The Sunny f/16 Rule

Many photographers rely completely on exposure data from their camera’s built-in light meter.  In today’s world of matrix metering on sophisticated digital cameras, this produces good results under many lighting conditions lighting conditions.  However, most early vintage cameras do not have light meters, and even a highly automatic light meter is not automatically right.  Experienced photographers frequently employ an extraordinarily useful rule of thumb known as the “Sunny f/16 Rule.”  This simple rule states:

On a sunny day, for correct exposure, set the camera’s aperture at f/16 and the  shutter speed to the reciprocal of the ISO film speed.

In other words, when shooting Tri-X, ISO 400, on a sunny day with no haze or cloud and a front-lighted subject, a perfect exposure will be obtained by setting the aperture to f/16 and the shutter speed at 1/400 sec.  For practical purposes, the nearest calibrated shutter speed of 1/500 will do fine.  For Panatomic-X at ISO 100 on the same sunny day, optimum exposure will be obtained with f/16 at 1/100 sec.  For other film types, just plug in the ISO film speed as the reciprocal of the shutter speed.

This rule is important for three reasons:

  1. It allows one to work without a light meter.  There are situations where experienced professional photographers do not use their exposure meters, but depend on this rule.
  2. Since the amount of incident light from the sun is quite constant (at least in the latitudes that most of us occupy) the rule can be used as a way of checking the accuracy of one’s light meters.
  3. Light meters measure either incident or reflected light (see Sekonic’s site for a discussion of incident vs. reflective metering).  Incident light readings, measuring the amount of light falling on the subject, are most accurate, but must be taken with the meter close to the subject.  Depending on the circumstances (see below), this may be impractical.  Reflected light measurements are most common (all on-camera meters measure reflected light), but the amount of light reflected toward the meter depends on the lightness of the subject.  Since most meters are calibrated to the amount of light reflected from a 14-18% neutral gray surface, it is necessary to adjust the reading for darker or lighter subjects.    The Sunny f/16 Rule, representing really the ultimate measure of incident daylight falling on the subject,  bypasses these problems, and is surprisingly accurate.

Incident Metering is a Bad Idea. Use the Sunny f/16 Rule

This rule can be tabulated for different film speeds as follows:

ISO 100 Sunny f/16
1/50 1/100 1/200 1/400 1/800 1/1600
f/22 f/16 f/11 f/8 f/5.6 f/4
ISO 200 Sunny f/16
1/100 1/200 1/400 1/800 1/1600 1/3200
f/22 f/16 f/11 f/8 f/5.6 f/4
ISO 400 Sunny f/16
1/200 1/400 1/800 1/1600 1/3200 1/6400
f/22 f/16 f/11 f/8 f/5.6 f/4

The Sunny f/16 rule can be extended to other lighting conditions, producing a table similar to that provided by many manufacturers on their film packaging:

Sunny
Distinct Shadows
Hazy Sun
Soft Shadows
Cloudy
Barely Visible Shadows
Overcast
No Shadows
F-Stop f / 16 f / 11 f / 8 f / 5.6
ISO 100 1/125 1/125 1/125 1/125
ISO 200 1/250 1/250 1/250 1/250
ISO 400 1/500 1/500 1/500 1/500
ISO 800 1/1000 1/1000 1/1000 1/1000

An extremely detailed tabulation of empirical exposure settings for a variety of light conditions is available on Karen Nakamura’s Photoethnography web site under the “Exposure” tab.

References:

Author Unknown.  “Guide to Film Photography:  The Sunny 16 Rule.”  http://guidetofilmphotography.com/sunny-16-exposure.html.

Folds, Ben.  “Sunny 16 Rule.”  http://en.wikipedia.org/wiki/Sunny_16_rule.

Glatzer, Charles.   “Sunny f/16 Rule.”  http://www.photomigrations.com/articles/0403200.htm.

Nakamura, Karen.  “The Science of Photography:  Exposure.”   Photoethnography web site.  http://johnlind.tripod.com/science/scienceexposure.html.

Ratty Brian.  “Understanding the Sunny f/16 Rule.”  http://www.photomigrations.com/articles/0403200.htm.

Sekonic Inc.  “Incident vs. Reflective.”   http://www.sekonic.com/classroom/classroom_2.asp.

