Can Better Shades Improve Lens Performance?

By Robert Zeichner Back to

Zeichner_MA_2007_1

Many leading photographers and instructors have commented that the tripod and cable release are the handiest accessories ever devised for improving picture sharpness.That fact can be proven with just about any combination of camera and lens. But what about lens shades? It seems obvious that eliminating the flare caused by bright sources of light that aren’t part of the picture, will increase contrast and therefore apparent sharpness.

In the motion picture industry, camera operators, through their assistants, have gone to great lengths to make certain that lenses are effectively shaded by using various types of matte boxes and hard matte inserts (black panels with windows cut for specific focal lengths) to effectively exclude any light that lies outside of the picture area. In such situations, the time and expense of taking these extra steps is rarely an issue given all that is at stake (not to mention that sufficient technicians are available to make all of this happen).

For the serious still photographer working alone, going to such extremes may be impractical. If working in remote areas, just the weight of such elaborate equipment would be a burden. Some manufacturers have offered lightweight compendium shades for medium-format cameras, complete with slide-in hard mattes. For those of us using view cameras, however, these may not be entirely effective because adjusting movements requires repositioning the win- dow to avoid vignetting. To be accurate, compendium shades with some adjustments designed for view cameras have been produced. One that comes to mind is a model from Calumet that was designed for its venerable C-1.

For years, I’ve been toying with different ideas for making an adjustable shade that could be adapted to the variety of lenses I use, but all I could come up with involved fabrication that was pretty complex. What I really needed was something simple and inexpensive. This would allow me to quickly set up some tests and confirm, once and for all, that a better shade would result in greater negative density range and increased local contrast in the lowest zones. If inconclusive, it would be back to my hat and dark slide.

Constructing the shade

I found a couple of four-way barn doors in my collection of junk that are presumably from an old 100-watt focusing Fresnel lighting fixture that has since disappeared. This fit perfectly over the Series 9 side of a variety of step-up filter-adapter rings I’ve amassed over the years. A couple of miniature spring clips held it securely to the adapter, which then screwed into the front of my test lens. The only additional requirement was to resurface the flat-black finish of the barn-door leaves with something less reflective. Even flat-black surfaces reflect glancing rays of light pretty effectively, so I rubber- cemented black velvet paper to the inside surfaces and trimmed it with a mat knife. My shade was made, and all I needed was a test subject.

Testing procedures

In order to compare the results of using the barn-door shade versus a standard round rubber shade, I decided to make pairs of negatives of different types of subjects under a variety of lighting conditions, using different lenses of varying vintages. Exposure, filters used, and processing were identical for each pair of negatives to assure that the only differences detected resulted from the shade. I selected a variety of subjects: some with considerable open sky, some backlit, and some with no sky but highly reflective foregrounds. I tried modern multicoated lenses as well as much older single-coated classics.

Using the shade

To adjust the shade, I first determined the exposure required and set the lens to the correct aperture. I then carefully adjusted each barn-door leaf by observing through the clipped corners of my ground glass as I was closing them, making certain no part of any leaf was visible. To adjust the top leaf, I viewed through a lower corner. To adjust the right leaf, I observed the left corner, and so forth. After completing the adjustment of all four leaves, I made one exposure with the barn-door shade and then, for purposes of comparison, I made a second exposure using a conventional round shade. I processed all the sheets of T-Max film at the same time in straight D-76 using a Jobo expert drum.

Evaluating the results

To see how the differences I noticed in the negatives would affect the actual finished photographs, I made pairs of prints in my wet darkroom. The two images shown here are from a pair of negatives that were scanned simultaneously into Photoshop and electronically processed exactly the same way. The differences in the two images are purely a result of the differences in the negatives from which they originated. If you look carefully at the large cavity in the tree trunk as well as the rocks in shadow below it, you can see a definite increase in local contrast in the example made using the barn-door shade. Even some of the detail in the fence to the upper right appears to be increased in the properly shaded photograph. The lens used for these pictures was a Schneider 165mm Angulon from 1965. Exposure was f/32 at 1⁄10 second.

Refinements

Midcourse corrections and modifications are almost always needed in projects such as this, and a couple immediately occurred to me once I began to use the shade. The first thing I noticed was that the gaps between the barn doors and the ring to which they were hinged provided a path for unwanted light to reach the lens. I solved this with a black velvet elastic hair band called a scrunchie. It fit perfectly around the barn-door ring. (Naturally, they come three to a package and the other two are of much lighter colors—thus useless for making a light trap. If you have young daughters though, I’m told they love these things.)

The second thing I noticed was that when shooting into the light in some situations, it might be handy to have an extension of the top barn-door leaf that could be unfolded to cast a longer shadow on the front of the lens. I was able to tape a piece of black card stock to the top leaf with 3M #235 photographic tape.

Conclusion

Can better shades improve lens performance? In almost every instance, the barn-door shade resulted in an increase in the tonal range of the negative. With older, single-coated lenses and in situations with highly luminous areas lying outside the image area, the difference was considerable, approaching what appeared to be between 1⁄2 and a full contrast-grade. In backlit situations, the difference was profound, as one might expect. What was surprising was that even with modern multicoated lenses, I could still detect a slight difference in the contrast in shadow areas. While I don’t use any uncoated lenses at present, I understand that a number of ultra-large format users do make use of vintage uncoated optics. I have to believe that excluding as much non-image-forming light in those situations would have a great effect on increasing the tonal range of those negatives. If working with a panoramic format, such as 4×10 or 7×17, the effect could be even more profound. Given the relative ease of adjusting the shade, and armed with enough adapter rings to accommodate just about every lens I own, it seems only logical that this will become a standard part of my field kit.

Sources for parts

The barn-door shade is made from an LTM Pepper 100 four-way barn door. LTM is located in Van Nuys, CA (www.ltmlighting.com; (800) 762-4291). Tiffen currently makes Series 9 filter adapters in three sizes: 72mm, 77mm, and 82mm; the part numbers are 72M9, 77M9, and 82M9, respectively, and are available through most photo equipment suppliers. Choose the size that corresponds to your largest lens and buy step-down rings as required. Please note that the barn door has a maximum opening of 64mm. Some lenses may be too large for this size barn door to be used without vignetting. A larger barn door from a 200-watt LTM Pepper light might be adaptable using an appropriate step-down ring. Velvet paper can be purchased in many craft or art-supply stores and scrunchies can be found at just about any dollar store. The clips can be gotten at the local office supply.


About the Author

Robert Zeichner
Contributor
Robert Zeichner has worked as a freelance photographer, graphic artist, film director, and cinematographer. Zeichner’s first limited edition portfolio of prints “Antietam— The Lost Images,” contains photographs of ultra-realistic Civil War scenes staged for a motion picture. His second portfolio of Silver Vitrographs has just been completed and a third, of photographs made in Death Valley, is nearing completion.