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The Lens

As woodworkers we are interested in photographing our work for show; either in a printed portfolio or on a website. I believe the most important part of photographing a piece is getting the exposure right. This starts with understanding the functions of the lens. I will use two lens examples to highlight the important functions:

  • Canon Zoom Lens EF 28-135 1:3.5-5.6 IS USM / Ø72mm
  • Canon EF 24-70mm f/2.8L USM / Ø77mm

 

Canon Zoom Lens EF 28-135 1:3.5-5.6 IS USM / Ø72mm Let’s go through the above examples and decipher the specifications. Both of the above lenses are members of the Canon EF line, meaning they can be used on any Canon EOS camera. They are both variable focal length or zoom lenses. Whether they are telephoto, normal or wide angle depends on the camera to which they are mounted. More on that later. The first lens has a variable focal length of 28mm to 135mm and the second lens 24mm to 70mm. The first lens’s maximum aperture opening depends on what focal length is set, that is, the maximum aperture opening is 3.5 at 28mm and 5.6 at 135mm. Aperture openings are measured in f/stops which we will discuss soon. The second lens has a fixed maximum aperture of 2.8 independent of focal length. The first lens is an “Image Stabilized” lens. Both have a “Ultrasonic Motor” used for auto-focusing. The last two numbers (72 & 77) are the diameters of the lens cap and filter attachments used on that lens. The L following the f/2.8 aperture specification stands for “Luxury” meaning it is a professional lens (lots of very high quality glass). The first lens sells for about $400 while the second $1,050.

Viewing Angle

Canon EF 24-70mm f/2.8L USM / Ø77mm OK, that was a once over. Lets go into a little more detail. Imagine driving through a long tunnel through a mountain range which exits on the other side to trees, a lake and homes. When you are one mile from the exit you have virtually no view of the trees, lake and houses, simply a spot of light. When 100 feet from the exit you might see a home or two and some trees. When 50 feet from the exit you recognize the existence of water, a field of trees an a few homes. Finally, when you are 10 feet from exiting the tunnel you get the whole view of the lake, the trees and a small town. This is similar to the view provided by various types of lenses. The 1 mile view is analogous to a pin-hole camera, the 100 foot view a long zoom lens, the 50 foot view a normal lens and the 10 foot view a wide angle lens.

The difference in all these views is the viewing angle and the corresponding “focal length”. Neglecting the pin-whole camera which we are not interested in, the 100 foot view may have a viewing angle of less than 10 – 20 degrees, the 50 foot view 50 – 60 degrees and the 10 foot view a viewing angle over 100 degrees. It is the same with lenses. A long focal length lens, say 250mm, has a viewing angle of 10 degrees on a 35mm camera. A normal 50mm lens a viewing angle of 45 degrees on a 35mm camera. Finally a wide angle lens of 15mm will have a viewing angle of slightly over 90 degrees on a 35mm lens. This is why telephoto (large focal length) lenses appear to enlarge things while wide angle (short focal length) lenses tend to shrink things relative to a normal lens.

Aperture & f/stop

To Halve Exposure Multiply f/stop By One Over The Square Root Of TwoThe aperture opening, as mentioned previously, is measured in f/stops or f-number written as f/# or N. An f/stop, or N, is a ratio of the focal length to the aperture diameter or f/D. You will not find a lens with an f/# of f/1; this would require the maximum opening to be equal to the focal length. This is difficult and expensive to achieve for reasons well beyond this post. However, f/1 is theoretically possible and is what f/stops are based on. Suppose we expose a picture with a shutter speed of 1 second (the length of time we allow light to enter the lens) and f/1 and discover it is overexposed. We wish to cut the amount of light in half. We have two options; set the shutter for 1/2 second or choose an f/# of f/1.4. Where did the 1.4 come from? High school geometry. If we want an aperture that has 1/2 the area of f/1 we need an aperture opening 1/(sqrt 2) or 1/1.414…… times f/1 or f/1.4 (truncation typical). Standard f/stops are those that follow the 1/2 exposure (or aperture area) progression and look as follows:

f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128

Each f/# is 1/2 its left neighbor or 2 times its right neighbor in terms of the amount of exposure it permits. If you have a 135mm focal length lens set at f/5.6 the aperture diameter is 24mm. At f/8 this same lens has an aperture diameter of 17mm and permits 1/2 the exposure. Note that the larger the denominator the smaller the opening and the less the exposure. This is a little confusing, but with use you will get accustomed to it.

