Builder/Architect Magazine :: Builder Architect Edition :: Ba Columns

Be Consistent from Job to Job

In past columns I have given tips on tools and techniques that are useful in making your construction photos as good as they can be. In the end, however, a construction photo is only useful if you or someone else can find it when they need it. Consistency in what pictures you take, how they are organized and how they are archived is key to easy access in the future.

If both John and Samantha take pictures of your projects, there will come a time when Samantha needs to find a picture that John has taken. If their images are stored in different computers using different file-naming conventions, it could take a long time to search and find the image of interest. If it takes too long, Samantha will probably do the job without the benefit of pictures, adding time and additional risk to the project.

Having a consistent process for taking, organizing and archiving construction photos will make those photos more useful to your organization. How are your projects stored? Do you refer to projects by their street ad- dress or by the client's name? Do you have a central server where you store data and images for all projects, or does each project manager keep their own files on their own computer? It pays to set standards for image management and then make sure everyone in your organization understands them.

It makes sense for a project manager or construction supervisor to have images of any projects they are working on, but they should also upload those images to a central location where other people in your organization can access them, if necessary. We deliver our images on the Web as well as on hard drives or CDs. We have had clients in the field call into the main office and ask what was behind a wall. In one case, a contractor responded to a homeowner who had just moved into their newly remodeled home. The homeowner noticed that a wall was very hot and was concerned there might by a problem in the wall. The contractor assessed the situation and then called the home office and asked them to look at the images of that wall before sheetrock. The stud bay in question had no wires or pipes or gas lines running through it. They ultimately concluded that a mirror on a discarded cabinet had reflected sunlight into the room and heated the wall.

Another contractor was meeting with clients in their home after a cabinetmaker had installed bookcases. The homeowners asked where they could tap the power wiring for an electrical connection at the back of the bookcase. The contractor didn't have images with him, and knew that there was no one in his office at that hour. He was able to use the homeowner's computer to log into our website and find the images he needed. Knowing how and where to find the image you need is key to enhancing the value of images to your organization.

Consistency from job to job will ensure that 10 years from now you will still be able to find images from the projects you are doing today. Set up a standard naming convention for the file directories used to store your images. Make sure that you and everyone else in your organization knows the conventions and abides by them. Designate a central file storage location where all images from all projects are stored. Archive past projects from that central location on a regular basis. If you archive to CDs or DVDs, keep those discs in a secure location or in two geographically separate locations to reduce risk of losing the archives to fire, flood or man-made disaster.

What I am suggesting may seem like a lot of work, but it can be as simple as finding the best practice in your organization and adopting that as your standard. A little bit of organization and forethought now can save you much pain in years to come. I know this from experience. We have evolved the file organization that we use to store our construction images. When I go back to access images from early projects, I have to think long and hard where to find the images I need. I kick myself every time that happens. Save yourself from that abuse. Be consistent.

August 2006 Builder Architect Edition Issue

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Download Your Images Daily

By Ken VanBree

Digital cameras are a great way to document many aspects of your construction projects. When compared to digital images, film-based images are more expensive and much more of a hassle to develop and print. But film rolls do have one advantage over digital memory cards. When a film roll has been exposed, you know it. You can't accidentally erase it and put it back in the camera.

By contrast, the flash card memory used in digital cameras is much more flexible than film rolls, but that flexibility can get you in trouble. You can accidentally erase one picture on the card or its entire contents. If you are busy shooting pictures on your construction site and you fill up the memory in your camera, you have several options. If you have another card with free space, you can put it into your camera and continue shooting. Or, you can erase selected images from any card and use the space you liberate to store additional pictures. The danger is that you may loose a shot that you really wanted.

There is nothing worse than inserting a memory card into your camera only to find that it has pictures of the kids that you forgot to download. You can choose to sacrifice those great pictures of your daughter scoring the winning run at her softball game last night, or miss the picture of a construction detail that may be useful in the future. Most people would choose the picture of their daughter.

If your camera says you have 10 images left, and you know you need to take 15 or 20, then you may be able to reduce the resolution of the remaining images in order to fit more pictures in the remaining space. Most point- and-shoot cameras allow you to set both the image size (number of pixels) and the level of JPEG compression that is applied to each image. Decreasing the image size or quality will increase the number of images you can store. For example, a 256 megabyte CompactFlash card on my Canon G3 holds 124 images in the superfine (highest quality JPEG compression) mode, 223 images in the fine mode and 444 images in the "normal" mode. But before you decide to sacrifice quality for quantity, be sure to test the various JPEG compression levels on the kinds of images you need to take. Low levels of image detail can make your pictures useless for some tasks. Be sure to choose an image setting that captures all the detail you need.

