Photomatix 5 Beta

I've been using Photomatix Pro 4.2.7 for a while now. I like the program, and yet it has proven too easy to make the photo look surreal. Halos around objects has long been a criticism of some HDR software, and halos were sometimes created using the standard presets in Photomatix Pro 4.2.7.

Photomatix 5 beta is now available. During image sequence setup, there is now an option to tell the software whether the images were captured using a tripod or handheld. There are fewer built-in presets, but that could change with the official software release. The Fusion presets, for example, are missing, but there are still plenty of Exposure Fusion controls in the left hand tool bar. What is most striking is the speed of the new software: it is much faster than version 4.2.7. Purchasers of version 4.2.7 are entitled to the new version 5 at no additional cost.

A Lightroom plug-in is included with version 5 beta. This allows you to export images from Lightroom directly into Photomatrix. If you use Lightroom's lens correction and other development tools, this direct export could form the basis for an efficient workflow.

Not all multi-exposure scenes can be improved through HDR techniques. For example, the Sherando Lake at the Fall Equinox looks better without HDR processing. After merging with HDR, the water part of the image was degraded: the circular ripple was less distinct as were the tree reflections. These results are due to the image merging process and the changing patterns in the water -- no HDR software can avoid scene movement between exposures. On the other hand, South Lake at Sherando was processed with Photomatix. Since the water was fairly still, Photomatix enhanced the image through the merge (rocks underwater in the foreground are more distinct) and the tone mapping brought out the colors very nicely.

The image rendered below was processed using Photomatix 5 beta (available here). I used 3 images captured at -2, 0 and +2 EV from a tripod. All 3 images were corrected for lens aberration using DxO Optics Pro 8 before being loaded into Photomatix. I applied the Photoshop curve tool to the Photomatix result to adjust the desired exposure level.

Copyright 2013 Philip N. Wheeler. All Rights Reserved.

Philip Wheeler Photography

Factory

White Balance

Achieving good white balance is critical for capturing accurate colors. White balance is usually left on 'auto' or AWB (auto white balance) as the default in your DSLR and this can lead to an unusual color-cast being added to your images. Setting a custom white balance is not difficult and it will improve the quality of your photographs.

The camera's built-in light meter sets the auto white balance based on a neutral gray, called 18% gray. This is the shade of gray half way between pure white and pure black. Using AWB, your camera's meter will decide upon some part of your scene that is more-or-less white and set it as 18% gray. Sometimes it is very obvious in the final photograph that AWB was used. For many landscape photos you might not notice it, but if you photograph a subject in a white sandy or snowy scene, your "white" sand or snow will become gray! The photo of the peppers below was taken on auto white balance. The peppers were sitting on a curved white cardboard. But the card looks gray in the finished photo because of the camera's meter and the AWB software. In this still-life photo, it might be considered part of my vision for the photograph, but in practice it was because I was too lazy to set a custom white balance.

Fortunately, setting a custom white balance is easy. Before photographing your subject, but in the same light, photograph an 18% gray card such that it fills the frame of your camera. It does not need to be in focus. Follow the instructions in your camera's manual to use this image to set a custom white balance.

18% gray cards are available from Adorama, B&H Photo, and other camera suppliers. The cards are inexpensive and easily stashed in your camera bag for use in location shooting.

What if you forget to set the white balance? If you save your images in RAW format, you can adjust the white balance during post processing. Both Canon and Nikon provide free software that lets you do this.

It is important for you to set the white balance in order to achieve the best quality photographs. Otherwise there will sometimes be an odd color cast in your images.

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.

Philip Wheeler Photography

Peppers

ISO Sensitivity

In an earlier article I discussed the basics of digital camera sensor size. Diffraction is a wave phenomenon that limits what can be achieved in capturing images through digital photography. At this point, digital camera sensor technology is close to the limits imposed by diffraction. Higher quality can be achieved with larger sensor size, not with more megapixels (MP).

Your DSLR's ISO setting is one of the three main exposure controls, the other two being shutter speed and aperture. In a dimly lit scene, increasing the ISO sensitivity helps you to get a good exposure. But there are limits above which noise starts to become apparent in your images.

