Posted by: In: Books, Guidebooks 06 Mar 2013 1 comment Tags: , , ,

I spend a lot of time reading. At times, I come across a book that is really well written, as well as informative and useful.

Bryan Peterson’s book – Understanding Exposure, (3rd Edition) is a testament to this ethos, and is simply genius in its descriptive ability to draw the reader in.

As a photographer of a few years now, I have been to evening classes, and spent a lot of time on photographic forums, picking up bits and pieces here and there, but nowhere have I found a book that so simply breaks down the photographic process as this. Even taking an A-Level didn’t educate me as well!

The author somehow takes the most simple of sentences and continues to draw the reader in. It’s almost as if you’re understanding it as you read it without actually knowing that you get it. It’s like a fine ale (if you’re a beer drinker) or good quality chocolate (if you’re a woman), or the Book Of Answers if you’re a photographer.Understanding Exposure at Amazon

I’ve been sat here a while now, thinking of ways to describe just how useful this book is, but sitting back and looking at realms of (now deleted) text, I wondered how useful that is to you, as a potential buyer.

I thought I knew it all, and to be honest, in my cluttered mind, I did know a fair bit. But this book sets everything into a logical order, and explains it with such childlike simplicity and clarity, that I found myself re-learning everything again, only this time, in the proper order. And to an engineer like myself, I was being told why I was doing it that way. Sometimes, once you grasp the concept of “why”, the rest all falls into place. A bit like the magic of hyperfocal distance…

Photography is all about exposure. The amount of light hitting your sensor/film. That’s it. It’s about obtaining that balance. It’s about how to manage/juggle shutter speed, ISO and Aperture to get the right exposure for you. And the emphasis is always on the last two words there. For You. And that’s another great thing about this book. It isn’t about telling you what to do to make a great photograph. This is about equipping you with basic fundamentals to allow you to make a great photograph. There is a huge difference.

As an example, I always used spot metering to evaluate the exposure in a scene. I didn’t really know why, I just did. I pointed the spot at my subject, took a reading, recomposed, then took the shot. That’s fine in most circumstances, but there are forms of photography where it’s not so clear. A sunset for example, or a long range shot of the moon. Within these pages, the explanation is so clear that it’s obvious where you need to meter from in order to take such a shot.

I read this on holiday. And spent a lot of time shaking my head in wonderment as things were explained to me that I really hadn’t bothered with before. But these things were explained with such simplicity, it was more a wonder of how I managed not to “get it” before.

If you have a few quid in your wallet, spend it on the shopping and order this on your card. No matter what level you’re at (professional photographers excluded!) you’ll find this book brilliant.

The book itself is a big glossy softback with some lovely images inside. It’s also got some bad ones too that illustrate how not to do it. The first few chapters are devoted to absolute basics and defining the “Exposure Triangle” of Aperture, Shutter Speed and ISO. These three ingredients are key to understanding different aspects of an image. Peterson tackles each of these three subjects in depth and explains what happens when you have high or low variations of the three options. By understanding what to expect with an Aperture of (for example) 2.8 or a low shutter speed of 1/20 second, or a high ISO of 1600, you as a photographer can elect to make these changes secure in the knowledge of what the effect will be on the final image.

The last major section of the book talks about light itself. This is an unusual chapter and really opens ones eyes to the way light falls on subjects, and how important it is to be able to recognise this. Different types of day and different types of weather can drastically affect how light falls on a subject. My 52 challenge this year is an exercise in learning about light. The same subjects all year round, but images taken in different lighting conditions and at different times of the day can dramatically effect the outcome. The most important aspect of this book is its ability to break down what might first appear quite complicated and make it seem simple. Even now, it still makes me smile when I read it.

Last of all, there is a section about special techniques. The use of filters, multiple exposures, HDR and flash are all discussed within the premise of the previous content. It’s a nice ending to a book that should be on every amateur photographer’s shelf. Well worth the investment!

Thanks for reading!

Ian

Posted by: In: In-Camera, Techniques 28 Jan 2011 0 comments Tags: , , ,

This is a follow up post to “What is HDR” and is the second in a trinity of posts about HDR. There are two phases to getting a decent image for HDR. Camera-side and Software-side. This post looks at the camera functions.

So – what do you need?

The answer to that, is that you need some form of manual control over your camera. You also need to know how to manually control your camera! Finally, you need a tripod, or a steady base for your camera (so that it doesn’t move)

As discussed in the last post, HDR is all about getting a balance between the lightest and darkest areas of your image. What I’m going to explain here, is how to take a range of images at different exposure settings so that you capture all the information. Beyond that (in the third post) I will detail how to blend these all together. But it’s important you know now that you’ll be blending these images in post-processing. That’s why the following is important:

– The camera must not move once you’ve started. The HDR software will cater for small movements in-camera, but you’ll be most likely shooting at low shutter speeds, and you need crisp, unshaky images to get the best results. Additionally, it’s probably wise to turn OFF auto focus and any image stabilisation. By reducing the light, the lens may want to hunt for focus giving you blurred images. When you’re set up with a tripod, find focus using auto-focus if you like, but then switch AF off.

