Help with Auto focus

I'm struggling a bit with auto focus .. ugh

I'm new to Nikon, using a D5500, although I do not think my issues are the camera. I love taking wildlife pictures, and low/soft light.

I'm colorblind, I'm nearsighted, and over 60, so need reading glasses. Landscapes, Stationary objects are no problem. Lower light wildlife, birds and moving animals are a bigger challenge.

I think my real question is which auto focus mode to use? I shoot almost always in aperture mode and for wildlife AF-Continuous.

The issue seems to be single point focus, 39 point focus, or something between? I know if I use a smaller hole in the lens, f16 or 22, more will be in focus, but I like the shallower depth of field. I also know a faster shutter speed will help with any issues that are related to camera shake.

Maybe I just answered my own question, but I would appreciate help from this very helpful community!

Thanks!

Ken

I keyed in on the "low/soft light" in your 2nd line. That suggests to me me you are probably using a slow shutter speed that image stabilization can't adjust for.

If that is the case, I would increase ISO in order to boost the shutter speed up above 1/125th, with around 1/250th a target speed.

In many cases, I think you are probably right. I looked closely at some images from this weekend, with a 55mm to 300 mm lens, and I do not see any part of the image in crystal clear focus, indicating for those that it is more than likely camera shake. With technology today, I can certainly bump up the ISO some without significantly impacting the image. For example, some images of a deer were shot at ISO 100, F5.6, 1/80th. No reason not to bump the ISO up 320 or 400, which would probably result in a ss of about 1/200th

1/80th of a second is too slow to stop much of anything moving. Add to that your own camera shake as you get to the longer end of your focal length movement becomes more of a problem. A good starting point for your shutter speed would be taking the focal length and putting a 1 over it. 300mm would be 1/300th of a second and up. The newer cameras do much better with the higher ISOs so don't be afraid to push it up to ISO 800 if you need to do it. Better a tiny bit of digital grain than a blurry image

Lots of things to think about. Practice some in great light, and get that shutter speed high enough to just not be a question. AF-Continuous is correct; you want the focus to be constantly tracking. As far as points go, do you have the hand/eye coordination to keep one point on target? If so, stick with one, preferably your center point. If not, use the auto-tracking functionality, but read the manual to understand how it works. Some cameras require you to put the center point on the target first; it then tracks whatever was centered at the point AF is activated. Others allow you to move the (starting) point around, and start from somewhere else.

Also, on a crop camera like a D5500, shutter speed on non-IS lenses needs to be 1/<focal length * 1.5>. IS can probably bring the equation to 8/<focal length * 1.5>, but as others have said, that may be enough to avoid camera blur, but subject blur could still happen.

Another thought: check if your camera or favorite editing software (or a plug-in for that software) can show you which focus point was used for a particular picture. This can help you confirm operator skill/error, and/or get a sense of how good/bad the tracking is if you're using it.

Remember that camera AF usually tries to focus on the closest thing it finds, so if anything closer crops into the picture, you'll see it.

1/80th of a second is too slow to stop much of anything moving. Add to that your own camera shake as you get to the longer end of your focal length movement becomes more of a problem. A good starting point for your shutter speed would be taking the focal length and putting a 1 over it. 300mm would be 1/300th of a second and up. The newer cameras do much better with the higher ISOs so don't be afraid to push it up to ISO 800 if you need to do it. Better a tiny bit of digital grain than a blurry image

Agreed. The case discussed, the subject was a deer standing still, but 1/80th was obviously too slow.

Thanks!

Lots of things to think about. Practice some in great light, and get that shutter speed high enough to just not be a question. AF-Continuous is correct; you want the focus to be constantly tracking. As far as points go, do you have the hand/eye coordination to keep one point on target? If so, stick with one, preferably your center point. If not, use the auto-tracking functionality, but read the manual to understand how it works. Some cameras require you to put the center point on the target first; it then tracks whatever was centered at the point AF is activated. Others allow you to move the (starting) point around, and start from somewhere else.

 

Also, on a crop camera like a D5500, shutter speed on non-IS lenses needs to be 1/<focal length * 1.5>. IS can probably bring the equation to 8/<focal length * 1.5>, but as others have said, that may be enough to avoid camera blur, but subject blur could still happen.

 

Another thought: check if your camera or favorite editing software (or a plug-in for that software) can show you which focus point was used for a particular picture. This can help you confirm operator skill/error, and/or get a sense of how good/bad the tracking is if you're using it.

 

Remember that camera AF usually tries to focus on the closest thing it finds, so if anything closer crops into the picture, you'll see it.

Good points. I'll see if my software can show the focus point; I've never looked for it.

Ken

Agreed. The case discussed, the subject was a deer standing still, but 1/80th was obviously too slow.

Deer are typically very good at standing still to avoid detection, so 1/80th might not be too slow from a subject perspective. 1/80th breaks the rules with respect to non-image-stabilized lenses, but if your lens has IS of a reasonably recent vintage (i.e. a claim of at least three stops of correction), the equation becomes 8/(focal length * 1.5). If you had a kit 55-250, for example, and you zoomed in all the way, you'd need 8/375, which I'll round to 8/400 for easier math. This reduces to 1/50th, so 1/80th would be fast enough for a shake-free shot, assuming you didn't camp out at Starbucks before camping out in the woods, etc.

I usually use single point focusing for wildlife in aperture, f/8, AF-C and then adjust from there if needed. If your model allows, you might consider back button focusing. You’ll find many reviews that encourage it. You’d be reprogramming the AE-L/AF-L button on the back of your camera. I changed those settings on mine and I haven’t looked back. Works fantastic.

Low light wildlife shots are a challenge for everyone. You should be able to push the iso up to 1000 on the D5500 without any significant increased noise.

I like the programming idea.

Thanks for the pointers.

Using a long focal length at 1/80 of a second can lead to camera shake and that can make things look blurry. You need more shutter speed to get rid of the camera shake and then even more shutter speed to stop action.

Thanks! I don't know how I let that happen:eek:

Good points. I'll see if my software can show the focus point; I've never looked for it.

 

Ken

If you are using Nikon's software (View NX?) to import or look at your photos there is a toggle to turn on the focus points for viewing.

I have never used their software. I'll give it a go.