ISO sensitivities above 3200 will always introduce some noise into the image. This is explained by the physics of light diffraction. Simon Crisp writes, "Once you get up to 6,400 you should expect photos to resemble camera-phone shots."

 Below ISO 3200 the noise in the image depends to a great extent on the amount of light captured by the sensor. This is why a full-frame sensor will introduce less noise into an image than an APS-C, or cropped, sensor. In turn, the APS-C size sensor will introduce less noise than the tiny sensors found in point-and-shoot cameras and those used in cell phones. Cell phone camera sensors must be small so they can be used with small lenses. If the phone makers used APS-C or full-size sensors, their phones would be huge! So when you read about a high MP cell phone camera (41 MP is the highest I've seen), rest assured that your trusty 12+ MP DSLR can produce higher quality images.

Full-frame digital cameras are now at the point where they can outperform 35 mm slide film in terms of resolution and low light performance. In order to help take advantage of this, it is necessary to use faster shutter speeds and other techniques to reduce camera shake. A shutter speed of 1/60 sec. has been a rule of thumb for the slowest shutter speed to use when hand-holding the camera, but this will not produce the best quality images. A sturdy tripod combined with a remote shutter release or 2-second delay, mirror lock-up, lens vibration reduction, and other techniques are important tools in producing the highest quality images. Proper exposure, critical focus, a steady camera, and good image composition are all needed to make good photographs.

Ultimately, the intended use of your images could drive the image quality that you need to achieve. If your goal is to create Web sites, almost any digital point-and-shoot or DSLR will do. Producing reasonably large prints demands a higher quality image. I suggest that you should always strive for the highest image quality possible.

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.
Philip Wheeler Photography

Mountain Shed

Depth of Field

In earlier articles I mentioned depth of field, or DOF, and indicated that it is related to the f-number of a lens. That is, a lens with a smaller minimum f-number can produce an image with a more shallow depth of field than a lens with a higher minimum f-number. Since you want to achieve critical focus on your subject, you need to understand how DOF affects focus.

The depth of field defines the nearest and farthest points in the field of view that are reasonably in focus. When your lens is set to a higher f-number, the depth of field is increased and more of the image is in focus. This is usually what you want in landscape photography. When making a portrait or photographing a single flower, for example, a shallow depth of field can be used to emphasize the subject while most of the other elements in the scene are thrown out of focus. 

If your DOF is extremely shallow, you will find that only part of your subject can be in focus. For example, with a 50 mm lens capable of a maximum aperture of  f/1.2, the extremely narrow depth of field at f/1.2 will make focusing difficult. In model or portrait photography a good rule is to focus on the person's eyes. f/1.2 may not the best choice of aperture for most portrait photography.

In macro photography, you photograph small subjects such as insects. It is common to see that only one part of the subject is in focus. If the subject is stationary, you can take two or more shots at different f-numbers and combine them in a program such as Photoshop to produce an image in which the entire subject appears to be in focus. This differs from capturing images for High Dynamic Range (HDR) image processing: for HDR you vary the shutter speed, not the aperture. Very interesting effects might be achieved with a series of photos captured at varying f-numbers, combined with a series captured at varying shutter speeds. Needless to say, using a tripod would be essential.

Although very low f-number lenses have many uses, the cost for a wide aperture/low f-number lens can be very high. For example, the Nikkor AF-S 85mm f/1.8 lens sells for about US$500, while the Nikkor AF-S 85mm f/1.4 lens sells for over 3 times as much. Unless you have a very specific reason to need f/1.4 instead of f/1.8, it might be difficult to justify spending the extra US$1,000+.

An important thing to remember is that a narrow depth of field demands more attention to focus.

A good photograph has a clear subject, and its composition focuses attention on the subject while reducing distractions. Effectively using depth of field is an essential part of the process of drawing attention to the subject.

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.

