Canon 7D Focus question
Sep 15, 2011 10:37:27 #
Hi nice people! I have been asking quite a few rudimentary questions and have been helped a great deal by this forum. Have tried (as suggested) Michaelthementor forum and it is okay, but I just feel I have had much more success and learned so much more in this forum so please bear with me if my questions show my lack of experience. Through your help I now see how the different focus points work, and need some clarification. I use the focus point "auto select" that has 19 point AF - but when taking a picture as I focus of course it selects what it thinks I want to focus- is there a good way to change the area it selects - I mean lets say there are three people in a row one each a little closer than the other - unless the focus points are on each person they will not be in focus - how can I fix this - dont understand how to make sure these focus points are on the things I want - I can readjust and refocus - is that the only way to do so? I am trying to find the best way to focus when there are several subjects - not all in a line up! that I want to have all in focus. I know I need to increase my depth of field with my aperature to keep all in focus but how about these focus points--how can I control this and make sure my main subjects are included in these focus points?!
Sep 15, 2011 13:03:38 #
Sep 15, 2011 13:05:20 #
debbiesweds wrote:
Nevermind I found the answer to my question - sorry for the interruption - haha!
:thumbup: for finding the answer on your own.
:thumbdown: for not posting it here for others to benefit from.
Sep 15, 2011 14:23:57 #
Oh, I am so sorry, I never thought of it that way - so sorry. I was thinking this will save someone trying to explain to me! Sorry Well, here is what I found, and may not hold true for everyone, but gives more control than using the auto 19 point selection. That is the problem, it does not always know what you want and randomly kind of selects subjects for you, so possibly?!...the best choice to use when selecting focus points on the canon 7D may be the "manual select - single point AF" selection- at least gives you the most control (and that's what we photographers are all about is control right). This way you can use the center one for regular shots and move the focal point to the area where your subject is if you need it to be more localized. I'm just not good at instructions and not sure my way of thinking is good enough for giving out any form of advice, but that seems when I experiment a little - to work.
Sep 15, 2011 17:15:47 #
In auto selection, it will generally pick the closes object in the frame to focus on.
I find it's easiest to use manual zone select, and use the joystick on the back to move the zones.
It starts off at the center of the screen. And if I need to focus on something in the other zone, I switch the zone with the joystick and let the camera pick the best point within that zone. It's really quick once you get used to it.
As an added benefit, you won't have to focus-and-recompose anymore unless you want to focus on something in one of the corners.
Pressing on the joystick brings the zone back the default one, which is the center zone unless you change that as well.
Such approach works really well with AI Servo. No need to focus-and-recompose, so you can continue using servo instead of one-shot focus.
And since with a fast lens, you can never be sure that your focus is good, you can take a few pictures without fully releasing the shutter button. AI Servo just keeps working.
With one shot auto focus, you would have to completely release the button and half-press it again for the camera to attempt to acquire the focus again. That takes more time.
So in short, my setup is AI Servo + manual zone select.
When taking a shot, I first compose the shot, then select the appropriate zone with my right thumb (while still looking through the viewfinder). Once I'm done, I half press the shutter button, let the IS settle and AI servo do its thing. After that, I go from half-press to full-press back to half-press a few times, never fully releasing the shutter button. And I end up with several shots, all with a slightly different focus. One of them is bound to be just perfectly focused, with any lens.
Hope this helps.
I find it's easiest to use manual zone select, and use the joystick on the back to move the zones.
It starts off at the center of the screen. And if I need to focus on something in the other zone, I switch the zone with the joystick and let the camera pick the best point within that zone. It's really quick once you get used to it.
As an added benefit, you won't have to focus-and-recompose anymore unless you want to focus on something in one of the corners.
Pressing on the joystick brings the zone back the default one, which is the center zone unless you change that as well.
Such approach works really well with AI Servo. No need to focus-and-recompose, so you can continue using servo instead of one-shot focus.