Shutter Speed

Shutter speeds have standard “stops” as well. They are defined also by the progression of halving (or doubling) exposure. These are the typical shutter “stops”:

1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1, 2 etc.

Note, if an exposure meter determines the correct exposure is f/5.6 at 1/250, you can choose a number of equivalent exposures by doubling f/stop and halving shutter speed or vice versa. For example, f/8 and 1/125 is equivalent exposure to f/5.6 and 1/250 as is f/4 and 1/500.

Depth Of Field

Depth of field (DOF) is another factor we need to consider. If we focus a lens on a subject there is a range of image depth that is in focus. The exact definition of DOF is beyond this post but here are a few things to remember. The image will be in focus a distance d in front of the subject and roughly 2d behind the subject. The size of d is a function of film format, lens focal length, aperture (f/#) setting, and distance of the subject from the camera’s focal plane. For example, a subject 15 ft from a 35mm camera’s focal plane, shot with a 50mm lens set at f/8 will have a DOF of 16 feet; 4.5 feet in front of the subject to 11.5 feet behind.

Camera Format & Focal Length Multiplier Or Magnification Factor

One last factor we need to discuss to complete our discussion of lenses is actually a discussion of camera formats. 35mm cameras use 35mm film. The exposed area of this film is 36 x 24 mm. Unless you purchase a professional DSLR, whose sensors are the same dimensions as 35mm film, the sensor will be substantially smaller. My Canon EOS 40D has a sensor that is 22.2 x 14.8 mm. If you take the ratio of the diagonals of these two formats you get 1.6. That is, the diagonal of a 35mm camera is 1.6 times that of the Canon EOS 40D. Another way to look at this is to compare the images produced by the same 50mm lens used to take a picture on a 35mm camera and then a Canon EOS 40D. The Canon EOS 40D picture will be 1/1.6 that of the 35mm picture. When both are printed on equivalent paper, for example 8″ x 10″, the Canon EOS 40D print will appear as though it were taken with a 80mm lens on a 35mm camera. Therefore, since the lenses used on DSLRs are based on the 35mm format I must remember to multiply a lens’s focal length by 1.6 to understand how it will work on my Canon EOS 40D. This factor is generally referred to in the literature as Focal Length Multiplier or Magnification Factor.

Relative Sizes Of 35mm Format & APS Format Versus Lens DiameterMost DSLRs are either full frame format (35mm equivalent) sensors or APS format (Advanced Photo System) sensors; the latter requiring a Magnification Factor typically between 1.5 – 1.6. Check the specifications for you DSLR to determine the correct Magnification Factor. These smaller sensors have both advantages and disadvantages for the photographer. One disadvantage is that it is difficult to use a high quality wide angle lens since wide angle lenses tend to be shifted to normal lenses when multiplied by 1.6. For example, a medium wide angle lens on a 35mm format camera would be a normal 50mm lens on an APS camera.

There are a couple of advantages though. A 135mm medium telephoto lens is equivalent to a 216mm lens when used on an APS format camera, which is a decent long range telephoto. In addition, since the sensor is smaller, its image is the product of the inner portion of the lens. Most lens aberrations are caused by its outer edges and these will tend to affect the 35mm camera more than the APS camera making the quality of the lens seem higher than it actually is.

Summary Of The Lens

We can summarize all of these lens related factors as follows:

  • Larger focal length lenses result in a smaller viewing angle and more apparent magnification
  • Moving a full f/stop is either direction either halves or doubles exposure
  • Moving a full shutter speed in either direction either halves or doubles exposure
  • Decreasing aperture diameter increases DOF – e.g. going from f/2.8 to f/8 increases DOF
  • Larger focal lengths result in lower DOF – telephotos have shallower DOF than wide angle lenses.
  • The larger the distance of the focused subject from the camera’s focal plane the larger the DOF
  • Smaller format cameras have a shallower DOF
  • Many DSLRs require the use of a Magnification Factor to determine the focal length equivalent for any given lens – for example – a 32mm lens on my Canon EOS 40D is equivalent to a normal 50mm lens on a 35mm format camera

 

Often, what we want to photograph as woodworkers can be quite large, for example a country hutch. Further, we want the entire piece to be in focus so that grain and crafting detail are sharply displayed. We would like a large DOF to accomplish this. This typically means using an f/stop of f/8 or smaller (f/16, f/22 etc.). I almost always use my Canon EF 24-70mm f/2.8L USM lens, because even with the 1.6 factor, it is a slightly wide angle lens compared to a normal 50mm lens on a 35mm format camera. Hence it helps to get the entire piece in the image and also helps with DOF. In addition, the lens quality is substantially better.

