Difficulties with focus when taking birds in flight. (1 Viewer)

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Pretty good! |=)|

Even better full size!

I have read where several people use manual exposure for BIF. Being a novice myself and never really using Manual I am intrigued as to exactly how this works. If you take a reading off something neutral like grass and use that for the exposure then surely the tone of the bird (light or dark) must play a part into whether or not it is exposed correctly or is this a silly question. Can anyone explain in simple terms (idiot proof for me :-C ) exactly how one goes about using manual exposure for bird photography as I would like to give it a shot.

Roy C said:

I have read where several people use manual exposure for BIF. Being a novice myself and never really using Manual I am intrigued as to exactly how this works. If you take a reading off something neutral like grass and use that for the exposure then surely the tone of the bird (light or dark) must play a part into whether or not it is exposed correctly or is this a silly question. Can anyone explain in simple terms (idiot proof for me :-C ) exactly how one goes about using manual exposure for bird photography as I would like to give it a shot.

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You've just explained to yourself why manual exposure is such a great tool. If you have a dark bird in the shot you want it to remain looking dark. You do not want autoexposure to decide for you that it would look much nicer at 18% grey. It's exactly the same with a light coloured bird. It should look light in the photo. Again, you don't want autoexposure to decide you're going to get an 18% grey bird whether you like it or not. What you really want in the scene is a grey bird (18% grey preferably) that you can use to set your exposure accurately. Then black birds will stay black, white birds will stay white and grey bird will stay grey. All other colours and shades will end up exactly where they belong. If you are not fortunate enough to have an 18% grey bird handy then you can use an 18% grey card and set the exposure from that. It will be just as effective as an 18% grey bird. Alternatively, meter off your palm (so long as it is in the same light as the birds) and set the exposure about +1 to +1 1/3 stops above the centre of the meter. Your palm does not tan and so can be used throughout the year as a fake grey card. Because your palm is paler (more reflective) than a real grey card you will need to dial the exposure in a bit over the zero to compensate. +1 to +1 1/3 will probably be about right, but you can test by trial and error exactly what works best for your skin and your camera.

This is no different to shooting grooms in black tuxedos and brides in white dresses. The exposure should be set according to the incident light falling upon the subject, not the reflected light coming off it. Black tux, white dress, it doesn't matter - the exposure should be the same for both - you still want the skin tones and background to match from one photo to the next. Weddings togs use manual exposure all the time. But with in camera metering you have to make do with reflected light, and if the subject metered is anything other than 18% grey in luminosity then you will need to dial in some EC one way or the other to compensate. That all seems a bit like hard (guess)work to me. Manual keeps things really simple, once you have the exposure set correctly.

Metering off grass is perfect, if the grass and the bird(s) are both enjoying the same lighting. If the grass is in bright sunshine and the birds are flying in the shadows of trees (or vice versa) then you'll have to find something else to meter off. If the bird is in shade then meter off some grass in the shade. If the bird is lit by open sky or direct sunlight then find some grass that is lit the same way. Grass does differ in tone, so you may have to manually choose to "overexpose" a bit or "underexpose" a bit. That's fair enough. If you're shoting in a snow scene you'll have to "overexpose" quite a lot, because all that bright white snow will cause the camera's metering to want to dim it down to 18% grey. Of course, you actually want the snow to be captured as brilliant (but not overexposed!) white. If you shoot with autoexposure you will likely need to dial in a couple of stops of +EC to tell the camera you want the whites kept white.

Apart from the tone of the bird altering, which should not change your exposure settings in any way, the exact same thing goes for the background, which will most likely dominate the meter reading more than the bird in any case. If a bird is flying level with the top of the treeline, sometimes against a blue sky, sometimes against the dark trees, you don't want the exposure to keep bobbing up and down with the bird. If the bird is lit constantly then the exposure for the bird should not change at all, regardless of what the background is doing. Suppose the bird is flying over ground and heading for a lake, with bright specular reflections all over it. Should the exposure for the bird suddenly change simply because we have a new, brighter background? I don't believe so. The bird may get a bit of extra light underneath, but the top of the bird, where the light originates from, will be getting no more and no less light than before. You want to fix the exposure for the bird. Nothing else.

