CocoaRoger Loc: Cocoa Florida

Last weekend there was an airshow and my first chance to use my D3100 seriously on moving objects. It seemed that almost all of the photos that I zoomed in on are out of focus while those I didn't zoom in completely were much sharper. I'm wondering now if this is more of a question or statement? As an example the of the two images, the fuzzy one is max zoom while the clear one I was backed off of max and cropped in post processing. I was using manual focus because for some reason a few weeks ago, whether I somehow disabled auto focus or it just went south on me I don't know, but I can't use auto focus with either of my lenses.

MT Shooter Loc: Montana

Number 1 looks like you may have manually focused all the way to infinity. At infinity the lens will actually overfocus. The second looks like you focused properly.
Are your lenses the AF-S kit lenses? You may have inadvertantly turned off your AF, I don't know where the control is on a D3100, but it might be something to check.

tk Loc: Iowa

Check the lens. On the side there is a A and M for focus. Putting mine away sometimes the dang fingernail hits it accidentally. That is the first place I look when I have trouble.

CocoaRoger Loc: Cocoa Florida

Yes to both. I know about the A and M switch. When I put it on A the shutter won't open as in it's dead. The lenses don't try to focus at all. I was on a hike and thought the battery was dead so when I got home I discovered it worked fine when I put the lens on manual so I tried my other lens and and it won't auto focus either. So I'm thinking maybe the motor in the camera body is dead, or somehow on my hike I turned something off and disabled it since I am still learning this camera. I've been through the manual, used the reset option to set everything to factory with no luck. As for the focus to infinity I think that might be the issue. But it's pretty much impossible to try to look through the viewfinder at a plane a mile away and try to back off and be able to see such a small thing in your viewfinder and focus it. What I did was take a shot, slightly move the focus and take another, and keep doing that in the hope of getting a good shot but I'd rather be able to do it right and get several good shots. I took over 1800 photos and discounting the static shots which were no problem mabye 50% of the photos of planes in the air are garbage.

MT Shooter Loc: Montana

There is NO motor in your body, that is why you need the AF-S lenses, they have the AF motor in the lens. If your AF functions are all activated then there is a communication problem between your body and lens, it may be mechanical or you may have a firmware problem. You might check the NikonUSA.com site for a firmware upgrade. It cannot hurt.

CocoaRoger Loc: Cocoa Florida

Thanks that's good to know. I just can't figure why both lenses would stop autofocusing the same day unless I switched something off while hiking. They worked fine that day even while hiking. Then suddenly as I said, I thought the battery was dead and didn't think much about it till I got home and just switched it to manual and they both work in that mode but not in auto. In auto, the camera is basically dead like its not even on, nothing happens. So I assumed it was the camera having the motor in the body and it went bad, or I switched off something. I'll do some further checking

docrob Loc: Durango, Colorado

how can a lens over focus at infinity? is there something beyond infinity?

CocoaRoger Loc: Cocoa Florida

I kinda wondered about that too. I've taken photo's of the moon at a quarter million miles and on infinity it's soft until I back off. So if the moon at that distance shouldn't be infinity then just what is???

Jay Pat Loc: Round Rock, Texas, USA

I don't have anything to add, I sure like image #2!!!
Pat

CocoaRoger Loc: Cocoa Florida

It is the only functioning and flying B 29 in the world now. I live near an airport and they were selling rides in it (too expensive for me) but it was really cool to have it fly over the house just a few hundred feet up. Here's a couple of it on the ground at the airport getting ready to take off

Joyfullee Loc: South FL

Were you using the 3-D tracking when this happened?

Edit: That should have been Dynamic, not 3-D, my mistake. Too many things getting jumbled in my brain at the same time. Sorry about that.

CocoaRoger Loc: Cocoa Florida

I was in manual. The camera doesn't work in auto

Joyfullee Loc: South FL

I have the same camera and had this problem when I first got mine, which was extremely frustrating to me, and I too, thought there was something wrong with the camera or lens.

Quote from: Magic Lantern Guides Nikon D3100

"The AF point you select in either Single-Point AF or Dynamic-Area AF can have a profound effect on the camera's ability to achieve autofocus, depending on whether it is a cross- or line-type. For example, the single cross-type sensor at the center of the frame is far more reliable in low-light or low-contrast conditions compared with the line-type sensors, which can often take longer (or even fail) to acquire focus in such conditions."

If you don't have this book, I suggest you get it as it helps tremendously in understanding the ins and outs of this camera.

madcapmagishion

Which AS-S lens were you using?

MtnMan Loc: ID

It is on the lens.