– The Aperture must not change once you’ve started. Different apertures give different depths of field, so if you change the aperture through your shooting, some images will be out of focus beyond the focal point, and some will be sharp. When they are blended, it looks messy. That’s why Manual mode (M) or Shutter speed priority (Tv) if manual mode scares you, are the best options.

– The camera must be changed to shoot in RAW mode. JPEGS do work, but the effect and clarity is much better in RAW mode. There is simply more information in the RAW files for the post processing software to work with.

– The camera should be set to spot metering. You’re going to take light readings from different parts of the scene (the darkest and the brightest) and averaged meter readings will mess everything up. Set to spot metering and the middle 3% of the sensor is where the light will be measured.

So let’s walk through this with an example. My living room is a great place to start, as it has content in shade, and content in bright light. Just snapping a shot of the sofa shows the problem. When we expose for the sofa, the light coming through from the room beyond is totally white. We can’t see any detail.

Shows how a scene with multiple=

So what’s the solution?

Here’s where you need to know how to understand your camera. Looking at the display, when I point the camera at the sofa (the middle point of the viewfinder – spot metering meters this point), it shows a correct exposure at 1/10 sec, f5.6, ISO 500. However, when I point the camera at the bright areas, it shows 1/125 sec (f5.6, ISO 500 unchanged remember!)

Exposing for the highlights to get the top reading for HDR photography

So now we know that to capture all the detail in the image, we need to shoot exposures between 1/10sec and 1/125 sec.

Most modern DSLRs shoot in anywhere from 1/3 stop increments to 1 stop. I generally set my camera to shoot in 1/3 stop increments to get the best exposure possible.

So, in 1/3 stop increments, I need to shoot the images at: 1/10, 1/13, 1/15, 1/20, 1/25, 1/30, 1/40, 1/50, 1/60, 1/80, 1/100, 1/125.

“Twelve shots for a sofa?” I hear you cry. Yes. In the above instance, I wouldn’t take twelve, but then I don’t see a lot of artistic merit in a sofa… Outside, with a nice landscape, those twelve shots would merge into a lovely looking HDR.

In all seriousness, taking this number of shots isn’t a big deal. If you have shutter speed set to one of the wheels on the camera, it’s just a case of shoot, rotate wheel one click, shoot, rotate wheel, etc etc.

Misconceptions about HDR: i.e. “Why does my HDR look bad?”

“Five Exposures is best”

Some people will tell you that 3, 5 or 7 exposures are best for HDR, but that must be taken as a guide. If you want the best image possible, you need to take the number of photos equal to the number of stops (or fraction of stops) between the lightest and darkest area. In the above example, that’s 12 exposures. If we went in full stops rather than thirds, it would be 1/125, 1/60, 1/30, 1/15, 1/8 (five exposures)

“Auto-bracketing works fine”

Yep. It does. But the quality of the HDR can be a bit hit and miss. Auto-bracketing basically takes one shot at the correct exposure, then more shots +/- one or two stops. This is fine if you meter for the “middle ground” and there are no more than 4 stops difference between the brightest and darkest areas. If you’re in a hurry, by all means use this method – I did for years, but I’m now a convert to using a tripod and taking two light readings, then  a sequence of shots from light to dark.

“Hand holding works”

Also true, but you’re asking the software to marry up images that will have moved, and the end result is an image that has ghosting around the edges of your lines. Even the brightest day (equating to fast shutter speeds) will need slow shutter speeds for the dark areas. Again – by slowing down with a tripod, you get perfectly aligned images, as well as having to pause to consider other artistic elements that make up a good image. Composition being the most important!

For the tl;dr Crowd

  • Use a tripod, turn off Image Stabilisation.
  • Stop and think about composition.
  • Make sure you’re shooting in RAW
  • Once you’ve focussed, turn off Auto focus.
  • Make sure the camera is set to Spot meter and then meter the brightest and darkest areas.
  • Take shot #1 at one end of the shutter speed scale (1/125 in the above example)
  • Step through the range, taking one shot at each stop (or fraction of, depending on how you set up your camera). The more images you take, the better the HDR result will be!

Next time: How to blend the images in HDR software. You could make your sofa look like this!!

A final example of an HDR image

Yeah – it looks terrible, but as I said above, I wasn’t going to take 12 exposures of the sofa! In this case, I took just four exposures to “see what would happen”. For the software tutorial, we will use a proper image.

Next… Using Photomatix to create the HDR image

-Sc