The impossible HOBBY took a TERN for the worse !

Discussion in 'Nature' started by bill_thorlin, Sep 11, 2006.

  1. Some may remember I posted some while back about photographing Hobby as a pair had appeared locally - suffice it to say as soon as I had it all planned they decided to leave, helped no doubt by a chap teaching his sons to fish along the little river they had been quartering. Rather than abandon my project I decided to have a try at Common Terns ( Sterna Hirundo ) which I knew frequented a nature reserve/bird sanctaury nearby. Not the brightest of choices to attempt as they are almost as good aerialists as the Hobby. Anyway I made the attempt and got some results ( variable quality ) but one problem has surfaced - when photographing a white bird against a bright blue sky the underside of the bird comes out inaccurately ( as regards the species ) dark. Does the rule of over-exposing for a white subject still hold good or is there something else one can do to alleviate this problem arising on the actual photograph ( i.e. not manipulating ) ?
  2. A blue sky approximates to "18% grey" so an automatic exposure should be "correct". Maybe the underside of the bird was in shadow? If so then the image is a correct representation.
  3. Hi Bill, the CLEAR blue sky at about 10 a.m. to 2 p.m. approximates an 18% reflectance. Often though, even a blue sky can be very hazy, and this can throw things out of whack, such that an underexposure situation can occur. John Shaw always says (I took a weekend seminar from him recently) to ask yourself what the most important part of the scene is, and set the exposure to get that part the way you want it. He might say, how do you want the white of the tern
    to look? If you want it white, expose to get that, and let the rest of the scene fall where it may.

    It is usually impractical to spot meter the white on the bird in a situation like this, so I would use manual metering off the blue sky (in advance if necessary) and adjust for haze (open 2/3 to 1 stop) if necessary. You might also set the camera to autobracket + or - about 1 stop if feasible given the situation (admittedly difficult when tracking a fast moving object). If you are using a digital camera, you can often judge the exposure by using the histogram, and if exposure is off, keep trying until it's right.
  4. HI, Bill. When I shoot flying terns on days with blue sky, I usually set for a 1/3 to 2/3 underexposure, use shutter-priority exposure, and generally get acceptable or good exposure. As you probably have discovered, some parts of a tern will be shaded (fortunately the white underside coloration mitigates the darkness of shaded areas) while others will be brilliantly backlit from sun shining through the feathers. In the digital world it's easier to deal with moderate underexposure than with blown highlights, so I find that underexposing works best for me.
    On a cloudy or overcast day I generally set for no compensation or for +1/3 or so. In these conditions, terns are good subjects, again because of their pale undersides, which don't contrast strongly with a white cloudy background.
    flying elegant terns, mostly sunny days
    flying elegant terns, mainly overcast days
  5. It is a matter of using the sun to your best advantage and positioning yourself so the sun is behind you, ie planning to shoot at certain times of the day - when the sun is low it will light up the underwing, during nrmal daylight it will be overhead causing shadowing

    If you can only shoot towards the sun you need a burst of fill in flash to lift the dark underwing, but at the distances you are shooting that meens a decent flashgun and some form of fresnel unit such as the better beamer.
  6. Thanks - I am not ignoring the responses but trying to find some valuable time to study them properly.

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