Philip Wheeler Photography

Ice Plant

Exposure Basics: The f-number

My brief articles on exposure used an 'f-number' when discussing relative aperture and lens speed. The f-number is a very important notation when thinking about exposure in photography. As you may recall, an aperture with a smaller f-number admits more light over a given period of time than one with a larger f-number. Here are the most common full-stop f-numbers, called f stops:

                               f/1.4    f/2    f/2.8    f/4    f/5.6    f/8    f/11    f/16    f/22    f/32

Each of these represents a doubling, or halving, of light exposure from the adjacent number. It is worthwhile to memorize this short sequence of numbers. Here are a few practical examples. Each of these represents a change of one f stop:

        f/1.4 admits twice as much light as f/2
        f/11 admits twice as much light as f/16
        f/4 admits half as much light as f/2.8

f/2.8 admits four times as much light as f/5.6, because f/2.8 admits twice the light as f/4 and f/4 admits twice the light as f/5.6, and 2 times 2 equals 4, or an increase of two f stops. So you see, the f-number, or f stop, is a convenient system of notation in spite of its weird appearance. Stay with me now as this is important!

The concepts of aperture, shutter speed and ISO are combined for exposure as follows.

Consider a shutter speed of 1 second (shutter open for 1 second). It admits half as much light as a speed of 2 seconds. 1/120 second admits twice the light as 1/240 sec. So a halving or doubling of shutter speed equals a change of one f stop!

ISO follows a similar pattern: ISO 100 is half as light sensitive as ISO 200: 1 f stop decrease. ISO 400 is four times (2 X 100 = 200; 2 x 200 = 400) as sensitive as ISO 100, for a 2 f stop increase.

Aha! In spite of the non-linear appearance of the f-number sequence, we see that f-number (aperture), shutter speed and ISO are closely related through this doubling or halving of exposure.

Lets say you are considering a shot at ISO 100 at 1/60 sec. but you are concerned about hand-held camera shake. If you go from ISO 100 to ISO 200 and simultaneously increase the shutter speed from 1/60 to 1/120 second...presto! Your camera sensor's light sensitivity is doubled and your shutter-open time is halved, leaving your exposure essentially unchanged. And yet your camera shake is reduced (unless you move your camera about wildly, of course!)

Another example: You want to use ISO 100 to obtain a shot with the lowest sensor noise. At the same time, you want a fast shutter speed. An initial setting might be 1/500 second at f/11, but you could change that to 1/1000 second at f/8 and achieve the same exposure with a faster shutter speed.

It takes a while to get the hang of the relationship between f-number, shutter speed and ISO. Practice, and you will soon be tossing these numbers about like a pro!

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.
Philip Wheeler Photography

M is for Manual exposure...do it!

Photographic Exposure Basics

Photographic exposure is a complex subject. Many books, courses, and lectures have been created solely on this subject. I will briefly review my current understanding of basic photographic exposure in this article.

The process of reproducing a scene as a photographic image requires film, a digital sensor, or some other material that reacts to the light that is allowed it strike it during a fixed period of time. One can think of this as capturing that light with the camera. The key to good exposure is to capture just enough light to achieve the desired image.

Available light is the light that exists in the scene. This is normally dominated by sunlight outdoors during daylight hours. Indoors, it might be light coming through a window. At night, available light could be moonlight, starlight, a campfire, artificial light sources, etc. At a music concert it could be the stage lights. Camera flash attachments as well as studio lights are not considered part of the available light since they are introduced by the photographer.

Here are the major factors that affect how much light strikes your film or sensor.

Lens: A lens is said to be fast if it can allow more light through in a given period of time. Lens speed is specified by an f-number. The maximum aperture is specified as the minimum f-number that a lens can achieve. A lens rated at f/1.4 can allow more light to pass through than a lens rated at f/4, for example. Faster lens speed generally comes at a higher cost.

Aperture: This is the opening inside the lens through which light travels. A fast lens allows a larger opening, allowing more light to enter in a given period of time. You control the aperture size, from the maximum allowed by the lens to the smallest allowed by the aperture mechanism. Any lens set at a very small aperture, such as f/22, allows very little light to enter, regardless of how 'fast' the lens may be.

Shutter: The shutter speed controls how long the film or sensor is exposed to the light admitted through the lens at the selected aperture.