And since with a fast lens, you can never be sure that your focus is good, you can take a few pictures without fully releasing the shutter button. AI Servo just keeps working.
With one shot auto focus, you would have to completely release the button and half-press it again for the camera to attempt to acquire the focus again. That takes more time.
So in short, my setup is AI Servo + manual zone select.
When taking a shot, I first compose the shot, then select the appropriate zone with my right thumb (while still looking through the viewfinder). Once I'm done, I half press the shutter button, let the IS settle and AI servo do its thing. After that, I go from half-press to full-press back to half-press a few times, never fully releasing the shutter button. And I end up with several shots, all with a slightly different focus. One of them is bound to be just perfectly focused, with any lens.
Hope this helps.
Sep 15, 2011 17:24:13 #
Quote:
I mean lets say there are three people in a row one each a little closer than the other - unless the focus points are on each person they will not be in focus - how can I fix this
You can't. They have to be on the same plane or only one of them will be in focus. The only thing you can do is increase the depth of field by lowering aperture.
Sep 15, 2011 17:56:04 #
Deb, I knew the answer would be "Don't use auto-select" but I wanted to see if that's what you found as well. Jest pullin' yore leg...
In all but a very few situations, auto-select of focus points will not produce optimum results. I changed my camera to center-point as soon as it came out of the box, and only reset to the factory setting on very rare occasions.
Auto-select is especially troublesome when your 'focus group' is arrayed perpendicular to the plane of the sensor, or in other words, "going away from you". A scene where most of the area you want in focus is more or less parallel to the sensor, "going side-to-side", is easier for auto-select to work on, since most of the object will be approximately the same distance from the camera.
Auto-select also does not work well when there are big variations in the brightness and contrast of the objects, and the object you want to focus on is not as bright, contrasty, or reflective as other parts of the scene.
In all but a very few situations, auto-select of focus points will not produce optimum results. I changed my camera to center-point as soon as it came out of the box, and only reset to the factory setting on very rare occasions.
Auto-select is especially troublesome when your 'focus group' is arrayed perpendicular to the plane of the sensor, or in other words, "going away from you". A scene where most of the area you want in focus is more or less parallel to the sensor, "going side-to-side", is easier for auto-select to work on, since most of the object will be approximately the same distance from the camera.
Auto-select also does not work well when there are big variations in the brightness and contrast of the objects, and the object you want to focus on is not as bright, contrasty, or reflective as other parts of the scene.
Sep 16, 2011 13:33:53 #
Thank you all for your helpful responses - again I am printing this out so I can read and re-read and try this stuff out and see how it works - but I understand all you are saying and it makes perfect sense - one question what do you think about the idea of al servo - would there be issue if i left it on al servo - and if i did i could not use the auto focus (the 19 point one) at all could i? or could i??
Sep 16, 2011 19:15:02 #
I don't believe AI Servo has any impact or bearing on the AF point selection mechanism - it's the way the camera re-focuses when necessary/if necessary as/if you recompose with the shutter half-way down. AI Servo is usually recommended for use with burst shooting.
Selecting a specific AF point, versus letting the AF system do it automatically, is completely separate from HOW the AF system does its job overall, and how often it recalculates the autofocus.
I think.
Selecting a specific AF point, versus letting the AF system do it automatically, is completely separate from HOW the AF system does its job overall, and how often it recalculates the autofocus.
I think.
Sep 16, 2011 19:31:39 #
[quote=KG]In auto selection, it will generally pick the closes object in the frame to focus on.
I find it's easiest to use manual zone select, and use the joystick on the back to move the zones.
It starts off at the center of the screen. And if I need to focus on something in the other zone, I switch the zone with the joystick and let the camera pick the best point within that zone. It's really quick once you get used to it.
As an added benefit, you won't have to focus-and-recompose anymore unless you want to focus on something in one of the corners
Pressing on the joystick brings the zone back the default one, which is the
center zone unless you change that as well.
Such approach works really well with AI Servo. No need to focus-and-
recompose, so you can continue using servo instead of one-shot focus.
