What Lens Is It? Comparing Apple Device Cameras To 35mm Lenses

A lot of times when you’re using your smart phone camera to take a shot of a set or location it would be nice to know what the equivalent view would be with a 35mm cinema / video lens.

I ran the numbers for most Apple devices and came up with the following equivalent focal lengths for both 35mm still cameras (full frame) and Super 35mm size sensors. Remember that although both formats are based on 35mm film stock, the frame for a still camera is a 1.5 aspect ratio with a frame width of about 1.417 inches. A Super 35mm frame is a 1.35 aspect ratio and the frame width is .980 inches.

Why only Apple? Well, the company readily makes their devices lens and sensor data available and it was easy to calculate. In the next post I’ll show you how to measure for your devices’ angle of view if the exact focal length isn’t published.

Please note in the following table the focal lengths for the given device have been rounded up to the nearest whole number so the equivalent lengths given are approximate.

Apple device lens comparison chart

A New Year’s Resolution – Check Your Insurance Coverage

This is a bit different than the other blog posts on this site, but I thought I’d pass along some information that you might want to consider as you head into the New Year.

Most of us now do quite a bit of traveling on pictures or shows away from where we live and most people spend more and more each year on the personal equipment that makes up the ‘tool kits’ that our jobs depend on. If you’re smart you’ve invested in a business insurance policy to cover that equipment since a normal homeowner or renters’ policy does not normally cover items used for business outside the home. What you may not know is that a typical business policy will not cover your equipment while you are out of town or in transit to a distant location.

Inland Marine Policies

There is a type of policy called an Inland Marine policy which you should look into getting if you do spend a great deal of time working out of town. These policies were originally created during the Industrial Revolution when there was an increase in transport by ship as a type of “all risk” insurance. Most insurance companies describe it as ‘insurance which generally covers property that is movable or transportable in nature’.

Check with your insurance company to see if your current business policy includes a ‘inland marine’ clause, you may have to add this to your policy or purchase this as a new type of insurance. It may save you from getting a very nasty surprise when your equipment is damaged and you find out you’re underinsured.

Have a happy and productive 2014.

3D Scanners For Your Pocket – Coming Soon, Very Soon.

There must be something in the water in Boulder. A lot of technology is coming out of that little town including two new devices which could continue to revolutionize the way we work. Location survey work has never been much fun and always comes with unknown challenges that often leave you stymied, ike that billboard you suddenly learn you have to measure, or the block-long row of buildings that you have to survey with two hours of sunlight left in the day.

Using 3D scanners for location surveying and object duplication in the past has been something people have wanted, but the price of most of these devices usually makes their use too cost prohibitive. The iPhone and the many apps that accompanied its popularity have been a real help in many Art Department workflows but their uses are currently limited as far as true 3D capture and augmented reality functions.

Two companies, Ike GPS and Occipital are trying to fill a need for low cost 3D scanners with two inventions which act as add-on devices for digital phones and tablets. By harnessing the power of these devices, their creations enhance products that most people are already using.

Ike is a company which has had previous success with hand-held scanners and was looking to create a device which could be small enough to fit on a smart phone. They’ve come up with a small device called Spike which attaches to an iPhone or other smart phone and uses the devices built-in accelerometer, compass and GPS functions to make it possible to measure the size, height or even the volume of buildings and even create a 3D model to export to a modeling program.

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The company is currently running a Kickstarter campaign to raise interest as well as funds to develop the device which they plan on having ready for the market by next May. The device will come in two versions; the Basic version and the Pro version which will generate 3D model files, geolocate buildings and allow for pulling measurements from the digital image.

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For a donation of $389, you’ll get a prerelease Spike Pro which the company says is around half of the final retail price, meaning the street price of the Pro unit is going to be somewhere in the $800 range. That may seem pricy but the next closest device I know of that can provide similar functions is about 5 times more,  both in size and price.

Here’s a video from the company website:

 

 

Occipital has developed a device they are calling the Structure Sensor which attaches to an iPad and can create 3D scans of objects or rooms up to about 550 square feet with a range of 3 1/2 meters. The file can be imported into a CAD package or output for 3D printing.

Structure Sensor

The Sensor Kickstarter program is fully funded but for a $330 pledge you can still get a Sensor at a significantly reduced price than it will retail for when it becomes available early next year.

Check out the video below:

Here are the links to the Kickstarter pages:

Structure Sensor

Spike Pro

Designing Without A Ruler – “By Hand & Eye” Explores Designing With Dividers.