The Store by the Road

The Store by the Road

Driving down the road late in the year in southeastern Washington, my eye was caught by this abandoned store under the naked limbs of a grove of huge maples.  Peering through the windows, I was barely able to discern piles of old furniture and discarded office equipment. The back porch was piled high with eddies of dried leaves that rustled with each swirl of  the chill autumn wind.  I propped my little pocket tripod on the hood of my car and took this image on XP-2 with my 1928 No. 1 Kodak using the f/6.3 Anastigmat at f/16.

Selecting A Vintage Camera IV: The Baby Pacemaker Crown Graphic

Pacemaker Crown Graphic with Kalart Rangefinder

For those who want to take a step up in technical capability, gaining ground glass focusing, basic camera movements, depth of field correction, interchangeable lenses, interchangeable film backs, and the ability to use short focus, wide angle lenses, yet still retaining the convenience of 120 roll film, stepping up to a minature (2 x 3 in format) “Technical” camera is the logical next step.  However, most of these, such as the Linhof, are quite expensive.  However, if one wishes to combine a reasonable price tag with most of these functions, the 2×3 Baby Pacemaker Crown Graphic is an amazing little camera.  Manufactured between 1947 and 1958, this small Pacemaker Crown Graphic is essentially a miniature large format camera boasting, with the exception of somewhat limited movements,  most the of the features  of a Linhof-type technical camera.

The Pacemaker Crown Graphic is a member of the class of cameras known as press cameras, the name deriving from the fact that these cameras were originally designed for use by press photographers.  Consequently, they were tough, well designed, enormously versatile, and capable of exacting results under the most difficult circumstances.  Although they were produced by many manufacturers, including Burke and James, Pressman, Linhof, Omega and Meridian, the term “Press Camera” will always elicit images of the ubiquitous Graflex cameras, especially the famous Speed Graphic and Crown Graphic.  Although originally aimed at journalists, the Graphic cameras became the workhorses for both art photography and general purpose commercial photography such as weddings, portraiture, product photography, documentary photography, and advertising.

The Graflex at War

The Speed Graphic was the still camera of World War II, and took many of the most famous images of that conflict.  On the home front, the most famous press photographer of them all, Arthur Fellig, a.k.a. Weegee, prowled the streets of New York with his Speed Graphic.

Weegee

After his first job selling candy, Arthur Fellig worked in a photo studio, a darkroom, and a photo agency before becoming a freelance news photographer in1935.  Specializing in the night shift between 10 pm and 5 am, he quickly became known for his gritty images of murder victims, fires,

Weegee at his Typewriter in the Trunk of his Chevrolet

and tenement life.  Installing a shortwave radio capable of receiving all police and fire transmissions in his 1938 Chevrolet, his reputation spread quickly for always being the first to arrive at a murder scene or fire.  Weegee’s nickname was a phonetic rendering of Ouija, due to his frequent, seemingly prescient arrivals at scenes only minutes after crimes, fires or other emergencies were reported to authorities. It is unclear whether he named himself Weegee or was named by the girls at Acme Newspictures. Weegee became one of new York’s best known and most flamboyant news photographers.  He went on to become involved in motion pictures and published several books, including the autobiographical Naked City, which inspired the movie of the same name.

The Confusing History of the Graflex/Graphic Name:

The folks who made the Graphic were as bad at naming their products as they were skilled at building cameras.  Consequently, it is worth noting the evolution of the Graflex company, particularly as it pertains to the nomenclature of the cameras and camera backs.

Original Graflex Reflex Camera

In 1887 William F. Folmer and William E. Schwing entered into partnership to establish a bicycle company, the Folmer and Schwing Manufacturing Company,  in New York City.  The company branched into camera manufacture, and in 1898, Folmer built the first of the famous 4×5 Graflex reflex cameras.  Since it was a single lens reflex, the original Graflex camera had no need for a ground glass focusing screen.  Film holders, film pack adapter backs, cut film magazines and roll film backs slipped into a channel on the bottom, and a sliding bar locked them in place from the top. These film holders and roll film backs are referred to as “Graflex” holders, and “Graflex” roll film backs, named after the camera they fit.  Many of Omogen Cunningham’s famous photographs were taken with her beloved reflex Graflex.

The firm was purchased by George Eastman in 1905, and in 1907, became the Folmer and Schwing Division of Eastman Kodak.   In 1926, as a result of a court order, this division of Eastman Kodak Company was offered for sale, but no buyers appeared. Consequently, the Folmer Graflex Corporation was organized in 1927 to take over the assets of the Division.  After a few more changes of status and name, the company finally became Graflex Inc. in 1945.  In 1956, it was purchased by General Precision Equipment, and in 1963, it was sold to the Singer Corporation.  Production ceased in 1973.

