SHARPSHOOTER

At workshops, I'm frequently asked, "Can 35 mm be a viable professional film or must a larger format be used?"   Never before has the potential of 35 mm been so dependent on the photographer's technique, but the very compactness and versatility of 35 mm conspire against it in the minds of many photographers who often view it as a glorified toy.  The factors that can affect the quality of 35 mm bear repeating. 

Although I use the term "sharpshooter", sharpness is not the only factor.  If we agree that a photograph is a bunch of points of information, then "sharpness" defines the quality of those points while "resolution" describes the number of points.  Two photographs could have identical resolution, as measured by line-pairs per millimeter (1 pmm), yet not necessarily appear the same. Human vision does not just assess fine detail; it also evaluates the edges of those details. The term "acutance" describes this edge-sharpness.

So what does all this mean? While lens tests give you a wealth of information, they aren't the whole story. Indeed, sharpness is mostly (or, perhaps, wholly) a perception, and perceptions are subjective. Even your own eyesight affects this perception. Further, many photographers have no basis for comparison as to what constitutes a quality image. In my workshops, there may be a participant who has shot mostly print film. When we use high quality slide films and loupe the slides, such an experience can be a revelation.

In light of the above, is the search for sharpness futile? No, but 35 mm, given the small size of the format, requires flawless technique. Happily, the versatility of 35 mm far outweighs this liability. In fact, a deliberate approach slows you down, which often produces stronger compositions. My philosophy is to find which of the following factors cause problems in the real world. Since some of these factors will work differently with various lenses, films, and personal techniques, each photographer needs to apply this information to his/her own work.

It seems every article these days extols the use of tripods, yet no other single factor is so responsible for image quality. If you're going to use a tripod, you might as well use a good one.  It's not the use of the tripod per se we hate so much; it's trying to use a cheap, poorly designed one that inspires expletives. The Bogen 3200 series is, perhaps, the best value in tripods. It features individual leg spreading, reasonable weight, and easy set-up. Add a good quality head, preferably one with a quick-release, and most of the battle is over. Gitzo tripods are the Cadillac of tripods, but Bogen is an excellent choice for most folks.

The Arca Swiss Monoball head is the finest ball head on the market. Be sure to buy it with the quick release head, but don't buy the Area Swiss camera plate. Rather, get your plate from Really Right Stuff.  Their plates are elegantly designed and well worth the cost. When using a tripod, extend it only as high as necessary. Use the center column only as a last resort. When the weather is windy, reduce the height even more.

Don't let a sunny day tempt you down the primrose path! We've all been taught the rule for hand holding: use a shutter speed of one over the focal length of the lens. Every time your heart beats, the blood coursing through your body causes motion. It's been estimated the motion caused by your pulse can be 0.2 mm or 200 microns. Further, the motion lasts about 1/10 of a second (note 1). Now 200 microns may not seem like much, until you consider its effect on resolving power. For instance, a high quality lens capable of resolving 100 lpm, drops to a 78 1pm at a hand-held shutter speed of 1/250 when subjected to a 200 micron movement. This is a twenty-two percent loss! And hand-held at 1/60, the resolution is only 30 1pm (note 2)! So, don't think you can hand-hold that nice 60 mm Micro Nikkor at 1/60 of a second and get crisp slides. Hand-held tests of a Nikkor 50mm lens showed incredible loss of resolution, even at 1/125 and 1/500! The bottom line: the use of a tripod ALWAYS improves quality.

Don't let the use of a tripod lull you into forgetting about subject movement. Even in a distant mountain landscape, there are probably fluttering leaves and moving clouds. So always consider both camera and subject movement. Another pitfall is zoom lenses. Consider the typical 70-200 mm lens. One moment you're using it at the 70 mm range with a suitable shutter speed. Then you quickly zoom out to 200 mm, BUT you don't choose a correspondingly faster shutter. At 200 mm, you're magnifying everything four times--including camera and subject movement.

Now that you've put your camera on a tripod, you may think you're home free--oh contraire! Just the act of pushing the shutter release causes vibrations, no matter how gently you do it. Use a cable release or the self-timer. Cable releases get lost fairly regularly, so carry a spare.

This advice may seem overly obvious, but how long has it been since you had your eyes checked?  I can pass a driver's license vision test without glasses, but I wouldn't dream of photographing without them. What kind of focusing screen do you use? Many photographers prefer a plain matte screen with grid lines. Often called an architectural screen, it facilitates level horizons and doesn't have distracting split-images and micro-prisms. Also, don't over focus. Your vision will be most discerning in the first two or three seconds.

The f-stops on a lens are not created equal, at least in terms of resolution. Almost always, there are one or two f-stops better than the others. Often, but not always, these are f8 or f1 1. I recommend you test each of your lenses to find that optimal aperture. Yes, f16 or f22 will yield more depth of field, which may give the perception of more sharpness, but the small f-stops actually resolve less (see diffraction).

This is one of those weird optical hooligans that keep our life interesting. When light passes through an aperture, the rays striking the edge of the diaphragm are diffracted (bent), while the center rays pass straight through and hit a precise focus point. However, as the aperture becomes smaller, more rays are diffracted, and the image starts to suffer. Diffraction is NOT a function of a cheap lens or poor design. I don't get too nervous about diffraction at f-16 or larger, but at f-22 and f-32 there's a noticeable loss of resolution. To repeat, one extra depth of field at very small apertures may give the illusion of offsetting this loss of resolution. Do some tests and decide for yourself what's acceptable to you.