By Hand and Eye

There are a lot of design books published every year and occasionally a few get written that are actually worth buying. By Hand & Eye is one of those. It’s a book that delivers where a lot of others have gone and failed. Written in an easy, nonsense-free style, the book sets out to explain the “art” of designing with proportions rather than numbers. I’ve found that a lot of books on design tend to read more like a doctoral thesis than something that will actually explain the material in easily understandable language. By Hand & Eye succeeds because  authors Walker and Tolpin are actually practitioners of their craft rather than just writers. It’s like taking a film course from someone who’s actually made a film rather than just talk about it.

Lost Art Press is a relatively new publisher who’s books are primarily aimed at the traditional woodworking crowd but you’ll be missing out on some gems if you assume their books are only useful to furniture makers. Their books are quality products both in their content and their construction. These are not the cheap perfect-bound high-acid tomes that are the product of most publishers and will end up disintegrating on you shelves. (With that in mind, If you do happen to be a furniture and book lover, and the name Andre Roubo means anything to you, you need to must check this page out immediately.)

Jim Tolpin was the most familiar to me as I own a number of his other books, but George Walker is relatively new to the publishing world. George writes a blog called Design Matters which is a record of his journey in the search for understanding what makes for good design. He and Tolpin met several years ago and found they were both on the same path but had approached it from different directions; Walker from a preference for traditional furniture and Tolpin from a more modern bent. Both were determined to discover the “magic formula” that meant the difference between a chair or building being handsome or ugly.

What they discovered is that numbers don’t matter. In fact much of the time they just get in the way. Most of the treasured icons of furniture and architecture were made before the measured rule was in use. It was the divider that ruled rather than the inch or foot. And this system of working when far beyond architecture and furniture.

The exercises they outline are especially helpful if you have only worked on a computer as you’ll be forced to think purely about the design process without the intrusion of a ‘digital helper’. By learning to think proportionally you’ll approach design from a much less restricted footing. A lot of times computers just get in the way of good design instead of enhancing it. Once you stop using numbers and just concentrating on ratios you’ll realize you can make things much easier for yourself.

The book are also a great introduction to traditional geometry and proportion if you haven’t really studied it before or a great refresher if it’s been a while since you exchanged a mouse for a compass. They are developing a website for online access to exercises in the book and you can download some sample animations of the exercises from this web page. You can also read more about the book and download a sample chapter on this page.

While the book does concentrate on furniture design the information translates to everything else in the design world as most of the principals are found in classic architecture.

column cannon ship

For example, traditional sailing ships and cannon have a lot in common with the classical orders in that they were all based on a proportional system. This not only insured that all the moulds would be in proportion to the length of a cannon barrel but that the trunions would be sturdy enough to carry the barrels weight and that the wall thickness of the tube would handle the explosions of the powder charges. The ship’s rigging was based on a similar system. If you knew the mast length you could figure the thickness of the mast stays and the diameter of every piece of rigging on the ship, all without a calculator.

Even an entire structure could and can be built with just a stick and a piece of cordage. Take a hewn log cabin. The picture below illustrates the only drawing you need for a house. It would be scratched out in the dirt with the cord and stick using the cabin width as the main unit of measure.

cabin plan

The length is easily determined in relationship to the width, resulting in a 1.6 plan ratio. The wall height is determined as 5/8s of the width. The same length determines the diagonal roof line which results in a 3/8 rise or a 9/12 pitch. The intersections would be marked with stakes and used as a full size pattern for cutting the timbers and joints without having to use a bevel gauge or fuss with estimating angles.

By doubling the cord the lengths are easily halved into eighths. The metric system is good if you’re working with numbers, multiples of 2 are better if you are laying out a pattern with simple tools.

At one time or another you have probably struggled with a badly proportioned room without realizing it. If you have ever had to design a paneled room and find that it’s impossible to get the panel sizes to work out correctly from one wall to the next, it’s most likely because the room was designed to a bad proportion. Get the proportion of width to length wrong and period details become a nightmare.

By Hand & Eye is now available through the Lost Art Press website. You can order the book here for $34. Also, if you have a peculiar aversion to quality paper products there’s a digital edition available for $16.

Three Types Of Dividers You Should Own

Thinking that you don’t need dividers if you work on a computer is a real mistake. If you have a set of compasses, a set of proportional dividers and a set of equal-space dividers you can accomplish a lot of things in less time than it takes for you to start your computer.