The company’s most famous product after the Graflex, the Speed Graphic, was a non-reflex press camera which  required a ground glass focusing screen.  The earlier models, produced 1912-1946, had a modification of the Graflex back with an integral, non-removable glass focusing screen.  This was designated as the Graphic (note the “ph”) back, or “Spring Back.”  In the Graphic back, the focusing screen was mounted in a frame on two pieces of spring steel which allowed it to be lifted away from the focal plane; the sheet or roll film holder would be placed under the frame, and the springs would hold it tight against the camera back.  This arrangement caused problems with roll film holders, with the early holders having to be partially disassembled and reassembled once they were in place on the camera.  Film holders for the Graflex and Graphic backs are not compatible.

Graphic Back with a Film Holder in Place

The next advance (and the introduction of one more name) was the introduction of the cast magnesium Graflok back, introduced in 1949. This is molded as part of the body, except for the “Super Graphic” and “Super Speed Graphic” models, which had rotating Graflok backs.  These backs accept accessories designed for either the Graphic or the Graflok back.

The Graflok back has two retention systems. Each system is a quick-release type. One system retains the focusing screen and hood assembly and the other system retains accessories such as roll film backs.

  1. The focusing screen and hood assembly has a pair of spring-loaded arms that engage a matching pair of hooks cast into the Graflok back. The arms are disengaged by pushing in on them; the focusing screen and hood assembly can then be slid slightly to the right to remove it from the back.
  2. A pair of sliding metal plates cross the back, one above and one below  the opening. These plates engage matching slots on the removable roll film backs.

Cut film holders are retained under the Graflok focusing screen and hood assembly in the same manner as with the Graphic backs. Cut film holders are interchangeable between Graphic and Graflok backs.  The Graflok system has been adopted by other manufacturers.

The Graflok Back

This hopefully will clarify the Graflex with an “f”/Graphic with a “ph”/Graflok situation.  This is an extremely confusing nomenclature, and photographic chat rooms frequently display messages from unfortunate individuals who have purchased a Graphic camera with an early Graphic back, only to discover that accessories for the back are difficult to find.  This is very perplexing, and causes newcomers endless frustration.  The degree of inconsistency engendered by this fine company’s permutations of nomenclature can be best appreciated when one considers that Graflex Inc, which did not exist until 1945,  never made the Graflex camera.  Furthermore, roll film holders for the later Speed and Crown Graphic (the majority of what is available on eBay) are prominently labeled as “Graphic” film holders, but, although they will fit a Graphic camera with a Graflok back, will not fit a classical “Graphic” back.

Manuals:

Copies of the manufacturer’s original manuals are available on Mike Butkus’ wonderful manual library at Orphancameras.com at http://www.butkus.org/chinon/.  The specific addresses for the Graphic manuals are noted in the references below.

Speed vs. Crown Graphics:

As noted, the model designation of Graflex cameras can be confusing, and the amount of literature on these ever-popular cameras, many of which are still in use today, is daunting and beyond the scope of this essay.  Suffice it to say that the Graphic press cameras of the mid-twentieth century can be divided into two main classes:  The Speed Graphics, which are equipped with a focal plane shutter in addition to the leaf shutter on the lens, and the Crown Graphics, which lack the focal plane shutter but are capable of working with lenses of very short focal length.

The Speed Graphics’  focal plane shutter is located within the camera body in front of the film plane.  This allows use of  lenses that do not have attached shutters (known as “barrel” lenses); however, this feature is of limited use.  In fact, for landscape and many other types of photography, the focal plane shutter is a decided hindrance, because it places an extra object between the film plane and the lens, precluding the possibility of using very short focal length lenses.  The Crown Graphic is unique in that the focusing track is hinged and extends into the case, allowing the front standard to approach very close to the film plane, and permitting the use of very wide angle, short focal length lenses.

General Features of the 2×3 Pacemaker Crown Graphic:

The Baby Pacemaker Crown Graphic has a sturdy mahogany body covered with black pebble-grained leather.  It is equipped with a Grafloc back that accepts a flip-up viewing hood, Graflex roll film holders, standard 2 x 3 in sheet film holders, and Graflex film magazines.  Like most press and technical-type cameras, the front cover folds down to form the front bed, revealing the double-extension focusing system controlled by two focusing knobs at the front of the bed (the 2×3 Graphic lacks the focusing lock noted in the image).

