Slow focus with 100-400mm - How come?

[Marvin]

It seems that my 100-400mmL is having trouble focusing quickly enough to catch

flying birds. I didn't realize just how slowly it was to capture the focus

until yesterday. I was standing surrounded by Nikon shooters. When a flying

bird came into view I heard a barrage of clicking shutters from the Nikons

while my 20D with the 100-400mm stayed impotently silent, unable to focus. Does

this sound right? Is there something that I could be doing wrong? I was set for

burst mode, 1/1000th sec, AI focus (I think AI focus words better than AI

Servo). Is it possible that setting Adobe RGB (which I'm using) takes longer to

focus than sRGB?

[bryan_lardizabal]

Several factors contribute to this such as which shooting mode was the camera in Av, P, etc. as well as focusing mode as you've stated, but Adobe settings would not affect it at all. As long as your lens was not set on manual, it is very tricky to get good at finding moving subjects.

 

Practice is most likely what is needed.

[bryan_lardizabal]

One thing that is missed. You stated 1/1000 sec. so you may have been in shutter priority mode. If the subject metered a slower speed this would likely be your problem.

[elliot1]

If you lens focuses fine otherwise, the problem is likely with your settings.

 

For shooting fast moving subjects, you would want to use AI Servo. You also want to use a single focus point, likely the center one with your camera, for best results.

 

I would review your camera's settings and try again. You will likely see a huge difference.

[sattler123]

I suspect user error, as I have no problems with the focus speed of my 100-400. As others have stated, you should use only the central focus point, use AI-Servo, I pre-set the aperture, not the shutter speed. RGB has nothing to do with the speed of your camera. Try these settings and your problems will go away.

[steve_byland]

Marvin

 

I used a 20d on flying birds and can tell you from experience that it is hard, but doable. My best luck with the same lens is to shoot IA Servo, activate all the focus points and make sure that the lens is set to 6.5 meters to infinity. It NEVER seems to find the bird set to 1.8 meters to infinity! Next, make sure that the camera is initially focused on something distant (tree line, etc). If you just bumped the shutter button at some point to turn off the display, it is probably focused way too close. Just point at something distant a refocus. Finally, make sure you can see the bird through the viewfinder before pressing the shutter to focus or the lens will start hunting and you will definitely miss the shot. If you absolutely lose focus, try to quickly focus on a distant object and try again.

 

If the bird is flying with a very busy background, all bets are off - although I have had some luck using the full-time manual focus to over-ride.

 

Good luck - this is an area where the more you practice, the better you will get, but sometimes you just miss out altogether. I do find that I am able to lock on and shoot now about 90% of the time

[geoff_foale]

I don't really like AI Servo because I'm never quite sure if it has focused correctly or not, but most times it does produce the goods when shooting moving images. Personally, I usually prefer the single centre autofocus point as I know that it is focusing on the intended object not another bird or something in the background. You are less likely to end up with only part of a bird on the image edge; but, I do totally miss a few shots this way.

[JosvanEekelen]

I always had the impression that AI-focus slowed focussing down significantly but that is based on only a short experience. I'd try AI-servo but YMMV.

[peterlyons]

I shoot moving subject all the time, so keep my 5D on AI servo and get fine results with that.

I've also had some focusing issues with my 100-400 recently. The problems turned out to be

symptomatic of a loose lens element. (Other symptoms included lack of sharpness and a

double-image in the bokeh (out of focus areas). Now with the lens fixed, focusing speed has

been restored. Mostly. Sometimes though, for a reason unknown to me, it'll focus very

slowly. Maybe 10% of its normal speed. It don't know if that's a problem with the lens or one

of the bodies. But that's another story!

[dangoldman]

Never mind Peter, what he does with cameras is sacrilegious and mean... throwing them in saltwater and what not...

 

 

Marvin, i dont have a 20D, but here are my thoughts from using my 350D. My 350D does not have the best AF, and i know for sure that when i use my 70-200F4L on it, it is not living up to its potential. I have found that using the center focus point and Servo have given me the best photos for moving objects <200mph... I also use the custom function that allows me to press the * button (normally exposure lock) to activate the AF amd IS if the lens has it. I then track the bird from as far out as possible. IE, you cant just put the camera up to your eye, and push the button. Keep the bird on the center focus point till where you want to take the picture, then take a short burst, recompose, focus and take another.

