bemyzeke wrote:
I switched from Canon and had no idea what trap-focus was. Now that I know about it, it sounds like an incredibly useful feature, for macro, wildlife, BIF, racing, and even some sports (as a alternate to high speed continuous shooting, which D800 does not do).
It can be quite useful at times. Some folks use it quite a lot, some don't use it at all and then there are some like me that use it when it is most convenient to get the shot I want. I've used it in conjunction with another body at a dog trials. I set one body on a tripod set for focus trapping, with a remote release shutter locked On. I then used another body to follow the action and let the "robot" take the shots when the dogs came into its view. Not all shots were keepers, but I was pretty happy with the overall results from the trap focus. I don't use it much now because I can't set it and walk away without worrying about the camera being there when I come back....
SoundHound wrote:
I believe that this discussion assumes that the shooter can capture the ultimate moment in a frame or two. That means that he can, compose and time the shot for the perfect posture and expression with no motion blur while the camera also peaks with optimum AF, VR (AE, etc?).
My experience is that there are substantial technical and animate subject variations so I shoot 9/10 frame bursts and select the best shot, or in the extreme, combine the best parts of two or more frames.
Your d3s should shoot max frame rate with trap focus. I just tested that with my d3s and it worked fine. Dunno about the d4, but I assume that it won't trap focus like the d800.
Kerry Pierce wrote:
I don't see any advantage to that, but of course I'm more than happy with the way my d3s, d700, d300 and IIRC, the d200 work with the focus, release, or focus+release settings in the menu under AF-C. Canon and the d800 don't allow the user to ensure focus is locked like the older Nikons do.
Kerry
The D800 AF1 release/focus priority mode settings for AF-C work fine, the same as Canon's focus/release custom function in AIServo. In single shot mode a Canon body won't fire unless focus confirmation is reached and holding down the shutter all the way (trap focus) doesn't work. So that by default ensures focus is reached before the shot can be taken on a Canon in single shot mode. The D800 I guess is the oddball because it will fire in single shot mode regardless of what AF2 is set to or whether it's in focus. For shutter AF that's obviously not a problem but for back button AF it could be if one constantly forgets to AF the body.
Some nice examples of trap focus techniques have been put out here and it would be a nice feature to have since it seems the AF2 setting on the D800 is useless for anything else.
Having come from a couple of Pentax K-5's to the D800E I can say that the Catch-in-Focus setting was extremely useful and is for manual focus lenses only on that body.
It can work in a couple of ways:
1. Frame your shot, select the focus point and rotate the focus ring of the lens whilst holding down the shutter button. As soon as the image is in-focus the shutter fires.
OR
2.Compose a shot where you expect the subject to pass and prefocus. Hold down the shutter button and when the subject enters the zone the shutter fires.
rd4tile wrote:
The D800 AF1 release/focus priority mode settings for AF-C work fine, the same as Canon's focus/release custom function in AIServo. In single shot mode a Canon body won't fire unless focus confirmation is reached and holding down the shutter all the way (trap focus) doesn't work. So that by default ensures focus is reached before the shot can be taken on a Canon in single shot mode. The D800 I guess is the oddball because it will fire in single shot mode regardless of what AF2 is set to or whether it's in focus. For shutter AF that's obviously not a problem but for back button AF it could be if one constantly forgets to AF the body.
Some nice examples of trap focus techniques have been put out here and it would be a nice feature to have since it seems the AF2 setting on the D800 is useless for anything else. ...Show more →
It's interesting that the Canon has focus lock in single shot mode. AFAICT, the d800 doesn't do that. It seems to be working much like you describe the custom focus/release function in AIServo.
I can remember using the focus lock while shooting low light action and, more than once, the FPS would slow down because the camera wouldn't fire at the FPS rating I had set because it had trouble achieving lock due to poor AF conditions. I wonder if the d4 would do that now.
I'd like to see them fix AF2 to work as before, but I don't have a problem with them giving the option to keep it the way it is. Shouldn't be difficult for them to do both.
But, they'll do what they want to do, so we'll have to wait and see.
Being one of the new kids on the block and coming from a place where focus trapping wasn't possible, I am having trouble understanding how the controls have changed and though it sounds like a good option to have I am having trouble picturing how it works. I assume that one uses AF-ON only or manually focuses (with AF active) to a predetermined spot that is empty until the subject moves into it. One then depresses the shutter button all the way but the camera doesn't fire because it has been instructed not to fire unless in focus. When a subject enters the focus zone, the camera automatically fires. Is this close to right?
If so, how could this possibly work with AF-C as the AF system isn't running (or it would have focused on something behind the "empty area" already)? If it only works in AF-S that seems pretty limiting for shooting something like a hurdler. If you are shooting 400 f2.8 at 2.8 you'd be lucky to get one frame in focus if the runner lifts is head and the AF point is triggered by a hit on the body. Obviously, I'm missing something so if someone would point me straight it would be appreciated.
Sounds like it will work in a burst shooting mode based on comments above. Subject comes into focus, cam starts shooting away, subject moves out of focus cam stops?
Could be good for unattended shooting, sort of like a focus based motion detector!
Do you ever remember this being mentioned on the Canon forum? If it was I sure missed it.
Hrow wrote:
One then depresses the shutter button all the way but the camera doesn't fire because it has been instructed not to fire unless in focus. When a subject enters the focus zone, the camera automatically fires. Is this close to right?
Correct.
If so, how could this possibly work with AF-C as the AF system isn't running (or it would have focused on something behind the "empty area" already)? If it only works in AF-S that seems pretty limiting for shooting something like a hurdler.