The Pacemaker Crown Graphic, Front View

The Graflex cameras have three ways to compose the image:  through a tubular viewfinder, apparent in the initial image at the beginning of this posting, via a pull-up press-type viewing frame incorporated into the front standard, and on the ground glass.  The tubular viewfinder is quick, but relatively small, and has adjustments for parallax.  It was originally provided with interchangeable masks for telephoto lenses, but these have such a narrow field of view that they are universally agreed to be unhelpful.  My viewfinder is masked for my 101 mm Ektar, and for other lenses, I use the ground glass.  The wire front frame finder is cleverly designed, pulling upward from the top of the front standard, and having click stops once it is extended to compensate for parallax.  It covers a field which, once again, is set for an approximately 100 mm., or “normal” lens.  For exact composition and focusing, the ground glass focusing screen is still the best option.

Movements:

The Pacemaker Crown Graphic has limited front movements, and no back movements. However, for landscape photography where the most critical adjustment is a modest amount of forward tilt to maximize depth of field, this repertoire is sufficient in horizontal orientation.  It should be noted that movements on the Graphics are accomplished in a somewhat unusual manner, but become second nature with a little practice.  There is one significant limitation however: the absence of front swing.  This is not a great problem in horizontal orientation, but does become a significant deficiency if one wishes to use the camera in the vertical orientation.  Since the back does not rotate, forward tilt when the camera is on its side for a vertical image would require a front swing, and this is not possible.  There are some mentions of modifications to the front standard to permit swing to be added, but the references are not readily available.

Front Shift:

To shift the front standard laterally, release the locking lever used to pull the front lensboard from inside the camera body. Press down on the small tab just below the lever, then slide the standard to the left or the right. Try not to move the front standard backward or forward after it is unlocked.  The amount of front shift is more limited when using short focal length lenses because the bed supports interfere with the full range of shift movements. With longer focal length lenses and more extension, there is no interference, and more shift is available.

Front Tilt:

The Pacemaker Graphics have no forward tilt, but possess a moderate degree of backward tilt. Forward tilt is accomplished by combining the drop bed with a moderate amount of front rise and varying degrees of backward tilt. After the bed is dropped, the formerly vertical front standard will point downward. In effect, this is a severe front tilt combined with a front fall. To correct this situation, apply front rise to bring the lens level with the film.  The amount of forward tilt is then determined by the degree of backward tilt.  With the full amount of back tilt, front tilt is zero, and the lens is parallel to the film plane.  With lesser amounts of backward tilt, the front standard and lens are effectively tilted forward.  This sounds unbelievably awkward, but is actually quite easy to do.  Setting up this movement is helped by the fact that the bed drop, rise and tilt are set up to coordinate nicely with each other, with a click stop on the bed.

Front Rise:

This is the easiest of the movements to use, and is accomplished by loosening the two knobs on either side of the front standard, raising the standard, and retightening the knobs.

Front Fall:

Similarly, it is possible to apply front fall by dropping the bed, applying full backward tilt to align the front standard with the back (thereby applying the maximum amount of front fall), and using the front rise to attain the desired amount of front “fall.”

Front Swing:

There is no front swing.  This is one movement that would be nice to have, as it restricts movements in vertical orientation.

Back Movements:

The Crown Graphics have no back movements. However, David Karp suggests the following method of achieving a back tilt:  “…it is possible to achieve a sort of back tilt by combining some of the front movements with an adjustment of your tripod head. First, tilt your tripod head back slightly. The degree that you tilt the head back will be based on your experience, because you won’t be able to see the effect of your movements for a little while. Next, drop the bed. Then, apply any necessary front rise. Finally, tilt the front standard backward until it is where you want it. Once you have completed all of these movements, you will be able to see the results of your “back tilt” and can make any fine adjustments.”

Lenses:

A variety of lenses are available for the Baby Graphic.  The one restriction is that the lens boards are small, limiting the selection of lenses to those having less than an approximately 50mm diameter rear element.