You'll only come unstuck with manual exposure if the light changes (clouds rolling in and out again) or the bird is ducking and diving in and out of shade. You can then choose whether to adjust your manual settings to suit the new conditions or take your chances with auto exposure of some kind, and manual exposure compensation.

If all else fails, and your are struggling with metering, for whatever reason, try the good old manual fallback of the SUNNY 16 RULE. It's all explained here - http://medfmt.8k.com/mf/sunny.html. You can, of course trade off shutter speed, aperture and ISO to maintain the correct overall exposure and get the shutter speed you need to control motion and the aperture you need to conrol DOF. So, for example, in sunny conditions, instead of f/16, 100 ISO, 1/100 you might choose f/8, 400 ISO, 1/1600 for the same exposure.

I've attached six images I just shot, in the sunshine, to demonstrate the differing results from different metering/exposure approaches. I left the camera on a tripod for each shot, to replicate each composition perfectly.

Top left - using the sunny 16 rule, this was shot at f/8, 400 ISO, 1/1600. There is almost nothing in the picture that is pure white or highly reflective. Using DPP to assess how much headroom I have before clipping I'd say I had 2/3 stop of spare headroom. That would be my safe margin to hold details for anything bright white, like a white bird, for example. If I'd stuck a sheet of white A4 in the scene it should have been near the top of the scale but, hopefully, unclipped.

Top centre - Av mode, pattern/evaluative metering. Still at f/8 and 400 ISO, the camera picked 1/1000 as my shutter speed. Spookily, the exposure is bang on and exposed beautifully to the right (I only shoot raw). If I increase the exposure by even 1/6 stop in DPP I see highlights get blown on some window frame in the distance.

Top right - AV mode, partial metering. Still at f/8 and 400 ISO, the camera picked 1/2000 as my shutter speed. Clearly the brightness of the wall of the house is pushing my exposure down a bit. The picture looks underexposed. Sure enough, I can push the exposure up by a full stop in DPP before my highlight clipping indicators appear.

Bottom left - Av mode, spot metering. At f/8 and 400 ISO once more, the camera has picked 1/3200 as my shutter speed. The spot meter was totally over the bightest part of the wall. Now the image is severely underexposed. In DPP I can push it 1.5 stops brighter to see just the barest hint of clipping. This is clearly down to bad metering technique, but it shows how susceptible the meter is to being pointed at the wrong thing. Tracking a bird with spot metering?.... a tough chalenge indeed.

Bottom centre - Av mode, CWA metering. At f/8 and 400 ISO, the camera picked 1/1250 as the shutter speed. That's a third of a stop brighter than my sunny 16 manual exposure. Pretty much perfect for this scene - I can only add 1/6 stop in DPP before getting the clipping warning.

Bottom right - Back to manual mode with the sunny 16 exposure setting. I used partial metering to meter the centre of my palm to see what the meter thought of it. The meter indicated that I was overexposing by between 1 stop and 1 1/3 stops. We know that the sunny 16 exposure does not overexpose so my palm was "lying" when it told the camera it was overexposed. I basically now know that my palm is about 1 1/3 stops brighter than 18% grey in the eyes of my camera. That means that if ever I need to set a manual exposure but have nothing reliable to meter off, all I need to do is meter my palm in the same light conditions as the scene/subject and make sure the needle is pointing at +1 to +1 1/3 stops overexposed.

tdodd said:

