/////Help me focus (Focal plane)
Help me focus (Focal plane)2017-10-17T11:46:43+02:00

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Help me focus (Focal plane)

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  • WayneThomas
    Participant
    Post count: 16

    Wonder if some of the more skilled photographers can simplify focal plane.

    My key concern is taking photos a group of people and getting them all tack sharp.

    Attached is an example of a photo I took with my canon 50mm f/1.4 with an aperture of f/2.8.

    As I understand focal plane, if you have people lined up toe-to-toe, then in theory they should all be in focus because they fall within the same focal plane?

    So in the example I have my subjects face-to-face, however my focus is very narrow with only one subject in focus, what am I doing wrong here, am I too close to the subject narrowing the depth of field even more?

    I wish to keep the shallow depth of field with the dreamy blurry background, so I do not want to go to a f/8 aperture for instance.

    [ATTACH]9600[/ATTACH]

  • Leo Theron
    Participant
    Post count: 1582

    @[email protected] 297909 wrote:

    Wonder if some of the more skilled photographers can simplify focal plane.

    My key concern is taking photos a group of people and getting them all tack sharp.

    Attached is an example of a photo I took with my canon 50mm f/1.4 with an aperture of f/2.8.

    As I understand focal plane, if you have people lined up toe-to-toe, then in theory they should all be in focus because they fall within the same focal plane?

    So in the example I have my subjects face-to-face, however my focus is very narrow with only one subject in focus, what am I doing wrong here, am I too close to the subject narrowing the depth of field even more?

    I wish to keep the shallow depth of field with the dreamy blurry background, so I do not want to go to a f/8 aperture for instance.

    [ATTACH]9600[/ATTACH]

    In the attached example it is clear that the focus is on the eyes of the lady, and the gent is just a little bit closer to the camera, that is the problem – his eyes are thus out of focus.

    You will have to assure that the two sets of eye are in EXACTLY the same plane to have them in focus. Otherwise, if they are not, you will have to stop down to make sure they are in focus.

    It will help you to have tool on your smartphone that helps with your DOF calculations – there are plenty. Download one and have a careful look. You will be surprised to learn how little DOF there is when you open up AND you move closer…

    HTH

  • WayneThomas
    Participant
    Post count: 16

    Thank you Leo,

    Very insightful, will keep that in mind for the next shoot and be sure to download DOF calculator.

    Nice gallery!

    Kind Regards

    Wayne

  • elsahoffmann
    Moderator
    Post count: 3717

    Leo is right – just go find a DOF calculator, put in some settings – and you will quickly see how little you get in focus. F2.8 wont cut it in this case
    Get your subjects as far as possible from the background – and you will get an out of focus background.

  • bomtek
    Moderator
    Post count: 1048

    @leo Theron 297910 wrote:

    In the attached example it is clear that the focus is on the eyes of the lady, and the gent is just a little bit closer to the camera, that is the problem – his eyes are thus out of focus.

    Otherwise, if they are not, you will have to stop down to make sure they are in focus.

    Or increase distance to subject/object. Those two factors which control depth of field.
    Later you can dive into the hyper focal calculations 😉

    btw, what camera are you shooting with?

  • Peter Connan
    Participant
    Post count: 817

    There is another possible issue. Field curvature.

    Most lenses do not have a flat focal plane, but have a focal plane shaped somewhat like an umbrella or even worse.
    Typically, the shorter the lens is, the worse the problem.

    I suspect it would be worth bracketing the aperture, going down a bit smaller than the DOF calculations recommend.

  • bomtek
    Moderator
    Post count: 1048

    @peter Connan 297917 wrote:

    There is another possible issue. Field curvature.

    Most lenses do not have a flat focal plane, but have a focal plane shaped somewhat like an umbrella or even worse.
    Typically, the shorter the lens is, the worse the problem.

    I suspect it would be worth bracketing the aperture, going down a bit smaller than the DOF calculations recommend.

    That’s not the case with this specific lens Peter.

    [ATTACH]9601[/ATTACH]

  • WayneThomas
    Participant
    Post count: 16

    Thank you Elsa, will take it into consideration!

  • WayneThomas
    Participant
    Post count: 16

    Thanks Terry,

    I’m using the Canon 750D, probably time for an upgrade!

    Thanks for the advice.

    Regards

    Wayne

  • HiltonP
    Participant
    Post count: 1696

    @[email protected] 297923 wrote:

    I’m using the Canon 750D, probably time for an upgrade!

    No need for an upgrade, the 750D is perfectly good. What bomtek was probably asking was whether your camera was full frame or a cropped sensor, which would have an impact on the depth of field.

  • bomtek
    Moderator
    Post count: 1048

    @hiltonp 297925 wrote:

    No need for an upgrade, the 750D is perfectly good. What bomtek was probably asking was whether your camera was full frame or a cropped sensor, which would have an impact on the depth of field.

    What Hilton said 🙂

  • WayneThomas
    Participant
    Post count: 16

    @hiltonp 297925 wrote:

    No need for an upgrade, the 750D is perfectly good. What bomtek was probably asking was whether your camera was full frame or a cropped sensor, which would have an impact on the depth of field.

    Would it be advisable to switch to full frame for portraiture photography? How does full frame affect the depth of field?

  • WayneThomas
    Participant
    Post count: 16
  • bomtek
    Moderator
    Post count: 1048

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