The two most common “normal” lenses usually found on the Baby Graphic are the 101 mm. Graflex Optar, manufactured by Wollensak, and the 101 mm Kodak Ektar, both four-element Tessar-type lenses.  The Ektar is an excellent lens (one of the best of the mid-twentieth century) and is capable of producing superb images.  The Optars are also solid lenses, but have a reputation for being somewhat less sharp.  Some Baby Graphics are found with Graflar or Trioptar triplets.  These are of lower quality and should be avoided.  Less commonly, high-quality optics by Rodenstock, Zeiss or Schneider, such as the 100mm Zeiss f/3.5 Tessar or the 80mm Schneider Xenotar can be found.  Another excellent lens that can occasionally be encountered is the 105mm f:3.7 Ektar, which has been described as having “…sharpness and bokah like a Summicron…”  Among modern lenses, the multicoated 100mm Schneider Symmar has been described as an excellent choice, providing top-notch optics with good coverage.

The most common telephoto lens found on this camera is the f/5.6 Graflex Tele-Optar, also by Wollensak, a good quality four-element lens similar to a Schneider Tele-Xenar. However, as far as the best image quality is concerned,  two better options  would be the five-element 180mm f/4.5 Rodenstock Rotelar or the 180mm f/5.6 Schneider Tele-Arton.

There are two common options for a medium wide angle lens, both in 65 mm. focal length; this is  roughly equivalent to  a 35 mm. lens on a 35 mm. camera.  The most common wide angle in this focal length is the 65mm f/6.8 Graflex Optar.  Higher image quality can be obtained from the 65mm f/6.8 Schneider Angulon, an excellent moderate wide angle lens.

One of the best features of the Baby Graphic is its ability to use very wide angles lenses, which can be difficult with some large format cameras.  The hinged focusing track allows the 2×3 Crown and Century (but not the Speed

Crown Graphic With Extreme Wide Angle Lens and Front Bed Dropped

Graphic) to rack and pinion focus these lenses right into the body.  The premier lens for this purpose is the Schneider 47mm f/8 Super Angulon.  47mm focal length on 6×9 cm. is equivalent to a 21-23 mm. lens on a 35mm camera.  This lens, in addition to its wide format, will cover the 6×9 cm.negative with room to spare.  Movements are limited due to bellows compression, but the ability to use this focal length outclasses some cameras with much larger price tags.  It should be noted that, while 65 mm. moderate wide angle lenses can be used on the 2×3 Baby Graphic with the bed in normal position, employing extreme wide angle lenses like the 47 mm. Super Angulon requires that the bed be dropped to avoid its appearing at the bottom of the image.

There are some other, less common lenses that one might consider; I speak not from personal experience but from a perusal of Kerry Thalmann’s Large Format Home Page, in particular his discussion of “Lightweight Lenses.”  For “normal” lenses, one might consider a 90mm. f/6.8 Schneider Angulon, a Dagor-type lens with six elements in two groups.  Postwar coated Angulons or those branded by Linhof are preferred as being of more consistent quality.  The 90 mm. f/6.3 Wide Angle Congo is also a possibility, although the quality of the Congo lenses may be variable.  In the short telephoto range, consider the 150 mm. f/6.3 Fujinon W, a four element, three group, Tessar design; the 150 mm. f/5.6 Schneider Xenar; and the 150 mm. f/9 Schneider G Claron.  In the 180-200 mm. range, the 180 mm. f/9 Fujinon A, the 200 mm. f/8 Nikkor M, and the 203 mm. f/7.7 Kodak Ektar are possibilities.  These all use shutters of Copal #0 size and have a good chance of fitting into the small Baby Crown Graphic lens boards.  It may be advisable to borrow one of these lenses and check the fit before purchasing.  Many of the more modern lenses are singly or multiply coated, with consequent increases in image contrast.  One caution, however: one’s geographic locale should be taken into account when considering lenses of f/8 or f/9 maximum aperture.  While these will be fine in desert sunlight, use of a lens with a maximum aperture f/8 or higher in low light conditions such as my typically overcast and cloudy Pacific Northwest weather and heavy tree cover may be quite a challenge.

Graphic Roll Film Backs:

The nomenclature and evolution of the Graflex camera back and its associated film holders is both complex and confusing.  This has been summarized on the Pacific Rim Camera page “Graflex Backs and Film Holders.”  This entry will focus on the  backs available for the 2×3 Baby Pacemaker Crown Graphic

Graphic Roll Film Holders: Original with Knob Winder (right) and Later Lever Action (Left)

Graphic Roll Film Holders: Original with Knob Winder (right) and Later Lever Action (Left)

Roll film holders for the 2×3 Baby Graphic were available in three formats: 6×6 cm., 6×7 cm., and 6×9 cm. The earlier model holders are designated either as “22” or “23”, the “22” indicating  6×6 cm. (2×2 in.) format, while the “23” indicated 6×9 cm. (2×3 in.) format. With the introduction of the 6×7 format, the designation changed to RH12 (6×6), RH10 (6×7) and RH8 (6×9). The number described the number of exposures obtained on a roll of 120 film. Other holders were designed for 220 film using a different pressure plate.