I think you may be confounding single vs continuous burst mode with single vs continuous AF. Remember, the AF drive setting is irrelevant when it comes to trap focus, because AF is not involved at all! You disable it either by switching the lens to manual focus (thus it stays at the desired focus distance) or you turn off the AF function on the shutter button (so the camera does not attempt to refocus). AF-S, AF-C, face-detect, etc., etc. are all out of the picture at that point. Trap focus is essentially a manual focus technique.
If you are shooting 400 f2.8 at 2.8 you'd be lucky to get one frame in focus if the runner lifts is head and the AF point is triggered by a hit on the body.
That would be addressed by choosing the shutter release mode: S, CL or CH. It is independent of the AF drive mode.
rd4tile wrote:
Sounds like it will work in a burst shooting mode based on comments above. Subject comes into focus, cam starts shooting away, subject moves out of focus cam stops?
Correct.
Could be good for unattended shooting, sort of like a focus based motion detector!
It would be really cool to combine that with the D800's face-detect algorithms, so it would not simply take a photo when just anything passes within focusing range, but only when a face is seen and in focus! On the D3S (and I imagine the same with the D700), you can have all 51 AF points active. The camera will thus fire whenever it detects anything in focus within the oval, not just at the central AF Point.
Do you ever remember this being mentioned on the Canon forum? If it was I sure missed it.
Since Canon DSLRs do not have this ability either, you'll probably only hear trap focus mentioned as a requested feature, or when discussing third-party firmware replacements. In fact, I'm not even sure if any of the Canon film bodies could do proper trap focusing. I remember sort-of getting the effect with my 40D by tricking the camera into thinking nothing is in focus, so it gives up trying to drive the lens. But then when you move something into focus, the camera wakes up and takes the photo. It's pretty kludgey, but it was better than nothing.
I think you may be confounding single vs continuous burst mode with single vs continuous AF. Remember, the AF drive setting is irrelevant when it comes to trap focus, because AF is not involved at all! You disable it either by switching the lens to manual focus (thus it stays at the desired focus distance) or you turn off the AF function on the shutter button (so the camera does not attempt to refocus). AF-S, AF-C, face-detect, etc., etc. are all out of the picture at that point. Trap focus is essentially a manual focus technique.
That would be addressed by choosing the shutter release mode: S, CL or CH. It is independent of the AF drive mode. ...Show more →
OK, so I am not missing something (which I usually am!) I see this as very useful in some situations but for narrow DOF shots it would seem too hit or miss to be useful. I realize that the AF isn't at play but acts as the trigger. In the case of the hurdler with a long lens wide open if the trigger point is the body rather than the face then the face has already pasted the point of critical focus and it doesn't matter how many frames get fired off as the base shot was already missed.
Even if it isn't missed, shooting at 150 ft with a 400mm at f2.8 you have approx. 7.2 ft of DOF with about 3.5 ft of that being in front. Assuming you hit the face perfectly, the runner is traveling at 22 ft/sec which means that they are out of the DOF area in less than 1/7 of a sec. If you are really lucky, you might get two frames with a usable focus but I would hope that the Nikon AF-C would be way better than that so I would question why one would use it in this case.
That's not to say I don't see the value of having this as an option. More options are almost always a good thing and I can see the merit of remote triggering based on focus, especially as a second camera but it doesn't seem very useful for something like track or racing.
Another quick question based on the bee example. Would it fire only when the bee hits a specific focus point or could one use focus point expansion so that you aren't reliant on a bee flying over a very specific and small focus point?
rd4tile wrote:
Sounds like it will work in a burst shooting mode based on comments above. Subject comes into focus, cam starts shooting away, subject moves out of focus cam stops?
Could be good for unattended shooting, sort of like a focus based motion detector!
Do you ever remember this being mentioned on the Canon forum? If it was I sure missed it.
If it was, I missed it too. I see the elegance here though the value seems to be very situation specific - not that that isn't true of many things in life.
taob wrote:
Example: You have your macro lens and sturdy tripod set up, with the camera aimed just above a flower where you hope to capture some bees. You manually focus at the spot where you want the bee to land. Using your trusty wired remote, you lock down the shutter button. Without the bee there, the AF point over that spot is not in focus, and thus the camera does not fire. But as soon as a bee lands on that spot, the camera reacts and takes a shot before it flies away again. Instead of you crouching down at bee level for 30-40 minutes waiting for the perfect shot, just let the camera do all the work!...Show more →
this will actually work??
if yes i will sell more 'stuff' and order the nikkor 200mm f2...
if yes i will sell more 'stuff' and order the nikkor 200mm f2...
Yes, if you set it up correctly. But remember what I said above... the camera isn't "smart". All it knows is that something is in focus under the AF point. As soon as it detects that, it will fire. Hopefully, it will be the bee you wanted to capture. But it could very well be another part of the flower, or a different insect entirely. Or maybe the bee flies in, but the camera fires right away before the bee stops moving, so now you have a blurry shot. Or you set it on a continuous burst, and the racket scares the bee away. It's not perfect, but it can be used as one of many techniques you should try.
In fact, I'm not even sure if any of the Canon film bodies could do proper trap focusing. I remember sort-of getting the effect with my 40D by tricking the camera into thinking nothing is in focus, so it gives up trying to drive the lens. But then when you move something into focus, the camera wakes up and takes the photo. It's pretty kludgey, but it was better than nothing.
It's not perfect, but it can be used as one of many techniques you should try.