting really long lenses in the cold. This is probably why I haven’t experienced this issue myself, either. Typically if I’m out in the cold snow in winter, I’m photographing the landscape or a person in the landscape and the longest focal length I’ll use is maybe around 150mm – not even close to the 600mm lenses used in Steve’s tests – and I also usually don’t use a lens hood unless I’m having flare issues.
Steve initially spotted the problem with both the Nikon Z9 with the Nikon 600mm f/4 E lens and his wife’s Canon EOS R5 and Canon EF 600mm f/4L. After coming up with a possible reason, he tested it with both of those combos along with a Sony body and Sony FE 200-600mm F5.6-6.3 G OSS lens. Tests confirmed the suspicions. The lens hood was actually making the images softer.
Steve’s hypothesis, which seems logical, is that the temperature differential between the cold air and the warmer front lens element is allowing warm air (from the lens) and cold air (from the environment) to meet and mix inside the lens hood causing the same kind of issue that causes distortion with long lenses on hot days. The warmer and cooler air will have a slightly different index of refraction and where they meet and mix there’ll be all kinds of different ranges.
He tested with all three systems and with the hood they were all soft. Without it, they were all sharp. So, he suggests either leaving your gear outside to acclimate to the colder temperature before you start shooting so that the heat in the front lens element has dissipated or just don’t use the lens hood – at least early on before your gear’s adjusted to the temperature. The lack of lens hood doesn’t stop the front element from giving off heat (it probably makes it happen more quickly), but the unhindered airflow takes it away quickly enough that it doesn’t cause any issues. In essence, the air inside the lens hood is acting like something of an insulator to slow down the cooling process when it’s attached, preventing the cooler outside air from pulling it away more quickly.
Obviously, Steve couldn’t test every lens and hood combo out there and posits that this might be an issue with some shorter lenses, too, depending on the design of the lens hood and it might not be an issue with some longer lenses for the same reason. But, if you’re facing softness when you’re out shooting in the cold, it should probably be the first thing you check before you try anything else.
Is this an issue you’ve come across before? Did you figure out what was causing it?