The original models utilized a knob to advance the film, while later models employed a lever for film advancing.  The designation “Singer”, often applied to these lever-action film holders, comes from the fact that the Singer Sewing Machine Company owned Graflex for some time and marked its film holders accordingly.

There has been considerable discussion about the difference in film flatness between these two models, as the lever-advance models had rollers to hold the film in place.  I use the older model holders and have not had a problem with film curling so far.  Doug Daley, of the Camera Clinic in Seattle, notes that, while the lever-action models have the advantage of the rollers, they also use a lever return spring which has a tendency to break and is almost impossible to replace.

It is important to note that the Graflex holders advance film based on the number of rotations of the internal rollers, not on the appearance of numbers on the paper backing.  Using the numbers on the backing, which is the case for all 120 roll film cameras and the detachable Rollex backs used on vintage plate cameras, ensures that images are evenly spaced.  With the Graflex backs, image spacing is dependent on the gearing built into the back, and can in theory be inaccurate if film thickness changes.  It has been said that modern films are slightly thinner than films produced in the 1950s, and this is a potential source of frame misalignment.

Noting that the edge of my first frame was cut off on my first rolls with the Baby Graphic, I tested frame spacing using a roll of outdated film, tracing each frame onto the film with the dark slide removed.  I found that both of my backs started the first frame too close to the beginning of the roll, indicating that the modern-day Kodak paper leader was slightly shorter than those produced in the 1950s.  After the first frame, image spacing was not a problem, indicating that film thickness for practical purposes was not a consideration.  Noting that there was room for a ninth frame at the end of the roll, I now start my pictures on the second frame, then wind the knob 1 1/2 turns after the last frame to obtain my eighth shot.

The Kalart Rangefinder:

A most useful accessory, found on many Graflex cameras, is the Kalart Rangefinder.  This is most often mounted on the side accessory bar, but may, in later models, be mounted on the top of the camera.  Depending on the amount of use (or abuse) to which it has been subjected, the rangefinder may or may not be functional and accurate.   If not properly aligned, the adventurous reader may undertake to disassemble, clean, and recalibrate the unit.  Disassembly and realignment of the Kalart is well documented at Jo Lommen’s posting “The Kalart Rangefinder.”  One word of caution, however.  Doug Daley, owner of the Camera Clinic in Seattle, notes that trying to readjust the Kalart rangefinder is a “…real pain in the neck…”  If Mr. Daley, who is a master technician of many years experience, feels thus about the Kalart, I would tend to approach disemboweling it with considerable trepidation.  Consequently, one may wish to explore all other possible options before advancing on one’s Kalart with screwdriver and lighter fluid in hand.

If one is fortunate, adjustments to the Kalart can be treated conservatively.  On receiving my Baby Graphic, I discovered that the two images in the rangefinder could not be aligned.  Fortunately, my rangefinder was equipped with the external adjustment screw, and a few twists brought the images into perfect alignment.  Then, using my 101 mm. Ektar, I focused a crisp image at infinityon the ground glass and reset the infinity stops on the focusing rail.  The rangefinder proved to be quite acceptably accurate at all distances, eliminating the need for further adjustments.

It should be noted that the Kalart is best set up for one lens, and changing its calibration to a lens of different focal length is not a small matter.  The Kalart itself is connected via a dedicated cam to a linkage which is in turn coupled to the movement of the front focusing rail.  Resetting the mechanism to a different focal length lens involves disassembling the cam connector, changing out the cam, and reassembling the linkages.  My Kalart is calibrated to my 101 mm. Kodak Ektar; for other lenses, I use the ground glass.

