Photography Tutorial - Exposure Scenarios

After a very busy few months over the summer I finally found some time to get to my computer to write this up... my apologies for taking so long to come back to this... so following on from the last tutorial here are a few scenarios to illustrate camera settings..

situation 1 - a landscape

Ideally we would want to have as much of the scene in sharp focus.. from right in front of us to way off on the horizon... and to do this we would generally need an f.stop (aperture) of f8.0 or more (preferably more).. a low ISO to retain as much detail as possible and our shutter speed is last in our order of priorities... so it can be set to pretty much anything (as long as we have a tripod to put the camera on !)

So for this photo of  Wastwater in the Lake District my settings were as follows:

ISO:   100

aperture:  f/16.0

shutter speed: 30 secs (with 10stop ND filter)

..this has created the effect of movement in the stream, clouds and trees but everything not moving is pin sharp from the rocks in the foreground to the lake and valley in the distance.

situation 2 - action - bird flying overhead

In most situations where you are photographing a bird flying high above you, you will inevitably be shooting against a bright sky.. whether sunny or cloudy in most instances the bird in question will be silhouetted. In these instances it's no good letting the camera do the exposing as your shots will inevitably be under-exposed and the bird will be nothing but a dark shadow...  so you definitely need to either expose manually or add in some exposure compensation if shooting in either aperture or shutter priority.

So what are the considerations here.. firstly it is a moving subject so shutter speed will be a priority.. depending on the light conditions our ISO will also play an important role and our aperture is also important as a moving object high up in the sky is a challenge for focussing...lots to consider.! the lens we are shooting on also comes into play here as the longer the focal length of a lens we use then the shallower the depth of field we can achieve at any given aperture.. to illustrate, here's a shot of Short-toed eagle I recently took on one of our wildlife photography workshops in Greece using a 300mm lens with a 1.4x extender...

...as you can see, the eagle is well exposed against the bright sky.. beak, eyes and leading wing edge are all sharp though the focus is staring to fall off at the bird's tail.. settings for this shot were:

ISO:   400

aperture:  f/8.0

shutter speed: 2500/sec 

I needed a fast shutter speed to freeze the movement and reduce any potential camera shake (hand holding a heavy camera + long lens is never easy!) but also a good depth of field to ensure eyes, beak and breast would be sharp.. hence my choice of a mid ISO of 400 

 Just a small aside.. in regard to photographing birds of prey... which are usually circling way up above our heads... whilst it's fine to try and get a couple of shots to help us id the bird.. please please don't waste your time shooting hundreds of pictures rapid fire when the bird is miles above your heads... the shots will never be good enough for printing, will lack any trace of artistic merit and will only add to the time spent editing.. for absolutely no reason whatsoever, Trust me... it is a pointless excercise.. a few shots to help in identifying the bird is all you need and you will save yourself a whole lot of editing time.

scenario 3 - a portrait 

The key to creating portraits with some impact is to separate your subject from the background.. this is easy if the background is a clear blue sky or some other plain background but becomes harder if the background is busy.  

The main tool at our disposal to achieve this is to be able to throw the background out of focus... and the way we achieve this is to open up our aperture as wide as we can so as to concentrate focus on our subjects eyes.  

It's also important to note, as I mentioned above.. that the lens on which we are shooting plays a very important role when it comes to depth of field because the longer the focal length of our lens then the shallower the depth of field..

for example... if you are taking a portrait of a bird perched on a branch on a 400mm lens, opening up to f/2.8 and focussing on the bird's eyes could mean the eyes are nice and sharp but its beak tip and breast could be out of focus.. not what we want at all.. so in other words you have to also learn (by shooting lots..!) the capabilities of any particular lens in your arsenal at different apertures... and taking a photo of that bird at f/8.0 on the 400mm could give you the shallow depth of field and blurred background you desire but still retain focus from eyes to beak to breast.

By way of illustration take a look at the following images... 

The Little Owl was photographed on my 300mm + 1.4 extender (giving an equivalent focal length of 420mm) at:

ISO:   400

aperture:  f/8.0

shutter speed: 500/sec

The eyes, beak breast, talons and the wall edge are all pretty much on the same plane and in focus and yet even at f/8.0 the focus falls off sharply just a few inches further back at the top of his head and at his tail.. note though the nice blurred background which isolates the owl and lets him stand out despite being relatively small in the frame.

The Dalmatian Pelican was photographed on my 300mm without the 1.4 extender at:

ISO:   400

aperture:  f/4.0

shutter speed: 1000/sec

The eyes, beak (which is much longer than our little owl's above) and breast are not at all on the same plane and yet all are sharp and at a much wider aperture than for the owl shot... all down to the increase in relative depth of field created by removing the 1.4 extender and making the lens' focal length shorter by 120mm... again the background drifts off out of focus isolating our subject making him stand out.

I hope the above examples will be of some help.. let me know if you want me to clarify anything and I'll get back to you either in person or in a follow up post.

g