AF & AF-S lenses

[Reschsmooth]

Trying to grab sharp images of a c2 y.o. toddler is difficult as they tend to move around more than a, well, thing that moves around a lot.

Having tried both a D200 & D700 with AFS lenses (17-35 & 24-70), and starting with the AF point on the ever-moving Alex, I find that the AF doesn't seem to keep up and I get soft images.

Ignoring the D700 for the moment (as I have to give it back soon ), what settings should I be using if I want to try to have the camera AF track the young man?

[PiroStitch]

Get a D3

Are you using continuous focus or single shot focus? If he's screaming around, then stick it onto multi-frame shooting as well.

Is the blurriness due to Alex moving or the camera not achieving focus lock? What shutter speeds are you looking at? Try going for ISO 400 or 800 and use a faster shutter speed.

[Reschsmooth]

Get a D3

Are you using continuous focus or single shot focus? If he's screaming around, then stick it onto multi-frame shooting as well.

Is the blurriness due to Alex moving or the camera not achieving focus lock? What shutter speeds are you looking at? Try going for ISO 400 or 800 and use a faster shutter speed.

Thanks Wayne

I don't think the baby bonus extends enough to cover the cost of a D3

The situations I am referring to are when I have the camera on continuous focus, but single shot capture. I think the blurriness is largely due the camera not achieving focus, but also not keeping focus. I have the shutter half-pressed at the time.

The shutter speed is not an issue as there is a plane of sharp focus.

I try to use smaller apertures such as f5.6 to f8 rather than really wide apertures such as f2.8.

I have tried the various AF modes (group dynamic, etc).

Am I expecting too much from the AF system and AF-S lens(es) or is there something I am not doing right (I am thinking the latter)?

[Alex]

Hi Patrick,

What focusing mode are you using? I understand you are using AF-C which is what I would use but what do you do for focusing areas? Are you using a single sensor or dynamic? I find that with kids in action the dynamic focus is a much better way to go as the focusing sensor is chosen for you and it will switch from one sensor to the other if Alex moves the position.

Cheers
Alex

[NeoTiger]

So do you mean that the focus speed is not fast enough to focus of your baby? Or is it achieving focus, but you find out that the focus is wrong after taking the picture?

It would still probably be the best idea to keep shutter speeds as fast as possible to minimise blur... even if you have good focus and the camera is steady, a moving object could be blurred. And on this note, having a brightly lit room or using a flash could help...

[surenj]

Hi Patrick,
Once you achieve focus, the easiest would be to use flash to freeze motion. I would suggest 2nd curtain sync in the hope that you can capture the tyke's movement without compromising picture quality. I am sure your Metz will be plenty powerful! [It certainly beat my 430ex hands down when I was trying] [Reminds me that I have to post the few photos I managed to make using your flash, BTW thanks for lending it!]

Addit: One method may be to use a vareity of shutter speeds and AF modes and add in flash to see which one's are to your satisfaction. You may be able to find out what problem your are having by process of elimination.

[Mrs Reschsmooth]

Please don't tell him a D3 will fix it!

[chrisk]

pat, i echo the above. you need flash first and foremost.

if i cant use flash i try and stay away from anything that isnt af-s, which is why i constantly bitch about the 85/1.4. they simply cant keep up and i want full time MF over ride. the 50/1.4afs i have found to be a revelation in terms of tracking kids. (but the 35L on a MkII was another world).

some strategies i use: prefocus, use MF, (with an af-s lens), as much has possible and have AF do the finishing touches, use trap AF if you know where they are running to. (use AF-ON button), af-c, dynamic area AF etc.

[Reschsmooth]

Thanks for the suggestions guys.

Here are two examples of what I mean (and I believe both indicate there is no camera shake, but focussing problems - either mine or the cameras). Also note that these are on two different cameras (D200 and D700) with two different AF-S lenses (17-35 & 24-70).

The first is at a slowish shutter speed (1/50th at f3.2) with bounced flash.



It may not be obvious, but the focus point is somewhere around his ears, not his eyes where I wanted it.

The second shot is using ambient at 1/500th at f5. This should have been plenty fast enough to capture sharpness. I recall that I was using single point focussing (granted, on the D700 which I was not accustomed to but believe this is what I was using) but tried to keep the focus point targeted on Alex's eye.

