Sunday, August 28, 2011

Perspective And Long Lenses

Long lenses definitely have their place when photographing distant subjects. Mention wildlife or sports photography and one instantly thinks of enormous telephoto lenses capable of photographing insects from a distance of one mile. Sorry to disappoint, but there aren't many lenses with that level of magnification.

This shot was taken in Richmond during a sand lot sporting event. Exposure was F 5.6, 1/2000 second, ISO 200. The lens, a 70-300 variable aperture lens, was set to 5.6 which is nearly wide open when the lens is set to 190mm, as it was in this photo. Megan, in the foreground, appears to be touching her brother Brandon, even though they are separated by a distance of nearly 3 feet.

Long Lens Perspective: Long lenses are believed to have a "flattening" effect, which is to say they bring the background closer to the foreground. I contend that it's the distance, not the lens, that creates the effect.

To illustrate, I mounted a 18-200 zoom lens on a D1X body and set it to 18mm. The camera was mounted on a tripod and the camera leveled with Kermit. This first image was taken at a distance of 2 feet.

All  of the images would be photographed at 1/6400 at F 5/6 at ISO 800. 5.6 was chosen because it was the largest aperture available at all focal lengths. No exposure adjustments were made, but the images were cropped square.

After the shot was made, the tripod was moved along a reference line in the pavement.

For this first pair of photos, I doubled the distance to 4 feet. The photo on the left was with the lens set to 18 mm. I then increased the focal length (zoomed) until Kermit again nearly filled the frame from top to bottom. Notice the scale of the background when compared to Kermit.

For this second pair, the distance was doubled again. The shots were made at 8 feet with the left shot at 18mm and the right shot zoomed in. Again, the background appears larger and less distinct than before.

This final pair of shots was made at 16 feet. Again, the left shot was at 18mm, while the right was made with the lens at 200mm, the longest focal length available. Now the background is barely recognizable, and Kermit is clearly the focal point of the photo.

Foreshortening: Foreshortening occurs when the background is rendered smaller in size when compared to the main subject in the foreground. While it is obvious that distant objects should be smaller, it is easy to overlook problems associated with foreshortening, especially when working at short distances.

If you look closely at the first image of Kermit (taken at 2 feet), you'll see that his feet appear to be as large as his head. In the image on the right, taken at a distance of 16 feet, you will see that the relative size of Kermit's foot is smaller than what we might expect. These two images illustrate foreshortening at both extremes. You need to remember that it's the distance to the subject that creates the disparity between the images and not the focal length of the lens.

This problem is generally associated with wide angle lenses, since they are often used whenever it is necessary to photograph a wide subject at close range. This shot, made during San Francisco's Carnaval in 2011, shows a group of dancers standing on the street. I used a Vivitar 283 flash mounted on a monopod, triggered by an extension cable passing through a Wein Safe Sync. The exposure was 1/2000 at F 8.0, ISO 200, which gave me an image that was underexposed by one stop. Ooops. Click on the image for a closer look.

If you look closely, you will notice that the fourth dancer from the left has her arm outstretched toward me. You will notice that her hand appears disproportionately large when compared to her head. This is how foreshortening sneaks up on you when you're in a hurry. The group's choreographer thought this would be the most theatrical pose, but as you can see, it doesn't work when you are forced to shoot at close range.

If I were to photograph this group again, I would have had them all position their arms nearly touching the dancer beside them. This would keep the hand within the same image plane of the face, minimizing the effects of foreshortening. 

Of course, if we did everything perfectly 100% of the time, our lives would be totally boring. At least, that's what I'm telling you.

Sunday, August 21, 2011

Variable and Fixed Aperture Lenses

I made a series of photos at an Arena Polo competition held at Horse Park in Woodside California. In many ways, the photos were what I expected, given the lighting conditions and the vantage points that were available to me.

My editor was pleased with the day's take, and asked the question, "What was the film speed?" She knows that film sensativity has a digital counterpart and that there is a relationship between a high ISO setting and correspondingly short exposure times. The data from this photo, recovered using Opanda, indicated my zoom lens was set to a focal length of 200mm. I normally shoot in Aperture Priority mode with an outdoor EV correction of - 1/3 stop. I had set the ISO to 400, while the shutter speed chosen by the camera was 1/8000 at my selected aperture of f 3.5.