References:

“Adjusting the Kalart Rangefinder.” Online Posting, Graflex.org.  http://graflex.org/speed-graphic/kalart-adjustment.html

Butkus, M.  “Pacemaker Graphic, Speed graphic and Crown Graphic.”  http://www.butkus.org/chinon/pacemaker_graphic_speed_crown/pacemaker_graphic_speed_crown.htm

Butkus, M. “Pacemaker Graphic.”  http://www.butkus.org/chinon/pacemaker_graphic/pacermaker_graphic.htm

Butkus, M.  “Graflex Pacemaker Crown Graphic/Speed Graphic.”  http://www.butkus.org/chinon/graflex/graflex_pacemaker_crown_speed/graflex_pacemaker_crown_speed.htm

Frederick, Todd.  “Modern Lenses for 2×3 Graphic?”  Photonet Online Posting.  http://photo.net/medium-format-photography-forum/001HwX.

“Graflex Backs and Film Holders.”  http://www.pacificrimcamera.com/pp/graflex/backs.htm.

Graflex.Org Web Site.  http://graflex.org/.

“The Kalart Rangefinder Adjustment Manual.”  http://graflex.org/speed-graphic/kalart-manual.html

Karp, David.  “The Pacemaker Crown Graphic as a Field Camera.”  http://www.largeformatphotography.info/cameras/pacemaker/.

Kingslake, R.  “A History of the Rochester Camera and Lens Companies.”  http://graflex.org/articles/kingslake/.

Lommen, Jo.  “The Kalart Rangefinder.”  http://www.xs4all.nl/~lommen9/kalart/index.html

Lommen, Jo.  “5 Ways to Focus the Graflex Camera.”  Online Posting.  http://www.xs4all.nl/~lommen9/focus/index.html

“New York on Fire: Images From the Gordon Archive.”  http://www.weegee.org/

Thalmann, Kerry.  “Lightweight Lenses.”  http://www.thalmann.com/largeformat/lightwei.htm.

Wikipedia articles on Press Camera, Speed Graphic, and Weegee.

“Weegee’s World.”  International Center of Photography.  http://museum.icp.org/museum/collections/special/weegee/.

“Weegee: Biography and Exhibition of the American Photographer in the Fotomuseum, Winterthur, Switzerland.  http://www.cosmopolis.ch/english/cosmozero/weegee.htm.

Aperture, f-Stops, and the U.S. System

Understanding the idea of aperture, or “f-stops”, is not always a straightforward concept for beginning photographers.  There are two ways of controlling the amount of light falling on the film: the exposure time, or shutter speed, and the size of the lens opening, or aperture.  The concept of aperture is complicated by the fact that, when comparing different lenses,

Canon 35mm Camera with Unusual f/0.95 Lens

having the same size opening does not necessarily mean that the same amount of light falls on the film.  Rather, the amount of light admitted by a given opening depends on the focal length of the lens.  In other words, if the iris diaphragm opening is 25 mm, it will expose the film only one-sixteenth as much on a 200 mm telephoto lens as it will on a 50 mm lens.

F-Numbers and the f-Stop System:

To resolve this dilemma, the lens aperture is expressed as the “f-number” (usually written as N), a dimensionless parameter  expressed as  ratio between the focal length of the lens (f) and the diameter of the pupil in the iris diaphragm (D):

N = f/D.

Although expressed as a ratio (e.g., 1:4.5) in Europe for many years, in English-speaking countries, the diameter of the aperture is usually expressed as a fraction of the focal length, e.g., f/4.5, or 1/N.  Consequently, our  50 mm lens with a 25 mm opening is a nice fast f/2 lens, while our 200 mm telephoto lens with a 25 mm opening is frustratingly slow at f/8.  This gives one some insight into why fast telephoto lenses are large, bulky, and expensive- a modest 200 mm telephoto lens with a maximum aperture of  f/2 has an opening of 100 mm, or about 4 inches!

The beauty of the f-stop system is that, at a given F-number, every lens will allow exactly the same amount of light per square centimeter to fall on the film.  Thus an exposure of 1/100 second at f/5.6 will be exactly the same no matter which lens or film size one uses. For exposure to halve or double between stops, the f number must change by the square root of 2, or 1.414. The numbering of the stops is therefore arranged in a geometric sequence based on powers of the square root of 2.

The first standard series of F-numbers was proposed by Franz Stolze:

f/1.1, 1.6, 2.2, 3.3, 4.5, 6.3, 9, 12.5, 18, 25, 36, 50, 71, 100, etc.