This is a good place to break for now. We have covered nearly all the important features and functions of lenses. Next we will discuss the camera body itself, talking more about the sensor, shutter, and RAW images. It will take several posts before we can start to tie all this together, so be patient – it will all make sense soon. See you in Part 3.

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Canon EOS 40D DSLRI have several hobbies and one of them is photography. Though a serious amateur, I do not consider my skills anywhere close to professional level. Nor have I ever written about photography on this blog. But the more woodworking I do the more I find that photography is a part of it; either to display my creations in a portfolio or to describe woodworking techniques and joinery on my website and blog. So I have decided to write a multi part tutorial. It is targeted for woodworkers who are beginning to show an interest in digital photography with the goal of demonstrating how their photography skills can be integrated into their woodworking.

This tutorial will appear in several posts, each post a stand alone section. When the last installment is complete I will combine the posts into one web page and a document that can be downloaded for future reference. Today I will start with suggested equipment and software lists and then discuss each briefly. More detail will follow in subsequent installments.

Equipment

  1. Digital camera – preferably a digital single lens reflex (DSLR) that shoots RAW
  2. Telephoto lens – 24mm – 70mm is a good range for APS size sensors
  3. Tripod – The sturdier the better but you don’t need a professional Tripod
  4. Cardreader – preferably Firewire
  5. Extra memory cards – nice but not necessary
  6. Gray Card – absolutely essential

Software

  1. Adobe Photoshop Lightroom – Substitute Adobe Photoshop Camera Raw or native camera manufacturer’s software, but Lightroom is really head and shoulders above the rest
  2. Adobe Photoshop – Photoshop Elements also works for most situations
  3. Adobe Photoshop Elements – not necessary, unless you do not have Photoshop, but nice for managing JPEGs

Note that I did not mention a flash attachment or filters. They are not necessary for shooting projects in the shop or outside. You can accomplish almost everything you need to without them. That said, if you have the money by all means add them to your photographic tool bag. Also, I am biased to Adobe products for software and Canon for photographic equipment. However, you can accomplish the same things I will cover here with other brands, though I will use these products exclusively in the tutorial.

Camera

Adobe Photoshop Lightroom 2The five things I strongly recommend in whatever camera you purchase is that it be a DSLR, shoots and stores RAW images, has a 10 second timer, has an aperture priority setting and has at least 5 mp resolution. This set of criteria is not difficult to meet since you would be hard pressed to find a DSLR on the market today that does not meet them.

Above 5 mp, resolution is not the most important purchasing criteria. Look for a camera with the least noise and best color reproduction. I will not present a lot of theory here or review cameras. Digital Photography Review is probably the best place for that. Other factors are of course cost, weight, feel, ease of menu manipulation, placement of controls, battery life and choice of attachments – especially lenses. Resolution is probably the most over valued criteria when choosing a camera. Consider what you want to do with it. If you are mostly interested in pictures for a website or blog 5 mp is more than enough; a 1920 x 1200, wide-screen computer display, is about 2.3 mp. If printing your own prints on an ink-jet is your thing, an 8″x10″ photo is 7.2 mp at a high quality resolution of 300 ppi. My cameras are both 10 mp, and I will not select my next camera body based on more mega pixels. However, 10 mp does offer an advantage. It allows a fair amount of cropping while still ending up with 5 -7 mp to work with. So for me this is the sweet spot in resolution.

As I said, my cameras are both Canon. I have a Rebel XTi with 28-135mm Ultrasonic Focusing and Stabilization lens and a EOS 40D with 24-70mm Ultrasonic Focusing and Stabilization L series lens. Since most of the picture taking I will discuss is with a tripod, stabilization is switched off.

Tripod

The Tripod is an inexpensive, but a most needed piece of equipment. You don’t need a professional tripod with a ball attachment. Go to your local camera store, for example Ritz Camera, and buy one of their best tripods for under $100. It will serve you just fine.

Cardreader

If you don’t already have a card reader get one that is Firewire compatible provided your computer supports Firewire. RAW files can be large and downloading a number of them can take a long time. Most cameras download directly via USB, but their implementations of the USB hardware are often slow. Card readers are inexpensive and a good investment.

Memory Cards

Memory cards are always a good investment. I like to have a number of high speed 2 GB cards as opposed to one or more very large 8 GB cards. I don’t trust that many pictures to one card, not because I think card reliability is bad, but because I don’t trust my handling of them. A 2 GB card holds approximately 150 RAW Canon images (it will be different for another brand) which is a reasonably long time between card changes.

