Hello everyone...I have had this issue on & off for no particular reason...and it may be entirely normal but I need your take. I use a Canon 40D and a Canon 100-400L and sometimes while trying follow/focus on moving subjects (such as ducks moving quickly or other birds) the lens will have trouble focusing and stopping when focused...rather it will constantly focus in & out forcing me to occasionally get frustrated a resort to using the manual focus (which is fine, but much harder for quick shots.) Is this a normal issue? Someday s it will focus quickly and others it will have trouble "sticking" with the subject. Also, a somewhat related question- how is it possible to focus within a split second to capture something moving quickly towards you? I'm trying to get a shot of a snake striking towards (but out of range lol) of my camera but I just can't focus quick enough on the snakes mouth as it opens (literally a 1/10th second or so.) Some of this may be simple stuff I'm just not familiar with...Thanks - Brandon
Hello Brandon,
The inability of the lens to hold or lock on to a point of focus is a repair issue and should be sent in to Canon or other qualified repair shop.
As to the focus speed of a snake strike, AI servo and lots of luck. I'm not sure if the 40D is fast enough to do that extreme of a task.
Good Luck.
Neil
Posted by Colin Smale on April 11, 2010 at 12:37 PM
Hi Brandon. Focusing 'problem'. Depends on how much light/contast there is for the auto focus to pick up and even then, sometimes it just wont happen I'm afraid. Whatever they say, lenses are not that good yet. It makes a difference if you use a TC too, that doesn't help, that's why most folk keep em to a 1.4.
Some of the tracking programmes don't perform anything like as well as manufacturers claims either and it doesn't matter if you use Nikon or Canon, they both suffer focusing problems sometimes and we have found when the Canon can't pick it up properly, neither can the Nikon. I have found the best bet is to use single point focus when trying to track birds in flight, keep it simple, works for us.
Always good to check the simple stuff first: Do you regularly check the AF distance parameter switch on the side? If you have it set to 6.5 meters (or whatever it is) instead of 1.8 meters, that would cause problems.
Also check your AF point and whether you are in AI Servo, AI Focus or One Shot. One shot will lock, but not hold a moving target, AI Focus does what IT thinks you want to do, AI Servo will follow your target, but if you are not using the center focus point, locking focus will not be as efficient. I think, not sure, but I think at f/5.6 or 6.3 it will focus more slowly than at f/4.0 (it has a non-constant aperture across the zoom range).
If it has this problem despite checking all of these settings, send it to Canon for sure.
Let's back up a bit here. Are you choosing the focus point or letting the camera choose it? If you are choosing center point and do not keep it precisely on the bird, the camera will then hunt. Any brand & any lens will do this and it's not that anything is broke. It's your technique. If the 40D will allow expanding the focus point via custom function as the Mark III will, then enable that. If you use servo focus it again is essential you keep your focus point on the subject as noted above. Soon as it drifts, the focus tries to find again. Also as noted, one thing you can do is set your 100-400 so it focuses at 6.8mm to infinity instead of 1.8m to infinity. Then when you do drift off target, it doesn't have so far to focus.
If you cannot expand focus point, you may then want to try one of the autofocus zones if offered on 40D. The 7D has multiple "zones" you can use and while I doubt the 40D has that, it may have some flexibility. Explore all your custom functions thoroughly and you'll be amazed at how you can tailor the camera to you. If after all this there is still a problem, then indeed you may have an equipment problem but, no offense, I doubt it.
Thanks everyone- I don't think it's a lens repair issue primarily because it will work fine sometimes and it doesn't appear to be a malfunction of any kind (it doesn't seem abnormal and has really always been doing this.) I always keep the lens at 1.8 meters so that I don't lose focus when things move in closer (ducks often can be quite curious.) I will try a few of the things you have mentioned and see if it makes a difference. Also, the 40D really isn't capable of that snake striking shot? What would I need then? Anything cheaper than a Mark III? I *may* be able to afford a 7D but I would be stretching my budget really thin. Then again...a friend of mine has a great hook up for Camera rentals....do you think renting a Mark III is the way to go? Also, I love the 40D because of the 1.6x.....how noticeable will the difference in zooming capability be on the Mark III? I really would prefer to just stick with my 40D but if it is physically incapable of producing certain shots I may have a problem...is this true?
All above advice is good. I would especially be sure you are using center point AF. Also you can be sure the AI Servo "speed" is set to slow. This will not affect acquisition speed, but will lengthen the time before the AF will try to shift to another subject if you slip and let the AF point drift off the subject. I would also turn off focus search. This is what is causing your lens to search so much when it loses AF.
Posted by Nate Chappell on April 11, 2010 at 6:19 PM
Hi Brandon
Is your snake going to be a controlled conditions shot where you can say where the snake will be or is it a totally wild situation? If you answer that it will give me a better idea of how you might handle this shot.
Ed...thanks! I did not know you could change the servo speed or turn off focus search! Nate- it will be wild, but with a wildlife ranger for safety precautions (with a 400 I don't I have much worry though.) I am going to be trying two species- a large and very old Southern Pacific Rattlesnake in Topanga State Park and...in a drastically different environment...a King Brown at Fogg Dam near Darwin in Australia. I have rangers in both areas that know where the individual is during certain times of day and, in Australia, I will have 7 days in this one area to accomplish this shot (and plenty of other shots as well.) Of course, each snake can have wildly varying striking speeds. In addition, figuring out how to freeze a snake in mid-strike will definitely make freezing a crocodile in mid-attack a simple task (actually, it shouldn't be hard at all.) Thanks and look forward to hearing your feedback.
