Trogon Photo Tours

March 2014 Newsletter - This newsletter discusses using manual exposure versus aperture priority for birds in flight with images to illustrate the technique.

In my wildlife and bird photography I use aperture priority about 80% of the time.  One of the things I really like about aperture priority is that I only have to change one variable the F-stop or shutter speed and the other changes automatically keeping the equivalent exposure as opposed to having to change both manually with manual exposure, it saves me time and I miss less shots fiddling with my controls.  Also if the light is contrasty or dappled, that is I am going from shooting in areas of sun to shaded areas aperture priority is certainly better as it automatically adjusts to the different lighting.  Where manual mode has a clear advantage is when you are photographing in consistent light and particularly for birds in flight in consistent light.

Short-eared Owl photographed at Malheur NWR, Oregon, May 2012.  Canon 7D 500F4 1.4x 1/1600 F5.6, iso 500, aperture priority exposure compensation +1, evaluative metering.  When photographing birds in flight against gray clouds or sky you are going to have to dial in positive exposure compensation to get a proper exposure.  By the way for the photos in this newsletter no exposure adjustments have been made, they are pretty much out of the camera except for a small crop and sharpening.  They aren't particularly good images (sometimes they are bad to illustrate my points) but they function to illustrate my points.  With this image with a bit more sky than brown marshland it's still a little bit dark even with the +1 added, if the bird were against pure sky I would have needed about +2 exposure compensation.

Short-eared Owl photographed May 2012, Malheur NWR, Oregon.  Canon 7D 500F4 1.4x 1/1250 F5.6, iso 500, aperture mode, evaluative metering a 1.0.  In this image with more of the marsh showing in the foreground the automatic exposure has dropped down to 1/1250.  It happens that this is about the correct exposure for this shot. 

Short-eared Owl photographed May 2012, Malheur NWR, Oregon.  Canon 7D 500F4 1.4x 1/640 F5.6, aperture mode, evaluative metering +1.0.  And here is where we really get into trouble, the owl which flies erratically dropped down so it was just against the brown marshland.  With +1.0 dialed in the camera reduced the shutter speed and exposure by a full stop down to 1/640 of a second.  This meant the whole image was overexposed by a stop.  In addition, the loss of shutter speed made the shot quite soft.  It was a pity because at this point the owl was much closer.  If I had set a manual exposure of 1/1250 F5.6, iso 500 before the encounter even started this would have been a sharper, properly exposed image.  In that case the bird's colors would have been rendered about the same against the varying backgrounds he flew across in the 3 images shown.  The exposure difference when you are working in aperture priority with birds in flight against varying backgrounds can be 3 or 4 stops easily and you just don't have time to dial the wheel that much and change the exposure while the action is going on. The answer to this problem is to use manual mode for most flight photography.

Bald Eagle photographed at Hood Canal, WA, June 2012.  Canon 7D 500F4 1/1000 F7.1, iso 500, manual exposure.  This image and the next 2 show a series of Bald Eagle shots against backgrounds showing a varying amount of dark forest and bright water.  Again, I haven't adjusted the exposure at all here they are straight out of the camera, close to being exposed correctly in camera - if anything they might need 1/3 of a stop more light.  Unlike the owl shots above the exposure is the same because I was using manual mode and had therefore "fixed" it.  Unlike the owl shots the exposure on the bird is fairly consistent against the varying backgrounds.  To determine the exposure I spot metered in aperture priority a neutral colored object, some light green grass that was growing on the ground and in the same lighting as the whole scene.  At that F-stop and iso the camera metered at 1/800.   I then reduced that exposure by 1/3 of a stop to account for the whites on the head of the eagle which I didn't want to blow out.  I then switched to manual exposure and dialed in 1/1000 F7.1, iso 500.   If I had wanted more shutter speed and a more blurred background I could have changed the exposure to 1/1600 F5.6, iso 500.  Often at the canal I use a fairly wide depth of field because of the amount of fights between multiple birds.   Again I haven't adjusted these images other than a bit of straigtening and sharpening.  To optimize this image I might try to pull a little more detailed from the shadow areas.

Bald Eagle photographed June 2012 Hood Canal, WA Canon 7D 500F4 1/1000 F7.1, iso 500. manual mode.  You can see in this image more of the bright water is included which if you were shooting in aperture priority would have caused the shutter speed to drop and the bird to be darker.  Actually in this image the underside of the bird is better lit but that's not a function of the exposure changing, it's the position of the underwing being completely lifted so that's not in shadow at all.  After you have selected your manual exposure and taken some flight shots be sure to check your histogram to see if you need to adjust your exposure.  If the quality of the light changes (for example it goes from being sunny to cloudy) be sure to check your exposure as you will probably need to change it.  Even without noticeable changes in lighting you should be checking your manual exposure occasionally. 

Bald Eagle photographed June 2012, Hood Canal, WA.  Canon 7D 500F4 1/1000 F7.1, iso 500, manual mode.  In this image there is quite a bit more bright water than forest in the background.  This would have caused a big swing in exposure using evaluative metering and aperture priority.  But again because the exposure has been fixed and the lighting is consistent the exposure is pretty much the same as the other images which were against mostly dark forest backgrounds. 

To summarize when photographing birds in flight in consistent lighting conditions you will get much better results using manual mode than aperture priority.  If you want to learn more about using manual mode and determining manual exposures we have spots available on our May Hood Canal Eagle tour www.trogontours.net/wa_eagles