I speak from firsthand experience on this issue. When we were building our house several years ago, flash memory cards were quite expensive, so I only owned one. When I went in to shoot images before sheetrock was in- stalled, I knew that I needed more space than I had available. I could have filled up my card with images of part of the house, then gone home to download the card to my computer and come back to take more images. Since I was short on time, I chose instead to reduce the resolution of the images that I took (i.e., shoot images with fewer pixels), in order to fit more images in the space that I had. As a result, the images I do have of the wiring, framing and pipes are grainy at best, and don't even show fine details such as the wires that connect to the alarm system sensors. If I had it to do over again, I would have taken the extra time or bought an extra card.

Today's digital cameras with sensors that can capture 6, 8 or more megapixels per image can fill up a memory card quickly. The best way to ensure that you will have plenty of space in your camera is to download images the day that you take them. After you have downloaded the images, erase the card. That way you should never have to sacrifice that image of your daughter in order to get the pictures you need for your business.

July 2006 Builder Architect Edition Issue

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Finding Leaks Before They Leak

By Ken VanBree

In my last column, I introduced infrared imaging and showed how it could be used to check for water leaks. Thermography can also be used to find latent defects that will turn into future water leaks.

A certain class of building defects continues to plague the construction industry despite a variety of defensive techniques put in place to prevent them. These defects occur when a nail or screw comes into contact with a copper water pipe and the problem isn't immediately detected. Galvanic action between the steel fastener and the copper pipe or oxidation of the fastener will eventually lead to a hole in the pipe; however, it may take months or years for the leak to develop.

Thermal imaging can be used to detect this class of latent defect before it becomes an expensive water leak or mold remediation. The technique relies on the high conductance of the metal screws or nails. By running hot water through the pipes, a metal fastener that is in contact with a water line will heat up more quickly than the surrounding wall board, providing a hot spot easily observable with an infrared camera.

The nearby picture shows four views of a test wall that illustrate the technique. The upper left image shows the wall after wall board has been installed but before tape and mud has been applied. The wall board screws are clearly visible. In the image on the upper right a thermal image of the wall has been superimposed on the first image. The thermal overlay shows that three of the screws are much hotter than the surrounding wall board. The reason is because these screws are in contact with a water pipe in the wall that is carrying hot water.

The image in the lower left shows the back side of the wall where a screw is resting on the water pipe without penetrating it. In the image on the lower right the additional screw is clearly visible in the thermal image. This last image also shows that the wall board screws are still visible in the thermal overlay despite the fact that they are covered with taping mud. The mud was still wet in this image, which accounts for the dark (cooler) streak on the right side of the thermal overlay.

The test wall in these images was built to develop the techniques for locating latent construction defects. Additional details on the technique and its application to real world situations are given in a paper entitled "Using Thermography to find a class of latent construction defects" given at InfraMation 2005. A copy of the paper can be downloaded from our website at: www.imagingperspective.com.

June 2006 Builder Architect Edition Issue

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Infrared Thermography

By Ken VanBree

This month's issue is devoted to indoor air quality. You may wonder what today's modern imaging technology has to do with air quality. Read on and I will introduce you to the wonders of infrared thermography.

As you know, cameras record images using visible light. Early photographers took pictures using black and white film that recorded differences in the intensity of light. The resulting black and white prints were often "colorized" to make them more familiar to the human eye that can distinguish an entire spectrum of colors. Colors at the upper (shorter wavelength) end of the spectrum appear blue or violet to our eye. Colors at the lower (longer wavelength) end of the spectrum appear red.

Visible light is only a small portion of the electromagnetic spectrum. Above the visible spectrum are ultraviolet rays, the ones that give you a sunburn, and X-rays that are used for medical diagnosis. Below the visible spectrum are infrared rays, micro waves and radio waves that carry radio and TV signals. Infrared rays are given off by warm bodies. They radiate heat. You have probably experienced them if you sat at an outdoor restaurant that used heat lamps to keep their customers warm.

Although the human eye can't "see" infrared wavelengths, there are sensors called bolometers that can measure the strength of the infrared waves much the way that digital cameras record the strength of the visible light. The resulting infrared images give information about an object's temperature much the way a photograph shows us an object's color.

The above images show two views of the same wall taken at the same time. The image on the left is a photo taken with a conventional digital camera. It shows a portion of a wall where the baseboard has been removed. Other than the missing baseboard and carpet the wall looks perfectly normal.

