Manual focusing with D3100

Boomer

New member
I just came back from a safari in east Africa and took about 3000 pictures. I'm new to DSLRs, having only bought my D3100 about 6 weeks before the trip. The camera took some amazing photos and I was very happy with it except for one thing.

I've concluded that the only thing that autofocus is good for is birthday parties! In the bush, there was always a tree or limb closer to me than the animal I was trying to photograph and the auto focus always locked onto it. I typically ended up using manual focus which is difficult without a focus ring or something in the viewfinder except your eyeball.

See attached photo. The leopard was laying on a limb at 20 feet and the autofocus selected the limb instead of the leopard. It's subtle, but you can see that the limb is more focused than the leopard's eyes.

I tried putting the camera on "single point" autofocus, but instead of using the center point it picked some other single point which wasn't what I wanted.

I want to understand this problem and how to get around it.

Any suggestions?
 

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JohnFrench

Senior Member
You can select the focus points by the knob on top of the camera. I think the one you want for shots like the feline would be a "Portrait". I have had the same issue with detail shots of buildings, and the automatic selection would choose a leaf or something closer instead of the detail area I wanted.
 

Will V|Photography

Senior Member
John is on the right track but a little off. Are you shooting in a "Scene" mode or A,S,P,M?

When using single-point AF, you can control which point in your viewfinder focuses by using the directional pad on the back of the camera. Move the point where you want it, half-press the shutter, then once you have what you want in focus, then you can change your composition while keeping what you want in focus.

As for manual focusing and looking through the viewfinder, you'll see a light in the lower left-hand corner that comes on when you have focus. I don't understand what you mean about a focus ring though, as I'm sure your lens has one. You wouldn't be able to manually focus without it.

Hope this helps a little bit!
 

Boomer

New member
Will V - thanks for the reply. I tried to shooting in several modes but often used the "sports" mode since it defaults to single point AF.

I didn't notice the light in the viewfinder. That's very helpful. Thanks!

Back three decades ago I had a film SLR and it had the circular area in the middle of the viewfinder used for manual focusing.
 

Will V|Photography

Senior Member
Ah, I get what you mean by "focus ring" now. Yeah, the light in the viewfinder is essentially the same thing.

Sports mode may seem like it has single-point focusing but in reality it uses the Dynamic-Area focusing for continuously moving subjects. Now, if you were in a moving vehicle and weren't able to stop for the shot then it is probably your best bet, but you will have to pick through shots like the one above where you didn't really get what you were hoping for. I don't know how often you go on safari, or if this was a once-in-a-lifetime thing, but knowing this stuff can help you out in any future situation you may find yourself in. I'm sure you've read the manual, but go through it a few more times. Heck, my manual is in my "literature" stack next to the toilet and I'm still constantly looking through it. Even if I think I have my camera completely figured out I usually find something I didn't know about. It will give you a bunch of good information on the various AF modes and AF assists, as well as tips for which situations they're better suited for. You can also check out Jared Polin at FroKnowsPhoto.com and his D3100 setup videos. They really helped me out tons when I first got the camera.

Feel free to ask whatever questions you may have and I'll try to answer them to the best of my ability. I've been learning a lot over the past year or so, and more in the past few months than ever. Just remember, you never stop learning and you can never know less.
 

darlenec59

Senior Member
While we're on the focusing discussion, I have a similar question. I too used to have a film SLR (back in 1979, the Minolta SRT-201 which I loved). It too had the focus circle in the lens. I never had a zoom lens, only a 50mm and a 135mm. When I wanted to focus on something pretty far off I would just turn my focus ring all the way to the right to just go to infinity. On my D3000 with the 18-55mm zoom, there is no infinity setting and when I'm manually focusing it seems that if I turn the focus ring all the way to the right it brings the things in the distance into focus but as I continue to turn the ring it brings closer items back into focus. It seems to go in and out of focus. For instance, if I go to an air show, I know the planes are definitely in the infinity zone of focus. How do I set my camera to focus so that it's ready for when the planes come by. Obviously, auto focus won't work in this situation as the camera doesn't seem to know what to focus on. Sorry for the long post. I hope I've explained this okay.
 

Will V|Photography

Senior Member
Darlene, from what I have heard, the "infinity" focus on the kit lens (and I think on all AF-S lenses) is all the way to one side like you said but then you back it off a little bit. Don't hold me to that as I have yet to experiment much with manual focus, but that is what I have heard.
 

Boomer

New member
I had the same experience. The true infinity location is not quite all the way to the right. I heard somewhere it's that way so the autofocus motor can overshoot without damaging the lens.
 

Mike150

Senior Member
Darlene, from what I have heard, the "infinity" focus on the kit lens (and I think on all AF-S lenses) is all the way to one side like you said but then you back it off a little bit. Don't hold me to that as I have yet to experiment much with manual focus, but that is what I have heard.

You're right about backing off infinity. The focus won't know when it's at the sweet spot until it has determined focus, then moved out of focus. It then backs up to focus a final time. If you think about it, the lens is emulating your movements when focusing in manual mode. Because of that, there is a need for movement beyond infinity
 

darlenec59

Senior Member
Makes sense Mike & Boomer. I'll have to play around a bit and see what I get. I live right in the flight path of the Niagara Falls Air Force Base in New York so I have planes going over my house all the time. I'll have to be ready this weekend when they're going over in the daylight. Thanks!
 
I too have had problems with the focusing in manual its seems that they've made these cameras for "point & shoot" auto totally relying on the sensors/electronics to pick your focal point. It seems to be a common problem with DSLR's.

I'm back in the game today after many years of not playing...cost of film, processing and raising a family. I started with an OM1 which had a split ring prism for focusing.

Has anyone used/use these katzeyeoptics.com ? It seems like a pretty inexpensive fix to manually focusing on what I want in my camera.
 

Will V|Photography

Senior Member
Pick your focus point with the directional pad, then as you're manually focusing through your viewfinder look in the bottom left corner for the focus-assist light. When the focus point you've selected is in focus then the light will come on and you snap your photo. Simple as pie ;) I've never tried the katzeye stuff so I have no input on that.
 
Thanks Will V ! Why couldn't I pick that up as easy from the manual?? Seen it right away after your explanation. And still so much to learn with these digitals... and to remember the stuff I forgot.

Did you look at the Katzeye stuff?
 

Snapping52Weeks

New member
I miss the old focus ring within the viewfinder from my old film SLR for this very reason. This has been a big change for me in the change over from film to my new D3100.
I am trying to master using the toggle when shooting landscapes to get what I want in focus in the AF mode. I turned the AF off for the first time yesterday and I can see there will be a bit of a learning curve.
 
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