New to the forum, with a couple of questions =)

Discussion in 'Photography Beginners' Forum' started by calvini, Jan 3, 2008.

  1. calvini

    calvini TPF Noob!

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    Hi all,

    I'm new to this awesome forum and am proud to say that I've been reading this forum for quite some time now and have been taking in advices and all.

    Been out and about yesterday and took about 300 + photos.
    Some of my questions that I would appreciate the help with is as follows:

    Some of the gear that I used:
    Canon 430EX Speedlite ( intended for fill flash ) under eTTL and high speed sync mode
    Canon 400D
    Tamron 28-75 2.8 ( shooting basically at f4 and f8)
    Evaluative Metering mode

    1) The day was sunny at the gardens with the exception of shades under trees. I noticed when I metered for the subject (people), the sky gets blown out (white in colour).. Any tips on how to remedy this situation and what sort of metering/ exposure I should get?

    2) As the lens AF mode was crappy, focusing on most odd parts or just continually hunts, I set the AF point to center and just focused on subject and recompose; which brings me to my next question;

    With a subject of 2 people in the frame, do I just point the center point to focus in on the eyes and then recompose?

    If the picture was to be quite a distant shot (not full body shots that fill the entire frame) the eyes remain relatively small, do I just point the focus point to the eyes or zoom in on the eyes and zoom out and recompose?

    3) I was shooting on burst mode and noticed that alot of the pictures turn out to be quite soft; 1 keeper in every 5, and was walking alot with subject moving and not posing (basically like a paparazzi shooting).

    Is this a problem with the lens being soft; or issit my focusing with only the center point on the subject with burst mode or ?

    Any hints would be greatly appreciated! =) Thanks!
     
  2. azruial

    azruial TPF Noob!

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    Hi, I'm still a noob too, but I think I can answer some of your questions.
    1) If you fire the flash (and the people are within flash range, of course) then their brightness will come up and maybe you could then expose for the sky, and the flash would make it so that the people wouldn't just silhouette due to the camera's low dynamic range.

    2) If the two people are on the same focal plane (distance from camera) then just focus on one of them, otherwise, you need to use a tight enough aperture to get sufficient dof for both to be in focus.
    The 'focus for the eyes' comes, I believe, from two things. First, the fact that dof extends 1/3 towards the camera and 2/3 back from the plane of focus, and the eyes are about set into that proportion on the face and second, that those crisp-looking eyes are so desirable in portraiture whereas the skin, which is naturally soft, doesn't need to be in the sharpest focus possible.
    Shooting at a distance, you aren't really making a portrait anymore, so anywhere on the face area should do just fine. I believe that on many lenses, the focus will change slightly (or a lot) while zooming, so I don't think that zooming after focusing would work well.

    3) In burst mode, it'll hold the focus lock that it gets before you start, so if the distance to the subject changes during a burst, then the focus will be off.

    Again, I have little experience compared to many others here, so I may be wrong, but I hope it helps, and I'm sure they'll be here soon to correct me if I am wrong! :)
     
  3. azruial

    azruial TPF Noob!

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    Hey, writing about that last question reminded me of something I read in my manual. The normal focusing mode is 'single shot' which obtains a lock on the focus distance when you half-press the shutter. There is another mode 'AI Servo' or 'predictive' or 'continuous' or something which locks the focus on the subject itself and attempts to keep that subject in focus as well as it can. I just tried it out and that does include in the middle of a burst. So to get better focus when moving and shooting in burst mode, try using that focus mode. Also, higher f-number (tighter, smaller aperture) means greater dof which allows a larger margin of error in focusing which is always useful when the camera or the subject is moving!

    Hope that works :)
     
  4. calvini

    calvini TPF Noob!

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    Thanks azruial for your comments, yup I did used the AI Servo mode. I would like to point further enquiry to:-

    1) If i expose for the sky, should i first half-press the shutter on the sky and press the Exposure lock button (*) then recompose my shot and focus my shot on the subject? or just meter the sky, set to M mode and use the shutter/aperture metered.

    I hope this is the correct term in trying to define my query


    2) I am still quite confused about the 1/3 2/3 definition of dof, could you clarify it in easier terms? sorry this may be such a newbie question

    I used quite a low dof/ large aperture because i wanted the bokeh effect in some of them..
     
  5. Mav

    Mav TPF Noob!

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    I can't help you operationally on the camera, but technique wise...

    If you're getting soft or blurred shots, make sure that your shutter speed is quick enough for the focal length. The general rule of thumb is to use 1/(focal length) for your SS. So if you're at 75mm, you should be using a shutter speed of at least 1/75s (1/80s). As far as keeping multiple subjects in focus, you need to stop the lens down so that you have enough depth of field to keep everybody in focus. f/2.8 will give a really narrow depth of field. At close range for head shots, f/5.6 is probably what you'd want. At longer distances with full body shots, you could probably still get away with f/2.8.
     
  6. azruial

    azruial TPF Noob!

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    1) Yeah the first one, although on my camera I don't have to press the shutter halfway before I hit exposure lock, I don't know about yours.

    2) Sometimes it's easier to explain graphically, this is how I understand dof:
    [​IMG]

    The blue shaded area is the dof of a larger aperture (say f/4) and the green is for a smaller aperture (say f/8). The red dots on the right are equally spaced for scale.
    I know that you understand the basics of small aperture = greater dof, but I included that just for the sake of completeness. ;)
     
  7. ghpham

    ghpham TPF Noob!

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  8. calvini

    calvini TPF Noob!

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    Ahh.. that visual representation does explain it clearer .. thanks for that !

    Still having a little difficulty understanding the DOF calculator on the link but I'll get around it sometime.. thanks !
     
  9. Mav

    Mav TPF Noob!

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    azruial, are you sure that diagram is correct? I've never heard of this 1/3 - 2/3 thing. At least according to the DOFmaster calculator, there's pretty much equal in focus area both in front of and behind the focus plane, and I think that's pretty much the norm. There's some trick lenses out there like the Nikkor 135mm f/2 DC (Defocus Control) that can shift that around forward or back, but that's definitely a very specialized lens.
     
  10. azruial

    azruial TPF Noob!

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    I have heard that 1/3 - 2/3 from several places, though of course I can't remember where now :lmao:, although the diagram on the dofmaster page seems to indicate similar proportions to my perception...?

    Using the calculator on that link, it looks like every variable affects the percent of the dof that is in front of the plane of focus, which means that this is definitely too complicated to understand by looking at the simple ratios and relationships, so.... it's google time!

    Okay, here's the answer:
    "The DOF beyond the subject is always greater than the DOF in front of the subject. When the subject is at the hyperfocal distance or beyond, the far DOF is infinite; as the subject distance decreases, near:far DOF ratio increases, approaching unity at high magnification. The oft-cited “rule” that 1/3 of the DOF is in front of the subject and 2/3 is beyond is true only when the subject distance is 1/3 the hyperfocal distance." -wikipedia

    Thanks Mav for bringing that up, I love going to sleep smarter than I was when I woke up :D.
     

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