Still Focus Issues with AF-C mode

[Paganman2]

Most of the EXIF got stripped by uploading here so I'd need a shot out of the cam.

But ignoring that, when you shoot release priority the cam will fire whether in focus or not. Checking the time-stamps, they're part of a burst so when the cam is firing one shot after the other, it will not improve focus since it only can focus in between the exposures. When shooting release you have to make sure it has obtained focus before you start firing else you have to hope it'll catch up and get something in focus by the third or fourth shot.

But as i explained before - even with using Focus Priority in AF-C mode it makes no difference, the question is still the same - why am i only able to get sharp in focus pictures if the camera chooses if it is moving or not in AF-A mode, the results i am getting are consistent and reliable in as much that in AF-C mode i can not get sharp focused pictures, and in AF-A i can and do.

P.

 

[J-see]

But as i explained before - even with using Focus Priority in AF-C mode it makes no difference, the question is still the same - why am i only able to get sharp in focus pictures if the camera chooses if it is moving or not in AF-A mode, the results i am getting are consistent and reliable in as much that in AF-C mode i can not get sharp focused pictures, and in AF-A i can and do.

P.

If you're shooting AF-A you let the cam decide which method it'll use. It implies it'll take a shot in AF-S when it sees fit and since that is only using the center point, it'll focus faster than when using AF-C d9. You can't select a release mode for AF-A so if you have AF-S set to release on focus only, it'll only take shots when it has focus. This doesn't mean AF-A performs better than AF-C. It just means you're doing something wrong and the cam is occasionally doing it right.

 

[Paganman2]

This doesn't mean AF-A performs better than AF-C. It just means you're doing something wrong and the cam is occasionally doing it right.

How can i be doing something wrong if all i am doing is pointing the cam at the same type of subjects and getting focused shots with AF-A, and un focused shots with AF-C ?

P.

 

[J-see]

What can be possible is that by using AF-A you cause a delay that gives the lens the time required to obtain focus which it does not get when you shoot AF-C. As I said, if you shoot AF-C it is critical you don't start shooting before the cam obtained focus since it only makes it harder to catch up.

When shooting fast lenses you can start a bit early since a f/2.8 gets focus quite fast and can manage quite well in between exposures but a slow lens will have a very hard time.

AF-A isn't a special focus method. It really is just AF-"S or C". You're never shooting any other method than one of both so if it does well in AF-A, it does well in either S or C.

If it works well in AF-A, you have to be doing something wrong in the other modes.

I can't know how you shoot in AF-C but if I have to guess, you might cause a problem by releasing too early and holding the button down. If I shoot a slow lens, even when I have obtained focus, I see in my shots when the lens starts to struggle during a burst and when it no longer can keep up. If you start out of focus, it's very possible you might only have one, or even none in focus during a 5-6 shot burst.

 

[Paganman2]

What can be possible is that by using AF-A you cause a delay that gives the lens the time required to obtain focus which it does not get when you shoot AF-C. As I said, if you shoot AF-C it is critical you don't start shooting before the cam obtained focus since it only makes it harder to catch up.

When shooting fast lenses you can start a bit early since a f/2.8 gets focus quite fast and can manage quite well in between exposures but a slow lens will have a very hard time.

AF-A isn't a special focus method. It really is just AF-"S or C". You're never shooting any other method than one of both so if it does well in AF-A, it does well in either S or C.

If it works well in AF-A, you have to be doing something wrong in the other modes.

I can't know how you shoot in AF-C but if I have to guess, you might cause a problem by releasing too early and holding the button down. If I shoot a slow lens, even when I have obtained focus, I see in my shots when the lens starts to struggle during a burst and when it no longer can keep up. If you start out of focus, it's very possible you might only have one, or even none in focus during a 5-6 shot burst.[/QUOTE

My question in return is - If i was standing side by side with you and we both had our D7100's with the same lens on both - 70-300VR, both at 300mm f8 and we both had the same cam settings and used AF-C, we were both following the same birds in flight and both fired the shutter in the same way at the same time, but my picture was out of focus and yours was in sharp focus, would this not indicate a problem with mine?

P.

 

[Paganman2]

sorry it got a bit mixed up there with the quote section missing.

P.

 

[cbg]

Just as a suggestion, have you tried remapping the AF-L/AE-L button to focus for back-button focusing? Doing that will separate focusing from the shutter release. That will give a better idea as to whether it is operator error or the camera.

 

[J-see]

My question in return is - If i was standing side by side with you and we both had our D7100's with the same lens on both - 70-300VR, both at 300mm f8 and we both had the same cam settings and used AF-C, we were both following the same birds in flight and both fired the shutter in the same way at the same time, but my picture was out of focus and yours was in sharp focus, would this not indicate a problem with mine?

P.

Since the problem has to be the cam, all left to do is bring it in for repair.

 

[bikeit]

Guys what is focus priority?

 

[Love Nikon]

The shutter will not release unless its in focus...ie the autofocus has locked on..set in menu

 

[Blacktop]

Here are four pictures taken from the same location and not to distant in time from each, the first two were shot in AF-C mode with release priority, and the next two where shot using AF-A and again with release priority, i have tried to show more EXIF info by selecting the extra option in LR4.4.
These are all set as 50% crops at 3001mp on the long edge.