I appreciate that flash may be the way to go and do so when the required shutter speed is too slow. However, I believe that there must be an ability for the camera system to retain focus on a relatively slow moving object.

My further comments are:

1. It is possible that, using single point focussing, (does the word 'focussing' have one s or two?) and AF-C, my camera holding technique was sub-par and I may have moved the camera at the time of shutter release, thus moving the focus point.
2. As Alex & Rooz intimated, I should probably better understand and use the dynamic area AF.

Thanks again - any more guidance appreciated.

[chrisk]

The first is at a slowish shutter speed (1/50th at f3.2) with bounced flash.

SS is far too slow for a 2yo boy thats on the move. i can see the focal plane on the silver coat hanger thing to the right.

The second shot is using ambient at 1/500th at f5. This should have been plenty fast enough to capture sharpness. I recall that I was using single point focussing (granted, on the D700 which I was not accustomed to but believe this is what I was using) but tried to keep the focus point targeted on Alex's eye.

yeah, SS is fine. hes just moved at the last second and the lens/ camera couldn't keep up. flash wont help these so i take that suggestion back. in both shots hes moving towards you, so the focal plane is drastically changing each millisecond.

i would suggest in shots like these you prefocus and use the trap method.

mind you, not a bad idea to get your lens and/or body checked for AF either to make sure its not backfocussing.

[Reschsmooth]

Thanks Rooz.

I think I will try to use the dynamic area method better.

[chrisk]

pat, are you using the AF-ON button ?

[Reschsmooth]

pat, are you using the AF-ON button ?

I hope I don't make myself sound foolish - I use the half-shutter depress AF method.

[chrisk]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

[Reschsmooth]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

I presume that you have to set the AF-C to only fire when in focus, as opposed to the default.

Sounds like a great, logical tip - many thanks. I will try it on the D700 rig before I have to (reluctantly) give it back.

[chrisk]

I presume that you have to set the AF-C to only fire when in focus, as opposed to the default.

Sounds like a great, logical tip - many thanks. I will try it on the D700 rig before I have to (reluctantly) give it back.

coirrect, sorry, missed that point. priority is focus.

[aim54x]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

I think I will have to give this a go as well. It sounds like it will work quite nicely in some circumstances. I love reading Thom's stuff but I have to admit that I have not seen this tip.

[losfp]

I have achieved best results by using the following:

- 1/250, f/4
- AF-S, focus priority

Point camera at small child, hold the shutter release button down and hope for the best - I don't really bother with half-pressing with Phoebe, she moves constantly!

Sometimes I use LiveView so I can make funny faces from just behind the camera and hopefully get some eye contact as well.

Normal kit is a D300, AF-S 17-55/2.8 and SB-800.

They're not the most artistic shots, have busy backgrounds and so on... but with kids, you have to get what you can get - at least until they are old enough to reason with

[Reschsmooth]

at least until they are old enough to reason with

Not sure I want to wait 34 years.

[NeoTiger]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

Is this only for the higher end cameras, or do the lower end Nikon's have this as well? D90 for example?

[chrisk]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

Is this only for the higher end cameras, or do the lower end Nikon's have this as well? D90 for example?

not sure how you would do it with a d90 cos i dont think it has an AF-ON button.

[DanW]

Is this only for the higher end cameras, or do the lower end Nikon's have this as well? D90 for example?

This can be done with a D90.

Custom setting f4: "Assign AE-L/AF-L button" lets you change the AE-L button to function as an AF-ON button. I've just had a play with it on my camera and it works fine.

[NeoTiger]

Oh cool. Thanks for that Rooz & Dan.

[Reschsmooth]

if you set your camera to...
af-c mode
shutter button - release only
AFON button to focus.

use the AFON button to preselect your focus point, (its actually the plane of focus you are after rather than the exact point), and keep the shutter button depressed fully. then as he runs into the focal plane it will "trap" him in focus. i found my keeper rate went up dramatically after i started using that method. (thom hogan tip).

sounds alot more complicated than what it is. takes a little practice, but well worth it.