The image on the right has a thermal image superimposed over part of the wall. The thermal image has been colorized with cool areas in blue, and warmer areas in warmer colors. In this image, you can see that the lower portion of the wall is significantly cooler than the upper portion of the wall. This is because there was a flood in the room on the other side of the wall that resulted in significant water damage. The lower foot of the wall is still wet from the flooding and evaporation of the water, which cools the wall. It could remain wet for days or weeks if it is not actively dried.

There are several forms of mold that feed on the paper that forms the outer skin of wall board. If this wall stays wet for more than 48 hours, there is a good chance that mold will grow inside the wall. Periodic wetting and drying caused by an intermittent water leak could grow a lot of mold inside a wall with- out ever being visible outside the wall. Mold spores can become airborne and adversely effect indoor air quality.

Thermal images can improve air quality be- cause they are useful in detecting water leaks that aren't visible to the naked eye. Early leak detection can help stop mold growth before it becomes a problem.

May 2006 Builder Architect Edition Issue

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Archive for the Long Term

By Ken VanBree

I have a photograph of my great-grandfather that was taken more than 100 years ago. It is printed on tin. Tintypes became popular during the American Civil War because they were more durable and cheaper then other photographic formats available at the time. Their popularity faded when less expensive paper photographs became widely available.

I found the tintype in the attic of my mother's home in the Midwest. It had been stored there for 50 years, subject to dry, freezing winters and hot, humid summers. Despite the environmental abuse, the image of my grandfather was still easily recognizable.

I recently scanned in a number of family photos and put them on a DVD that I sent to my relatives. If someone finds that DVD in an attic 100 years from now, I wonder if they will recognize it as a repository of family photos, let alone be able to extract and view the photo of my great-grandfather.

The age of digital photography has made it easy to take a lot of pictures. This bounty of images has created another problem - how to store those images for the long term?

Fortunately the National Institute of Science and Technology (NIST) has addressed this problem in their report entitled, "Care and Handling of CDs and DVDs: A Guide for Librarians and Archivists." This 50-page report is a must-read for anyone seriously interested in archiving digital files for the long term. It includes a quick reference guide with practical tips for ensuring your CDs and DVDs last as long as possible.

To get the longest life from your archive disks, you should start with the highest quality disks available. Recordable disks (CD-R, DVD-R) with a gold reflective layer are recommended. Taiyo Yuden and Mitsui hold the original patents on recordable media and are still the choice of archivists, but beware of imitations. Lifetimes of 70 to 100 years are quoted for data storage on high-quality disks. Unfortunately, even the best media can degrade quickly if it is not handled properly during and after recording.

Because the recording layer is near the top (label) side of a CD-R, it can be easily damaged during the labeling process. I learned this the hard way when I used a fine-tip pen to label a CD of holiday music. Within two years the disk was unusable, due to damaged data that caused the CD to skip whole sections of songs. Broad, felt- tipped pens with water-based solvents are the best pens to use for labeling. If you can smell the solvent in your felt-tipped pen, it is probably bad for use on CDs.

The dyes used in recordable disks are sensitive to light. These dyes will degrade if subjected to strong light for long periods of time. Do not leave your archival disk on the dashboard of your truck if you want to be able to read it in 20 years, let alone two years. The NIST recommends that archival CDs and DVDs be stored at temperatures between 39 degrees Fahrenheit and 68 degrees Fahrenheit, at a relative humidity between 20 percent and 50 percent. The lower end of the range of temperature and relative humidity is recommended for extended-term storage.

Other tips for handling archival disks are to store them upright (book style) in plastic cases especially made for CDs and DVDs. Never touch the recording surface of the disk, instead grasp the disk by the edges or the center hole. Remove disks from their cases just before you plan to use them, and return them to storage immediately after use. When cleaning dirt from the data side of a disk, use a CD/DVD-cleaning detergent, isopropyl alcohol or methanol. Clean by wiping from the center of the disk to the rim. Never clean a disk by wiping it in the direction of rotation.

Remember that construction photographs are only useful to you if you can access them when you need them.

Following a few simple precautions when archiving your digital photos can help ensure that you have images to use in remodeling and repair work for years to come.