This system became accepted in Europe, and many vintage European lenses are marked according this system. More modern lenses are marked with a slightly different series that has become the international standard, with the numbers rounded off to make them easier to engrave and remember:

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

Early Aperture Systems:

The origins of the concept of the F-number date back to the mid-19th century.  In 1867, Sutton and Dawson defined the “Apertal Ratio” as the ratio of the stop diameter to the focal length (i.e., 1/N), but used it only as an indicator of depth of field.  In 1874, John Henry Dallmeyer  stated that “…the rapidity of a lens depends on the relation or ratio of the aperture to the equivalent focus…”  However, it was to be many years before there was universal agreement on a mathematical scheme to formalize this principle.

Before today’s f-stop system became the standard, a variety of systems were in use to express lens aperture.  In 1899, a summary of the most common systems looked something like this:

Aperture Systems Circa 1899

Clearly, the situation with respect to lens aperture at the turn of the century was extraordinarily confusing.  Fortunately, the majority of these schemes are largely of historical interest and are rarely encountered.  Modern day camera collectors need only concern themselves with three aperture systems:  The modern f-stop method, the “U.S.” system, and a very simple numerical aperture scheme used by Kodak on their cheapest folding cameras.

This table does contain the seeds of our modern, streamlined system of f-stops in the first column.  Even though the numbers are not neatly rounded off in the manner to which we are accustomed (2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45, and 64) this column is recognizable as f-stops as we know them.

The second column summarizes the older “U.S.” or Universal System (also called the “Uniform Scale System”) found on many pre-1920 cameras.   The U.S. System was adopted by the Royal Photographic Society of Britain in 1881, and was one of the first attempts to establish a standard for lens apertures.. At first glance, the numbering for the U.S. system appears similar to an f-stop scale, and is easily confused with the modern system:

Lens with U.S. System Aperture Scale

This system is encountered frequently on older  lenses of American manufacture, and is frequently seen on Kodak folding cameras with Rapid Rectilinear lenses.   Based on a simple numerical progression which doubles at each stop, thus maintaining proportionality to the exposure, the system is derived from the formula:

U.S.= N2/16.

Thus f/16 becomes U.S. 16, the intersection point of the two systems, and f/4 is designated U.S. 1.  Consequently, the U.S. system numbers correspond to settings on the modern f-stop scale, and a lens with U.S. markings can be used in the same manner as a conventionally-labeled lens by counting up and down from f/16 (see table below).

The numerical system consists of only four stops (1,2,3,4) corresponding approximately to f/11, f/16, f/22 and f/32.  Most commonly, it is encountered on inexpensive folding cameras such as the Kodak Vanity line as a simple punched wheel allowing rotation of various sizes of aperture in front of a meniscus lens:

1920s Kodak Vanity Camera with Simple Numerical Aperture System

Occasionally, the numerical system can be found on base level Kodaks with iris diaphragms and Ball Bearing Shutters,such as this No. 1A Kodak Junior with a meniscus lens:

1A Kodak with Meniscus Lens and Numerical Aperture System

The relationship between the U.S. and modern systems can be expressed more simply as follows:

f/stop 4 5.6 8 11 16 22 32 45
U.S. 1 2 4 8 16 32 64 256
Simple lens (Approximate) 1 2 3 4

Once again, note that the U.S. and modern systems intersect at f/16, and therefore the U.S. system can be used readily by counting stops up and down from this point.. 

References:

“F-number.”  Wikipedia Article.  http://en.wikipedia.org/wiki/F-number.

Konig, Mischa.  Kodak Classics:  Kodak Folding Cameras (Includes discussion of f-stop systems).  http://kodak.3106.net/index.php?p=213.

“Uniform System of Lens Apertures.” http://www.sizes.com/tools/uniform_system.htm.

Thinking at the Fire

Thinking at the Fire

One weekend in October, I took a camping trip through the eerie landscape left behind when the five cubic miles of water from prehistoric Lake Missoula gouged its way through the Palouse wheatfields at the end of the last ice age.  Carving out the Columbia Gorge from Western Montana to Portland, Oregon, this seven hundred foot-high wall of water must have been heard and felt for hours before it carved its way through the rolling hills, scooping out Grand Coulee and Palouse Falls.  I camped in my little tent  next to the cascading waters of Palouse Falls in below-freezing temperatures, warm in my sleeping bag under a space blanket.  Each night, my fire kept me warm and cooked my supper, then made my morning coffee after I broke the ice out of my water bucket.  One night, I set up my No. 1 Kodak on my little pocket tripod, then sat pensively gazing into the flames for several minutes while I took this exposure.  My image is partially transparent, as if I am not totally present in that time.  It matches the unearthly quality of this eroded landscape in the moonlight.