Nikon D7100 Auto Focus Issue: Hi, I am using a D7100 with a 105mm 2.8 lens. I went to a butterfly exhibit yesterday I was using aperture priority as well as manual and I got a lot of...

roche8410 Loc: Arizona

Hi, I am using a D7100 with a 105mm 2.8 lens. I went to a butterfly exhibit yesterday I was using aperture priority as well as manual and I got a lot of hunting on auto focus. I had camera and lens both set to auto and adjusted the lens to limit distance and still had a lot of issues with hunting. I can't figure out why. I ended switching to manual focus and it was ok. I haven't had this issue with this setup before any ideas? Also does white balance affect this I had it tried cloudy and full sun as the lighting was a bit tricky. Thank you.

Macro Butterfly Exhibit

Monarch Butterfly Exhibit

MT Shooter Loc: Montana

It is because the DOF is so incredibly shallow and no matter how steady you may thing you are, the slightest movement on your part will cause the lens to try to re-focus. You were obviously using AF-Constant mode when this happened. Also, butterfly wings are seldom totally still, their slight movements will also cause AF to hunt.
Try using AF-Single mode and set your AF to SPOT, that will eliminate much of the issue you describe, or just focus manually.

jelecroy Loc: Huntsville, AL

What do you mean by "adjusted the lens to limit distance"?If this statement means that you set the side switch to the infinity-to-0.5-meter setting, that is likely the source of the problem. That setting would prevent the lens from focusing on subjects closer than 1/2 meter. Unless you were absolutely sure that all of the subjects were more than 20 inches away from you, that setting is a bad idea.

photon56 Loc: North America

MT Shooter wrote:

It is because the DOF is so incredibly shallow and no matter how steady you may thing you are, the slightest movement on your part will cause the lens to try to re-focus. You were obviously using AF-Constant mode when this happened. Also, butterfly wings are seldom totally still, their slight movements will also cause AF to hunt.
Try using AF-Single mode and set your AF to SPOT, that will eliminate much of the issue you describe, or just focus manually.

Agree. If you are using Auto, then the D7100 will anticipate the subject and continually auto focus.

roche8410 Loc: Arizona

Because of the paths I was actually greater than 20 inches when I used the 0.5m-Infinity setting. I didn't realize that the movement of the wings would keep it hunting. Some of the shots they were perfectly still and still had more usual hunting. Thank you that gives me a little better understanding of how this works. You can study and study and still not know very much. Part the enjoyment of the journey.

Dbrogers Loc: Shenandoah, Iowa

I'm not familiar with hunting, can anyone explain this term? Thanks,

SteveR Loc: Michigan

Dbrogers wrote:

I'm not familiar with hunting, can anyone explain this term? Thanks,

Hunting....you know....HUNTING!!!!

Ith Wabbit Theathon!!
Ith Wabbit Theathon!!...

roche8410 Loc: Arizona

That is where your auto focus on your camera doesn't. It keeps jumping and won't lock in on your subject you are photographing. In this case the small movement of the butterflies was the culprit I believe and I as a result shot with manual focus since I'm not sure how or if you can correct this. It will do the same thing if there isn't enough contrast an example is some white flowers. The camera basically gets confused. Hope this explains it for you. I'm still a work in progress! Silly Wabbitt

Monarch buttterfly

skiman Loc: Ventura, CA

roche8410 wrote:

That is where your auto focus on your camera doesn't. It keeps jumping and won't lock in on your subject you are photographing. In this case the small movement of the butterflies was the culprit I believe and I as a result shot with manual focus since I'm not sure how or if you can correct this. It will do the same thing if there isn't enough contrast an example is some white flowers. The camera basically gets confused. Hope this explains it for you. I'm still a work in progress! Silly Wabbitt

As MT Shooter said using AF-S and single point AF will help.

Dbrogers Loc: Shenandoah, Iowa

Hunting is what happened to me when I was photographing geese. It could never actually focus on any one thing. I had it on CF. Was I using the right technique for flying geese?

roche8410 Loc: Arizona

That makes sense to use single point focus. Something to experiment around with. It is always a learning experience when you go to a new place and shoot new things. Which is why I think photography is so great. Thank you all for your comments on this.

Jerry Green Loc: Huntsville, AL

I use AF-C and shoot a burst at 1/320 to 1/500 sec if hand holding which usually gives me at least one photo that is sharp.

marcomarks Loc: Ft. Myers, FL

roche8410 wrote:

Hi, I am using a D7100 with a 105mm 2.8 lens. I we... (show quote)

I've seen people complaining about auto focus on D7000 and D7100 on here several times before. You might want to use the Search function above this box and see what their solution was.