AI Servo and 300D [Archive] - Canon Digital Photography Forums

symes

13th of May 2005 (Fri), 04:21

Cadwell

13th of May 2005 (Fri), 04:29

I realize that the only place AI SERVO can enacted is in the SPorts MOde.

My question is: IS AI SERVO what I hear as it refocuses a hundred times as I am shooting?

I have also heard that you can trick it into AI SERVO by slightly adjusting the focal length with the shutter half depressed...but his is anythin but consistent...

Thanks for answering this question...

Matt

Yes.

Tricking AI servo, three ways I know... (works in ANY mode)

1. Achieve focus lock on a subject and then whilst keeping the shutter half depressed and the subject centered, move the lens focus ring - camera drops into AI servo and will stay there as long as the shutter is kept half depressed. (Only works with lenses that support full time manual focusing such as Canon USM and Sigma HSM lenses)

2. Achieve focus lock on a subject and whilst keeping the shutter half depressed use the lens zoom mechanism to zoom in slightly. Camera drops into AI servo and will stay there as long as the shutter is kept half depressed. Obviously only works with zoom lenses and doesn't work with parfocal lenses.

3. Achieve focus lock on a relatively close subject and then whilst keeping the subject centered, and the shutter button half depressed take a step forward. Camera drops into AI servo and will stay there as long as the shutter is kept half depressed.

All three methods take a little practice and some methods work better with some lenses than others. Fairly easy to do though.

symes

13th of May 2005 (Fri), 05:05

My next question is then: Is this the only way to maintain focus on moving people? The reason I ask is that I am trying to get a certain image to come out that highlights the bookbags of our academy...This involves capturing students who are walking away from the Camera...

I am assuming the only two ways are to achieve focus and get it quickly with a high shutter speed or knocking it into AI SERVO?

Cheers...

PhotosGuy

14th of May 2005 (Sat), 20:46

(works in ANY mode) Really? On the 300D? I'll have to try that tomorrow.

CyberDyneSystems

14th of May 2005 (Sat), 21:51

Yes,. the 300D's only Focus mode is "AI Focus" which means it will automatically switch from single shot to AI servo when it thinks it should...

On the 10D this mode is selectable.. but not a good choice. Like anything else you get better results if you make the decision yourself,. rather than letting the camera decide. Especially when the only time the camera seems to decide to switch to AI servo is when you do one of the methods listed above :lol: :lol:

PeaPicker

17th of May 2005 (Tue), 16:08

Wow! Just tried this and works great. Learn something new here everyday. Thanks boys and girls!

PeaPicker

17th of May 2005 (Tue), 16:09

One more. Why is there not a red triangle on my posts?
Thanks again

Brands

17th of May 2005 (Tue), 16:15

One more. Why is there not a red triangle on my posts?
Thanks again

that's for reporting a bad post to the mods ;) which you are unlikely to do with one of your own

PhotosGuy

17th of May 2005 (Tue), 19:02

I tried it out. 1st pic is a grab shot - just hitting the shutter release & taking whatever happened. Focus was on the front of each car.

2nd pic was using Cadwell's first option. I found that it worked best by racking the focus out&in fast to get the servo to engage. While holding the focus ring I could feel the servo working. This is the best one of a series of about 6 shots. Some weren't as sharp. I haven't figured out why yet.
Any ideas?

Cadwell

18th of May 2005 (Wed), 03:50

Some possible causes:

1) OK, well first I'm assuming you're using a single focus point - preferably the centre one?

2) Cars can be tricky, there's sometimes not enough contrast on the front of them for the AF mechanism to lock on to so you need to select where you put your focus point with care. I don't know whether the 300D/dRebel has a visual indication of this. On the Mark II there's a little dot in the bottom right hand corner of the viewfinder that flashes if it can't achieve AF.

3) The AI servo AF system needs a little time to settle. You will need to track the target for between half and three quarters of a second before firing the shutter in order to give it a fighting chance.

4) I don't know what lens you were using, but some lens AF mechanisms can't respond quickly or accurately enough to make good use of AI Servo AF.

PhotosGuy

18th of May 2005 (Wed), 06:59

Thanks for the reply. Those are 100% crops BTW.

