Focusing

sep9001

sep9001

Messages
5,421
Name
Kev
Edit My Images
Yes
Hi

Need some help please with focusing. I was trying to take some pictures today and had the setup as below, the star in each one shows where the focus was:

01.jpg

02jpg.jpg
The f stop was at f5.6 and not everyone's eyes are sharp. The cross shows whose eyes were the sharpest.

Is this because of the f stop I am using, should I be using a higher f stop like f8 or f9 if I want the eyes of very sharp or should I be focusing at a different spot.

Thank you

Kev
 
What focal length were you using? What are the distances of the three heads from the camera? What was the distance of whatever point the camera was focused on?
 
Don't think I have all that info, will check what is on the exif and post back.

Thanks
 
Chris,

Sorry don't have all the info. Looking at LR I was shooting at 70mm, distance would have been approximately 1 to 1.5m. The focus was on the last subject so the max would have been 1.5m.

Thank you
 
All i can see are blobs of solid colour on my ipad ??
 
Last edited:
Well the question isn't clear.

The answer is simpler.

Focus on the nearest set of eyes and ensure that there's enough DoF to cover all the eyes.

Be aware there's a difference between DoF and 'in focus', there's only one plane 'in focus' so there's no way to get 3 sets of eyes sharp if they're all at different distances. The best you can get is 'acceptably sharp'.

Then you're up against your photographers critical eye, where what you see as unsharp other people might see as sharp.
 
Phil V said:
Well the question isn't clear.

The answer is simpler.

Focus on the nearest set of eyes and ensure that there's enough DoF to cover all the eyes.

Be aware there's a difference between DoF and 'in focus', there's only one plane 'in focus' so there's no way to get 3 sets of eyes sharp if they're all at different distances. The best you can get is 'acceptably sharp'.

Then you're up against your photographers critical eye, where what you see as unsharp other people might see as sharp.
Click to expand...

Thank you Phil.

Will give that a go the next time.
 
Phil, I am interested in your reply as I have been roped in to shoot some outside shots at a christening, why do you recommend focusing on the nearest eyes and then getting sufficient DOF to cover those behind? As I understood it the 'acceptable focus' area includes a third in front of the focus point and two thirds behind (approximation), as such wouldn't it be better to attempt to focus with this in mind? Or is it simply that for ease in a shooting situation to select the foremost and then have a small enough aperture to get the rest in? Thanks
PS. I will probably be using a 7D with the Canon 17-55 2.8
 
Last edited:
fitzer said:
Phil, I am interested in your reply as I have been roped in to shoot some outside shots at a christening, why do you recommend focusing on the nearest eyes and then getting sufficient DOF to cover those behind? As I understood it the 'acceptable focus' area includes a third in front of the focus point and two thirds behind (approximation), as such wouldn't it be better to attempt to focus with this in mind? Or is it simply that for ease in a shooting situation to select the foremost and then have a small enough aperture to get the rest in? Thanks
PS. I will probably be using a 7D with the Canon 17-55 2.8
Click to expand...
For a large group, I'd take into account the amount of DoF in front of the plane of focus too.

But for 3 heads, our brains draw us to the nearest set of eyes.

So it's 2 different questions, hope that helps.

ETA, for a large wedding party, I'm still likely to focus on the front row if that's where the bride is ;) remembering that it might be a 'group' but one of the subjects is the one people will look at.
 
Last edited:
Sorry to be late in responding, thanks for that Phil, it was a very informal set up so lots of people at varying distances from the camera, fortunately a good bright day so f8 gave plenty of DoF and I managed to keep most people in focus (where intended). Cheers
 
The depth of field is smaller for telephoto lenses, so the range of what is in focus will be less at 70mm that it would be at 35mm, for that reason it's best to (safer) to shot groups with a lens wider than a 50mm. I do shoot small wedding groups with a 50mm which gives lovely bokeh, but I ensure everyone is the same distance away to ensure sharpness of everyones eyes. Are you able to try a similar shot at a different focal length to compare?
 
Karen Julia said:
The depth of field is smaller for telephoto lenses, so the range of what is in focus will be less at 70mm that it would be at 35mm, for that reason it's best to (safer) to shot groups with a lens wider than a 50mm. I do shoot small wedding groups with a 50mm which gives lovely bokeh, but I ensure everyone is the same distance away to ensure sharpness of everyones eyes. Are you able to try a similar shot at a different focal length to compare?
Click to expand...

Sorry but that is not correct as in it needs expanding and clarifying.

If we have a subject and we have the same crop and the same aperture then the photographer has to be twice as far away (to go from 35mm to 70mm) and we get the same depth of field approximately.

If we maintain the same photographer to subject distance, same aperture and change the focal length then the depth of field will reduce as the focal length increases

Try it http://www.dofmaster.com/dofjs.html

Mike
 
Spot on! I confess to not usually moving, so only the 2nd one typically applies to me & I'd totally forgot about the first point you made! #seniormoment
 
I'm not sure I understand the diagrams... is the + where the focal point was and the star the plane of focus? In both images the plane of focus is in front of where the focus point was placed?

1-1.5meters is pretty short for a lot of lenses at 70mm... what lens was used and what is it's minimum focus distance?
 
You must log in or register to reply here.
Back
Top