Sorry to dredge up an old thread, and I will admit I haven't tried the technique yet, however, I am puzzled - the AFON button will focus on what is ever in the AF area - do I need to try to focus on Alex or some point that he will run into? If the latter, I expect the AFON button will not necessarily create a plane of focus in front of Alex if the AF area is pointing at a point behind him. If I target a point/plane that is in front of him, and the camera finds focus, the camera will fire the shutter.

I can understand the technique if you suggest manually fousing on a 'plane' in front of Alex.
I think there is something basic that I am missing here.

[aim54x]

I have to admit that I have little success with this technique as well...I find that even if I have created a plane of focus in front of my subject (in this case ppl walking down the aisle of a graduation ceremony) I either have the camera fire when I go to depress the shutter or completely miss the trap...I will have to have another play with it.

Patrick...try using an AF point at the periphery of the frame then hit your d-pad to centre up the active AF point to create the trap...that is what I have been doing.

[chrisk]

Sorry to dredge up an old thread, and I will admit I haven't tried the technique yet, however, I am puzzled - the AFON button will focus on what is ever in the AF area - do I need to try to focus on Alex or some point that he will run into? If the latter, I expect the AFON button will not necessarily create a plane of focus in front of Alex if the AF area is pointing at a point behind him. If I target a point/plane that is in front of him, and the camera finds focus, the camera will fire the shutter.

I can understand the technique if you suggest manually fousing on a 'plane' in front of Alex.
I think there is something basic that I am missing here.

use AF-ON, (or just manually focus if you prefer) to pick the point alex will run into. make sure your shutter button is set to NOT af when half pressed and that shot priority is given to focus, (as opposed to release). so what you are doing is effectively saying to the camera, do not release the shutter unless the subject is in focus. then just keep the shutter button fully depressed as alex is coming towards you, as soon as it attains focus it will release.

the reason i say pick a point with AF is that what you're doing is picking the distance, thats it. so pick a point on the floor, grass or whatever, point the camera at it and then tilt it up and dont AF anymore. the distance to the lens doesnt alter cos you're raising the camera on the vertical plane. but yes, if you prefer, you can manually focus it and achieve the same result i guess...never tried it. i hate manual focus. lol

the benefit of this is that the lens is not being engaged and trying to keep up; as soon as something hits that AF sensor then the camera releases the shutter instantly. the success rate, from my experience, (and practice), is much higher with slower focussing lens. with the 24-70 for example i dont bother trying to do this cos it keeps up easily, but the 35/2 and to a lesser degree the 50/1.4G have no hope.

its a real coincidence you brought this thread up cos yesterday a mate borrowed my camera and said it wasnt focussing. since i have used this technique so often now, i have my camera permanently set to this method with shutter release button only releasing and use the af-on button for af. when i first started doing it, it felt very awkward but now i got used to it, i use it all the time.

[aim54x]

If you have it working...then I am sure me and Pat can get it working...I'll give it another go soon.

[gummi]

its a real coincidence you brought this thread up cos yesterday a mate borrowed my camera and said it wasnt focussing. since i have used this technique so often now, i have my camera permanently set to this method with shutter release button only releasing and use the af-on button for af. when i first started doing it, it felt very awkward but now i got used to it, i use it all the time.

It's a coincidence for me that you guys have brought this back as well, I've been trying to take pictures of my niece and nephews when they're at play and wanted to increase the keeper rate, so I started to read about focus trapping. Couldn't really get a handle on how it worked until I read the tips on this thread. I'm so happy about learning & using another feature on my D300. It is a little awkward initially (and prob will be until I get more practice) but it's really helped with planning ahead for the shot & the satisfaction in nailing it. Just wanted to say thanks for the awesome advice provided!

[Reschsmooth]

Thanks Rooz, you have explained it really well.

If we consider the photo of Alex walking down the path, if I either manually or, by using the AF-ON button, focus on that cracked bit of concrete near his foot when he is further up the path, but running to it, and then recompose to the framing I want, that concrete spot won't be in the AF area so the camera won't 'be in focus'. Once Alex runs into the plane of focus, the camera will 'be in focus' and the shutter will fire.

I will try this on the weekend. I guess one of the issues to take account of is to not use too wide an aperture as the DOF may be too shallow.