How shallow DOF can a beginner control? Novice?

Discussion in 'Digital Photography' started by Chris7, Feb 27, 2010.

  1. Chris7 macrumors 6502

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    #1
    How shallow DOF can a beginner control? Novice?

    I was considering purchasing a EF 50mm f/1.4 USM for low light portraiture until I realized the DOF at 1.4 with a FOV of 3 ft. on a 1.6x crop sensor camera is about 3-4 inches. Is this DOF something a beginner like myself could hit more shots than miss (with a subject that is standing in the same spot but moving a bit for different looks)?

    If no, what’s a good minimum DOF to start learning with?

    Thanks in advance for your time. I can find plenty of tutorials on the Net on how to calculate DOF at various focal lengths, distances and apertures, but very little on this.
     
  2. willie45 macrumors regular

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    #2

    I wouldn't let the shallow DOF worry you at all. You will learn to control it with practice. The only way to learn to control it is with practice. The only way to get practice is to have the lens :) You will be absolutely fine with this lens and a modern camera's AF system. If you want a challenge get some extension tubes and use it for macro where the DOF is infinitesimal and usually measured in mm.

    Also its not really difficult. In portraits focus on the subject's nearest eye. The resulting sharp eye with diminishing sharpness on either side will be pleasing. If you need more DOF close the aperture down a bit. Its not a problem and this lens gives you the option of opening it up to f1.4 when you want.

    Most lenses tend to perform better closed down a stop or two from wide open so if you use your 1.4 at 2.8 you are likely to get a better result than if you used a 2.8 wide open. Lastly forgetting about DOF the lens will give you a brighter viewfinder for general composition etc and will be more pleasant to use than a less fast one.

    If you're unsure then you might want to consider the 50mm f1.8 which is nearly as fast, a really good lens for image quality and very very cheap. It doesn't have great build quality but it is adequate and for the price you can't go wrong.

    Willie
     
  3. FrankieTDouglas macrumors 65816

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    #3
    It's actually easier on a crop sensor. If you were to try that composition on a full frame sensor, you'd have to be closer to your subject, therefore reducing you depth of field even greater (by X1.6, I believe). So what you have is good practice. If you shoot with enough shutter (say, 1/125 or greater) it shouldn't be an issue.
     
  4. ChrisA macrumors G4

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    #4
    THe besttest thing to learn is how to use it to best advantage. The technical part is easy. but you will need to remember "focus the eyes" and not the nose and forehead. And you can always open back up to f/2.8 or whatever.
    But at f/1.4 you have to think about focus, not technical hard, just that youhave the think about it every shot

    With a cooperative subject it is very easy to get right. Much harder however to shot pic of sports or your dog a f/1.4
     
  5. Nostromo macrumors 65816

    Nostromo

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    #5
    The key is how you handle autofocus.

    Many just let the autofocus on automatic, and it often focuses on nose tips and shoulders and leaves eyes blurry, which makes the photo useless.

    For precise focus you need to tell the autofocus what is most important to you, on what he must focus on.

    In single shot you tell the autofocus what to focus on, e.g. the eyes.

    If you do that (and your autofocus works well), it is not a big deal and can be handled by a beginner.

    Just consult the manual of your DSLR on the autofocus modes, and try it out before you do a shoot.
     
  6. TheReef macrumors 68000

    TheReef

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    #6
    You might want to consider using a tripod, the slightest movement front or backwards @ f/1.4 can throw off your focus.
    Then you only have to worry of your subject's movement.
     
  7. Chris7 thread starter macrumors 6502

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    #7
    Questions: camera's with adequate autofocus, focusing with burst shooting

    Thanks for your time, Willie45, FrankieTDouglas, ChrisA, Nostromo, and the Reef…

    Do the current Rebel series cameras have autofocus systems adequate for this kind of thing, or would I need something further up the line? (currently shooting with an old XT)

    Also, no camera can re-focus in the middle of a burst, right?

    Do people generally shoot with the faster shutters when doing shallow DOF? I thought 1/80 would be adequate with this lens on a crop sensor body.
     
  8. FrankieTDouglas macrumors 65816

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    #8
    It's a broad question. 1/80 isn't too far off from 1/125 (it's in-between the full stop from that to 1/60). Odds are, if you're shooting f/1.4 in anything other than candlelight or television light, your shutter will be above 1/60. I just suggest quicker shutter speeds so your subject won't shift out of focus between the time of focus and the end of the shutter.
     
  9. NoNameBrand macrumors 6502

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    #9
    Depends on the AF mode. Read your manual. You may have to release the shutter-release half-way when you want to re-focus. Also, look for 'focus priority' vs 'release priority'.
     
  10. nickXedge macrumors 6502

    nickXedge

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    #10
    I'm also a beginner in photography but I believe the AF system is part of the lens. I could definitely be wrong about this. And I think if you want to re-focus between bursts, you should use AI SERVO focus which is an option on the camera, it is mainly for shooting sports and other quick movement so it refocuses between each shot. I could also be wrong about that, but I think I'm correct on both accounts. Open to be corrected as needed.
     
  11. NeGRit0 macrumors 6502a

    NeGRit0

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    #11
    I'm an amateur, only been shooting for a year or so. I just purchased the 50mm 1.8 and wow, what a change from the kit lens (18-55mm). The DOF is shallow, but quite manageable if you pay attention to what you are doing. Just make sure your focus is in the eyes. and you should be fine. this was my first ever attempt at a portrait, i shouldn't have used Manual focus, as i was clearly off a little, but im trying to force myself into more manual focusing.