February 2006 Builder Architect Edition Issue

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Organize Photos Early and Often

By Ken VanBree

Organizing digital construction photos is a challenge. Most people agree labeling and organizing photos is a good idea, but few people find the time to do it on a consistent basis. As I pointed out in a previous column, if you want to photograph every interior wall and ceiling of a 1,000-square- foot remodel, you need to take about 200 pictures with a digital camera. The most common way of organizing digital photos is to put them in a file folder labeled with the date they were taken. If you take 200 pictures on a single day and put them in a single folder, you will need to search a lot of images to find the one you are looking for. If you take the time to separate the pictures of each room into different folders (for example, folders named Office, Bedroom No. 4, Bath No. 4, etc.), you will make it much easier to find an image when you need it later.

A more natural way to organize construction images is to display them graphically along with their relation to the floor plan. A simple approach is to write the name of the digital photo (for example, CX4N0001. JPG) on a copy of the blueprint near where the photo was taken. This approach makes it easy to find the images you need, assuming that the blueprint and the photos don't get separated in the future.

The screen shot at left shows Imaging Perspective's version of the photo-on- blueprint approach to organizing images. Photographs are electronically keyed to the floor plan and available on the Web. When the user mouses over a room, the images of that room appear on the screen along with an indicator that shows where each image was taken. The screen shot shows two images of the south wall of bedroom No. 4 taken at different times. The larger image shows the wall before sheetrock was installed. The smaller image shows the same wall after sheetrock. The cursor in the smaller image points to a spot where an outlet was covered over by the sheetrockers.

Better organization of construction photos can help you work in new ways, like finding covered outlets from your office by viewing photos on the Web.

December 2005 Builder Architect Edition Issue

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Make Your Photos Self-Documenting

By Ken VanBree

In past columns I have written about the best kinds of pictures to take, and the best way to take them. But I have not said much about how many pictures you need to take to thoroughly document a home under construction. Ideally, you should take overlapping pictures of every interior wall so that you can find and fix any issue that may come up with wiring, plumbing, cracking or water intrusion in the future. This raises the question of how many pictures are required to cover every interior wall. The answer may be more than you think.

A typical digital camera zoomed out to its wide angle setting has a field of view equivalent to a 35 mm wide angle lens on a 35 mm film camera. If you stand eight feet from a wall and take a photograph with a 35 mm lens, your image will cover a wall area of about 4 x 8 feet, or roughly the area of a sheet of plywood or sheetrock. If you can only stand four feet from the wall or ceiling because the room is small, or because you don't feel like lying on the floor to photograph the ceiling, then your image only covers the area equivalent to 1/4 sheet of plywood. A simple rule of thumb is that to thoroughly cover all interior walls you need as many photographs as you need pieces of sheetrock. This results in about 20 pictures to cover the walls and ceilings of a 10 x 10 x 8 foot room, or 200 pictures per 1,000 square feet. This means that a 10,000-square-foot new home could require 2,000 photographs to document the studs round alone. With that many photographs to keep track of, it is easy to forget which photo belongs to which room. An example from our own home building experience illustrates the point.

When my wife and I built a new house several years ago, we installed a Lutron HomeWorks lighting control system. Every light switch in the house has a bundle of low-voltage wires attached. Our electrician had written cryptic numbers on the studs surrounding each light switch that indicated which low-voltage control wires were attached to that switch. I went around and took close-ups of every switch in our house before sheetrock was installed, so that I would be able to maintain and upgrade the system in the future. I have two images of three-gang switch boxes named P2450041.jpg and P2450042.jpg. The problem is that five years after building the house I have no idea which light switch belongs to which photograph. The pictures that I took during construction are essentially useless to me now.

In retrospect, I should have included some sort of markers in the light switch images in order to identify them later on. A simple solution would be to hold up a portion of the floor plan with a pointer indicating the switch location and photograph it along with the switch box. Not only is the photograph self-documenting, but also, the annotated floor plan can never get separated from the switch box image.

If you take pictures at multiple job sites every day, you can make the job site photos self-documenting by starting the photo sequence at each job site with an image that contains the street address of the site. Similarly, if you need to record details of several rooms in a house (for example, all electrical boxes), take an overall picture of the room before you record the details. If you need to take multiple pictures of a wall in order to document the wiring and piping before installing sheetrock, you can make your life much easier by consistently taking images from left to right then top to bottom. If you are taking detailed images of all walls in a room, start with an overall picture of the room that includes the starting wall, then do each wall in sequence in a clockwise direction. A little time thinking about how you will identify photos in the future can save you a lot of frustration five years from now.

November 2005 Builder Architect Edition Issue

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Cameras Should Have Three Legs

By Ken VanBree

If you have already bought a digital camera to document your construction progress, you may be looking for the next piece of equipment that you can buy to improve the quality of your pictures. I would like to put in a plug for an underused tool that you might already own, namely a tripod.