Here are the three types of dividers you should have and where to find them.

Compasses / Dividers

There are a large number of compass and divider styles available. You need to find the best type to fit your work methods

There are a large number of compass and divider styles available. You need to find the best type to fit your work methods.

Dividers and compasses are both the easiest and cheapest of all three types to find and have the greatest variety. If you are just doing the exercises from the book or doing small design drawings on vellum you only need a typical compass. You don’t need to settle for a cheap office store/elementary school type, there are plenty of quality compasses available on Ebay for as little as a few dollars. Usually they will come as part of complete drafting sets, which aren’t a bad thing to own, but often you can find them as one-offs. A compass around 6″ in length should be all you need. If you are feeling like drawing something larger, you’ll need a beam compass. I own one like this which is the best I have ever found. It’s called a Feranco Beam Compass and it was made by a small firm in Cincinnati. They’re out of business but you can find them second hand. Or, you can use a metal straight edge with a set of trammel points like these.

Proportional Dividers

proportional dividers come in a number of styles, most will work for design except for the type manufactured for nautical calculations.

proportional dividers come in a number of styles, most will work for design except for the type manufactured for nautical calculations.

These are definitely more expensive than a set of dividers but are a huge time saver if you are trying to scale a drawing to a different size or want to design to a giver proportion. The cost for a set of these will run anywhere from $30 to $300 depending on the vintage and make. The pair on the left are a 1810 pair made in London. The legs are of iron which are dove-tailed into the German silver body. The tolerances are very tight on these dividers and they stay put when you set them which is often a problem with cheaper dividers. The vintage sets have points which are triangular in shape and come to a very sharp point, which they need to be. Dull points require tuning with a very fine file or emery cloth. This should be avoided if possible because the accuracy depends on the lengths of the legs being a definitive ratio to each other. The modern sets have round pins which come to a point. The advantage of this being that if the dividers are dropped the pins can be replaced, something impossible with traditional sets.

The vintage sets came in two types: standard or second quality in which the indicators ‘Lines’ and ‘Circles’ are engraved on the front, and first quality in which besides these the indicators ‘Plans’ and ‘Solids’ are engraved on the reverse side. For 2D line work you only need the first two indicators. Also, when you are looking for a used set, be sure that one of the indicators does not say ‘Speed”. These are a pair made for nautical use and won’t be very useful for our purposes.

The better quality sets had designations for solids and planes which are for volumetric calculations

The better quality sets had designations for solids and planes which are for volumetric calculations

When you set the dividers to a ratio, the difference in distance between the longer and shorter legs will mirror this. Set the ‘Line’ scale to 8 and then spread the long set of legs along a straight line. The distance between the short legs will be 1/8th the distance. The same method works with circles. Set the scale to , say 5, and them spread the long legs across the diameter of a circle. You ‘walk’ the legs around the circumference of the circle to divide it into 5 equal segments.

The '10' setting under circles gives you the ratio for the Golden Proportion.

The ’10’ setting under circles gives you the ratio for the Golden Proportion.

If you like designing to the Golden Proportion, you can set the Circle scale to ’10’ and you will have a proportion of 1.618 between the two sets of legs.

Equal Space Dividers

Equal space divider come in two sizes: 6" and 12"

Equal space divider come in two sizes: 6″ and 12″

This type of divider is the most expensive of the three, but for scaling or proportion work from drawings or photographs they are impossible to beat. These are the dividers I use the most of all I own and if I lost them I’d have to replace them immediately, despite the steep price. I bought my set decades ago for $130, new now they list for $350. Ouch. My 12″ set were handmade my Alteneder & Sons in Philadelphia and are collectors items. You may get lucky and find a pair on Ebay. New, a 12″ pair runs from $400 to $500. I’d recommend finding a second-hand pair but make sure the tips are not bent or the accuracy will be nil. These dividers are sometimes referred to as 10-space or 11-point dividers. Check the Ebay sites in Britain and Canada. I’ve seen them show up there as well.

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With these dividers you can very quickly divide a space into as many as 10 units. I used to use them mainly for laying out stairs or room paneling but now they are irreplaceable for scaling off a photograph or drawing while simultaneously drafting on the computer. Trying to scale the material from the computer screen while doing this would be much slower. For the times I do have an image in digital form and need to scale from the screen, I’ll flip a piece of acetate over the monitor to keep the sharp teeth from scratching the screen. It’s fun to watch people with expensive monitors see me do this and gasp in horror.

