Moving the focus point in the camera vs moving the camera to position the focus point....
Dec 12, 2020 10:11:15 #
gvarner
Loc: Central Oregon Coast
Wingpilot wrote:
I would say that if you are shooting a distant object, say a landscape type of scene and you wanted to emphasize a certain part of the scene, focusing on that object then recomposing is not a problem. However, if you are shooting something close, especially something with a lot of detail, say a macro or close up, or you need a bird’s eye in sharp focus, then moving the focus point is a much better choice.
I totally agree. The greater the subject distance the less the problem is.
Dec 12, 2020 10:16:27 #
Gene51 wrote:
On most cameras, the center focus point is most ac... (show quote)
Ditto what Gene said. That is what I do 99.9% of the time with BBF. And if time and subject permits, sometimes I tweak the focus manually after I have taken the shot using AF.
Dec 12, 2020 10:19:36 #
Jeffcs wrote:
Ok lots great info above one thing that wasn’t touched on
Metering
When you move camera to lock focus most of the time the exposure is also locked
I much prefer to move the focus point for that reason
As well as above
Metering
When you move camera to lock focus most of the time the exposure is also locked
I much prefer to move the focus point for that reason
As well as above
Check your menus. You might find the option to separate AF and AE.
Dec 12, 2020 10:24:46 #
Recomposing I don’t do anymore. My first dslr-2004- I used recomposing because it took to long to set the focus point.
When you recompose you moving the hole camera and you may get move a bit You be “out of focus” latest if I use a big aperture....
When you recompose you moving the hole camera and you may get move a bit You be “out of focus” latest if I use a big aperture....
Dec 12, 2020 10:25:29 #
Gene51 wrote:
On most cameras, the center focus point is most ac... (show quote)
I use BBF with center point focusing.
(I don't care (nor do I know) whether my camera used PADF, CADF, or whatever, nor do I worry about any focus shift, I just focus.)
Dec 12, 2020 11:04:03 #
bamfordr
Loc: Campbell CA
srt101fan wrote:
Thank you all. Good, helpful comments. Seems like this is another one of those "it depends" kind of situations.
I guess I need to learn to identify the situations that warrant in-camera adjustment of the focus point. And then I need to pay more attention before I press the shutter button!
I guess I need to learn to identify the situations that warrant in-camera adjustment of the focus point. And then I need to pay more attention before I press the shutter button!
Several replies point out the biggest concern for me - unless light meter/aperture is locked it changes to wherever the focus point ends up when you recompose.
Dec 12, 2020 11:28:24 #
bamfordr wrote:
Several replies point out the biggest concern for me - unless light meter/aperture is locked it changes to wherever the focus point ends up when you recompose.
That's why I sometimes (depending on what I'm shooting):
1. use BBF to focus on what I desire.
2. use spot metering (mostly) on what I desire to meter (press half-way to lock).
3. compose the scene and click the shutter.
Dec 12, 2020 11:34:21 #
bamfordr wrote:
Several replies point out the biggest concern for me - unless light meter/aperture is locked it changes to wherever the focus point ends up when you recompose.
Yep, that’s why if your camera allows it (as does mine), you can uncouple the metering and the focus point and set each separately. Of course, this is only a problem if you spot meter (or maybe center weighted if you move the focus point substantially), if you use average or “matrix” metering, it doesn’t matter as the camera is metering the entire frame anyway.
Dec 12, 2020 11:55:17 #
Curvature of Field is an optical property of the lens system. People use camera settings to minimize, but it is always there
User ID wrote:
Curvature of field is the main reason. I think you know what that is. If not just google. It’s not an obscure topic. A lesser but real problem at rather near distance is that when you re-aim you tilt the focus plane differently than when you focused. The relocated plane might not intersect the detail you focused on. Add both of those minor problems together and at wider apertures your focus may be off by enough to be visible.
Dec 12, 2020 12:21:50 #
I would suspect it has a lot to do with the distance of your subject and DOF. If you are shooting close up subjects, or macro/super macro, then your DOF is very narrow and I typically move my camera for better composition and to make sure that the subject is in the center of my frame so that when/if I crop, I have room. Landscape, probably matter a bit less.
If you are doing super macro, I would use in camera focus shift before moving camera or subject using a CNC rail. If you do. Make sure you use a settle time and mirror up to eliminate camera and shutter shake. JMO.
If you are doing super macro, I would use in camera focus shift before moving camera or subject using a CNC rail. If you do. Make sure you use a settle time and mirror up to eliminate camera and shutter shake. JMO.
Dec 12, 2020 12:37:26 #
I realize that there is some inaccuracy by using the center focus point and then recompose but I wonder why no body brought that up during the film days. Rangefinder cameras can only focus at the center of the frame and for those who used the split image focusing aid with SLR they could also focus only at the center of the frame.
Dec 12, 2020 12:46:24 #
BebuLamar wrote:
I realize that there is some inaccuracy by using the center focus point and then recompose but I wonder why no body brought that up during the film days. Rangefinder cameras can only focus at the center of the frame and for those who used the split image focusing aid with SLR they could also focus only at the center of the frame.
Interesting as it still existed with film cameras. It doesn't matter whether one uses a AF system, range finder, or micro-prism, the film plane is still at the focal point and it moves forward or backwards as the camera is tilted up or down. We also didn't have social media back then where comments reached thousands of people.
Dec 12, 2020 13:03:13 #
BebuLamar wrote:
I realize that there is some inaccuracy by using the center focus point and then recompose but I wonder why no body brought that up during the film days. Rangefinder cameras can only focus at the center of the frame and for those who used the split image focusing aid with SLR they could also focus only at the center of the frame.
There is a website I can't find showing the simple trig to calculate the difference. It's not much in normal shooting, but it we can now do a little better with just a little extra effort, might as well give it a go.
Dec 12, 2020 13:05:41 #
bleirer wrote:
There is a website I can't find showing the simple trig to calculate the difference. It's not much in normal shooting, but it we can now do a little better with just a little extra effort, might as well give it a go.
I know that. I just wonder why nobody talked about it during the manual focusing days with rangefinder and split image focusing.
Dec 12, 2020 13:14:52 #
BebuLamar wrote:
I know that. I just wonder why nobody talked about it during the manual focusing days with rangefinder and split image focusing.
Nah, most of us just focused and shot.
We didn't have a hundred focusing & metering spots either.
We used the twisty thingy to focus; matched the needles (+/-); and shot.
Life was so much simpler then, not having so much stuff to worry about.
Then again, maybe we simply didn't worry.
(Guess I still don't worry, I just use the tools.)
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