Digital cameras come in many weights and sizes, but they need a fair amount of light to record an image properly. The equivalent film speed on most digital cameras is around 50 ASA. This means that in bright sunlight you can properly expose an image at an aperture of f16 and a shutter speed of 1/50 sec.

Using a normal or wide-angle lens, a shutter speed of 1/50 sec is fast enough for most people to shoot hand-held without inducing motion blur. Some people have a steady enough hand that they can get acceptable images at lower shutter speeds, but a good rule of thumb for normal and wide angle lenses, is don't shoot hand-held at shutter speeds below 1/50 sec.

When using a zoom lens, this minimum acceptable shutter speed goes up roughly by the zoom factor. A Canon G3, for example, has a zoom ratio of four. This means that when the lens is zoomed out to its maximum telephoto setting, you will need to use a shutter speed four times faster (that is, 1/200 sec) in order to shoot hand-held without motion blur.

But the interior of homes under construction are seldom as brightly illuminated as outdoor scenes in sunlight. Inside lighting levels can be anywhere from 7 to 12 f-stops below the outdoor level. It may be a bright and sunny day outside, but the inside of an interior bathroom may be darker than a witch's lair illuminated by a single candle. In order to get an acceptable image, you'll need either additional lighting, or use a shutter speed longer than 1/50 sec, which means you'll need to use a tripod.

You may think you could increase the film speed to deal with low light situations, but the concept of film speed in digital cameras is a ruse, a case of digital trickery akin to digital zoom. Increasing the film speed on a digital camera actually reduces the amount of light that falls on the sensor. Digital cameras make up for the lack of light by post-processing the image to bring out detail that would otherwise be lost in the shadows. In a brightly lit scene, the results may be acceptable, but in a dark room you will lose detail.

Using your camera's flash is no panacea for dealing with low-light situations. The light from a flash falls off as the square of the flash-to-subject distance. Although objects four feet away from your flash may be properly exposed, objects that are 16 feet away will appear to have fallen into a black hole because they will receive 16 times (four f-stops) less light from the flash.

The lowly tripod is an underused tool in construction photography. It is the most reliable way to ensure that your images are sharp and properly exposed, even if you are photographing that lair by candlelight.

September 2005 Builder Architect Edition Issue

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Expose Your Shots Properly

By Ken VanBree

Automatic exposure compensation has been one of the most important advances in photography in the last 30 years. When thru-the-lens built-in light meters were first introduced, they freed the photographer from the need for a separate light meter to properly expose each photograph. The first systems simply showed a needle in the viewfinder that moved up and down as the aperture and shutter speed were varied. To get the correct exposure, the photographer manually adjusted the settings until the meter needle was centered. These simple needle- matching systems gave way to more and more complex automatic metering systems that analyzed the exposure in multiple zones, and compared the exposure in each zone to a standard set by analyzing thousands of professional photographs.

Although the automatic exposure systems on today's digital cameras are extremely capable, they suffer from a limitation left over from the days of shooting film. The sensors in modern digital cameras cannot accurately record images that have a wide dynamic range, that is, a wide range of light values. If a scene contains objects that are in bright sunlight and objects that are in dark shadows you have a choice of exposing for the highlights or exposing for the shadows. The camera's digital sensor will record one or the other, but not both. This is illustrated in the figure nearby. In the left most image, the exposure was set to capture the highlights of the outdoor patio. The result is that all detail in the couch is lost in the shadows. Similarly, the middle exposure brings out the detail of the fabric in the couch and the pattern on the pillow, but the outdoor scene is completely overexposed. The issue is that the camera's sensor does not have enough dynamic range to expose all parts of the image properly.

Film photographers have dealt with this issue for years. Ansel Adams developed the Zone System to deal with this problem when shooting black and white film. By carefully controlling the exposure of the film and the film development time, black and white photographers are able to record images in which the light value differs by 10 f-stops. But color slide film and digital cameras can record less dynamic range, about seven f-stops. This means that if you are photographing a scene with widely varying light values, such as the inside of a wall around a window looking out on a brightly lit outdoor scene, you will have to choose which parts of the scene you want properly exposed. You will need to over- expose the objects outside the window in order that the walls inside the house will be properly exposed.

One trick the pros use to deal with high dynamic range scenes, is to capture two or more images of the scene and compose them together in the physical or digital darkroom. The right most image shown here was generated by taking the outside highlights from the image on the left and the shadow detail from the center image and combining them in Photoshop. The resulting image shows good detail over a wide dynamic range of light values that could not be captured in a single photograph. It helps to use a tripod to steady the camera between shots when you are doing this type of high dynamic range (HDR) photograph.