Posted by Nate Chappell on April 11, 2010 at 10:41 PM
Most of the shots that I've seen of snakes striking have been taken with a captive snake in controlled situations. The Phototrap, a device which triggers your shutter when something passes through it is excellent for a controlled setup. A couple of slave flashes are setup where the snake will be striking. If anyone wants to see more info on the phototrap they can check out http:www.phototrap.com.
I think getting this shot with a wild snake will be difficult and potentially dangerous. You would kind of have to know when and where the snake was going to strike. You wouldn't want to use a Phototrap because you would have to get too close to the snake to put the flashes in the right spots. If somehow you know when and where the snake is going to strike and you are not using a Phototrap you could manually prefocus on the strike area. I imagine that working without flashes you would need a pretty fast shutter speed and depending on the light high iso. So, it might make sense to rent a Mark IV for the project especially if you are going to rely on autofocus rather than manually focusing on the area that you know will be the strike area.
Personally, I can't see any situation that is causing the snake to strike that is worth a photo. A snake strikes when it needs to kill food for it's own survival. It's best to just leave the snake alone. I also have to wonder about any Ranger that is pointing you toward a place where you can pester the wildlife. Rangers are not professional snake handlers. What happens if you get bitten? I think your Ranger friend might find himself in a bit of trouble. Probably not too good for you either. Just my 2 cents.
A phototrap, or something along the lines of this rig would be needed to capture a striking snake.
I really can see no lens / camera combo that will be able to track a striking snake, it simply is to little movement in a to short timespan
But as noted above take care whit snake's as to not endanger yourself nor the snake.
Thanks...and Charlie the snakes welfare is of the greatest concern to me...hell, when I'm shooting in the wild I put all wildlife's safety ahead of my own since I'm in their territory (although I never put myself at risk either.) I have not talked with my Australian guide specifically about striking...rather just fast movement and the ability to get the head in focus. Here in California we have plenty of time and I don't think I made it clear but I don;t want the snake striking directly at the lens...but rather at prey. My ranger knows where the large southern pacific rattlesnake waits at dusk and has seen it with prey plenty of times. Of course, it's still going to require pure luck...but regardless, knowing how to get a fast moving snakes full head in clear, sharp focus fast enough to get a shot is my primary goal here. Sorry for the confusion.
Brandon,
Seeing that a rattlesnake it's strike is extremely fast, i suggest you use a flash to freeze the action.
you will find that allot easier than trying to get the required shutter speed, especially seeing you plan to shoot at dusk. You should also prefocus on the prey or a bit in front of it, you will have a greater chance of getting a sharp shot that way.
Discussion
13 repliesThe inability of the lens to hold or lock on to a point of focus is a repair issue and should be sent in to Canon or other qualified repair shop.
As to the focus speed of a snake strike, AI servo and lots of luck. I'm not sure if the 40D is fast enough to do that extreme of a task.
Good Luck.
Neil
Some of the tracking programmes don't perform anything like as well as manufacturers claims either and it doesn't matter if you use Nikon or Canon, they both suffer focusing problems sometimes and we have found when the Canon can't pick it up properly, neither can the Nikon. I have found the best bet is to use single point focus when trying to track birds in flight, keep it simple, works for us.
Also check your AF point and whether you are in AI Servo, AI Focus or One Shot. One shot will lock, but not hold a moving target, AI Focus does what IT thinks you want to do, AI Servo will follow your target, but if you are not using the center focus point, locking focus will not be as efficient. I think, not sure, but I think at f/5.6 or 6.3 it will focus more slowly than at f/4.0 (it has a non-constant aperture across the zoom range).
If it has this problem despite checking all of these settings, send it to Canon for sure.
If you cannot expand focus point, you may then want to try one of the autofocus zones if offered on 40D. The 7D has multiple "zones" you can use and while I doubt the 40D has that, it may have some flexibility. Explore all your custom functions thoroughly and you'll be amazed at how you can tailor the camera to you. If after all this there is still a problem, then indeed you may have an equipment problem but, no offense, I doubt it.
Let us know how you resolve it.
JR
Is your snake going to be a controlled conditions shot where you can say where the snake will be or is it a totally wild situation? If you answer that it will give me a better idea of how you might handle this shot.
I think getting this shot with a wild snake will be difficult and potentially dangerous. You would kind of have to know when and where the snake was going to strike. You wouldn't want to use a Phototrap because you would have to get too close to the snake to put the flashes in the right spots. If somehow you know when and where the snake is going to strike and you are not using a Phototrap you could manually prefocus on the strike area. I imagine that working without flashes you would need a pretty fast shutter speed and depending on the light high iso. So, it might make sense to rent a Mark IV for the project especially if you are going to rely on autofocus rather than manually focusing on the area that you know will be the strike area.
I really can see no lens / camera combo that will be able to track a striking snake, it simply is to little movement in a to short timespan
But as noted above take care whit snake's as to not endanger yourself nor the snake.
Wim.
Seeing that a rattlesnake it's strike is extremely fast, i suggest you use a flash to freeze the action.
you will find that allot easier than trying to get the required shutter speed, especially seeing you plan to shoot at dusk. You should also prefocus on the prey or a bit in front of it, you will have a greater chance of getting a sharp shot that way.
Wim