Selective AF or MF when taking group portraits?


weeloong

New Member
Jan 4, 2011
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#1
a newbie question:

If say for some reason, I wish to take a group picture (i.e any pic more than 1 person) with the background blurred, should I use AF, selective AF point (for which I dun who to focus on) or go with MF?

I quite sure on how to produce the effect when taking individual shots (I usually use selective AF points to focus on the subject's eyes but find that I sometimes have to lock the focus 1st then de-select AF on my lens if I have to re-compose the shot)

but when there more than 1 person I find that I usually end up using MF instead - aside: how to ensure that your MF is accurate? There were a couple of shots I took using MF but still have to use PP to adjust the sharpness.

Appreciate the advice.. thanks
 

Rashkae

Senior Member
Nov 28, 2005
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#2
i always do selective AF and make sure my aperture is closed enough to make all subjects sharp. If you want your background blurred, your subjects have to stand in a plane parallel to the camera focal plane, or there needs to be sufficient distance to the background.

For MF, I use the focus confirmation light on my A900 camera, or the manual focus magnification aid on my NEX.
 

ZerocoolAstra

Senior Member
Mar 13, 2008
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rainy Singapore
#3
I would still go with AF.

If you use large aperture, then must be careful of possible thin DOF causing some subjects to be OOF if they are at different distances from you.
If focus-recompose doesn't quite nail the focusing, then can try shift the AF point to be on your subject, so that you don't need to recompose.
 

weeloong

New Member
Jan 4, 2011
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#4
Hi thanks for the replies..

@ Rashkae

Do you mean to say you can still achieve background blur even if your aperture is closed enough as long as the background is far enough or the subjects closed enough to you?

If the aperture is small, is there still any point to use selective AF? My impression is that centre AF will produce the same results?

@ZerocoolAstra

Yes. I realised this when using my Canon 50mm f1.8. At f1.8, even when the subject is in a slightly slanted position, some parts of the face will be OOF since the DOF is so thin. Aside - I find that sometimes when I shoot with this lens the color tone (saturation) seems to be very pale.. any pointers on this?


Thanks
 

Rashkae

Senior Member
Nov 28, 2005
19,105
12
0
#5
Hi thanks for the replies..

@ Rashkae

Do you mean to say you can still achieve background blur even if your aperture is closed enough as long as the background is far enough or the subjects closed enough to you?

If the aperture is small, is there still any point to use selective AF? My impression is that centre AF will produce the same results?
1. Yes, this is the basics of how it works - so long as you didn't set your lens for hyperfocal distance and your aperture is not too small (think f/5.6 vs. f/22) you should be ok.

2. Yes, I would still af on the subjects rather than letting the camera accidentally focus on the background.
 

Mar 17, 2010
1,388
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#6
you can use AF to focus on someone/something, and anyone/anything in (or near) the same plane will also be in focus. basically you'll need to stop down i.e. decrease the apature opening. quite a bit of trial and error at the initial stage is normal. :)
 

brapodam

New Member
Jun 12, 2009
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AMK
#8
Hi thanks for the replies..

@ Rashkae

Do you mean to say you can still achieve background blur even if your aperture is closed enough as long as the background is far enough or the subjects closed enough to you?

If the aperture is small, is there still any point to use selective AF? My impression is that centre AF will produce the same results?

@ZerocoolAstra

Yes. I realised this when using my Canon 50mm f1.8. At f1.8, even when the subject is in a slightly slanted position, some parts of the face will be OOF since the DOF is so thin. Aside - I find that sometimes when I shoot with this lens the color tone (saturation) seems to be very pale.. any pointers on this?


Thanks
When you shoot wide open at f1.8, this lens is rather soft and lacks saturation. You'll have to boost them in PP. If possible, stop down the lens to around f2.8, it will produce excellent results.
 

ZerocoolAstra

Senior Member
Mar 13, 2008
9,522
0
0
rainy Singapore
#9
Hi thanks for the replies..

@ZerocoolAstra

Yes. I realised this when using my Canon 50mm f1.8. At f1.8, even when the subject is in a slightly slanted position, some parts of the face will be OOF since the DOF is so thin. Aside - I find that sometimes when I shoot with this lens the color tone (saturation) seems to be very pale.. any pointers on this?


Thanks
Yes DOF is quite thin @ f/1.8 and if you are fairly close to subject.
Most portrait shooters find it a boon though :)

I guess you were intending to photograph some friends in a group photo, and disappointed that some turned out OOF. I had that problem happen on a number of occasions too. Forgot how thin the DOF was :embrass:
 

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