Focus problems

Hiddendragon02 · Jun 18, 2015

Hello,

I have been taking pictures for years, mostly of wildlife, but I have never learned to use the advance functions of my camera (Nikon D3100). In the winter I took a beginning photography class to learn more about it. The problem is that during the class we changed many settings on our cameras, and ever since that class I feel like a much larger percentage of my photos are out of focus. I know it has something to do with some setting I changed, but I can't figure out what it is. I can take photos of a rabbit sitting 10 feet away and half of them will come out blurry. It seems like the camera is constantly refocusing even when I'm holding it relatively still, and I think that's the root of the problem. Can anyone give me advice of what setting I may have changed and what it should be?

AceCo55 · Jun 19, 2015

Check to see if your focus mode is set to AF-C (continuous-servo focus when shutter is half pressed. Keeps refocusing - great for subjects that are moving) or AF-S (single-servo focus. Locks focus when shutter is half pressed and does not change even if subject moves. Great for stationary subject).

Also check to see if you have shutter release set to take the photo:
* only if focus is acquired (locked on)
* regardless if focus is acquired (locked on) or not
(see manual for this)

You could also reset the camera back to factory settings and start again (see manual for how to do this).

Hiddendragon02 · Jun 19, 2015

Thanks. I'd been going back and forth between the AF-C and the AF-S trying to figure out which one worked better. Knowing your camera is good advice, and that's what they taught us in class too. The problem is the class was in the winter and I take almost all of my photos in the summer so I already forgot half of what I learned.

wfooshee · Jun 20, 2015

Which one works better depends entirely on what you're doing, and whether your subject stays in the same general area of the viewfinder. Non-moving subject, steady camera, AF-S every time. Subject moving across the frame, I'd still stay with AF-S. Subject moving towards you or away from you, AF-C.

There is also a very significant difference in AF-C capabilities between camera lines. The D3100 has an 11-point AF system, which covers a wide area of the viewfinder, but not continuously. The sensors have large areas in between them, and if your subject is not on a sensor, then AF-C can't stay with it, and AF-S can't even find it. When I upgraded from a D5000 (11-point AF) to a D7000 (39-point AF) I was amazed. When I first read the description I was asking myself, why the heck do you need, or even want, 39 focus sensors??!?!?! Well, I can tell you now: AF-C actually works when you have enough sensors to cover the frame.

I NEVER got satisfactory results with AF-C on the D5000, and it's almost never missed on the D7000. The 11-point AF system is a limitation of the D3100 that you simply have to be aware of, and work around it. Most of the frame is simply not sensed by the AF system.

astroNikon · Jun 20, 2015

Focus Mode is page 38 & 55 of your manual
you can see it in the middle far right of the rear screen as M, AF-C AF-S

- you press the Info button on the bottom left of the rear of the camera
- use the multitool (round button on the right I assume) to select the focus mode on the monitor
- press OK to get selection of options,
- highlight an option then select OK

you have
1 - AF-S Single Servo mode
2 - AF-F Full automatic mode
3 - and M Manual mode

then you select the AF-area mode of (not selectable in M mode)
a- Face Priority
b- Wide Area
c- Normal Area
d- Subject Tracking

it's different from the upper end bodies how this is selected and what options are available. Read your manual for more details.

d3100 Manual ==> http://cdn-10.nikon-cdn.com/pdf/manuals/noprint/D3100_ENnoprint.pdf

Hiddendragon02 · Jun 20, 2015

wfooshee said:
Which one works better depends entirely on what you're doing, and whether your subject stays in the same general area of the viewfinder. Non-moving subject, steady camera, AF-S every time. Subject moving across the frame, I'd still stay with AF-S. Subject moving towards you or away from you, AF-C.

There is also a very significant difference in AF-C capabilities between camera lines. The D3100 has an 11-point AF system, which covers a wide area of the viewfinder, but not continuously. The sensors have large areas in between them, and if your subject is not on a sensor, then AF-C can't stay with it, and AF-S can't even find it. When I upgraded from a D5000 (11-point AF) to a D7000 (39-point AF) I was amazed. When I first read the description I was asking myself, why the heck do you need, or even want, 39 focus sensors??!?!?! Well, I can tell you now: AF-C actually works when you have enough sensors to cover the frame.

I NEVER got satisfactory results with AF-C on the D5000, and it's almost never missed on the D7000. The 11-point AF system is a limitation of the D3100 that you simply have to be aware of, and work around it. Most of the frame is simply not sensed by the AF system.

The problem for me is that almost all of my photographs are of wildlife. One picture might be of a bird sitting still in a tree and the next of a heron flying across a lake. I don't have the time to be switching my settings back and forth, especially if the subject appears suddenly and I need a quick shot. I need one setting that works in most situations. Under Focus Mode my choices are AF-A, AF-S, AF-C and MF. AF-A claims to select the best choice, but that's what I was using most recently and it wasn't working well. Under AF Area Mode I have a choice of single-point AF, Dynamic Area AF, Auto-area AF and 3D tracking. I try the combinations that sound like they should work, but they aren't working well. Whatever I had it set on before my class worked well, but I can't figure out how to get back there. Currently I'm trying AF-S with single point AF. I'm going to Florida next week and want to figure this out so I don't get home and find out that 2/3 of my photos are out of focus.

astroNikon · Jun 20, 2015

try AF-C single vs AF-S Single those are the two I find most valuable.

wfooshee · Jun 20, 2015

AF-C 3D is theoretically your best choice, as it should lock on the subject and follow it if it moves around the frame. The issue is the lack of focus points actually adjacent to each other. It's quite easy for the subject to be in between focus sensors, in which case the system goes to the background.

Dynamic area mode selects the best focus, not necessarily the focus you want, and it's nearly useless in your situation. It "lights up" all the sensors and picks the one with the sharpest available focus.

AF-C single-area would work as long as you subject stays centered; not always practical.

AF-C 3D starts with a single sensor (you can select which one, I think, but I don't know how on the 3100 - on my camera it's the cursor buttons) and tries to follow the subject. If there's not enough contrast between the subject and the background (certain animals against trees, for example) it will have difficulty following.

There is also a setting somewhere for use during 3D tracking AF for how long the camera must wait to make a large change in focus. In other words, if the subject moves off the sensor, does it immediately refocus or is it forced to wait some amount of time before refocusing, during which time you've hopefully reacquired your subject. That adjustment is comparative, not specific, though. The menu selection is Focus tracking with lock-on, and the settings range from short to long. I have no idea how long "short" is versus "long."

Finally, there is a setting for focus priority, which means, does the camera wait for focus to trip the shutter? Again, not sure about the D3100, but in both my D5000 and my D7000, you could adjust the setting for both AF-S and AF-C modes, between focus and release priority. Focus priority inhibits the shutter until focus has been achieved, and release priority allows the shutter to fire regardless. AF-S defaults to focus, AF-C default to release.

Still, I will say (based on my experience with my D5000) that 11 focus points is not enough for good use of Continuous auto-focus of moving subjects. Expect a discard rate of at least half your shots.

chrisscoggins · Jun 20, 2015

All the answers above are great and answer your question. There is a lot of significance to photography and if your like me, I learn better if I am shown. I take an on line class but I also do Kelby One training which is similar to Linda.com but strictly for photography. I strongly recommend this. You can download your classes and refer back to them. Hope this is helpful. Chris