Rendering In Sketchup

For those of you who work in Sketchup and are new to rendering, or are confused by all the different rendering software packages available, a new book is coming out March 25 that will help. Daniel Tal, landscape architect and author of Sketchup For Site Design, has written a new book, Rendering In Sketchup, which is now available for pre-order or as a digital download.

rendering in sketchup

There are now a number of rendering programs on the market for use with Sketchup, with a majority of them working from within Sketchup without having to exit the program. This can be a plus or a minus depending on how you work. Even though most of the programs offer free-use trial periods of their software, It can be pretty difficult and time-consuming to decide which is  the best one for your workflow and budget.

Daniel is an excellent teacher and has written a very thorough and detailed book on the process of rendering from Sketchup using a variety of software programs as well as explaining post-rendering work with Photoshop. While not every rendering engine is covered, he does go into a great amount of detail explaining not only the basics of rendering, but his own methods using Shaderlight, SU Podium and Twilight Render.

The book covers workflow, hardware requirements, how to model efficiently for renders, use and teaching of textures and a lot more. At over 600 pages, the book is both a reference and a guide and can be read for pertinent chapters rather than just cover to cover.

You can get more information on the book here, and you can view the videos on Daniel’s Youtube site here

Here is a really good tutorial by Daniel you should watch which is based on the material from his book:

Land8 Webinar: Rendering in SketchUp – Daniel Tal from Land8.com on Vimeo.

If you want to know all of your rendering engine options, here is a list of rendering programs that work with or within Sketchup;   ( Prices are as of March, 2013. )

From within Sketchup:

Shaderlight – $299 full license; timed access from $50

Twilight Render – $99

V-Ray – $800

ArielVision – $175

Bloom Unit – free software , cloud-based, priced per render

Caravaggio – $295

Indigo Renderer – $220

IRender nXt – $499

Light Up – $189

LumenRT – $295

Maxwell – $995

Raylectron – $99

Render[in] – $160

Renditioner –  $99,  Pro $199

SU Podium – $198

Thea Render – $420

Standalone Software

Artlantis

Kerkythea – free

Understanding Model Scales – A Comparison Study

Comparative Scale Figure Diagram – You can download a pdf copy of this diagram below.

Even with the large number of computer 3D modeling programs available to designers, there is  (and I think always will be)  a place for physical scale models. Although the modeling programs continue to produce more and more realistic looking images, they are still only a 2D image that utilizes correct perspective. And even the programs or systems that are ‘true 3D’ are really only offset 2D images meant to trick the mind into thinking it’s seeing a dimensional physical shape.

Some of the advantages of a physical scale model are:

-The physical size of a set are much easier to grasp than from a digital model where you can zoom in endlessly.  I once built a model of an area of geography that the producers couldn’t seen to understand exactly how big an area it was until I put in the final piece, a model of the 260 foot ship they planned to use for a crew base. The huge ship measured only 3/16″ in the model scale. They got it instantly.

-A number of people are able to simultaneously view the model and discuss it. A lot of revelations often come from being able to look at a model from many different angles at once.

-The brain isn’t spending effort trying to do the mental tricks required to process fake 3D images. The model is somehow “more real”, because it is.

The Diagrams

I created the chart above as well as the list below from many years worth of notes and scribbles. The calculations are mine so any mistakes are solely mine as well. The visual chart will give you an easy way of determining the size of figures in the various scales that will be most common to concept models.

The list describes what I think are the most useful model sizes  from 1:700 to 1:6 with inch equivalents for each scale as well as the length of a linear foot and meter for each as well. The last column gives the common uses for the scale to help you determine what products exists for purchase. The Size Chart also lists the most common Imperial and metric drawing scales so you can find the model sizes that most closely match.

Determining The Size Of Your Model

Your first calculation will probably be how large the overall model needs to be. You’ll want the model to be as detailed as possible but probably won’t want it to take up and entire room. Using the Size Chart, multiply the overall actual size of the area you need to cover by the foot or meter equivalents and then determine which scale is best for the space you have available. Also note that 1/32 and 1:32 refer to the same scale.

Next, determine what model items exist in that scale. For the most variety in objects and vehicles, stick with the train gauge scales. If you need a lot of detailed plastic trucks or cars, 1/24th scale is going to probably be best, which is also the same as 1/2″ to the foot and is close to the German “G” train gauge.

