Joe and Mary Ann McDonald's

Wildlife Photography

December 2004-January 2005

Question of the Month

Can You Match the HISTOGRAMS?

Exposures should be fool-proof with digital photography, as photographers can rely both on the analog display of their exposure meter and the LCD view of the image's histogram. For the record, Mary and I use spot-metering and manual mode to make our exposures. Usually, we do not rely upon the histogram to check our exposures, although on occasion, to make sure we're not clipping highlights, we'll check. In the field we've observed too many photographers wasting too much time checking their histograms after every shot when, indeed, if the exposure was done correctly the histogram should be fine. Surprisingly, at our Digital Complete Nature Photo Course, the primary concern of most photographers is still exposure -- getting it right without having to resort to the histogram.

Make no mistake, the histogram display is a great thing, but it should not be used as a crutch. If your exposures are accurate your histogram display should be fine, and you really shouldn't need to check it. However, in areas of high contrast, or with questionable exposures, the histogram is invaluable. Further, the histogram is a better representation of your image than is the actual LCD image, since the display may be darker or lighter than the 'real' image, depending upon the brightness of the screen. Also, the histogram may be easier to see, and easier to interpret, in bright light when an actual image display might be almost invisible. Both displays -- image or histogram -- are based upon in-camera processing, and essentially match a jpeg-style image. RAW images and their histograms are converted in-camera and do not necessarily reflect the full, broader range of the actual RAW data. That's a good thing, as you'll probably have more range in your RAW histogram than the camera's LCD indicates.

At any rate, there is no perfect histogram, and each image has its own unique graph. Some histograms can be 'bad', in that the resulting image may be a lousy exposure, but that's a reflection of the image, not of the histogram itself. The following histograms are all of technically good images, yet the histograms differ greatly. Can you match them?

All of the images were shot on the second safari of our Kenya Photo Safari in late November-early December 2004. The wildlife images were shot with a 1D Mark II, the scenics with a 1Ds. The portfolio is equally represented by Mary and I -- three shots each. For more images from the trip, see our Kenya Trip Report or the Kenya Safari Participants' Portfolio.

Challenged? These were some interesting histograms! In every case the RAW exposures were fine, although I'd do a bit of exposure 'tweaking' on the falcon, and a Curves RAW adjustment with the bright sun to bring it down to a white a bit lower than 255. Below is an analysis of each:

The leopard silhouette is peaked at two levels -- the slightly brighter than middle tone sky and the silhouettte. Using Levels, we could increase the contrast even further. You can see the difference in contrast.The histogram would then be spiked on both ends, reflecting clipping on both ends:

The falcon histogram is shifted way to the right, and again, in a RAW conversion, the exposure could be shifted to slightly underexpose this original, uncorrected RAW image.

 

 

 

I was a bit surprised at this histogram, because I actually expected the black to be clipped. As you can see, it is not. To increase the contrast, in a finished image I would probably adjust the black slider in Levels to come just a bit closer to the black data, and probably do the same with the white slider-- spreading out the contrast a bit more.

 

 

This was an interesting one, because the in-camera histogram was an even more narrow, spiked graph --- essentially it looked like one bar of a bar graph, with all the values in that one area. In Photoshop a broader set of values are shown -- a more accurate treatment, really, but seeing the original in-camera histogram clearly showed me how the camera's histogram can be a bit misleading. It will be accurate enough to determine an exposure, but it may not reflect the full range of values. Question is, does that even matter?

 

This should have been the easiest of the images to match. A broad range of values without any clipping on either end. This is an unadjusted jpeg straight from a no-frills RAW conversion. Everyone should have guessed this one correctly.

 

 

This histogram is spiked at both ends. It should be obvious on the white end -- the sun is burned out, but the foreground black is clipped as well. That's OK -- at the black end, and a Curves adjustment on the light end, for the sun, would reduce the too-bright look to the sun. Adding a hint of color to the sun in Photoshop would also enhance this image.

 

Don't worry if you didn't get all of these histograms correct. My point is to simply illustrate that there is no perfect histogram, that you may get clipping at one, or both ends in a 'good' exposure, and that a given histogram might be 'spikey' at one end, two ends, or in several spots.

We explore the mystery of histograms, and the importance of spot-metering, manual mode exposure, in our Digital Complete Nature Photo Courses.

Previous Questions of the Month

KEY:

 Exposure

 DIGITAL

 Camera Techniques
 Flash-Remotes

 In the Field
 NANPA

How can you capture a sharp image and angel hair on a windy day?

What is the best Car Window Mount?

 How would you meter these images?

 Why should you know Manual Mode? 

  The Sunny 16 rule -- is it worth knowing today?

  How do you shoot silhouettes?

 How would you meter these challenging images?

 Who should go Digital,
and when?

 What do we really think about digital photography?

 What do we think of the Canon D30 digital camera?

 How long will film be around?

 Is the Mark II the ultimate wildlife digital camera?
 How can you reduce contrast and the effect of wind for flower and macro photography?

 What is the best season to do a photo safari in East Africa?

 What is our initial Digital Workflow?

 What is our Digital Workflow in the Lab?

 Is Shooting in the RAW format worthwhile?

 Is an L-Shaped Camera Bracket worth the Money?
You bet it is!

 Using Zoom lenses with tele-converters and extension tubes -- can you use both together?

 What the heck is the Scheimpflug Law?

  Reciprocity Failure

 What is the Best Composition?

 Are Image Stabilization Lenses Worth the Money?

 Hyperfocal Distance

  How do you determine distances?

 Should you have a depth of field Preview button on your camera?

 Flash and Tele-flash Techniques

 What is the most versatile remote release camera firing system?

 What the heck is a Plamp?

 What is the best flash for closeup and
macro photography?

 How do you shoot high-speed action images?
 How did I photograph that flying wasp?

 What is the Fotronix's
Flash System?

 What Film Lab do we use, and why?

 Is Digital Manipulation - a benign alternative to interacting in the natural world?

What is the Big Lie?
Tfhe truth about Kenya's Tourism--it is SAFE!

 How can you attract insectivorous birds to your feeding stations and bait sites?

 How do you make things happen in wildlife photography?
 What is our Favorite bird-shooting location?  What are our Five Favorite Shooting Locales?  Which binoculars do we just love to use?

How Easy is Whale Photography?

 What is the best
Game Caller?

  How do we carry our film when traveling?
 Is NANPA for you?  What is NANPA and how will it benefit me?

 Is it time for a summer NANPA Summit?

Contact us by e-mail: hoothollow@acsworld.com