Automatic exposure compensation is a wonderful thing, but it can easily be fooled by scenes that have a wide variation in light intensity. In such cases, you may need to switch to manual control and set the overall exposure for the photograph using the portion of the scene that is of most interest to you.

August 2005 Builder Architect Edition Issue

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Focus, Focus, Focus

By Ken VanBree

Most modern cameras today have auto-focus lenses that for the most part do an excellent job of providing well-focused images under standard lighting conditions. However, there are three main ways in which the auto-focus mechanism on modern cameras can be fooled: low light, low detail and objects at widely varying distances from the camera. To get the best results from your digital camera, it helps to know the limitations of auto-focusing in general and of quirks related to your particular camera.

When taking construction images, getting the image properly focused is second only to composition in determining the quality of the result. PhotoShop can do wonders to recover lost detail out of shadows and to correct the color balance of your image, but if the picture is out of focus, there is nothing you can do to improve the sharpness after the fact. If the image is just a bit blurry because the focus wasn't tack sharp, you will still be able to use the image for most purposes, but if it is severely out of focus, it is equivalent to not having an image at all.

The first situation that can fool most auto-focus mechanisms is low light. Most digital cameras can get acceptable results with shutter speeds up to two seconds, allowing the digital sensor to pull detail out of rooms that are almost too dark to walk around in without a flashlight. But although the camera may be capable of taking an excellent photograph in low light, the auto-focus mechanism may not work in those same conditions. One way around this problem is to bring in additional light, like a flash or a portable work light. That might allow the auto-focus mechanism on your camera to work properly, but can cause other problems with non-uniform lighting of the scene. Another method is to set the focus manually if your camera allows you to do so.

The second situation that can fool your auto-focus mechanism are subjects with little detail, such as new sheetrock walls. In this case you are shooting a uniform field of gray with only the screw-heads sprinkled throughout the scene. If your camera's auto-focus mechanism uses one or more small areas of the image to determine focus, it may have trouble focusing on the uniform gray area. You can help the camera by putting something with more detail, such as a tape measure, in the scene. But if that doesn't solve the problem, you may need to resort to manual focusing.

Even if there is plenty of light and plenty of detail, an auto-focus system can give poor results if there are objects at widely different distances within the scene, such as shooting framing before sheetrock. If the camera focuses on the nearest object in the scene, the farthest objects may be out of focus, or, if the camera focuses on the farthest object in the scene, the nearest objects may be fuzzy beyond recognition. To solve this problem you may again need to switch to manual focus and set the focus point to somewhere between the nearest and farthest, what photographers call the "hyper focal distance." The hyper focal distance will achieve maximum sharpness for all objects located between one-half the focal distance and infinity. For example, the hyper focal distance of a prosumer digital camera with a 24mm wide-angle lens set at f/8 is 11.8 feet. At these settings, all objects between 5.6 feet (11.8 divided by 2) and infinity should be acceptably sharp. This means that if you are standing in the middle of a room that is 12 feet square with 12-foot ceilings, you can set your camera at f/8, manually focus your lens at 11.2 feet and shoot in any direction, and your photos will be well focused.

The table below shows the hyper focal distance for various f-stop and lens combinations, where images should be acceptably sharp from one-half of the distance listed in the table to infinity. Notice that the use of wide-angle lenses at small apertures (i.e., large f-stop numbers like f/8 or f/11) produces the shortest hyper focal distances.

July 2005 Builder Architect Edition Issue

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Finding Leaks Before They Leak

By Ken VanBree

In my last column, I introduced infrared imaging and showed how it could be used to check for water leaks. Thermography can also be used to find latent defects that will turn into future water leaks.

Thermal imaging can be used to detect this class of latent defect before it becomes an ex- pensive water leak or mold remediation. The technique relies on the high conductance of the metal screws or nails. By running hot water through the pipes, a metal fastener that is in contact with a water line will heat up more quickly than the surrounding wall board, providing a hot spot easily observable with an infrared camera.

The nearby picture shows four views of a test wall that illustrate the technique. The upper left image shows the wall after wall board has been installed but be- fore tape and mud has been applied. The wall board screws are clearly visible. In the image on the upper right a thermal image of the wall has been superimposed on the first image. The thermal overlay shows that three of the screws are much hotter than the surrounding wall board. The reason is because these screws are in contact with a water pipe in the wall that is carrying hot water.