1. Yes

2. 300D/dRebel does not have a visual indication listed in the manual that I could find. As I said, "I could feel the servo working." & didn't take the shot unless it was. A few times it wouldn't engage at all in the 2-3 sec before the car was going by. Probably my fault, or maybe I'm expecting too much? Three of the cars with missed focus were white & one was black. Maybe I slipped up to the hood where the contrast was non-existant. I'll try some more this afternoon & concentrate on getting that right.

3. I tried to give it a full 2 sec to let the car get close since I was using the...

4. 28-70 f/2.8 L @70mm. (Sorry, I should have said that.)

I tried to put the focus point on an area that had some contrast. It was pretty bright out (for Michigan) & I was shooting at ISO 100, 1/800sec. I expected it to snap right into focus at that light level, & stay there. Again, maybe I'm expecting too much?
;)

PaulSands

18th of May 2005 (Wed), 07:13

Cadwell

18th of May 2005 (Wed), 07:57

I can't comment about the 300D but I am having serious doubts about the AI Servo on my 10D. It's heading back to the shop in a few days as I don't think it's holding the focus like it should. Way too many wasted shots while snapping motor racing events

It depends a lot on the conditions. My 10D was having fit at the FIA GT/WTCC meeting on Sunday due to the harsh lighting / reflections / headlights. I stopped using it entirely and relied on the 1D Mark II instead. It was coping better.

PaulSands

18th of May 2005 (Wed), 14:34

So the more pro the kit the more pro the results..stands to reason I suppose

tabrandt

18th of May 2005 (Wed), 21:19

Where was this tip before I sold my 300D and picked up a 20D? <smile> This is a really great tip.

PhotosGuy

19th of May 2005 (Thu), 07:01

Where was this tip before I sold my 300D and picked up a 20D? <smile> This is a really great tip. It's put off my upgrade plans for at least 6 months! ;-)

Medic1

19th of May 2005 (Thu), 13:05

It's put off my upgrade plans for at least 6 months! ;-)

lol....I'm thinking the same thing. Everything I read said AI servo simply wasn't achievable on the 300D except in sports mode. Since I shoot mainly aviation photography, I went to the 20D....one of the reasons (among many) was the true AI servo...

Now I got this damn 20D.....oh well, guess I will just have to live with it.... :) :) :)

foxbat

20th of May 2005 (Fri), 05:56

[...]This is the best one of a series of about 6 shots. Some weren't as sharp. I haven't figured out why yet.
Any ideas?If I remember correctly the exposure is locked at the time you half-press. This means that if you track into an area of different light conditions then your exposure will be off. I'm pretty sure that's the case but am ready to be corrected.

PhotosGuy

20th of May 2005 (Fri), 06:54

You're right foxbat, but it's not an issue for me. It's always locked 'cause I shoot 99.999% of the time on M & use RAW so I can correct when I have brain fade! ;-) I can see where there might be issues for the jpg shooters, though.

webcase

22nd of May 2005 (Sun), 04:07

So the more pro the kit the more pro the results..stands to reason I suppose

Don't fall for that trap .Its the operator 99% of the time . I have a 300 D and all i shoot is motorsport and over a short period of time my shots have improved by miles due to perserverance and knowing my gears limits and limitations . Moto is a hard subject to photograph at the best of times and its easy to blame the gear .

Cadwell

22nd of May 2005 (Sun), 11:12

Don't fall for that trap .Its the operator 99% of the time . I have a 300 D and all i shoot is motorsport and over a short period of time my shots have improved by miles due to perserverance and knowing my gears limits and limitations . Moto is a hard subject to photograph at the best of times and its easy to blame the gear .

Nice to know you think I don't know how to shoot motorsport with my 10D. Thanks for that. :rolleyes:

Molydood

22nd of May 2005 (Sun), 16:27

webcase

23rd of May 2005 (Mon), 04:03

Nice to know you think I don't know how to shoot motorsport with my 10D. Thanks for that. :rolleyes:

I didn't imply you don't know what your doing, i didn't even quote you nor was i refering to you.Nor did i imply that PaulSands doesn't know what he's doing .Apologies if thats the impression i gave you Paul. I simply meant that people seem to be overly keen to buy top of the range equipment expecting largely improved shots .I'd hate to see people sell themselves short with a 300D ,20D,10D or whatever and buy a dearer camera in search of results that aren't necessarily the cameras fault .Its a bit like someone buying a Les Paul and expecting it to make them a better guitar player .