Download The Files Here

Comparative Scale Figure Diagram

When you print this diagram, be sure that you print it at 100%. Check the inch and metric scales to be sure it is at full size for an accurate representation.

Other Articles

For more information, you can refer to the following articles:

List Of Scale Model Sizes

Combining Figures With Models

Converting Scale Ratios

Finding The Right Scale For Your Model

The Best Chair You’ve Never Heard Of

On campaign during the Boer War, 1900. Major-General R. Pole-Carew , right, is seated in a Roorkhee campaign chair. National Army Museum, London

It’s all our fault. America and India, that is. When the British Empire was at it’s height of power it was sending troops to three continents. It would have been an extreme hardship for the officers, gentlemen in a class above that of the common soldier, to have traveled to these far-off places without the comforts and trappings that they were used to at home.

That meant that the campaign tents that were pitched in the American wilderness and the jungles of India had to be filled with proper furniture. Soon the best furniture makers in London, including Thomas Chippendale were turning out pieces which were designed specifically for, well, camping. To maintain the prestige of the British Army the furniture they brought with them had to be practical, portable and stylish.

A suite of Victorian walnut campaign furniture from 1863. From the book British Campaign Furniture by Nicholas Brawer

These were more than just a few choice pieces which were tossed into a cart. Some officers, when ordering their camp furnishings at the British Crown’s expense, selected nearly 50 pieces including beds, chests, writing tables,  bookcases and chamber pot holders. The size of some of the tents they inhabited while on campaign would have rivaled the size of the average room in a fine country estate. Not to mention the caravan of wagons and horses necessary to carry it all from place to place.

I first learned about campaign furniture while I was working on The Patriot in 1999. We reproduced some Georgian campaign chairs like the one below and I was struck by the ingenuity of the design. Some of the comfort may have been compromised but not the style. Sure the stretchers were flat and mostly featureless but the overall lines were there.

George III caned mahogany folding chair, 18th century. Christopher Clark Antiques, Ltd., Glos., England

Three years later I came across Nicholas Brawer’s book, British Campaign Furniture 1740 – 1914. It still remains, amazingly, the only book on the subject. Brawer explains that the real explosion in campaign furniture came after the Napoleonic Wars, when a brisk increase in travel both on the continent and abroad created a huge market for portable and functional furniture.

In 1899, the British Army experienced an entirely new type of war. The Boer War in South Africa changed the way people thought about modern conflict and the idea of a ‘Gentleman’s War’ was gone. The over-designed and over-stuffed campaign furniture of the Victorian Era was unpractical for the new hit-and-run tactics which demanded something lighter and more austere. The Roorkhee Chair came out of this need for a chair that was both simple and still robust enough to stand rough treatment. Weighing between 11 and 13 pounds, the chair was usually covered in canvas with leather straps for arms and easily broke down for travel. The design also had the advantage of allowing the chair to sit with all four feet level no matter how uneven the ground was. The name of the designer is lost to history, but the chair was named in honor of the Indian Army Corps of Engineers in Roorkhee, India.

Roorkhee chair fitted with canvas seat and back. From British Campaign Furniture by Nicholas Brawer.

Chair disassembled for travel

another style of leg

Victorian Mahogany campaign chair from the 1870’s. The ancestor of the Rorrkhee chair, it wasn’t as robust even though it could break-down as well. The pieces were carefully numbered to match their corresponding pieces to make assembly easy for anyone.

Unfortunately Brawer’s book has been out of print for years, so if you find a copy you should grab it. There are reproductions being made including some very nice ones by Lewis Drake & Associates.

If you’re handy with tools, you can try making your own. Christopher Schwarz, contributing editor at Popular Woodworking Magazine, and living patron saint to hand tool woodworkers everywhere, has done an article on making a Roorkhee you can find here. And you can download his Sketchup model of the chair here.

“Where’s That Submarine Research?” – Cataloging Your Stuff

I took the big file of submarine research, surveys and photos and tossed it in the trash. Then I stopped to think about it. Was I really ever going to use this information again? I’d done three sub movies before, what were the chances of ever doing another one. I looked at it sitting on the trash pile and then scooped it back out, just in case.

That’s been my constant dilemma, what to do with the dozens of boxes of files from past film projects. I finally decided that if  there was no way to easily put my hands on a file, I might as well toss all of them.