Gray Card

Adobe Photoshop CS3Since we will be shooting only RAW images we need some way to correct color, that is, adjust white balance. If you don’t know what RAW or white balance is, don’t worry, I will go into each in more detail in the next installment, soon to follow. A gray card is a card that is printed with a neutral gray, half way between black and white, which will reflect 18% of a “total light spectrum”, that is daylight (the purist will say this is not technically correct, but it is close enough for our understanding). If we include this card in a test picture – of say a piece of furniture in a fluorescent lit shop – we will know the color it should be after correcting for the bluish cast of fluorescent lighting. A Kodak gray card pack-of-two can be purchased from Amazon.com for under $20. More on gray cards later.

Adobe Photoshop Lightroom

As I said I am biased toward Adobe when it comes to photographic or graphics software. Adobe is what most professionals use and it is largely an industry standard. There are many other competing brands out there and I don’t want to get into religious wars. Make your own choice, but Adobe is what I will work with in this tutorial.

Photoshop Lightroom, in my opinion, is the most value for the money one can expect in a “darkroom” software package. I use to develop and print my own 35mm film in a chemical filled darkroom. Boy, do I love digital photography. And wow, do I love Photoshop Lightroom. The combination of RAW images and Photoshop Lightroom is about 90 percent of everything a photographer needs to do. Correct color, lighting, sharpness, crop, rotate, manage a photo library – you name it – and you can do most of it with Photoshop Lightroom. What it doesn’t do is the graphics design that Photoshop does – that is, work with layers and canvasses, distort images, artistic filtering, etc. Lightroom is relatively inexpensive as graphics software goes. You can get a full featured version from Amazon.com for $272 as of this writing.

Adobe Photoshop CS4 and/or Adobe Photoshop Elements 7

Adobe Photoshop Elements 6If you can afford both packages, I recommend getting both Adobe Photoshop CS2 or later and Adobe Photoshop Elements. Adobe Photoshop CS4 full version is very pricey and is currently listing for $699. However, you can probably find deals on CS2 or CS3 that cost substantially less and upgrade later if you choose. Alternatively, get Adobe Photoshop Elements 7 currently listing at $100. Adobe Photoshop Elements is an excellent photo manager and in addition has most of the key features of Photoshop CS4. We will use these packages to isolate our creations, place them on non-distracting backgrounds, remove reflections, combine multiple separate images and display them with simulated studio lighting. It is this last feature that allows us to eliminate flash and lighting equipment from the equipment list.

I will use my own photos for this tutorial, but in the interest of making this and interactive tutorial, if I get a request from a few readers to attempt something on their photos, I will accommodate them – as long as I don’t get too many that is. This concludes the introductory installment. Each installment will be titled “Woodworkers And Digital Photography – Part 1″ and numbered sequentially until the final which will be titled “Woodworkers And Digital Photography – Final Part”. This will make it easy to find all installments if you don’t follow along regularly. See you later.

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One Of Many Transformers DownThe weather forecasts all included major storm warnings for the New England and Eastern New York area. I read them all and fully expected a nasty day. But as usual I automatically downgraded the forecasts in my mind. After all, in this day of class action suits we all know the forecasts are significantly biased to the worst case.

So I spent Thursday evening, December 11, 2008, watching the news until CNN was lost due to bad weather – a common occurrence with satellite. I switched to a movie channel and began watching – you guessed it – Class Action. A few minutes into the movie power went out. It returned a few minutes later.

About three quarters into the movie the power went out again – approximately 9 pm. It didn’t return. I went to bed with a flash light and read.

Looking Up My Driveway While Standing On West StreetThe following morning I was to leave early for Boston to see my daughter sworn in and licensed by the Massachusetts bar. This was a proud moment for me.

When I awoke the power still hadn’t returned. A cold shower was the worst I thought I would suffer. However, when I looked out my window I could see power lines and trees down in my driveway. I thought "the power outage must be limited to me and my daughter’s house" (my eldest daughter who lives on the same driveway as I).

The Storm Can Be BeautifulThen it dawned on me – trees and power lines are blocking my driveway. I ventured outside and walked the length of my driveway to the street. My heart sunk. I wasn’t going anywhere. I still had phone service, though my daughter did not. I called the power company and they informed me that this was a major storm affecting most of eastern New York and New England, perhaps a million outages.

Broken hearted and somewhat depressed, not to mention a little angry that the gods picked that particular day, I called to inform my daughter. She would soon be an officer of the court; I would miss the day we both had been waiting for.

