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50d BIF 9 point focus V centre point focus

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Old Tuesday 31st March 2009, 15:39   #1
Nikon Kid
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50d BIF 9 point focus V centre point focus

50d BIF 9 point focus V centre point focus

If a bird is in the sky would 9 point focus v centre point focus be any different for sharpness.

And would that be the same for the 450d
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Old Tuesday 31st March 2009, 15:51   #2
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Centre point is best for BIF. The focus assist points on the 1 Series are excellent, but the 50D doesn't have these. Try to keep the bird as centred as you can, and stop down a bit so that DOF will help you out a bit.
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Old Tuesday 31st March 2009, 15:55   #3
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When you use 9 AF points in AI Servo mode you must first lock focus with the centre point. In this regard the operation of AI Servo with all points is completely different to One Shot AF. As I'm sure you know, One Shot will lock onto the nearest "subject" it finds with adequate contrast, with any one or more of the AF points. With AI Servo you must get the centre point fixed on your target first or all bets are off.

Assuming you do correctly establish focus lock with the centre point the focus should continue to track your subject if it moves off the centre point, only if the subject is large enough to cover the centre point and at least one other point at the same time. Once the centre point lets go the other point(s) will take over. The camera can hand off from one point to another so long as the subject always covers at least two points. If the subject is so small that it slips between points the you can lose focus completely, very quickly.

Assuming you establish focus accurately and continue to track accurately I see no reason for a difference in sharpness whether you use one point or all. One difference there might be is when your DOF is so shallow that only parts of the bird are in focus. Then, if you want focus to be exactly where you intend, you'll be better off with a single point.

With my xxD bodies I generally tend to find that I get better results using a single focus point, simply because my subjects are often too small in the frame to cover more than one point at a time. With my 1D3 I tend to favour a single focus point with six assist points enabled. Against a completely clear sky then all 45 points (Ring Of Fire) can work well and ease the burden on the photographer. The fact remains, however, that if your DOF is thin you need to aim very precisely and you need a tight grouping of focus points (or one only) to nail your intended point of focus. Let's say you have a largeish bird - goose or cormarant - in flight. You'll (probably) want the head to be in focus far more than the near wing tip. You therefore need to use AF point(s) that allow you to cluster around the head area while avoiding other parts of the bird. On a 50D I'd have to recommend a single AF point to accomplish that. On a 1D3 you would probably be fine, and find it an easier job, with a single point plus either two or six expanded assist points.
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Old Tuesday 31st March 2009, 16:04   #4
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Thanks guys that has explained it well, I have been on centre focus all the time, but did not want to think I was missing out on something.
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Old Thursday 2nd April 2009, 17:48   #5
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Quote:
Originally Posted by tdodd View Post
When you use 9 AF points in AI Servo mode you must first lock focus with the centre point. In this regard the operation of AI Servo with all points is completely different to One Shot AF. As I'm sure you know, One Shot will lock onto the nearest "subject" it finds with adequate contrast, with any one or more of the AF points. With AI Servo you must get the centre point fixed on your target first or all bets are off.

Assuming you do correctly establish focus lock with the centre point the focus should continue to track your subject if it moves off the centre point, only if the subject is large enough to cover the centre point and at least one other point at the same time. Once the centre point lets go the other point(s) will take over. The camera can hand off from one point to another so long as the subject always covers at least two points. If the subject is so small that it slips between points the you can lose focus completely, very quickly.

Assuming you establish focus accurately and continue to track accurately I see no reason for a difference in sharpness whether you use one point or all. One difference there might be is when your DOF is so shallow that only parts of the bird are in focus. Then, if you want focus to be exactly where you intend, you'll be better off with a single point.

With my xxD bodies I generally tend to find that I get better results using a single focus point, simply because my subjects are often too small in the frame to cover more than one point at a time. With my 1D3 I tend to favour a single focus point with six assist points enabled. Against a completely clear sky then all 45 points (Ring Of Fire) can work well and ease the burden on the photographer. The fact remains, however, that if your DOF is thin you need to aim very precisely and you need a tight grouping of focus points (or one only) to nail your intended point of focus. Let's say you have a largeish bird - goose or cormarant - in flight. You'll (probably) want the head to be in focus far more than the near wing tip. You therefore need to use AF point(s) that allow you to cluster around the head area while avoiding other parts of the bird. On a 50D I'd have to recommend a single AF point to accomplish that. On a 1D3 you would probably be fine, and find it an easier job, with a single point plus either two or six expanded assist points.
Hi Tim,

I just bought myself a 5DMII, I am holding on it and following step by step on what you explained (9 AF points in AI Servo), but why there is no beep sounds and there is no green indicator confirmation/confirmation light even I adjust either 9 AF points or 1 point right on the middle???. is that what it should be? but when I change to One Shot and AI Focus, I can hear the beep sounds and I see the green indicator/confirmation light on the view finder.

