+ Trả lời Chủ đề
Kết quả 1 đến 7 của 7

Chủ đề: dpreview - kĩ thuật chụp ảnh MTB

Hybrid View

  1. #1
    Mông dân cực kỳ hèn hạ alooooooo123's Avatar
    Ngày tham gia
    Jul 2010
    Bài viết
    1,112
    Thanks
    541
    Thanked 337 Times in 178 Posts

    dpreview - kĩ thuật chụp ảnh MTB

    Thấy trên dpreview có bài viết khá hay, xin chia sẻ zới bà con:


    Mountain bike photography technique
    By SebRogers | Published Sep 18, 2011 | Photo Techniques



    Good sports photography isn’t easy. Many popular sports - football or motor racing, for example - give amateur photographers limited access. To make matters worse, getting close enough to the action for worthwhile shots can involve expensive long lenses that are beyond the financial reach of many photographers.

    Mountain biking is different. Whether it’s on a recreational level in beautiful surroundings or part of the race scene with pro-level riding, access is straightforward. A DSLR with standard zoom is all you need to get started, and the techniques for bike photography translate to other sports too. It’s a great way into sports shooting.


    Panning
    ------------------------------------

    The fundamental point about an action photo is that, by definition, the subject is moving rather than stationary. While this may well be a case of stating the obvious, it leads to an equally obvious point that underpins all sports photography techniques: if the subject is moving, the camera should be moving too. It’s a technique that most people call ‘panning’, but I prefer to refer to it as ‘tracking’. Tracking the subject accurately in the viewfinder is the key to consistently good action shots.

    Here’s how it works: as you record an image with your camera, the shutter is open for a brief period of time. During that time the lens projects an image of the subject onto the camera’s sensor. If the projected image moves while the shutter is open, the resulting image is blurred. If it doesn’t move, the image will be sharp. So the idea of tracking your subject is to keep the projected image of your subject - in this case, bike and rider - in the same position on the image sensor throughout the entire duration of the exposure. That way the bike and rider will be sharp. If the background moves a lot during the exposure it’ll be blurred, but that’s okay because it simply adds to the sense of speed.

    Two tricks will help you get better tracking shots. First, don’t try to follow the entire bike and rider. Instead, pick one small area - the rider’s head usually works well, because however rough the terrain it’ll tend to move fairly smoothly - and concentrate on keeping that locked into a specific area of the viewfinder. Using an AF point helps, or imagine that you’re a sniper tracking a target. Rotate with your hips and follow through after you’ve taken the shot, much like a golf swing.

    Second, practice using different shutter speeds to achieve different effects. Higher speeds mean you don’t have to track as accurately but won’t blur the background as effectively. Slower speeds make a precise pan more critical, but emphasise speed with a creamy blur behind the rider.



    ISO 200, 1/60 sec, F16



    ISO 200, 1/250 sec, F8



    ISO 100, 1/15 sec, F9


    The degree of background blur depends on subject speed, distance from the camera position and shutter speed. 1/60sec is at the lower end of usable speeds for reliably repeatable results, while 1/250sec makes life easier but reduces the effect of the background blur and makes the bike look as though it’s going slower. By the time you’re down to 1/15sec results are very hit-and-miss - the shot above works because the rider’s glasses are sharp, giving a focal point for the viewer to concentrate on.

    Lens choice

    Unlike many sports, mountain biking usually allows photographers to get up close and personal with the action. Most race venues have trackside spectator access and, if you can ride yourself, you’ll have access to an infinite variety of shooting positions on any recreational trail.

    In practice this makes mountain bike photography incredibly accessible. All you need to get started is a camera with standard or kit zoom. The wide end of the zoom range allows you to get close to the action or include some context, while the longer end gives scope for some cropping.

    Because bikes tend to follow a predictable path along a trail, it’s relatively safe - with a bit of experience - to get in very close trailside. Ultra wide lenses - to 10mm for APS-C or around 15mm full frame - can work incredibly well to pull the viewer into the thick of the action, giving a powerful sense of involvement that tends to be lacking with long lens pics.

