Unfocused Lightning at Infinity

[Tony Laubach]

Here's a question to you lightning photographers...

I'm enjoying a crazy week down here in Arizona and was plagued with an issue tonight. The storms of interest were far enough away where I had to bust out the 70-300mm lens. On the LCD screen, my images looked fine, but when sent to the computer, I noticed many of them were out of focus at lengths greater than 150mm (give or take). With the abundance of shots I took tonight, I was fairly disappointed to see those results. Fortunately the lightning was very vanilla, thus I didn't lose out on any shots-of-a-lifetime.

The camera, a Nikon D40x; the lens, a Nikkor 70-300mm. It was tripoded and I've eliminated motion as a possible cause. Anyone know why at infinity, the lightning bolts were out-of-foucs and anyone have suggestions, experience, or advice on this?

Thanks!!!

 

[Eric Treece]

Not sure if this is the same problem I have had, but I have had similar results with the Canon 20D as well. The best cure I have found so far is to focus on somekind of lighted subject......a town, a lighted billboard, a couple of street lights in the distance......with the autofocus, after the focus is locked on to the object you focused on, turn the AF off, and then shoot the pictures. This has worked well for the most part for me when there was something to focus on. When I am in the middle of nowhere with nothing to focus on, I had the very same results you got. Hope this helps.

 

[Jayson Prentice]

Sometimes I've found that if you move the focus clear past infinity, essentially as far as it goes, that the pictures will still be out of focus. So Eric has the right idea here in find an object that the AF can work on in the distance and set the focus on that. Those zoom lenses are especially touchy with focus distances...

 

[Hank Baker]

With Nikon lenses, if you go all the way to infinity the pics will be out of focus. The way nikon designs their lenses is to leave room for expansion from heat and cold, therefore if you go all the way to the edge on infinity you are actually focusing past infinity, that is why your images are out of focus. I usually put the focus mark right in the center of the infinity symbol. If you focus further than that the pics will be out of focus.

 

[Tom Mitchell]

ditto Hank. Infinity is only infinity at the perfect temperature.

Also check hyperfocal distance on wikipedia...you may want to increase your fstop. That being said, I am terrible with numbers unless they are 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, or 22.