And since with a fast lens, you can never be sure that your focus is good, you can take a few pictures without fully releasing the shutter button. AI Servo just keeps working.
With one shot auto focus, you would have to completely release the button and half-press it again for the camera to attempt to acquire the focus again. That takes more time.
So in short, my setup is AI Servo + manual zone select.
When taking a shot, I first compose the shot, then select the appropriate zone with my right thumb (while still looking through the viewfinder). Once I'm done, I half press the shutter button, let the IS settle and AI servo do its thing. After that, I go from half-press to full-press back to half-press a few
times, never fully releasing the shutter button. And I end up with several shots, all with a slightly different focus. One of them is bound to be just perfectly focused, with any lens.
Hope this helps.[/]
:thumbup: Perfectly explained. The multi controller is the quickest way to adjust AF points. I'll have to try the half press technique that's a new one on me. Thanks for the tip.
I find it's easiest to use manual zone select, and use the joystick on the back to move the zones.
It starts off at the center of the screen. And if I need to focus on something in the other zone, I switch the zone with the joystick and let the camera pick the best point within that zone. It's really quick once you get used to it.
As an added benefit, you won't have to focus-and-recompose anymore unless you want to focus on something in one of the corners
Pressing on the joystick brings the zone back the default one, which is the
center zone unless you change that as well.
Such approach works really well with AI Servo. No need to focus-and-
recompose, so you can continue using servo instead of one-shot focus.
And since with a fast lens, you can never be sure that your focus is good, you can take a few pictures without fully releasing the shutter button. AI Servo just keeps working.
With one shot auto focus, you would have to completely release the button and half-press it again for the camera to attempt to acquire the focus again. That takes more time.
So in short, my setup is AI Servo + manual zone select.
When taking a shot, I first compose the shot, then select the appropriate zone with my right thumb (while still looking through the viewfinder). Once I'm done, I half press the shutter button, let the IS settle and AI servo do its thing. After that, I go from half-press to full-press back to half-press a few
times, never fully releasing the shutter button. And I end up with several shots, all with a slightly different focus. One of them is bound to be just perfectly focused, with any lens.
Hope this helps.[/]
:thumbup: Perfectly explained. The multi controller is the quickest way to adjust AF points. I'll have to try the half press technique that's a new one on me. Thanks for the tip.
Sep 16, 2011 19:35:44 #
JimH wrote:
I don't believe AI Servo has any impact or bearing on the AF point selection mechanism - it's the way the camera re-focuses when necessary/if necessary as/if you recompose with the shutter half-way down. AI Servo is usually recommended for use with burst shooting.
Selecting a specific AF point, versus letting the AF system do it automatically, is completely separate from HOW the AF system does its job overall, and how often it recalculates the autofocus.
I think.
Selecting a specific AF point, versus letting the AF system do it automatically, is completely separate from HOW the AF system does its job overall, and how often it recalculates the autofocus.
I think.
That is correct. Once you have chosen the AF point the the AI servo will use that point to continually focus on.
Sep 17, 2011 13:01:34 #
Thank you all for the input - again this weekend I will put these tips and this info to trial and I am most thankful for the suggestions. I'm AM gonna get this! I have a sign that says Make a wish and then make it come true. This is my wish. I have told my friends I have photo class every night - they asked who and where - actually i am the teacher and the student - its called home schooling. I have been learning a great deal every day from other internet and photot sites and books (some referred here) and reading all i can absorb. But i find this forum is the best source of useful and helpful information that there is around. So many kind and knowledgeable experienced photographers- I personally thank you all for making that possible. i have lots and lots of questions, and you all seem to have all the answers...thanks for sharing!
Sep 18, 2011 11:39:35 #
Okay, I just remembered why this could be a problem - if use are in al servo -- and you do try to recompose a shot in a few of these focus clusters - i believe it can confuse that movement and ruin the shot - because you are moving the camera - does that make sense.
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