You've just explained to yourself why manual exposure is such a great tool. If you have a dark bird in the shot you want it to remain looking dark. You do not want autoexposure to decide for you that it would look much nicer at 18% grey. It's exactly the same with a light coloured bird. It should look light in the photo. Again, you don't want autoexposure to decide you're going to get an 18% grey bird whether you like it or not. What you really want in the scene is a grey bird (18% grey preferably) that you can use to set your exposure accurately. Then black birds will stay black, white birds will stay white and grey bird will stay grey. All other colours and shades will end up exactly where they belong. If you are not fortunate enough to have an 18% grey bird handy then you can use an 18% grey card and set the exposure from that. It will be just as effective as an 18% grey bird. Alternatively, meter off your palm (so long as it is in the same light as the birds) and set the exposure about +1 to +1 1/3 stops above the centre of the meter. Your palm does not tan and so can be used throughout the year as a fake grey card. Because your palm is paler (more reflective) than a real grey card you will need to dial the exposure in a bit over the zero to compensate. +2/3 will probably be about right, but you can test by trial and error exactly what works best for your skin and your camera.

This is no different to shooting grooms in black tuxedos and brides in white dresses. The exposure should be set according to the incident light falling upon the subject, not the reflected light coming off it. Black tux, white dress, it doesn't matter - the exposure should be the same for both - you still want the skin tones and background to match from one photo to the next. Weddings togs use manual exposure all the time. But with in camera metering you have to make do with reflected light, and if the subject metered is anything other than 18% grey in luminosity then you will need to dial in some EC one way or the other to compensate. That all seems a bit like hard (guess)work to me. Manual keeps things really simple, once you have the exposure set correctly.

Metering off grass is perfect, if the grass and the bird(s) are both enoying the same lighting. If the grass is in bright sunshine and the birds are flying in the shadows of trees (or vice versa) then you'll have to find something else to meter off. If the bird is in shade then meter off some grass in the shade. If the bird is lit by open sky or direct sunlight then find some grass that is lit the same way. Grass does differ in tone, so you may have to manually choose to "overexpose" a bit or "underexpose" a bit. That's fair enough. If you're shoting in a snow scene you'll have to "overexpose" quite a lot, because all that bright white snow will cause the camera's metering to want to dim it down to 18% grey. Of course, you actually want the snow to be captured as brilliant (but not overexposed!) white. If you shoot with autoexposure you will likely need to dial in a couple of stops of +EC to tell the camera you want the whites kept white.

Apart from the tone of the bird altering, which should not change your exposure settings in any way, the exact same thing goes for the background, which will most likely dominate the meter reading more than the bird in any case. If a bird is flying level with the top of the treeline, sometimes against a blue sky, sometimes against the dark trees, you don't want the exposure to keep bobbing up and down with the bird. If the bird is lit constantly then the exposure for the bird should not change at all, regardless of what the background is doing. Suppose the bird is flying over ground and heading for a lake, with bright specular reflections all over it. Should the exposure for the bird suddenly change simply because we have a new, brighter background? I don't believe so. The bird may get a bit of extra light underneath, but the top of the bird, where the light originates from, will be getting no more and no less light than before. You want to fix the exposure for the bird. Nothing else.

You'll only come unstuck with manual exposure if the light changes (clouds rolling in and out again) or the bird is ducking and diving in and out of shade. You can then choose whether to adjust your manual settings to suit the new conditions or take your chances with auto exposure of some kind, and manual exposure compensation.

If all else fails, and your are struggling with metering, for whatever reason, try the good old manual fallback of the SUNNY 16 RULE. It's all explained here - http://medfmt.8k.com/mf/sunny.html. You can, of course trade off shutter speed, aperture and ISO to maintain the correct overall exposure and get the shutter speed you need to control motion and the aperture you need to conrol DOF. So, for example, in sunny conditions, instead of f/16, 100 ISO, 1/100 you might choose f/8, 400 ISO, 1/1600 for the same exposure.