[geoffs1]

Don't forget to try shifting the AF to the "*" button (Cn.F-4=1).

 

I don't shoot avians much, but I do take a lot of pictures of flying things with a 100-400mm. I've found that AF-Servo, "*" AF, all AF points, and focus limiter set at 6.5m gives consistent results. My technique is to pickup the subject in the finder further away than you would want to start shooting. Place the center AF point on the subject and press/hold the "*". This starts the AF (and IS). Keep holding the "*" button while you're tracking the subject and fire frames as you want. When you're ready for the next subject release the "*" and start again.

 

I'd suggest always shooting a burst of two or more frames because the 20D will take the first shot when you press the shutter release, but subsequent shots will only fire when the AF system says it has a "good enough" focus.

[dan_hall4]

I have the lens myself but lack the experience to help you much. I just got it a month or two back and rememeber reading reviews online (their are many) and there was some discussion about this oriented towards the bird photography crowds. It was not in one specific review, but in several. Seems to me it was a focus setting issue as someone mentioned above. If you put Canon 100-400 review into google I am sure you would find some information that may help you. There wasa lots of reviews/praise/critique from the bird photography community to be found. Maybe something there would help you out. The only time I have had a similar problem with mine was with light gathering issues. When there is decent light, I have had no problems. What a wonderful and versatile lens.

[Marvin]

Thanks, for all the good ideas.

For those who mentioned it I did use the center focus point. I chose the 1/1000 sec Tv rather than the Av to make sure that that shutter speed was fast enough. I also opened the exposure compensation to about +1 t because i was hooting skyward. I don't yet know what CN 14 is - but i'm gonna check it out.

I've not been good with AI autofocus - maybe I'm not using it right.

Practice may be the answer but I've been shooting quite a bit - with mixed results.

When I can pick up the bird at a distance and when it is flying slowly I don't do so badly. It's when the bird appears suddenly and approaches me at a fast rate of speed that I'm left flat-footed while the Nikon shooters are clicking away.

 

Thanks to all.

[jimstrutz]

AI Focus is an auto mode takes time for the camera to determine that the subject is moving, and then switches into Servo. That time is killing you. Never use AI Focus.

[mendel_leisk]

"CN 14" is actually CN.F-4=1, which is one sorry and truncated acronym for:

 

Custom Function 4, set to 1

 

Custom functions are in the camera's menu structure, and outlined in the manual.

 

I never came near to understanding all the permutations of Custom Function 4 (the manual is rife with acronyms, and very terse). What I *did* come away with:

 

Setting 0 is the camera's default.

 

Setting 1 leaves everything more or less the same as 0 except half depressing the shutter button no longer activates auto-focus. That function is transferred to the back button (under your right thumb).

[mendel_leisk]

" back button " should read " asterik (*) button, on the back ".

 

(Geez it would be nice to have say a 30 minute grace period to edit your posts.)

[Marvin]

I have characteristically used AI focus so that when photographing a still subject, e.g., a bird standing still in the water, I can focus and then re-compose the subject in the viewfinder. In that circumstance it works fine. I have had less success (and less experience) with the Servo mode for moving subjects. For example, I like to position myself at the far turn at the racetrack and shoot the horses as they are coming toward me. I think that I have had more out of focus shots with Servo than with AI focus. Maybe someone can suggest a reason - but I confess that it may be user error.

[image.a.nation]

Marvin you haven't commented on whether you are set to 1.8m min focus or 6.5m. It makes a huge difference to the 100-400's focus speed. Many is the time I have lost an opportunity with moving birds because I didn't think to set it back to 6.5 after shooting closer subjects. At 6.5m min distance my lens is blazingly quick to focus.

 

Of course skill in tracking your subject is absolutely key. I always use the center focus point, so if I don't track that point with the bird the camera has no chance and I know I would do no better on a Nikon.<div></div>