    Some discretion is needed, of course. It’s possible to get close enough to a rider for a stray pedal, handlebar or elbow to snag an unwary photographer in passing. Wide lenses also tend to ‘pull’ wheels into oval shapes in the corners of the frame, which can look disconcerting.

    At the other end of the scale long lenses can be useful for a couple of reasons. In some situations it may not be possible to get close to the action. If you need to pull the subject in to fill the frame, a long lens may be your only choice. But a long lens can also be used to compress the apparent perspective in a shot, appearing to bring the background closer to the rider in a way that can sometimes work well.

    This compression can work against the photographer, though. It’s generally harder to incorporate a sense of movement into long lens images of mountain biking, so they can have less immediate visual impact. Good composition and an aggressive riding style are often key to successful long lens bike images.



    Nikon D3, 120mm focal langth Nikon D3, 24mm focal length

    Here’s the same rider on the same section of trail, shot from different positions on different lenses. The longer lens compresses the apparent perspective, making the distant hills and lake appear larger relative the rider. The wide shot is more dynamic, making the viewer feel as though they’re right next to the bike - but the background is far less prominent. Each shot works, but gives a completely different view of the same scenario.

    Lighting

    The vast majority of mountain biking takes place outdoors during daylight hours, with obvious benefits for photographers. Natural light is generally plentiful and always free, so there’s little need to break out the strobes except in specific circumstances.

    Most cameras perform best with a preset manual white balance. Auto white balance can throw a curve ball at any time, giving inconsistent results even when the light hasn’t changed. I prefer to set my cameras to 5000k and make small adjustments as necessary during raw processing. Setting ‘sunny’ or ‘daylight’ works pretty well too. Even if you habitually shoot jpeg, a white balance that’s consistently very slightly too warm or cool is easier to sort out than one that fluctuates all over the place.

    The best natural light occurs at either end of the day when the sun’s shining. If you have the luxury of being able to choose both where and when to shoot, the long shadows and warm light of early morning and late afternoon can give the same kind of modelling and ‘feel’ that many landscape photographers strive for. For shooting under heavy tree cover, on the other hand, it’s best to pick an overcast day. Strong sunlight creates exceptionally high contrast under the tree canopy, creating unattractive pools of either burnt out highlights or blocked in shadows.

    There are times when flash can help - when the light’s low, any time you’re shooting in close with a wide lens, to fill in deep shadows in the subject, or just to make use of a strobe’s very brief duration to help freeze the action. Newcomers to flash should begin with a shoe-mounted strobe set to TTL automatic, which allows easy experimentation with shutter speed and flash ratio (via exposure compensation) to light bike and rider.

    For maximum versatility, though, nothing beats remote off-camera flash. Most riders aren’t the least bit bothered by flash while riding, so it’s normally possible to position the light where you need it. A single strobe can be used to provide the main light, while a second unit can add a rim or back-lighting effect for extra impact.



    Remote-flash setup



    ISO 400, 1/100 sec, F6.3, shot with remote flash

    Remote flash can help to add contrast and life on a dull overcast day, or to reduce contrast in situations where deep shadows and bright highlights would otherwise cause a severe exposure headache. The brief duration of a strobe’s light output also works well with slow shutter speeds to give an effective mix of sharp subject against a blurred backdrop.

    Composition

    The single biggest contribution to lacklustre composition in any action photography is a DSLR’s autofocus system. All of them, by necessity, are designed around a central focus point, creating a tendency for centralised - and boring - compositions. Want to improve your composition? Turn off the AF. Or, at the very least, prefocus and recompose.

    It isn’t as hard to do this with mountain bike photography as you might imagine. Mountain bikes largely follow a predetermined path - usually on a narrow trail - and cover the ground at relatively low speeds - up to 40mph or so, but usually much slower. The combination of these factors means it’s not hard to pre-visualise the shot you want, pre-focus the camera on the point where you want the bike and rider to be, then squeeze the shutter button at the appropriate moment. By not relying on the camera’s autofocus system to track the bike and rider you’re now free to ignore the position of AF points in the viewfinder, allowing much more dynamic composition.

