The guaiac-based fecal occult blood test (gFOBT) is a widely used screening tool for the early detection of colorectal cancer. This non-invasive test involves collecting small samples of stool and applying them to a test card that contains a chemical called guaiac. When guaiac comes into contact with blood, it produces a blue color, indicating the presence of blood in the stool. The main idea of the guaiac-based fecal occult blood test is to detect hidden blood in the stool, which can be a sign of colorectal cancer or other gastrointestinal conditions. The test is typically recommended for individuals who are at average risk for colorectal cancer and should be performed every one or two years, depending on the specific guidelines in place. It is important to note that a positive guaiac-based fecal occult blood test does not necessarily mean that a person has colorectal cancer.
First impressions, yes there is new material, the book is the same format as the last edition and it is definite a bit thicker. There is a lot of recycled material too (which is not going to really surprise anyone), the diagrams are going to look familiar but they've updated some of the examples.
During a career spanning over three decades, he has worked for such clients as America Online, US News, Time-Life Books, Life Magazine 27 covers , the National Science Foundation, and National Geographic. Steven Biver has over 20 years of experience as a commercial photographer specializing in portraits, still life, photomontage, and digital manipulation.
It is important to note that a positive guaiac-based fecal occult blood test does not necessarily mean that a person has colorectal cancer. There are several factors that can cause blood to be present in the stool, including hemorrhoids, ulcers, and certain medications. However, a positive test result should be followed up with further diagnostic tests, such as a colonoscopy, to determine the cause of the bleeding.
Book Review: Light – Science & Magic
Light – Science & Magic by Fil Hunter, Steven Biver and Paul Fuqua is probably the most important book on lighting that you will ever read. Moreover, if you only ever read one book on lighting, make it this one. This is, indeed, a rather bold statement. In fact, some readers who are new to shooting images may actually be puzzled by this praise once they read the actual book. The information there can be fully appreciated after you’ve fought a bit with real-world lighting problems.
Lighting is about the relationship between lights, subjects and camera (viewpoint). The third part of this triad is not immediately apparent to everyone. It is surprising (then again, maybe not) how many people “with experience” actually struggle when they face basic problems like removing an unwanted specular highlight in a multi-light setup. They then start switching lights off and on, or moving them around to localize the offending light. And that’s not even in the domain of hard things to do: lighting a shot with lots of glass or glossy surfaces in it can be an intimidating task if you don’t fully grasp how light works.
How does light work?
How many times have you seen this question asked? Then how many times have you seen “I have $1000 for a lighting kit. What lights should I buy?” or “How do you light this shot [insert-reference-link]?”? Yeah. Lots of people asking about lights, no one asking about light.
Light – Science & Magic (An Introduction to Photographic Lighting) actually attempts to answer this question. It is by no means a fully detailed work, and the approach may not be to everyone’s liking (it is quite heavily biased towards product photography). But it is the only book I’ve seen that attempts this. And that’s why I believe it is the first book on the subject of lighting that people should read. You can then move on to other books like Set Lighting Technician’s Handbook or Film Lighting, for example. These are also good books on their own, and will likely get reviews here.
Light – Science & Magic covers the basic photographic properties of light: brightness, contrast, color. Also, typical information like hard and soft, or small and large light, or applying the inverse square law. But where the book really shines is in the exploration of the interaction of light and subject, and light and camera. Transmission, absorption and, of course, reflection. I haven’t seen another book that can teach as much about reflection management.
Specular (direct) reflection, diffuse reflection, polarized reflection are all covered with an emphasis on the family of angles causing direct reflection. The book then goes on to show how this is relevant in revealing surface texture and subject shape, and for the purpose of separation and delineation. This is further detailed in two great chapters on lighting metal and glass. The first material is highly reflective, the second – both reflective and transparent. This is all essential knowledge about suppressing or exploiting specular reflection, and applicable to a myriad of subjects and situations.
Then there is one of the better overviews of portrait lighting, based on the functional properties of the lights involved. Followed by a very useful chapter on the connection of characteristic curves (transfer curves) and exposure, and how this connection relates to overexposure and underexposure. This is an often misunderstood (and sometimes underestimated) concept. Its significance is fundamental when purposefully exposing for a specific part of the transfer curve.
Most of the examples in the book are based on product photography lighting. But once you grasp the concepts, the rest is really a matter of scale. A popular saying has it that if you can light a human face, you can light everything. Well, after reading this book the obvious conclusion is: “If you can light a small glossy box, you can light everything”.
Light – Science & Magic won’t teach you about specific fixtures or light types (although, there is some info on the latter in the last chapter). Nor will it teach how to envision beautiful lighting. What it does is enabling you to realize your vision by knowing, controlling and finessing light.
This entry was posted by cpc on July 16, 2012 at 1:31 pm, and is filed under Book Reviews. Follow any responses to this post through RSS 2.0.You can leave a response or trackback from your own site.
Light – Science & Magic by Fil Hunter, Steven Biver and Paul Fuqua is probably the most important book on lighting that you will ever read. Moreover, if you only ever read one book on lighting, make it this one. This is, indeed, a rather bold statement. In fact, some readers who are new to shooting images may actually be puzzled by this praise once they read the actual book. The information there can be fully appreciated after you’ve fought a bit with real-world lighting problems.
The guaiac-based fecal occult blood test is a relatively inexpensive and simple screening tool that can be performed in the privacy of one's own home. However, it is important to follow the instructions carefully to ensure accurate results. For example, certain foods and medications can interfere with the test and lead to false positive or false negative results. Overall, the guaiac-based fecal occult blood test plays a crucial role in the early detection of colorectal cancer. By identifying hidden blood in the stool, this screening tool allows for early intervention and treatment, ultimately improving outcomes for individuals with colorectal cancer. It is important for individuals to discuss their screening options with their healthcare provider to determine the best approach for their specific situation..
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