Let's say I am trying to shoot bird in flight in the open area on the broad day light
1. What picture style effects should I use ( Standard, Portrait, Landscape or Neutral)?
2. What AF Mode should I use (One shot, AI Focus or AI Servo)??? I do believe you were suggesting AI Servo, am I right???
3. What AF point should I use ( one single focus point in the middle with six assist points enabled OR all 9 points??
4. What metering mode should I use??? (Evaluative or Spot mode)
5. Should I use Aperture Priority or Shutter priority??? I am using Aperture most of the time and I am not sure if it is a correct way???

I thank you very much in advance and I hope you will help me on these matters.

Best Regards,
WW
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Old Thursday 2nd April 2009, 18:30   #6
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WW - some answers....

0. There is no beep in AI Servo mode because the camera is focusing continuosly and may lose focus and then regain it. One beep at the start would be of limited use and you could hardly have the thing beeping non stop while it was focusing. You only get the beep in One Shot mode (perhaps in AI Focus too but I never use that). It's the same thing with the confirmation light.

1. Picture style is a personal choice. If you shoot raw your choice makes no odds because your raw processor will ignore the picture style completely or, if you use DPP to process it will apply the selected picture style but you can freely change the style in use. If you shoot to JPEG then you do need to have your picture style decided before you shoot. If you shoot only to raw I would recommend choosing the Neutral picture style, in order to get a slightly more accurate histogram reflecting your raw capture. If you shoot to JPEG or raw + JPEG I recommend you choose the Standard picture style. There are no hard and fast rules here. Choose whatever pleases your eye. I would recommend you shoot raw, (a) because you just should :); (b) because if you use DPP you can play around with the settings after you take the shot and then figure out what you like best.

2. For BIF, always AI Servo. For static subjects AI Servo (but with focus only enabled on the AF-On button, not the shutter) or One Shot. Never Never Never use AI Focus. I don't know why these cameras have it. Pretend it does not exist.

3. There are people more expert than me in these things but I would suggest choosing a single point only, possibly/probably with the assist points enabled but rarely all points on anything less than a 1 series. The truth is that the answer really depends on the size, speed and predictability of the path of your subject and how skilled you are in following its movements. The better you are, or the easier it is to track (big, slow, steady) then the fewer points you should use. Using all points will only work well if the subject is large enough to cover multiple points at once. If it is not that large you will be wasting your time using all points.

4. Mostly I use manual exposure and spot metering. I try to avoid using autoexposure if I can. If you want to use autoexposure then the choice of metering mode really should be dictated by how the subject fits in with your scene and how much effort you want to put into twiddling the EC control. There are many ways to tackle the problem of exposure. The right way is whatever suits you and the subject/scene and lighting conditions you are facing.

5. If you're not going to use manual exposure then both Av and Tv modes have their uses. If controlling movement is of paramount importance then picking your preferred shutter speed might be the better choice. That would likely be the case when shooting BIF. When shooting perched birds then shutter speed won't be so much of an issue other than to avoid camera shake. You might choose to select your aperture in order to creatively isolate your subject from the surroundings or deliberately include them. You might also want to ensure that you didn't inadvertently tread into diffraction territory by ending up with an unusually small aperture, as might happen if you were to chose a modest shutter speed with a high ISO. The bottom line is you need to consider both aperture and shutter speed and you need to ride your ISO control to place both within boundaries that satisfy all needs.

At the end of the day I find manual exposure gives me the control I want on all fronts. If the lighting is constant I also find manual exposure about a million times easier to use than the auto modes. Put simply, if the lighting is constant, one you've metered and adjusted once that's the end of that chore. Shoot away happily while concentrating on framing, focusing and timing. Exposure will be one less thing to worry about.

Take today as a typical example. I was out with my camera. Conditions were bright/sunny with a little haze but no clouds. The light was barely changing at all, maybe dropping 1/3 stop every 30 minutes as the sun went down. I was walking along a dusty path, fairly pale and maybe about 1 1/3 stop above middle grey in brightness. To my left was a dark hedgerow, maybe a stop or more below middle grey. To my right was a grassy field, perhaps bang on middle grey in tone. Above me was the hazy blue sky, about 1 stop above middle grey. My camera was set with manual exposure off the palm of my hand at +1 1/3 stops. I was ready to shoot anything that appeared anywhere within a 180 degree field of view before me, both left/right and up/down. My exposure was set. Whether a crow flew by or an egret my exposure would be correct. No need to worry about the tone of my subject. No need to worry about the tone of the background, or if it was a mixture of tones. No fiddling around with EC or worrying about metering mode. Just see it, aim, focus, fire. That's why I like manual exposure.

Cheers,
Tim.
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Old Friday 3rd April 2009, 03:25   #7
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Quote:
Originally Posted by tdodd View Post
WW - some answers....
Cheers,
Tim.
Hi Tim,

Thank so much and I am outside the balcony at the moment to test on those what you suggested.