Buy the best you can afford! This topic alone is worth a separate discussion, but you get what you pay for. Today, even generic lens manufacturers have super-computers to design excellent optical formulas. But, while generic lenses can be very sharp, the manufacturers must save money somewhere.  They usually choose the physical construction, which tends to be less durable and rugged. Also, an expensive lens may not be as sharp wide open as a name brand lens will be. If you shoot slow speed film, this difference can be critical.

These are two-edged swords. The use of a tele-converter will always cause a loss of sharpness.  Sometimes this loss is small and quite acceptable, but do some tests.

A filter adds two more surfaces, which causes image degradation. Certainly, there's some loss, at least theoretically. But the question is, how much loss? Is it acceptable? My approach has been to buy only very good filters. I like Nikon, Hoya and B+W. Tiffen filters are not solid glass but, rather, a piece of plastic sandwiched in glass, yet Tiffen did fine in my tests. I like the protection a UV or skylight filter affords, but the choice is yours.

All the forgoing advice about lenses and filters is meaningless if they're dirty, scratched, or smudged and fingerprinted! Dirt can cause a loss of resolution and also create ghosts and flare, especially when pointed toward the sun.

Lens hoods are fairly cheap in the scheme of things and add excellent protection. More importantly, they help prevent loss of contrast. Wide angle lenses need lens hoods the most. At the least, use your hat or gray card to shade the lens.

Although not often thought of in context with sharpness, the direction of light greatly affects our perception. Side light and back light increase the edge detail, making the image look sharper. As an added benefit, this type of light is usually more interesting, too.

If your image is washed out from over-exposure or too dark from under-exposure, it won't seem as sharp. The new super sharp slide films have very narrow latitude and require perfect exposure. Now is the time for you to get your camera off "Automatic" and learn to meter in the manual mode. Maybe that stupid piece of eighteen percent gray cardboard has a use after all!

Slow speed films are sharper.  It's that simple. Always pick the slowest speed film that will do the job, remembering that sometimes the job requires a faster film. It makes no sense to have a fine-grained, blurry image! For nature photographers who grew up on Kodachrome 25 and Fujichrome 50, the advent of Lumiere and Provia in 100 speed represents nirvana!

When you push the shutter release, the mirror has to flip up, out of the way. Take your lens off and watch your mirror move as you trip the shutter. Obviously, that much glass moving around has to cause vibrations. In the good 'ole days, the camera manufacturers put a mirror lock-up in the body. This allowed you to raise the mirror, wait a few seconds, and then make the exposure. Now, in the infinite wisdom of the marketing gurus, the mirror lock-up has all but disappeared. My Nikon F3 has a lock-up as does an F4. But the Nikon 8008 and N-90 do not. Nikon states the latter two are not considered professional cameras and, hence, don't warrant this feature. (I don't know about you, but the price of an N-90 seems pretty professional to me!)

Fortunately, the vibrations caused by mirror slap generally cause trouble at just a few speeds--usually around 1/8 or 1/15.   Unfortunately, these speeds are often used by nature photographers working in low light with slow film. Obviously, mirror slap is worse with telephoto lenses. What can you do? First, check your self timer. On some bodies, when you activate the self timer, the mirror flips up right away. When the photograph is actually taken several seconds later, the mirror vibrations have died away. Otherwise, you need to conduct some tests. Some bodies are much worse than others. George Lepp has reported results on several cameras in his newsletter. You can easily test you own cameras to identify the shutter speeds to avoid. Very slow speeds are not a problem, because the mirror vibrations are only a small percentage of the total exposure time. At any rate, complain bitterly to camera reps every chance you get.

You can test in two ways: qualitative and quantitative. For qualitative results, a good loupe and light box are all you need. I suggest using a dollar bill, a sheet of commemorative postage stamps, or even newspaper want ads. Whatever you decide on, mount them on a smooth, stiff board. Next, create the very best image you can. This would likely be with your 50 mm normal lens or a macro lens. You might want to use flash to eliminate any possibility of vibration. Use a slow, fine-grained film. Good candidates are Velvia, Provia or Lumiere slide films. Ektar 25 (now called Royal Gold) and Tech Pan are great negative films. Don't have prints made; you'll evaluate the negatives or the slides. Label the resulting slides or negatives as your reference standard. From now on, in any tests you do, compare the new images against your reference. Evaluate with a good loupe on a light box.  For quantitative work, you need a lens testing chart. You also need a 50x or 100x microscope to evaluate the results. Either the Edmund or Radio Shack models work well and are less than twenty dollars.  Be consistent in your approach, and always eliminate all variables except the one you're testing. Don't change to a different chart half-way through or use a different loupe.

Conclusion

The trick to dealing with all these factors is to form good habits now. Develop a standard procedure. Eventually, it becomes second nature.   However, I issue you a stern warning: You MUST comply with ALL the factors. You can't select those you like and ignore the rest. Many have tried this approach, and their waste cans are full of the results!  The weakest link dictates the final image quality. For example, you can't put a five dollar K-mart filter on your expensive lens. Don't use Velvia film with a cheap, wobbly tripod. Why pay five hundred dollars for an apo-chromatic lens and then not use a lens hood? You can't hand-hold that 400 mm lens. Can you even hand-hold a 50 mm lens?

I challenge you to sit down and take stock of your photography. How committed are you to producing quality images? How will these images be used? What testing do you need to do? What philosophies need to be adopted? Photography is both an art and a craft. When the craft side is well controlled, the art side blooms and prospers!

Note 1: Williams, John B., (1990) Image Clarity: High Resolution Photography. Boston: Focal Press, p. 30.
Note 2: Ibid., p. 37