A shooting aperture of f 3.5: What manner of magic is this?

For starters, the photo wasn't made with a lens that you'd normally find at a big-box electronics store. And the lens definitely didn't come with the camera body when I bought it. In short, it wasn't a kit lens.

Variable Aperture Zoom Lenses: I am sure that the first lens that you mounted on your digital SLR was a "kit" lens. These are inexpensive but often surprisingly sharp lens designed to meet a price point consistent with your new camera body. They are usually sold as a package, or "kit", with the body. Because of the lower price point, they are designed to be inexpensive to manufacture. And while they can be quite sharp when stopped down, they are usually "slow" lenses, having optical elements that are relatively small in diameter. Another compromise is what I call the "variable aperture syndrome". This means that the maximum f-stop decreases when the focal length increases.

Try this experiment:
  1. Turn off your camera.
  2. Mount your kit lens on your camera body.
  3. Set the lens focal length to the shortest possible setting (lowest number on the zoom ring).
  4. Set the Mode Dial to Aperture Priority.
  5. Rotate the Sub-Command Dial on the camera body until the largest aperture (lowest value) appears in the  Control Panel.
  6. Rotate the Zoom Ring on the lens to increase the focal length (higher values).
As you rotate the Zoom Ring, you will notice that the your original 3.5 aperture will re-set to smaller maximum aperture settings. Taking the typical 18-55mm Nikkor AF-S G series kit lens, you should see the following apertures at the following focal lengths:
  • 18mm:  f 3.5
  • 24mm:  f 4.0
  • 35mm:  f 4.8
  • 45mm:  f 5.3
  • 50mm:  f 5.6
A similarly priced lens, the  55-200 AF-S G lens has similar numbers:
  • 55mm:  f 4.0
  • 70mm:  f 4.5
  • 85mm:  f 4.8
  • 200mm: f5.6
I jumped over some of the intermediate focal lengths, but I think you get the idea.

This exercise is to point out that when  you need a longer focal length to "reach out and touch" a distant subject, nearly all zoom lenses will get incrementally "slower". In the first example, the lens' effective f-stop value of 5.6 at the 50mm setting now requires 1 2/3 more light when shooting wide open than it did at 18mm. In the 55-200, the loss is one stop when going from f 4.0 to f 5.6. Another shortcoming is the decreased light through-put which makes your focusing brackets that much less sensitive. It's all bad.

Prime Lenses, Fast and Cheap: In an earlier post I referred to two non-zoom lenses (called fixed focal length, or prime, lenses) that, by comparison, allowed much more light to pass through. These would be the 35mm 1.8 and the 50 1.8 lenses, each costing a little more than  $200.00 to own. If you plan on doing much low-light work, consider buying, or renting, one of these lenses. However, if you only have prime lenses and decide that need a different focal length of your lens, expect some delays while you change lenses.

Nikon still manufactures prime lenses for lens "purists" and those photographers who need ultra high speed lenses. Be warned, when you venture beyond the so-called "normal" lenses, the prices can be astronomical.

Fixed Aperture Zooms: For rapidly changing situations, the zooms definitely give you an edge. As the action moves to and fro, you can zoom in and out to optimize your framing and composition. But the variable aperture lenses will reduce your maximum aperture as you zoom in for a close-up. You can get around this by considering a fixed aperture zoom lens. Another shot, 1/3200 @ f 4.0, can be seen here. It appeared in the August 22 edition of the San Mateo Daily Journal. Click here to read the original article.

Both Canon and Nikon have set the standards for fixed aperture zooms. For the most part, the "sweet spot" for these lenses is a consistent maximum aperture of 2.8, with a focal length range of from 70 to 200mm. This combination of maximum fixed aperture and focal length range has been a "must have" for working photographers for many years. The big advantage of the 2.8 lenses at the long focal lengths is the relatively large amount of light available for the auto-focusing sensors. The more light that is available, the more responsive the focusing system.