I spent from 9 pm on Thursday evening until 1 pm on Sunday with no heat, electricity, and only what water was in the tank. The nights ranged from 7 to 17 degrees. The days were in the 20s. The house was literally freezing and I was afraid my pipes would freeze. I called my brother and he informed me his son-in-law had an extra generator. On Sunday my nephew and brother delivered the generator from Westerlo, New York.

After nearly three days without energy of any kind my house feels like the Ritz Worthington now. Power is still not restored. But this is comfort I can live with.

Beauty & The BeastI would like to say that even though we are still without power, the work of the Worthington Volunteer Fire Department, the Western Massachusetts Electric Company and all the visiting tree services and power companies from all over the US, and Verizon has been exceptional. These people are working in the cold, wet weather 24/7 and doing yeoman work. My thanks to them.


Merry Christmas Well it never fails. I just returned from a Lie-Nielsen tool show in Sturbridge, MA. An LN-62 followed me home like a new puppy.

I had it in mind to buy the large scraper plane for finishing figured woods such as tiger maple. I actually bought it. But Chris Becksvoort was at the show and after a long conversation he convinced me that a better option was the Low Angle Jack and several blades.

With each blade sharpened to a different angle, from the stock angle to 50 degrees (62 with the bed angle of 12 degrees), I would have several well tuned tools in one and could then select the best one for the job. I had actually heard this argument before from Chris Schwarz. So I gave the LN 62 a go, right there at the show, on some particularly tough grained tiger maple. It worked beautifully. It left the surface smooth as a baby’s bottom.

I canceled the Large Scraper order and substituted the LN-62. I am happy to report that both Chiefwoodworker and LN-62 are doing well.

Now the saw is a different story. I am known in my family as a hum bug kinda guy (it’s not really true, I just like to pretend). My family is always trying to find ways to get me in the Christmas spirit. So my son and daughter-in-law gave me this saw, intended to be a welcoming sign for my shop during the Christmas season. But I thought I might clean it up (get rid of all that paint), sharpen it and add it to my fine tool collection. I have some sawing I have to do this week and this saw should work just fine.

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Wall Hanging Hand Tool Cabinet - Doors ClosedFinally finished except for hanging chisels, screwdrivers, measuring devices, coping saws etc. in the doors. The tiger maple really shows itself, especially the door panels. The panels were originally from one very wide board, but owing to the tangential curvature of the plain cut, the center of the board didn’t have much figure. It all appeared on the outside of the board. So I ripped the boards down the middle, turned the two pieces so that all the figure was in the middle and glued them back together. Then I used my band saw to re-saw the boards to achieve 1/4 inch thick panels. Finally, I cut the panels to width keeping the glue line in the center. The result is a highly figured panel that shimmers in the light.

Wall Hanging Hand Tool Cabinet - Doors OpenThe is one significant change from the original SketchUp model. I made the drawers twice as wide reducing the number from four to two. This allows me to place things that are over one foot long in the drawers. In the picture at right you can see that I have yet to hang any tools in the doors. Placing tools is a very personal task and is best done over time as you understand how you will use the cabinet and the tools inside. It may take me six months or more to fully utilize the cabinet space. You can see that I have made room for planes I intend to buy in the future. Also there are shelves for some consumable materials that are frequently used and need to be close by, such as pocket joinery wood screws.

Wall Hanging Hand Tool Cabinet - Drawer OpenThe drawers currently contain my measuring devices, marking gauges, marking knives etc. Much of these things will also end up in the doors. It is unclear what the final use of the drawers will be. Originally the design had no drawers, but I was convinced by many woodworkers who had built their own chests to include a few. I generally find them a catch all, and hence difficult to organize. We will see.

Believe it or not, I paid about $1 a bd ft for the material. I almost never pay more than $2 bd ft for any of my wood. I have cultivated local sources and even cut my own on occasion. See http://www.srww.com/blog/?p=28 for a better explanation.

The project requires approximately 70 bd ft depending on your estimate of waste. Wall Hanging Hand Tool Cabinet - Drawer Full

I never keep track of my hours since this is a hobby and this project dragged on due to other family events and trips. Also, there is a lot of hand dovetailing, hand planing and hand sanding in this project, which takes quite a while. If I were to estimate the time it spent it would be a pure guess. That said, maybe 60 hours. But that is 60 hours of pure joy!

I may post one final update six plus months down the road when I have the cabinet full of woodworking toys. Til then, happy woodworking!

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