Thanks so much!!!

Cheers,
WW
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Old Friday 3rd April 2009, 16:43   #8
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Tim is spot on with his post above.
Rob.
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Old Friday 3rd April 2009, 17:41   #9
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Quote:
Originally Posted by tdodd View Post
WW - some answers....

0. There is no beep in AI Servo mode because the camera is focusing continuosly and may lose focus and then regain it. One beep at the start would be of limited use and you could hardly have the thing beeping non stop while it was focusing. You only get the beep in One Shot mode (perhaps in AI Focus too but I never use that). It's the same thing with the confirmation light.

1. Picture style is a personal choice. If you shoot raw your choice makes no odds because your raw processor will ignore the picture style completely or, if you use DPP to process it will apply the selected picture style but you can freely change the style in use. If you shoot to JPEG then you do need to have your picture style decided before you shoot. If you shoot only to raw I would recommend choosing the Neutral picture style, in order to get a slightly more accurate histogram reflecting your raw capture. If you shoot to JPEG or raw + JPEG I recommend you choose the Standard picture style. There are no hard and fast rules here. Choose whatever pleases your eye. I would recommend you shoot raw, (a) because you just should :); (b) because if you use DPP you can play around with the settings after you take the shot and then figure out what you like best.

2. For BIF, always AI Servo. For static subjects AI Servo (but with focus only enabled on the AF-On button, not the shutter) or One Shot. Never Never Never use AI Focus. I don't know why these cameras have it. Pretend it does not exist.

3. There are people more expert than me in these things but I would suggest choosing a single point only, possibly/probably with the assist points enabled but rarely all points on anything less than a 1 series. The truth is that the answer really depends on the size, speed and predictability of the path of your subject and how skilled you are in following its movements. The better you are, or the easier it is to track (big, slow, steady) then the fewer points you should use. Using all points will only work well if the subject is large enough to cover multiple points at once. If it is not that large you will be wasting your time using all points.

4. Mostly I use manual exposure and spot metering. I try to avoid using autoexposure if I can. If you want to use autoexposure then the choice of metering mode really should be dictated by how the subject fits in with your scene and how much effort you want to put into twiddling the EC control. There are many ways to tackle the problem of exposure. The right way is whatever suits you and the subject/scene and lighting conditions you are facing.

5. If you're not going to use manual exposure then both Av and Tv modes have their uses. If controlling movement is of paramount importance then picking your preferred shutter speed might be the better choice. That would likely be the case when shooting BIF. When shooting perched birds then shutter speed won't be so much of an issue other than to avoid camera shake. You might choose to select your aperture in order to creatively isolate your subject from the surroundings or deliberately include them. You might also want to ensure that you didn't inadvertently tread into diffraction territory by ending up with an unusually small aperture, as might happen if you were to chose a modest shutter speed with a high ISO. The bottom line is you need to consider both aperture and shutter speed and you need to ride your ISO control to place both within boundaries that satisfy all needs.

At the end of the day I find manual exposure gives me the control I want on all fronts. If the lighting is constant I also find manual exposure about a million times easier to use than the auto modes. Put simply, if the lighting is constant, one you've metered and adjusted once that's the end of that chore. Shoot away happily while concentrating on framing, focusing and timing. Exposure will be one less thing to worry about.

Take today as a typical example. I was out with my camera. Conditions were bright/sunny with a little haze but no clouds. The light was barely changing at all, maybe dropping 1/3 stop every 30 minutes as the sun went down. I was walking along a dusty path, fairly pale and maybe about 1 1/3 stop above middle grey in brightness. To my left was a dark hedgerow, maybe a stop or more below middle grey. To my right was a grassy field, perhaps bang on middle grey in tone. Above me was the hazy blue sky, about 1 stop above middle grey. My camera was set with manual exposure off the palm of my hand at +1 1/3 stops. I was ready to shoot anything that appeared anywhere within a 180 degree field of view before me, both left/right and up/down. My exposure was set. Whether a crow flew by or an egret my exposure would be correct. No need to worry about the tone of my subject. No need to worry about the tone of the background, or if it was a mixture of tones. No fiddling around with EC or worrying about metering mode. Just see it, aim, focus, fire. That's why I like manual exposure.

Cheers,
Tim.
I agree about this being spot-on - everything I would like to say (especially the bit about Manual exposure) but cannot because I am c##p with words. Cracking post Tim
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Old Friday 3rd April 2009, 23:19   #10
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Great post Tim! I have learned a lot on this forum from contributors like Tim and Roy. I had the opportunity to photograph sandhill cranes, geese, and ducks at a wildlife refuge a few weekends ago and used what I learned about BIF and manual exposure. The photos came out great thanks to such good advice.

Thanks
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