While I was using a Nikkor on this assignment, I could have just as easily used a Tamron 70-200, and lens that I also own and have found to be a great performer. While it lacks the Nikon's Vibration Reduction and AF-S internal focusing, the Tamron performs well, especially after it is stopped down a bit. It is also reasonably priced, and therefore a viable candidate if you are looking for a longer lens. Remember that if you buy any lens that is NOT AF-S, you will be stuck focusing manually if you have a D40, D60, or a D5000/D3000 variant.

Monday, August 15, 2011

Calumet Wireless Trigger Kit

April 3, 2015:  Sorry for the late update. Calumet has downsized considerably, leaving only its three Illinois rental/retail stores. They do not appear to have an on-line retail presence. I don't know if this unit is still available.

Photo from
The most pleasing photographic light does not come from a speedlight locked in the hot shoe on top of your camera.  On-camera lighting, when used as a main light source, eliminates any sense of three dimensionality in your subject while introducing pronounced specular highlights (think shiny white spots). If we could remove the speedlight from the camera's hotshoe and place anywhere we wanted, we could introduce a dozens of variations of light and shadow, therefore adding depth to our subjects. 

We can fire our speedlights by connecting them physically to our camera bodies. By utilizing a Nikon AS-15 hotshoe to PC adapter and a properly configured PC cable, you can hard-wire your  speedlight to your camera, but the cable can be a darn nuisance*. However, it is a relatively cheap and reliable solution. For a Strobist's take, click here and here

Photo sensitive slaves will also work providing you keep your flashes within the prescribed maximum transmission distance and the slaved units are in the "line of sight" to the master unit. It gets worse. The photo sensitive slaves would respond to any flash fired within range, definitely not the best solution when working in a crowd.

Enter the Calumet Wireless Trigger Kit. At about $75.00, the Nikon version is significantly more expensive that the E-Bay wonders, but it has some important features that are worth looking into. Those features include:
  • Full ITTL control of a suitable Nikon speedlight when mounted in the hot shoe of the transmitter unit. This means that you can combine conventional non-ITTL flashes (used manually) with properly configured Nikon remote speedlights.
  • Receiver units can be used to trigger a variety of Nikon DSLR bodies wirelessly. Three receiver cables are provided, allowing your transmitter to mimic the Nikon MC DC1 (D70s, D80), MC DC2 (D90, D3100, D5000 & D7000 ) and the MC 30 (D300, D3, etc) cable releases.
  • Both receiver and transmitters use 2 AAA batteries. No exotic batteries for these babies, just easy to obtain AAAs.
  • Additional receivers can be purchased to trigger other non-iTTL speedlights Think $50.00.
I'll be playing with the units in the near future, and will report on how well they work in a future post.

For more information, click here.

*If you are connecting a (Nikon brand) speedlight that has  a supplimentary PC outlet you will need a PC cable with male connectors at both ends. If you can locate the genuine locking Nikon PC cables (SC-11 or SC-15), so much the better. Also remember that you'll need to protect your camera from high triggering voltages with a Wein Safe Sync when using non-Nikon speedlights.

Sunday, August 7, 2011

I See 'Um, I Gotta Buy 'Em

There are some things in this world that you can't have too many of. Take electronic flashes, or Speedlights, as Nikon calls them. I will admit that Joe McNally is my hero in this regard. He often creates incredible photographs using a dozen or more Nikon speedlights, placed singly or in groups, to achieve spectacular lighting effects. Remember that phrase, "in groups", as this was my reason for accumulating the dozens of speedlights I now own.

David Hobby first advocated buying older Nikon speedlights when nobody else wanted them. If you followed his blog, you would know that he's a fan of the older, non-iTTL units since he would use them in the manual mode exclusively. In addition, these older units could be triggered using either their external PC ports or their hot shoes, so that wireless and optical triggers would have two contact points. Another advantage is their ability to use the  locking Nikon PC cables that positively stay attached. Hobby's top choice of the Nikon non-iTTL units is the SB-26 because it has a built in optical slave to simplify multiple flash setups. When set to manual, you can reduce the output to 1/64 power in 1/3 stop increments. Add to this a 270 degree rotating (180 degrees counterclockwise, 90 degrees clockwise) and tilting head with a manual zoom from 24mm to 85mm (the built-in wide-angle diffuser increases the spread to accommodate an 18mm lens) and you have the deal of the century. While they are still available on E-Bay, the price has gone up considerably, often going for about $150.00 or more. However, they also turn up in camera stores from time to time, so keep your eyes open. I found one at Keeble and Shuchat in Palo Alto, California, for $70.00. It was in pretty good shape, complete with gaffer tape and Velcro firmly attached. A little Goo Gone and I now have a high build-quality flash for a very good price. A point to remember: the flash came without a box or instructions, so you may need to acquire a manual somewhere. One place to check for instructions for obsolete Nikon speedlights is Nikon USA. Click here if you want to download a PDF of the SB-26 user manual. If worse comes to worst you could probably find a copy of the original manual on EBay. Hey, read and memorize the darn thing and sell it back on E-Bay! If you find an SB-26 or any other piece of discontinued equipment, remember to ask about the return policy if your purchase doesn't work. If you're really on the hunt, keep a set of batteries with you, just in case you need to try something out. For some additional information on the SB-26, click here.

