Forum Index > Photography Talk > focus and recompose
Previous :: Next Topic  
Author Message
iron
getting old



Joined: 10 Aug 2008
Posts: 6420 | TRs
Location: kenmore
iron
  Top

getting old
PostWed Nov 20, 2019 8:50 pm 
Reply to topic Reply with quote
if one focuses, then pivots the camera to recompose, without refocusing, is the target generally in focus, or do you lose some crispness due to the rotated angle?

i assume it's probably worse for up-close subjects than far away ones.

--------------
man, you go through life, you try to be nice to people, you struggle to resist the urge to punch 'em in the face, and for what?

--- moe sizlack
Back to top
View user's profile Search for posts by this user Send private message Send e-mail Reply to topic Reply with quote
GaliWalker
Have camera will use



Joined: 10 Dec 2007
Posts: 4161 | TRs
Location: Pittsburgh
GaliWalker
  Top

Have camera will use
PostThu Nov 21, 2019 6:02 am 
Reply to topic Reply with quote
The answer to both questions is yes. However...
To know how much something will get out of focus depends on two things, the aperture and how far away the subject is. e.g.
f/4:   <      |s |                   |   s          |
f/22: <   |   s           |  |          s                                                                               |
where:
< = Camera
s = Subject
| | = Area in focus (depth of field).
Generally, if I'm too close to the subject, want to shoot with a wide open aperture, and none of my camera's focus points fall on the subject I'll switch to manual focus.

Also, crispness has a lot to do with shutter speed, maybe even more so than focus. I think of focus affecting blurriness, while shutter speed is better linked to crispness. Here's how: If you don't use a fast shutter speed and you shake the camera even a tiny bit, say while pressing the shutter button, and if the subject is a fair distance away, then it will gyrate wildly, leading to a loss of crispness. And in the case that the subject is too close to you, camera shake may move the focus point out of the depth of field. That is why I nearly always use a tripod, which allows one to get away with slower shutter speeds.

--------------
'Gali'Walker => 'Mountain-pass' walker
bobbi: "...don't you ever forget your camera!"
Photography: https://www.flickr.com/photos/shahiddurrani/albums
Back to top
View user's profile Search for posts by this user Send private message Reply to topic Reply with quote
Bosterson
Member
Member


Joined: 12 Sep 2019
Posts: 45 | TRs
Location: Portland
Bosterson
  Top

Member
PostThu Nov 21, 2019 8:55 am 
Reply to topic Reply with quote
I have never had this be an issue. If you do it as a thought experiment, if you focus and then rotate slightly, the focal plane is a tangent line intersecting the top of the arc at the end if the focal distance straight in front of you and running to your subject, meaning the subject is not truly in the focal plane anymore. In reality, unless you're shooting < f2 at a telephoto distance and your focal subject is extremely close, I think you'd be unlikely to ever tell a difference in the perfection of your focus, and this can be safely ignored. Things on either side of the focal plane are still in focus due to depth of field.

GaliWalker wrote:
And in the case that the subject is too close to you, camera shake may move the focus point out of the depth of field.

But this would only come up if you're shooting macro, and I expect Iron is asking about taking pictures of his children.  wink.gif

--------------
We must move forward, not backward; upward, not forward; and always twirling, twirling, twirling towards freedom!
Back to top
View user's profile Search for posts by this user Send private message Reply to topic Reply with quote
iron
getting old



Joined: 10 Aug 2008
Posts: 6420 | TRs
Location: kenmore
iron
  Top

getting old
PostThu Nov 21, 2019 9:33 am 
Reply to topic Reply with quote
Bosterson wrote:
I expect Iron is asking about taking pictures of his children.

ding ding!

--------------
man, you go through life, you try to be nice to people, you struggle to resist the urge to punch 'em in the face, and for what?

--- moe sizlack
Back to top
View user's profile Search for posts by this user Send private message Send e-mail Reply to topic Reply with quote
GaliWalker
Have camera will use



Joined: 10 Dec 2007
Posts: 4161 | TRs
Location: Pittsburgh
GaliWalker
  Top

Have camera will use
PostThu Nov 21, 2019 10:48 am 
Reply to topic Reply with quote
At that distance I wouldn't worry too much about focusing and then recomposing, even at wide open apertures.

--------------
'Gali'Walker => 'Mountain-pass' walker
bobbi: "...don't you ever forget your camera!"
Photography: https://www.flickr.com/photos/shahiddurrani/albums
Back to top
View user's profile Search for posts by this user Send private message Reply to topic Reply with quote
  Display:     All times are GMT - 8 Hours
Forum Index > Photography Talk > focus and recompose
  Happy Birthday Otter, CampChamp, Wolfman!
Jump to:   
Search this topic:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
   Use Disclaimer Powered by phpBB Privacy Policy