Congratulations. If you’ve come this far you know how to capture the exposure that you want – most of the time. Now we need to consider the problem of difficult lighting – which may keep you from getting what you want. By difficult lighting I mean:
- situations where the tonal range of the light, as displayed on the histogram, is greater than the camera’s sensor is capable of handling. This is the case when both sides of the histogram’s graph won’t fit within the histogram without touching the left and right edges.
In this post and the next, we’ll consider ways to deal with difficult lighting.
Here are your options:
- Film/digital approach #1
- Expose for highlights and let shadows fall where they will
- Expose for shadows and lose the highlights
- Film/digital approach #2
- Use a graduated neutral density filter
- Digital approach
- Take multiple exposures and blend in the computer
In this post we’ll consider #1 & #2 and save the last for the next post.
Approach #1 might be called something may be better than nothing. In order to do this, you simply check the histogram and
- When exposing for highlights, change EV in a negative direction until the right side of the histogram graph no longer touches the right edge
- To expose for shadows, reverse the above step (increase EV until the left edge is not touching)
The left two images were exposed for the highlights – that is, for the scene outside the window. In cases like this, letting the shadows “fall where they will” is often not bad. It can add drama or mystery to the scene. Also, enough shadow area detail usually is retained to complete the story – we’re in a cabin looking at a barn or in a church looking at the graveyard. In these two not much more detail was needed or desired. Note – from a focus standpoint, neither is a shoot-through in spite of the windows 😉 If anything, they demonstrate the use of hyperfocal distance.
For the image of the black bear cub, I didn’t care about retaining detail from the bright background. In fact, totally blown out white would have been ideal. As it is, you can see a green cast and some blotches in the background (all easily cleaned up, if desired). On the other hand, I wanted as much detail as possible on the cub. So – I exposed for the “shadows” – the dark fur of the cub. Letting the camera “have its way” would have been a disaster – largely in the form of a dark cub silhouette.
Approach #2 is more effective than #1, but has its limits as well. This approach mostly applies to landscape photography. It requires the use of a graduated neutral density filter. You will note in the previous video that half of the time was taken just attaching the filter to the camera. A filter holder is unnecessary. I (and many others) simply hand hold the filter in front of the lens; no problem when your camera is on a tripod (as it should be for the type of shots where this filter is needed).
The “graduated” part of the name comes from the fact that the filter is darkest at the very top and gradually transitions through ever lighter shades of gray. The bottom half is clear and has no effect on exposure.
Here is an example of what the filter does. Note that it doesn’t effect the lower part of the scene (the clear filter bottom). It “holds back the light” of the bright upper portion. From left to right three different “densities” of filter are shown – 3-stop, 2-stop, 1-stop and no filter. Note especially the effect on the bright sky. (Note – the bright part of a scene is usually at the top, but not always – water for example. This is no problem as you simply put the dark part of the filter at the bottom of your scene.)
These filters come in several “flavors”.
- As shown in the above image, they are available in different strengths.
- Also, the division between dark and light halves can be either hard or soft. I prefer soft as the edge between light & dark blends more naturally in the captured photo.
- If you hand hold the filters, you can stack them to achieve higher densities. A 2-stop + a 3-stop stacked is the same as a single 5-stop.
- They are also available in a “reverse” style
- Go to this site and scroll from top to bottom for pictures of the filters and pictures made with the filters – and more.
Here are some graduated ND filter illustrations. I made these at Sleeping Bear Dunes National Lakeshore Park for demonstration at a workshop.
A 3-stop soft edge Grad-ND filter From left to right – what the filter looks like, the scene with & without the filter, the final image.
For comparison – a “Reverse” 3-stop Grad-ND filter, which is darkest in the center (and not the top as in the normal Grad-ND)
You see in this case that the reverse (which very few photographers know about; they all preach straight Grad-ND) does a better job in lightening the foreground. This comes with a penalty-
- The expense of another filter as you’ll still want a straight Grad-ND. The straight is more flexible. I find the reverse useful only right at sunrise/set when a narrow slice in the middle of the scene is the brightest. But – when you need it, you really need it.
- I find the reverse much harder to use effectively. It’s hard not to show an unnatural darkening near that critical narrow middle slice of the image. Alignment of the filter with the scene’s bright slice is critical (and for me, not that easy).
- Here’s a with/without reverse image. This is the type of scene where the reverse excels and the straight Grad-ND shows its weaknesses (recall that the darkest part of the straight is at the top and it gets lighter as it moves toward the center. That’s not ideal for this situation where the scene’s brightest part is near the center – not the top.)