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Thanks for taking the time to respond in a way that even I can understand. I have just been out in the garden and had a play around, metered off the grass, set manual exposure and rattled off a dozen shots of different scenes like chimney pots, brickwork, a dark blue car, white house ... and they were all exposed spot on. Magic :t:

Good to hear. In the right conditions (stable lighting) manual exposure simplifies everything. Just set it and forget it (until the light changes).

I've just had a thought. If you have a camera like the 40D you could even save some different manual settings in your C1, C2, C3 custom presets. C1 could be for brilliant sunshine, C2 for deep shade, and maybe C3 for regular cloudy. When you get to a location you could set them up precisely to suit the exact conditions at the scene.

By the way, if you follow the link in my signature (Shameless plug) you will see one example of around 220 shots taken in 40 minutes, all with manual exposure. Once the exposure was dialed in properly I could happily forget about it completely and concentrate on timing and framing the shots. It didn't matter how much snow or sky was in the scene, or what the jumping boarders/skiers were wearing. Every exposure was bang on.

tdodd said:

Good to hear. In the right conditions (stable lighting) manual exposure simplifies everything. Just set it and forget it (until the light changes).

I've just had a thought. If you have a camera like the 40D you could even save some different manual settings in your C1, C2, C3 custom presets. C1 could be for brilliant sunshine, C2 for deep shade, and maybe C3 for regular cloudy. When you get to a location you could set them up precisely to suit the exact conditions at the scene.

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Thanks again for that. I do have a 40D and at the moment I use the custom presets for exposure compensation (0, +1, +2 with all other settings the same) so using it like you suggest would be a similar thing but more accurate than me guessing.
Just one more silly question, when you obtain the meter reading off something neutral like grass the metering mode you use could influence the reading which is fair enough but how does the metering mode influence anything when shooting in manual or is it irrelevant.

The only thing to watch for when you first meter to get your manual settings is to ensure you fill the frame with the meter target, or choose a metering mode like partial or spot, to make it easier to aim at exactly what you need. Once you're set up and moving the camera around the meter will bob about but the camera will obey your manual settings.

paul goode said:

Pah!! eezy peezy stuff.

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Actually, you're not wrong - they are "easy" (yeah, fulmars are a doddle! ) - but I think they prove that the 40D and all focus points isn't an entirely lost cause.

Where are the Terns?

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Let's see what this weekend brings..!



As an aside - this recent influx of black terns must be pretty much unprecedented, I'd have thought. They're everywhere...

tdodd said:

The only thing to watch for when you first meter to get your manual settings is to ensure you fill the frame with the meter target, or choose a metering mode like partial or spot, to make it easier to aim at exactly what you need. Once you're set up and moving the camera around the meter will bob about but the camera will obey your manual settings.

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As I thought, many thanks again Tim.

paul goode said:

Pah!! eezy peezy stuff. Where are the Terns? B B
(nice shots though)

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Here are the Terns Paul, not sure if it is the right type though

Roy C said:

Here are the Terns Paul, not sure if it is the right type though

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Thats more like it - proper birds! (I will allow the Fulmar )

Proper birds - and pretty big in the frame too, I'll warrant!

Keith Reeder said:

As an aside - this recent influx of black terns must be pretty much unprecedented, I'd have thought. They're everywhere...

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Certainly seem to be significant numbers this year. I did consider another session with them today but decided to take the easy route and go for the local Cetti's Warbler. Much much easier! :-O:-O

Cans of worms?

Firstly, my thanks to Adrian (photovision) and Keith (Reeder) for your replies to my post about using all focus points and blurred backgrounds. I've yet to experiment, but am encouraged by your experiences.

