Focus

[Giovanni Frescura]

Hello
I have a problem
I made my setting for Canon 7D and Canon Mark IV 1 D as Arthur Morris instruction (I bought his notice and all was very ok) but I have some problems with focus.
Sometimes , using both cameras, also if the focus point is right (seeing it by zoom browser) the shoot isout of the focus.
I attach an example. The focusponit is ok and also the speed of the shoot.
Could anyone help me ?

The lens and the camras ar ok as front or back focus (so said me the canon assistance...)
Thanks a lot
Giovanni
gioeli@quipo.it

[John Chardine]

Hi Giovani- Could you post the image with the focus point showing. Maybe this is possible in Breezebrowser but if you bring the image into Canon's Digital Photo Professional and set it to show the focus point, then capture the screen, crop, save as a jpeg and post.

[Giovanni Frescura]

Thanks for help

[Roger Clark]

Giovanni,

This is a common problem with a bright scene in the background. The AF system sees the bird as a relatively small signal compared to the bright, high contrast background. So it locks on to the background. The only solution in this case is to move the AF point to the next low one to get the bird's body. The next solution is to move the AF point to the bird's feet. If your subject were larger in the frame, the AF point on the head would work better.

Roger

[Andrew Merwin]

With this image, I suspect that the contrast was too low to achieve proper focus. I also think the low light levels contributed to the inaccurate focus.
Is this happening frequently or repeatedly? Or is it happening infrequently?
Check out this article by Cambridge in Color for some insights re. your situation.
http://www.cambridgeincolour.com/tutorials/camera-autofocus.htm

[Giovanni Frescura]

[Thanks it could be right...but there are two problems about :
if the camera used a wrong point of focus why no focus on the backround ?
I think the problem was connected using servo in this situation because it is very sensitive with static subjet so little...
With one shoot this problem could be less
No frequently...sometimes with moving animals I have problem for out of focus the first shoot

[Roger Clark]

[Thanks it could be right...but there are two problems about :
if the camera used a wrong point of focus why no focus on the backround ?
I think the problem was connected using servo in this situation because it is very sensitive with static subjet so little...
With one shoot this problem could be less
No frequently...sometimes with moving animals I have problem for out of focus the first shoot

Giovanni,
What was your exposure time, f/ratio, ISO, and what lens?

[Geoff Warnock]

I would say that your camera pretty clearly focussed on the first line of reeds. This fits nicely with Roger's first reply.

That line of reeds doesn't look all that sharp, but as Roger's question implies, that could be an effect of slow shutter speed in windy weather etc.

[Giovanni Frescura]

Giovanni,
What was your exposure time, f/ratio, ISO, and what lens?

Canon 7D
Canon 300 f.2,8 + extender 1,4
iso 500
f.4,5
1/8000

[Andrew Merwin]

No frequently...sometimes with moving animals I have problem for out of focus the first shoot

I know with AI one needs to allow the camera a second or two on the moving subject for the camera to acquire focus. If you are tripping the shutter immediately upon seeing your subject in the view finder, this could explain why the first image is soft & subsequent images of the same subject are sharp.

[Roger Clark]

Canon 7D
Canon 300 f.2,8 + extender 1,4
iso 500
f.4,5
1/8000

Giovanni,

That tells us a lot, thanks. The scene was quite bright, so no problem with low light.

It looks like the AF system locked on to the reed just below the bird's head. The phase angle is quite high resulting in your view of the bird's head being on the shadow side. Thus, the backgrounf was brighter with the high contrast reed, so the camera locked on to the the brighter subject.

Regarding first frame out of focus, this too is common if, as you swing your lens to your subject, and start imaging, the lens is moving to lock on to the subject and the system fires just before the image is tack sharp. This happens if the lens has had to move focus a long way. A solution is to try and keep you lens close to your subject's focus. For example, if you are anticipating a subject will move to a certain spot, pre focus to that spot (or near it) then wait. Then the lens does not have to move focus as far and it is a higher chance the first frame will be in better focus.

The 1D cameras have a custom function setting on when to fire in AI servo mode: only when focus is achieved, or at any time. Maybe the 7D has this too. I keep my 1DIV on fire any time and most of the time the first frame is in great focus, but sometimes not with the conditions above. Note the 1DIV focuses faster than a 7D so this problem will be less in general.

Roger

[Giovanni Frescura]

[Thanks a lot
Could you give me your setting of Mark IV (I have too) so I could try if it is differentes from Morris's setting ?
Ciao
Giovanni

[Steve Uffman]

I am a relative newbie to this having been taking digital images for just 18 months. So take what I am saying with a grain of salt. My results were similar until I made a series of adjustments.

For background, on a recent trip to Galapagos shooting my 7d and my wife's t2i, I found often the t2i's focus was sharper...I noticed even on higher contrast images than yours that my focus point was on lets say the ducklings eye but it was soft and the hen behind was sharp. I sent to Canon along with some printouts showing the image and the focus point. Canon adjusted for the issue and the camera is "right" now.

Also, I found I sometimes was rushing with the shutter button also controlling focus -meaning I often fired before focus had been achieved. After I attended a workshop a few weeks ago with Mr Amoruso and Mr Otoole, I reprogrammed the * key to handle focus.

Now it is a two step process (press* then shutter) but my results are much improved (although it took a bit getting used to). Now I am much more conscious that focus has been obtained before firing the shutter. And after practice, I don't think I miss a beat.

This is really a big help with BIF and I now understand why so many shooting BIF use this setup. also, we did adjust some settings on c.fn III which may have made a difference too

[Desmond Chan]

Also, I found I sometimes was rushing with the shutter button also controlling focus -meaning I often fired before focus had been achieved.

I think you can set it up so that it won't fire until focus is achieved. You can check the camera manual on that.


I reprogrammed the * key to handle focus. [snip] This is really a big help with BIF and I now understand why so many shooting BIF use this setup. Really ?? :w3

[Steve Uffman]

I think you can set it up so that it won't fire until focus is achieved. You can check the camera manual on that.

you can affect it with the settings in c.fn III in terms of priority

Really ?? :w3
Yes Really