I've recently acquired a couple of telephoto lenses, a Canon FD 100-300 f/5.6L and a Nikon 180 f/2.8 AIS, and both of them exhibit a strange pattern on the images, especially when stopped down. I've seen this on both the Canon and two copies of the Nikon, so it's not just an adapter issue, or a single lens issue. And I have no filters on the lenses, BTW. Here's what it looks like, a shot of the clear sky with the Nikon at f/22, with the contrast boosted in Lightroom to exacerbate the condition. Has anyone seen anything like this, or have some idea what might be the cause?