Now, turning to tdodd's eloquent exposé on manual exposure. On reading it the cogs started turning and I remembered that somewhere I have a Weston Mater V exposure meter with incident light cone. So this afternoon I dug it out and used it to test the theory. First, I set the ASA speed rating (which I know(?) equates to current ISO ratings), ascertained suitable shutter speed/aperture by both incident and relected light (almost exactly the same) and set them on my 20D. Then I tried some test shots of reasonably neutral subjects - brickwork and garden greenery. Results? Anything between 1 and 2 stops over-exposed as indicated on the camera scale and verified by blown highlights "flashing" in the image and of course, the histogram. Not sensible I thought - am I on the wrong track with ASA/ISO being the same? Checked that they are by research on the net and now back to square one! I do like the idea of "setting and forgetting" as tdodd says so what can be the problem, I ask? Incidentally, the lens in use is Canon 100-400 IS Zoom.

Anyone have any views please?

Adrian

If it was sunny when you did the test it's not hard to get "hot" brickwork and greenery, even though they're supposedly neutral...

Could you post an example or two, Adrian?

Boy George said:

Now, turning to tdodd's eloquent exposé on manual exposure. On reading it the cogs started turning and I remembered that somewhere I have a Weston Mater V exposure meter with incident light cone. So this afternoon I dug it out and used it to test the theory. First, I set the ASA speed rating (which I know(?) equates to current ISO ratings), ascertained suitable shutter speed/aperture by both incident and relected light (almost exactly the same) and set them on my 20D. Then I tried some test shots of reasonably neutral subjects - brickwork and garden greenery. Results? Anything between 1 and 2 stops over-exposed as indicated on the camera scale and verified by blown highlights "flashing" in the image and of course, the histogram. Not sensible I thought - am I on the wrong track with ASA/ISO being the same? Checked that they are by research on the net and now back to square one! I do like the idea of "setting and forgetting" as tdodd says so what can be the problem, I ask? Incidentally, the lens in use is Canon 100-400 IS Zoom.

Anyone have any views please?

Adrian

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I did used to have a Weston something or other, courtesy of my dad, but never really used it and now I can't find it. I think the last time I saw it was maybe 20+ years ago. So I did a bit of digging on the internet, Googling for "Weston Master V calibration". From what I found it seems that (a) there is a "zero" adjustment screw on the back, so maybe that needs looking at; (b) there is a calibration service for them - so I guess they can go out of whack.

Here's an example article - http://haardt.net/wmv.htm - and another - http://www.acecam.com/photography/719.html.
Manual here - http://www.cameramanuals.org/flashes_meters/weston_master_v.pdf

I guess the thing to do is point it at the sun, with the dome in place, on a clear, blue-sky day, and see how close the meter gets to "Sunny 16" readings. i.e. at f/16 and 100 ISO does it read off with a shutter speed of 1/100? If not, how far is it off and in which direction? If it says you need 1/50, for example, then it is going to give you a 1 stop overexposure. If it says 1/200 then it will give you a 1 stop underexposure. Once you know the offset from the Sunny 16 standard maybe you can dial in a permanent adjustment to the meter or simply remember that you need to add or subtract a bit of a stop one way or the other.

Yep, that was to be my next suggestion: is the light meter still accurate?

Keith Reeder said:

Yep, that was to be my next suggestion: is the light meter still accurate?

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That has occured to me too, as the logic of your previous reply regarding "hotspots" begins to fall down when, as I said, the reflected reading was virtually identical to the incident.

I have a Grey Card somewhere - I think I'll did it out and do some testing.

Thanks to you all for your thoughts.

Adrian

Cans of worms

Following my last post, I have found my Grey Card and compared an incident meter reading with a full frame shot of the card using the camera's own Evaluative Metering system. The Weston Master is clearly inaccurate, giving me nearly 2 stops over-exposure when compared with the camera shot which shows the single graph peak plumb in the middle of the histogram.

So as TdoddT said "(b) there is a calibration service for them - so I guess they can go out of whack." I have used the links you kindly provided and have contacted Megatron Ltd in London who indeed confirm that they can calibrate and if necessary replace the selenium cell for the modest sum of £42 all in. The meter will be in the post to them today.

Thanks again to one and all.

Adrian