If you're wondering about the two silver pins just below the red face plate, they are two of the three contacts that connect the flash to the Nikon SD-8 or SD-8A supplementary battery pack. The contacts are normally covered by a plastic cover plate. I assume that the former owner used one of these power sources because the plate was missing when I bought it. No great loss.

Another Nikon Speedlight to consider is the SB-80. When in manual mode, the output can be reduced to 1/128th of full power. It too has a built in slave and an external PC port. It is smaller than the SB-26, and appears to have the same body dimensions as the now discontinued SB-800. This will make it easier to fit the Lumiquest CTO filters that you'll eventually want to get. It too is overpriced, just like the SB-26.

Next on my list of things to watch for is the SD-8 power supply for  Nikon speedlights. Now before you remind me about the Chinese knock-offs, listen to this. The SD-8 power cable will not fit the current SB-800 or SB-900 flashes, but for about $20.00 plus shipping, Nikon will replace the cable with one that will. If you can score a clean SD-8 for $20.00 ($30.00 in 2015) and send it to Nikon for a new cord, you can have a power supply comparable to the $150.00 SD-8A for a fraction of the cost. So a used SD-8 is definitely worth looking for whenever you find used photo equipment for sale. I've bought them for as little as $20.00 plus shipping a year ago. One last bit of trivia: If you're wondering about the little screw/s in the middle of the body, they are there to cover a 1/4 hole in the battery pack. There apparently was an OEM screw that passed through the hole, allowing you to attach the battery pack to the tripod socket in the base of the camera. I almost owned one such screw, but it was apparently lost in the mail, never to be seen. The Chinese knock-offs include the screw, strange as it may seem. This one is shown without its nylon cover.

Addendum - September 24, 2015: Nikon no longer offers the cable replacement. I just had two SD-8's returned, unmodified. I have plenty of older Nikon Speedlights that can use the battery boost. I just have to find a way to keep them from getting mixed in the the SD-8a compatible upgrades. Maybe this is why there were so cheap.

Last but not least, the SC-17 flash extension cable. This is the gray colored cable with the screw-type lock at the hotshoe/camera end, and a 1/4 x 20 thread at the speedlight end. There is some misinformation on the web about the compatibility of this cable with current production (SB-700, SB-900) flashes. For the record, the gray SC-17 flash will function properly in the TTL mode with these two flashes, but will NOT function when you attempt to use any of the iTTL features. This means that an SB-900 connected with an SC-17 will not function in the commander mode. But if you are using only one flash, the extra 3 feet can give you a solid, hard-wired connection if you choose to put your speedlight on the end of a stick. It also works in High Speed FP sync mode. I've seen SC-17s for as little as $10.00 at camera swaps, but not very often.

If you're lucky enough to own a D40, D50, D70/D70s, or a D1/D1X/D1H camera body, you can synchronize you flash at just about any speed. A simple modification to the SC-17 will allow you to use the cable to access those higher sync speeds. Click here for read David Hobby's original article.

Disclaimer: A quick note that bears repeating: Buying used equipment always carries the risk that the item may not work. For simple (and relatively inexpensive) items like cables, you pay your money and take a chance. When the items get more expensive, you may do better check on the vendor's return policy. Many "brick and mortar" stores will give a 14-day trial period so you can test your purchase. Some on-line vendors will offer similar, albeit shorter, return periods should the item not function.