June 2005 Builder Architect Edition Issue

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It's Always the Glass

By Ken VanBree

Today's camera market is filled with an overabundance of choices of models that can be used as a tool by architects and builders. In this month's column, I will give some guidelines on what to look for when selecting a camera that will be used to take construction photos.

Let me start by saying a few words about film cameras versus digital cameras. If you are looking for a camera to shoot high- resolution photos for use in advertising brochures and large format posters, film cameras are still the best value. But if you are looking for a camera to document your construction projects, digital cameras offer excellent image quality, ease of use and low operating costs. If, like many builders, you take thousands of pictures a year, the savings in film and development costs will easily pay for a quality digital camera within a year or two.

Several years ago, a panel of experts in photography was organized by the Tech Museum of Innovation in San Jose. The panel was headed up by a Silicon Valley venture capitalist who asked each panel member what they would look for when purchasing a digital camera. The recommendations from most panelists revolved around size, weight, ease of use and resolution of the digital sensor. But the advice from one panelist, Karen Mullarkey, has always stuck with me. Karen Mullarkey began her career as the producer for Life Magazine's coverage of the Apollo Space Program. She has directed photography departments at Rolling Stone Magazine, Sports Illustrated and Newsweek, and was the first woman to head the Photography Department at a major news magazine. She has a lifetime of experience selecting images from the best photographers in the world, taken with the best camera equipment that money could buy. When the panel's moderator asked Karen what was important to look for in a digital camera, her answer was short and to the point. She said simply, "It's always the glass."

So the first thing to consider when looking for a great digital camera is the quality of the lens. Leica lenses are legendary among photographers. Nikon, Canon, Carl Zeiss and Olympus make excellent lenses as well. An excellent lens will not guarantee that your pictures will be sharp and clear, but a poor lens can defeat all of your best attempts to clearly document your construction progress.

After you have chosen a good lens, the next question is how much resolution you need in the sensor that provides the digital equivalent of film. A pixel (a contraction of Picture Element) represents the finest detail that a digital camera can resolve. Cameras are rated by Megapixel, which is the product of the number of pixels across one side of an image multiplied by the number of pixels down the other. The more pixels your camera can record, the higher its resolution. A 3 Megapixel camera should be adequate for most of the photos that you will need to document your construction projects.

There are three types of digital cameras on the market today. At the low end of the range are point-and-shoot cameras, including the Canon Powershot series or the Nikon Coolpix series. These cameras are small and convenient to carry, and are available in a wide range of resolutions, but they are limited by the fact that most do not have interchangeable lenses. They also aren't available with lenses wider than about 35-mm. This can be a problem when photographing in tight spaces. At the top of the range are professional cameras, such as the Canon 1Ds and the Kodak DCS Pro. These are Single Lens Reflex (SLR) cameras with interchangeable lenses. They have all the features needed by professional photographers, but their $5,000 base price put them out of range for most consumers. Sitting between the point-and-shoot cameras and the professional cameras are prosumer models like the Nikon D70 and the Canon Digital Rebel, which list for just under $1000. They have most of the features of the professional models and allow you to use the same interchangeable lenses preferred by professional photographers.

One drawback to prosumer cameras is that they don't have full frame sensors. By that I mean that the area of the sensor (the digital "film" if you will) is smaller than the standard 24 x 36 millimeter frame that has been a standard for film cameras for years. The smaller sensor size means that only the center of what the lens sees is recorded digitally. This effectively increases the focal length of the lens. Nikon has standardized on a conversion factor of 1.5 for its digital SLRs. This means that a standard 50-mm lens will shoot like a 75-mm medium telephoto lens. This is an issue for construction photography because you often need to shoot in small spaces like bathrooms. A film camera using a 24-mm lens can capture an eight-foot wall from floor to ceiling from about five-and- one-half-feet away. If your digital camera has a 1.5x focal length multiplier, that 24-mm lens becomes a 36-mm lens that would need to be eight feet away to shoot the same wall. That is difficult to do in a bathroom that is only five feet wide. To solve this problem, the prosumer cameras often come with wide-angle zoom lenses. The Canon Digital Rebel is often bundled with a Canon 18 - 55- mm zoom lens, which is equivalent to a 28 - 85-mm zoom on a standard SLR. Although zoom lenses are popular, I've found that fixed focal length lenses are often lighter and give you more light-gathering power (that is, larger apertures). This is important when you are taking pictures in the low light conditions that often occur inside of buildings under construction.

April 2005 Builder Architect Edition Issue

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Viewing the Invisible

By Ken VanBree

The emergence of good quality inexpensive digital cameras in the last few years has added a new tool to the tool chest of builders and architects. Cameras can be used in construction to save time and improve quality by providing the power to view the invisible. A few examples will illustrate my point.