    [​IMG]
    Clickable...
     
  12. Nostromo macrumors 65816

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    #12
    Yes, any current Rebel will have a decent autofocus.

    It's key you study the manual and get familiar how the different autofocus modes work.

    Regarding bursts, I don't shoot in bursts. I use single shots. But I can't imagine why autofocus wouldn't work shooting bursts. Burst are often used for sports and quick moving wildlife and action, and it would really be ridiculous if the autofocus wouldn't work in such situations.

    You just need to choose a continuous setting, not single shot of course.

    I never shot with Rebels, so I'm not familiar about the exact models. How old is yours? I can't imagine the autofocus being so slow on your Rebel. People often run and buy new equipment while their old one would work perfectly well if they knew how to use it. If your Rebel isn't that old, save your money and get a really good lens instead.

    Usually, focusing problems are pilot errors.

    Of course there can be a technical issue with the camera. I had to get my Canon down to Canon in Irvine, CA to calibrate the autofocus. But I'm particularly picky. They said it was within factory specs, but after they calibrated it it worked to my satisfaction.

    To check if your autofocus is not working well you can do a simple test: put a newspaper page on the wall, choose single shot, focus, and shoot. If the letters are out of focus, you have an autofocus problem (be careful to choose a short enough exposure time of at least 1/125th, or better 1/250th, or you'll get motion blur, which would void the whole experiment).
     
  13. Chris7 thread starter macrumors 6502

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    #13
    FrankieTDouglas: Thanks. I should have mentioned that I’m into shooting at dusk. I’ve even done some (tried to do some) shots under streetlights at night (in the snow) with the 28mm 1.8. Would have been gorgeous if I were shooting with a newer (and pricier) camera at higher ISO. But the shutter does want to go lower for correct exposure, and even 2/3 stop seems to matter...

    NoNameBrand and nickXedge: this is cool. I didn’t know this feature existed (re-focus within a burst), but I guess it should be easy since the camera can take in focus info every time the mirror goes back down, even if shooting 8 fps. (I posted a new thread on which camera does this well).

    Using an XT. Old. Looking to upgrade, but trying to be patient, as things seem to be moving fast with Canon. Really curious what the next D50 will look like at high ISO...
     
  14. Chris7 thread starter macrumors 6502

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    #14
    Moving subject: How do I maintain focus on an eye?

    Just looked at some shots taken with the Rebel T2i. Looks like ISO 3200 might be acceptable with this camera (at least comparable to the Nikon D90), and with a 1.4 would allow low light work…

    I just talked to a former pro photographer about focusing on the eyes and he said there is no AF mode to spot or track an eye, and he either uses manual (which I cannot do quickly at all), or just the most basic center point autofocus (he owns multiple cameras, including the 1D Mk. IV, so he has plenty of autofocus options). I'm not implying his way is “right” -- it may just his preference…

    The problem is, I want the subject to be moving a little so I can catch something that looks real. How do I lock/track focus on an eye with a moving subject? Which mode would you use?
     
  15. Edge100 macrumors 68000

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    #15
    If you're shooting moving subjects at very large f/stops, you're going to get a fair number of OOF shots, irrespective of what AF system you're using. The DOF is so small, you have almost no margin for error.

    If you're using AI Servo mode, you'll almost invariably want to use the centre focus point, unless you have access to a camera where the outer AF points perform well (e.g. any 1-series camera, 7D, perhaps the 40D and 50D).

    However, you're talking about tracking the eyes of a moving person, which is incredibly difficult, given the size of the eye. My approach would be to stop down a bit to give a little more DOF flexibility, or else be ok with having a high percentage of OOF shots. Remember, f/2.8 is still REALLY shallow DOF for most lenses; and working there instead of at f/1.8 or even f/1.4 gives you the added cushion of enough DOF so that you dont have to absolutely nail the focus every time. Also, you'll gain some added sharpness by stopping down a bit.

    Not to say that you shouldn't use your fast primes wide open (that's why you bought them!), but perhaps you shouldn't do so with moving subjects.
     
  16. Chris7 thread starter macrumors 6502

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    #16
    Thanks for the info, Edge -- very helpful. I think I am going to pass on this lens for now, as its fast aperture is not going to help much for low light portraiture (of moving subjects).
     
  17. flosseR macrumors 6502a

    flosseR

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    #17
    Well I'd argue that what you are trying to achieve is something that most Pro's even struggle with. It doesn't depend on the lens or the AF, it depends on you AI Servo will work just fine but YOU have to move with the cam following the face (eye). Any AF tracking will only go so far. You are trying to track an eye (which in itself moves btw.) on a moving person in low light? good luck. I could bet that anyone who tries will have a magnitude of OOF shots compared to anything in focus.
    If you want it to look "real", why not tell the person to do something and then hold that pose for 1second?

    The f1.4 WOULD help you with your ISO though. What good is it if you get the shot and its noisy as he**?

    //F
     
  18. NeGRit0 macrumors 6502a

    NeGRit0

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    #18

    That makes sense. Hand held self portraits are hard. I shot this with a 50mm f/ 1.8 @ f/ 2.0... I'm thinking that had i used f/ 2.8 my eyes would be in focus too.
    [​IMG]
     

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