ISO: Film is rated according to its sensitivity by an ISO number. Lower f-numbers indicate less sensitivity. ISO 100 is a good choice when there is bright available light. Higher ISO ratings, such as ISO 1000, are used to designate film that more sensitive to light. Higher ISO is good for low light situations and when shutter speed is set very fast to freeze motion, for example. Digital sensors can have their ISO sensitivity varied through the camera's electronics and software, providing you with another tool to help control exposure. However, higher ISO settings can result in more noise, or graininess, in your images.

Since your control over the available light is limited, it is important to measure it in order to help you choose appropriate exposure settings. Almost all cameras have a built-in reflected light meter. This in-camera meter often has options such as spot metering, center-weighted averaging, etc. Regardless of those options, the in-camera meter measures the light that is reflected from the subject and enters the lens through its aperture. A standalone light meter, separate from the camera, has an incident light metering mode, which indicates the proper exposure settings given the light that is actually striking the subject. Incident metering is often more accurate than reflected light metering but it requires that you invest in a quality light meter and take the time to learn how to use it effectively.

Whether you use a reflected light meter reading, incident light reading, or both, correct interpretation of the reading(s) is essential to achieving your vision of the image that you wish to capture. Auto exposure bracketing (AEB) can help by providing several alternate exposures of the same image with very little extra effort. This is extremely valuable when your subject would be difficult if not impossible to re-photograph at a later time.

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.

Philip Wheeler Photography

Manual Exposure, Part 1

Ahh, putting your DSLR on Manual...its not scary once you know the fundamentals. But instead of launching into theory and lots of technical details, I'll dive into this quick and dirty Get Started guide. Your goal is to learn to set the camera's exposure controls manually and obtain a photo with a reasonably good exposure. You should be outdoors in the daytime, cloudy or not, and choose a reasonably stationary subject to photograph. For some of the settings discussed, you will need to refer to your camera's manual to learn how to vary the settings. It is well worth your trouble to learn this stuff!

First a couple of brief definitions:
Over-exposed   -- your photo looks too bright, washed out. Too much light has been collected.
Under-exposed -- your photo is too dark. Not enough light has been collected.
Depth of Field -- a shallow depth of field means objects far away from your subject are blurry. A greater depth of field means that more of the objects in the scene are in focus, from near to far.

OK here we go in 360 words or less!

1. Set your camera into Manual mode, usually designated M on a selection dial.
2. Select your ISO. I generally start at ISO 100 since it introduces the least amount of noise.
3. Select your aperture. This is referred to as an f stop, designated as f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, etc.  A lower numbered f/stop allows more light to reach your camera's sensor. The smaller the f number, the shallower your depth of field. For a landscape shot, select a higher number. For a flower close-up, select a lower number.
4. Look at the exposure meter built into your camera. It will form a reading indicating the exposure based on the available light, your ISO setting, your f stop setting, and your shutter speed. If it shows over-exposure, increase your shutter speed. If it shows under-exposure, decrease your shutter speed. Note that your shutter speed needs to be faster than 1/60 second to help reduce camera shake. Otherwise, use a tripod.
5. Frame your subject, focus with care, and take the shot.

If you can't get a reasonable shutter speed setting, such as when there is not enough light available for your chosen f stop, increase the ISO and try again. Note that going much above ISO 800 will start to introduce some noise into your photo. You can also vary the aperture: lower f stops allow more light to reach the sensor. Watch your LCD display after the shot to get an indication as to whether the exposure was good. Moving clouds cause the light to change rapidly, so be ready to modify your shutter speed as that happens.

This method is not to be confused with aperture priority. It is similar, but when you switch your camera into aperture priority you are not only giving it control of your shutter speed, but also your ISO setting. You need to maintain control over all three of the main settings for exposure: ISO, aperture, and shutter speed.

That's it! Quick and dirty. In future posts I'll explain the details behind each setting, and talk about photographing non-stationary subjects. But for now -- practice!

Copyright © 2013 Philip N. Wheeler. All Rights Reserved.
Philip Wheeler Photography