One silicon valley executive I know was extremely impressed with his architect, because the architect carried a digital camera everywhere he went, and used it to save his client time. The demands of a job with a global manufacturing company kept the executive constantly on the move. He had limited time, during which he and his wife could meet with their architect to discuss the remodel of their San Francisco home. Many decisions needed to be made during their meetings in order to move the project forward. The architect selected light fixtures, faucets, vanities and other architectural details from suppliers he had visited around the world. He took photos of these elements and showed them to his client on his 17-inch Apple PowerBook. He would superimpose a photo of a wall sconce on a picture (or a CAD rendering) of a wall and say, "I think this lamp would go well here, what do you think?" If the answer was yes, the sconce was added to the project, and the composite photo could be used later to ensure that the right sconce was installed in the right place by the lighting installer. The architect was using photographs to show his client something that did not yet exist. In essence, he was allowing his client to view the invisible future wall sconce.

Contractors often use photographs to do the same thing. A contractor I work with was visiting a client who had moved into their remodeled home a month earlier. The homeowner had installed built-in book- cases, and was looking for an electrical wire he could tap in order to power a light in the bookcase. Since the contractor had all of his construction images organized on the Web, he was able to use the homeowner's computer to access the images and show them exactly where the electrical power behind the bookcase was located. There was no need to cut into a finished wall (let alone the back of the built-in bookcase) looking for a wire that may or may not be there. Once again, photographs were used to view the invisible. The fact that his images were readily available on the Web, meant that he could satisfy the homeowner's request on the spot. No need to search for the photo when he got back to the office. No need to make a return trip to the client with photo in hand to answer the question about wiring. He saved himself time by accessing his images on the Web. He saved his client money by knowing where to open the wall in order to tap into the power line.

Architects and contractors aren't the only ones who benefit from easily accessible construction photos, homeowners can benefit as well. A year or so ago, I was installing a cutting-board rack on a wall in my kitchen. I was concerned what I might hit when I drilled into a wall that I knew contained water-pipes, drain-pipes and electrical wires. For esthetic reasons, the rack needed to be centered between two cabinets. I got out my stud finder to locate the studs, and sure enough, they were not anywhere near where the mounting screws for the rack needed to be. I knew that I needed molly bolts to ensure that the rack was properly mounted on the wall. I marked the location for molly bolts and drilled a small pilot hole. The drill penetrated the sheet rock and hit something solid. I was faced with three choices: I could continue installing the molly bolt and hope that I wasn't drilling into a water pipe or an electrical wire. I could look for the construction pictures that I knew I had taken to see what I had hit. Or I could abandon the project entirely. Fortunately, I knew exactly where the construction images I had taken many years ago were located. Within minutes I had the answer. The wall that I was drilling into was a shear wall. The drill had hit the plywood of the shear wall and not a water pipe. The area I was drilling into was free of pipes and wires, so I abandoned my plan to use molly bolts, and simply attached the rack to the shear wall using wood screws. Once again my photographs allowed me to view something that had been invisible not only to me, but to my stud finder.

Three properties are essential for a construction photo to be useful. It needs to be in focus and well-exposed, it must contain the subject of interest, and you must know where to find it. The first property, focus and exposure, is handled reasonably well by today's modern cameras. The other properties, composition and organization are dependent on the photographer. You can only use photographs to tell you what is behind a wall if someone took a picture of that particular wall before the sheet rock was installed and you know where to find that picture. Some contractors tell me that they can tear out a lot of sheet rock for what it would cost them to take and organize pictures of their project. That may be true during early stages of construction, when all they need to tear out is sheet rock. After adding tile, molding, paint, wallpaper or built-in cabinetry, the cost of opening holes in the walls goes up considerably. After the homeowner occupies the project, the cost of bringing in a crew to open walls, locate and fix wires or pipes, patch the walls, match the finishes and clean up after every stage can be substantial.

In future articles, I will give tips on the best techniques and equipment to use for construction images. For now, I will list 10 simple rules for taking and organizing construction photos:
1. Start with a great camera.
2. Decide what pictures you need to take.
3. Focus, focus, focus.
4. Expose your pictures properly.
5. Use a tripod instead of a flash.
6. Include markers and reference images to set the context.
7. Download and back up your images daily.
8. Organize pictures early and often.
9. Archive images for the long-term.
10. Be consistent from job to job.

March 2005 Builder Architect Edition Issue