P.View attachment 160100

View attachment 160101


View attachment 160103

View attachment 160105

With a smallish bird (300mm +50%crop) that far away you definitely need to be in 'focus priority" mode. Preferably AF-C as well. Even then, it will be hit and miss. Also when you're shooting in AF-C with shutter speeds well over a 1/1000th of a second, the VR will make things worse by having it on. Turn it off.

In recap.
High shutter speed. Dont be afraid to push the ISO to 1600. I have exactly the same setup as you shooting BIF.

Stop down on the aperture. f/8 is fine

AF-C with single point and Focus priority.

VR off!!

Anything that far away, you need a steady hand to keep the focus on the bird as it's moving.

 

[Blacktop]

What can be possible is that by using AF-A you cause a delay that gives the lens the time required to obtain focus which it does not get when you shoot AF-C. As I said, if you shoot AF-C it is critical you don't start shooting before the cam obtained focus since it only makes it harder to catch up.

When shooting fast lenses you can start a bit early since a f/2.8 gets focus quite fast and can manage quite well in between exposures but a slow lens will have a very hard time.

AF-A isn't a special focus method. It really is just AF-"S or C". You're never shooting any other method than one of both so if it does well in AF-A, it does well in either S or C.

If it works well in AF-A, you have to be doing something wrong in the other modes.

I can't know how you shoot in AF-C but if I have to guess, you might cause a problem by releasing too early and holding the button down. If I shoot a slow lens, even when I have obtained focus, I see in my shots when the lens starts to struggle during a burst and when it no longer can keep up. If you start out of focus, it's very possible you might only have one, or even none in focus during a 5-6 shot burst.[/QUOTE

My question in return is - If i was standing side by side with you and we both had our D7100's with the same lens on both - 70-300VR, both at 300mm f8 and we both had the same cam settings and used AF-C, we were both following the same birds in flight and both fired the shutter in the same way at the same time, but my picture was out of focus and yours was in sharp focus, would this not indicate a problem with mine?

P.

Not necessarily. Could be your technique. Could be you have a jerkier tracking motion. maybe your hands are shakier. Could be a lot of other things beside just settings.

 

[Spottydumplings]

Sorry for possibly hi-jacking this thread but I'm a newb around here and haven't had my D7100 long...

Given that "AF-A isn't a special focus method. It really is just AF-"S or C"." why does it have it's own setting?

From memory "out of the box" the focus settings for mine were:

AF-S - D9
AF-C - D21 (or 51 can't remember)
AF-A - 3D

Could this be why the OP is seeing differences in ability to focus?

For the first couple of trips out I had the camera set to AF-A (as I always have on my D90) and I had "hells own game" getting the active focus point where I wanted it; as it kept jumping from one to another. Last trip was to a botanical garden so I selected AF-S.

 

[J-see]

Sorry for possibly hi-jacking this thread but I'm a newb around here and haven't had my D7100 long...

Given that "AF-A isn't a special focus method. It really is just AF-"S or C"." why does it have it's own setting?

I assume the area mode you set in AF-A is the one being used when the cam decides to use AF-C.

 

[Spottydumplings]

Yes I had read that. As it is doing the same for stationary objects as well I assume that the AF-A setting is overriding those set for them individually; which is a nuisance! The only way around this that I can see is to set all three modes to the same setting - or at best
AF-A to the same as one of them; which seems to rather defeat the object.

 

[J-see]

I personally see little use in AF-A. If the cam can distinguish if a subject is stationary or moving, I can do that too.

And better.

 

[Paganman2]

In my personal experience i can not get any satisfactory results from AF-C not matter what individual setting i use with it, or what subjects or distance from camera, the only success i get with any moving objects of any type is AF-A mode.
I dont know the reason for this - cam or lens issue? but its just how it is and i guess i will have to live with it.

P.

 

[Spottydumplings]

I personally see little use in AF-A. If the cam can distinguish if a subject is stationary or moving, I can do that too.

And better.

Whilst that is true, if you are shooting AF-S and the subject begins to move; even if it only the breeze blowing a flower head, you have to: remember to switch to Continuous, get an out of focus image or miss the shot whilst changing mode. I have just gotten used to leaving my D90 on AF-A and not having to switch; no matter what I am shooting.

Paganman2; I'm sure you have but just in case... Have you tried changing AF-C to the same settings as AF-A?

 

[J-see]

Whilst that is true, if you are shooting AF-S and the subject begins to move; even if it only the breeze blowing a flower head, you have to: remember to switch to Continuous, get an out of focus image or miss the shot whilst changing mode. I have just gotten used to leaving my D90 on AF-A and not having to switch; no matter what I am shooting.

I shoot back-button which is AF-C and AF-S but under my control. There's one thing we can do which a cam will never be able to: anticipate. That always makes us better than these kind of auto-functions.

 

[Horoscope Fish]

Whilst that is true, if you are shooting AF-S and the subject begins to move; even if it only the breeze blowing a flower head, you have to: remember to switch to Continuous, get an out of focus image or miss the shot whilst changing mode. I have just gotten used to leaving my D90 on AF-A and not having to switch; no matter what I am shooting.

Paganman2; I'm sure you have but just in case... Have you tried changing AF-C to the same settings as AF-A?

Well there are other options, like waiting for the breeze to die down, adjusting your depth of field, etc. That being said though, maybe what would work for you is AF-C or AF-s (your choice!) in conjunction with Back Button Focus (BBF).

There are several articles and YouTube videos on the topic should you wish to research the topic further (and I would encourage you to do so) but here's one to get you started: Back Button Focusing
,,,,,