I’ve been in the midst of trying to catalogue and organize my collection of +2000 books and decided the research needed to get catalogued the same way.

The thought of trying to manually type in the info of all those books kept me from even starting the project until I found Delicious Library. When you open the program you are presented with a virtual bookshelf.

This is the way your books appear on the virtual bookshelf

You just wave the barcode on the book in front of the screen and the program searches the internet and within 3 seconds it loads a photo of the cover of the book onto the shelf. The window along the side records the publisher, date, value, reviews and a lot more. There are multiple ways of organizing and viewing the items including by Dewey decimal system, author, title, location or value.

If the book is older and doesn’t have a barcode, you can enter the ISBN number and it will log it. You can also input older books by inputting the title and author and it will search for all the books editions.  If, like me, you have a LOT of books, or DVDs, when you purchase the program you can also purchase a handheld barcode reader that allows you to scan about a hundred items at a time. When you plug the scanner into your computer, the program will download and record the items onto the ‘shelf’.

The program is also a great way of cataloguing anything else, including research. I created a system of boxes and have the various files noted as to which box they are in so I can do a word search in the system and an icon of the file and its location pop up.

The only downside is that Delicious Library is  for Macs only. For PC users, the nearest similar products which work similarly are  Librarian Pro 2, or All My Books.

Measuring Heights Without A Tape Measure

No, it doesn’t involve Google Earth or Sketchup. That was covered in an earlier post. Here are three high-tech to no-tech ways to calculate the height of a building or tree or pole or anything else you need to know the size of but can’t determine with a tape measure.

1. Theodolite Pro

Theodolite Pro is an app for the iPhone, iPod Touch and the iPad.  Made by Hunter Research & Technology , it’s a multi-function augmented-reality app that combines a compass, GPS, digital map, zoom camera, rangefinder, and two-axis inclinometer. Theodolite overlays real time information about position, altitude, bearing, range, and inclination on the iPhone’s live camera image, like an electronic viewfinder.

At $3.99, it’s worth more than 4 times the price.

Theodolite Pro screen

The apps screen data gives you your position in either latitude and longitude or UTM units, as well as the time and date and your elevation. On each side are the horizontal and vertical indicators in tenths of a degree. The device has a one-button calibration function as well as a 2x and 4x magnification for pin-pointing a particular object. There are several options for the center crosshairs, one of them are a pair of multicolored floating boxes which merge and turn white when you are plumb in both directions.

You’ll get a much better result if you mount the device on a tripod. For an iPhone, the method I like is with a Snap Mount. It has 1/4″ female sockets for mounting in either a vertical or horizontal direction.

Snap Mount device for the iPhone 4

Once the phone is mounted, you point the center at the top of the object and push the “A” buttton to take a reading. Then tilt the device toward the bottom of the object and take  the “B” reading.

Then the app will ask you for your distance to the object. The more accurate your answer the more accurate the result will be. So, you’ll either have to pace off your position or measure the distance with a reel tape or laser measure device.

If this isn’t possible, you can use the option to determine the distance and height, although this will probably not be as accurate.

There is also an optical rangefinder built into the view screen that works by way of a series of concentric circles in either size factors or mils, that you can use to determine distance if you already know the size of an object in the foreground.

optical rangefinder rings

This app has been a best-selling navigational app for some time and has become a very useful tool in many different fields. You’ll find it’s very useful when doing field surveys and it’s certainly a lot cheaper than an analog theodolite.

2.  Clinometer

A clinometer, or inclinometer is a device which measures the angle of slope and uses basic trigonometry for estimating height. My clinometer is a combination clinometer and optical compass made by the Finnish company Suunto and is called the Suunto Tandem. Like the iPhone, you’ll get better results if it’s mounted to a tripod and the Suunto has a 1/4″ socket for this.

The Suunto Tandem

You look through the peep sight, leaving both eyes open. The graduated scale is superimposed over the object you’re centered on and you can read the results as either a percentage of slope or degrees of elevation.

You sight the top of the object in the device and read out the angle. Then you refer to the cosine table on the back of the device. From there it’s just a simple trig calculation. Adding the height from the ground to the center of the clinometer will give you a very close figure for the objects height. Like before you need to know your distance from the object you’re measuring, so it would be a good idea to determine your average stride to have a semi-accurate way of pacing off distance when surveying.

The back of the Tandem has tables of cosines and cotangents printed on it to make calculations easy.

