Quick background..........I have always wanted to get some good shots while snow was falling. Well, yesterday was my first attempt at this type of photo.
mk3 w/600, no sun, snowing relatively hard, and breezy
I had two issues
1) the cam had issues aquiring focus lock (NEVER have this issue normally)
2) the out of focus snow has "donuts", not very pleasing to me visually
I figured you to be at the nest yesterday. Glad you could, Al I think the donuts could actually be on the water spots on the front glass. With that wind somehow they got past that big hood and became specular highlights. There are white dots that appear to be snow spots sharp and clear.
Are these any less intense with less sharpening? I do think it is snow on the front element.
Hi Karl.........yea, I had the same thought when I originally previewed the pics in camera, snow on the lens. But, I was very careful in keeping snow off of the glass, checking regularly. They show up promently in the raw files before sharpening.
Donuts are a product of the lens's characteristics when rendering specular highlights out-of-focus ("bokeh"). Something to consider: even if you are familiar with how your glass renders highlights in the background, a lens's bokeh will be different for images in front of the plane of focus (as these seem to be). Your only option may be to photoshop the objectionable bits -- easy enough to do.
Also, frankly, these donuts aren't so bad. If you look at some of them, they only have a very faint ring at the very edge of the circle (perhaps a sharpening halo?) The weird ones are the reverse donuts: brighter in the *center*. I've never seen that before.
I think you have to test this lens a bit more, to figure out what precisely is producing this effect.
That image *is* in fact oversharpened. It would be interesting to see how those circles look with very little sharpening applied. (The outer edges of the eagle, in particular, are jagged, with halos -- as are the beak and eye. I suspect that this has affected the snow as well, making the defects more prominent.) Also, try using the blur tool, selectively, on the snowflakes -- might make a huge difference.
Hugely preferable. In fact, that's pretty nice bokeh. The only circle that still looks weird is the large one, about two-thirds of the way up, slightly to the right: the one with a bright dot in the center. And who knows where that came from -- light can do odd things. The rest of the circles just look like snow, to me. Unfortunately, as Karl pointed out, they could also be mistaken for water droplets on the lens -- but that's probably unavoidable: snow simply looks like that.
The picture also works better in lower contrast -- since that's what you expect of a bird flying through a snowstorm. (I mean, you probably want to pump up the contrast somewhat -- which should also help cover the chromatic aberration on the trailing edge of the wing -- but it's a nice snowy picture...)