    The key point is to place bike and rider somewhere other than the centre of the frame. It doesn’t particularly matter whether they’re on a rule of thirds intersection, in a corner, or somewhere else entirely. The very fact that they’re not central will immediately help to grab the viewer’s attention. Conventional wisdom also suggests that a moving subject should have space ahead of it to move into. Turning this idea on its head so that the rider is about to exit the frame can create more tension and add to the sense of action.

    A de-centralised rider is a start, but of course the remainder of the image needs to have the right elements too. Once again, mountain biking’s reliance on a trail can often help. A visible path can be used as a lead-in line to draw the viewer’s eye across the frame towards the rider, particularly if the shot is composed so that the trail runs diagonally through the frame. Add a dramatic backdrop lit with low sun at either end of the day and you have the makings of a great mountain biking image.


    Mountain bike trails provide a compositional anchor for photographers, offering a ready-made lead-in line that can be used to draw the viewer’s eye through the entire image. Keeping the rider away from the centre area of the viewfinder adds dynamism, while making use of available scenery provides useful context.

    Ref: http://www.dpreview.com/articles/321...aphy-technique

  2. The Following User Says Thank You to alooooooo123 For This Useful Post:

    icemain (20-09-2011)

  3. #2
    Mông dân icemain's Avatar
    Ngày tham gia
    Mar 2011
    Bài viết
    425
    Thanks
    177
    Thanked 246 Times in 119 Posts
    Dịch tóm tắt và gửi link được rồi.
    Bố Cú - Mẹ Kún yêu Sóc + Thỏ con nhiều nhiều...

  4. #3
    Mông dân hèn hạ Na nát nhoét's Avatar
    Ngày tham gia
    Jul 2011
    Bài viết
    271
    Thanks
    2
    Thanked 106 Times in 70 Posts
    Hiếp ảnh là ánh trăng lừa dối nhỉ!

  5. The Following User Says Thank You to Na nát nhoét For This Useful Post:

    alooooooo123 (20-09-2011)

  6. #4
    Mông dân cực kỳ hèn hạ alooooooo123's Avatar
    Ngày tham gia
    Jul 2010
    Bài viết
    1,112
    Thanks
    541
    Thanked 337 Times in 178 Posts
    cái này, tóm ... khó

    Làm Hiếp ảnh za ko dễ, Đăng nhỉ

  7. The Following User Says Thank You to alooooooo123 For This Useful Post:

    flamencol77 (23-03-2012)

  8. #5
    Mông dân dự bị flamencol77's Avatar
    Ngày tham gia
    Jan 2012
    Bài viết
    62
    Thanks
    88
    Thanked 115 Times in 65 Posts
    Trích dẫn Gửi bởi alooooooo123 Xem bài viết
    cái này, tóm ... khó
    Khó qué gì... kiếm cái máy quay HD xịn xịn rồi quay, về nhà tách frame... đảm bảo ko lọt lưới bố con thằng nào.

    Thậm chí lôi Canon Mark IV ra mà quay cho mấu

  9. #6
    Đánh trống múa rối Casper_HN's Avatar
    Ngày tham gia
    Jul 2010
    Đang ở
    Nơi nào đó có em
    Bài viết
    2,027
    Thanks
    1,634
    Thanked 1,670 Times in 672 Posts
    Toàn tiếng lước ngoài, mềnh đọc không có được.

  10. #7
    Mông dân dự bị NTB2012's Avatar
    Ngày tham gia
    Mar 2012
    Đang ở
    Hà Nội
    Bài viết
    5
    Thanks
    0
    Thanked 0 Times in 0 Posts
    Long cátper có kinh...nghiệm chia sẻ cho ace mông dân chụp choẹt mỗi lần đi để có ảnh mà kể. Bác Long chuyên gia mà.
    Đời thay đổi khi Ta đổi thay!

+ Trả lời Chủ đề

Quyền viết bài

  • Bạn Không thể gửi Chủ đề mới
  • Bạn Không thể Gửi trả lời
  • Bạn Không thể Gửi file đính kèm
  • Bạn Không thể Sửa bài viết của mình