The list price of the Tandem isn’t cheap, but I’ve seen them go for $20 on Ebay, so you should check there before you buy a new one. The results may not be quite as accurate as with the Theodolite app, but you’ll never have to worry about a dead battery and the device will still work perfectly 50 years from now. Like the Theodolite app, it’s good for shooting grades and taking elevation surveys as well.

A handy addition to both the above devices is to get a Keson Pocket Rod. It’s a collapsable surveyors stadia that rolls into it’s case. It has black and white graduated scales on one side and red and white on the other. It’s a great tool to have to put in location survey photographs as well for accurately scaling details from photos when you don’t have time to measure everything at a location. They come in both Imperial and metric units.

Keson Pocket Rod

3.  Biltmore Stick

This is the cheapest and easiest method of determining height but it’s also the least accurate. This is a trick I learned from my Boy Scout days. It’s based on the Biltmore Cruiser stick which is a way of determining the heights and widths of trees and how much lumber they would yield. The Biltmore Stick ( sometimes called a hypsometer ) gets it’s name from the famed Biltmore Estate in Asheville, North Carolina and was invented in the 1890’s by a German forester named Carl Schenk who was the master forester at the estate.

A real Biltmore stick has graduated markings that take into account for foreshortening but there’s a less expensive method. We were taught to use a yard stick (not very compact) or a 6 foot folding rule, which is a little wobbly to hold vertically. I like to use a Four Fold rule which is the original folding rule from the mid 19th century. They were sometimes called Blindman’s rules because the numbers are large and easy to read, making them perfect for this use. Garrett Wade carries a good reproduction of them. They fold down to just 9 inches long and fit nicely in a survey bag.

The way to use this one is to pace off 25 feet from the tree, building, etc. Turn and face it, holding the rule at arm’s length. 25 inches from your eye is the ideal distance. hold the rule so that the bottom of it lines up with the bottom of the object, like so:

using the Four Fold rule as a Biltmore stick

Read off the number than lines up with the top of the object and that will give you the height in feet. If the object is above the 25 inch mark, back up another 25 feet and multiply the results by 2. If it is still above the 25 inch mark, back up to 75 feet away and multiply the results by 3, and so on.

This method won’t necessarily give you a really accurate height, but it will give you a number that will be pretty close, say within 3% to 4% of the true measurement, providing you are very close in the distance increment and the rule is very close to 25 inches from your eye.


A “Sweet” and Cheap Architectural Detail Resource

Yes, I thought it was time for a bad pun. The “sweet” resource I’m talking about is the Sweet’s Indexed Catalogue of Building Construction. Not the modern version, mind you, but the earlier volumes. In particular I’m talking about the first one ever printed, in 1906.

Reprint copy of the first edition of Sweet’s

I found my copy in a used bookstore about 25 years ago, back when 3rd Street in Santa Monica was still a sleepy street lined with great used bookstores instead of chain outlets. It was a 1970’s reprint of the original, in great condition. But the most striking thing about it was how different it was from it’s modern relatives. This book was printed for people who actually drew details, and both wanted and needed to know how things were built.

Most of the products pictured throughout the book had either detailed drawings or photographs of the items, with dimensions and cutaways showing how they operated and how they were integrated into the architecture of the building. This was a far cry from the ‘updated’ version, void of details, which was meant only to be a means of calling out the correct ‘part number’ on a drawing rather than giving the architect a full understanding of the specifics.

The original volume, if you can find a copy, has a green cover. The reprints will have a tan cover. The most useful ones for our work run from 1906 to the 1930’s. They aren’t easy to find but Google has solved that problem. Among the millions of books they have digitized for their ebook site are the 1906 and 1907 editions of Sweet’s. The digital editions aren’t as crisp as a printed copy, but the details you’ll glean from them are priceless. You can download it as a pdf and have it on your computer whenever you want to refer to it. Here is some of what you’ll find:

A sample of a typical advert featuring both photos and detailed sections

details of furnace and ducting showing how the duct and registers are attached to the wall framing

One of hundreds of photos showing details such as trim, ironwork and tile.

Detail of large furnace for an office or apartment building

An early central vacuum system

And here’s proof that people had MUCH bigger heads 100 years ago

Another good source in Google Books is a magazine from about the same time period called The American Builder which has some good articles with details. This ad for a drafting course is great. Considering an average draftsman would have made about 35 to 40 cents an hour at that time, $100 a week would have been top dollar.