Greenhouse Wall

The Scene

I discussed a photo of a door located at Gibson Greenhouses in the last blog post and today we will discuss another image acquired at the greenhouse complex. Today’s image along with six other photographs from the complex can be seen at  by clicking on the “Galleries” tab at the top and then clicking on the “Gibson Greenhouses” image to view small thumbnails of all seven photos. Move the cursor over a thumbnail and then click to view a larger image.

I generally work very deliberately to incorporate important scene attributes into a photograph, including things that are abstract. In my photograph “Athabasca Indians Keeping Watch,” for example, I tried to visually develop a feeling that native Indian spirits were present at the scene. The dominant scene attribute for today’s post was very concrete and visually obvious. A greenhouse is designed to allow an impressive amount of light to pass through its walls and roof and the specific goal of today’s image was to produce a print which conveyed the feeling of an enormous amount of light falling onto a greenhouse wall.


When I arrived at the greenhouse, the wall was fully illuminated by direct sunlight except for shadows produced by vertical pipes. This seemed like an excellent opportunity to capture an impressive amount of light but I decided that a uniformly illuminated wall provided a limited sense of bright light even though the light was very strong. I thought strong sunlight could be sensed by the human brain more readily if it was compared with light that is not as strong. Contrasting bright, direct sunlight with soft, indirect light ought to allow the eye and mind to provide meaning to the bright sunlight more readily.

I decided to wait until the shadow from the roof overhang high on the wall moved lower to add contrasting light to the wall and I returned an hour later to find the shadow from the overhang stretching nicely down the wall. The wall’s lower region was illuminated brightly by direct sunlight whereas its upper region was shadowed by the roof overhang and illuminated only indirectly by the blue sky. This contrast seemed to more effectively communicate a sense of bright light than earlier when the wall was illuminated nearly uniformly by bright sunlight.

Two composition decisions were quickly made. First, I decided to hurry so an image could be acquired before the shadow from the roof overhang moved low enough to reach the concrete blocks. I wanted to position the line of contrast (direct versus indirect illumination) on the textured glass panes of the wall. A position located precariously close to the concrete blocks was selected to add tension to the image.

Second, the wall was flat physically so I decided to prominently incorporate one of the gutter pipes in the composition. The wall was seriously flat between the pipes and a pipe provided the best opportunity to add much needed depth to the image.

I knew the photograph would benefit by using a slightly wide-angle lens because it would allow me to get closer to the subject and “pull” the pipe out of the wall better to emphasize depth. I selected a 120 mm lens for my 4inch x 5inch camera (a “normal” lens for a 4×5 is 150 mm) and set up the camera quite low to the ground so approximately half of the scene was illuminated by direct sunlight and half was illuminated only indirectly by blue sky. I hoped that dividing the image nearly in half would direct attention toward the interface between harsh sunlight and soft shadows.

The ground glass of my view camera showed that textures illuminated acutely by direct sunlight contrasted nicely with soft shadows illuminated indirectly by blue sky. I felt the composition would effectively communicate the enormous presence of bright sunlight in the image and I was excited by what I saw on the ground glass.

My light meter indicated that the exposure would be straightforward. The darkest wood frames surrounding the glass panes (located slightly above the concrete blocks) were placed on Zones I-II (nearly black with no texture – very dark with slight texture) to form a solid visual “anchor” for the image. The brightest areas of the scene were located on small sections of the curved pipe which reflected sunlight strongly and those areas fell on Zone VIII-IX (very bright with slight texture – nearly white with no texture). Since I wanted the feeling of strong sunlight to dominate the image and the brightest areas of the pipe were small, placing the brightest areas quite high on the exposure scale was fine and normal film development was appropriate.

My light meter is a one degree spot meter which can sample small areas of a scene. A spot meter was indispensable for measuring the brightness of this scene and determining the appropriate exposure for it.

The cloudless sky provided plenty of light so a sheet of Kodak Tri-X black & white film (ASA 320) was exposed for 1/30 sec at f/32-45 (read as half way between f/32 and f/45). I was excited and hoped the photograph captured the feeling of bright light flooding the wall that I experienced.


I scanned the 4inch x 5inch black & white negative with a drum scanner by capturing 5,000 ppi with 16-bit pixel depth. The scan was straightforward and no adjustments were needed during scanning.

Editing the image in PhotoShop was easy. I began with a global curve modification (i.e. the curve for the whole image was adjusted). Dark pixels of the image were darkened by bending the dark section of the curve downward. Bright pixels were brightened by bending the bright section of the curve upward except for the brightest pixels of the photo (gray levels brighter than 238) which were not altered.

The global curve modification strengthened the image but I remained surprised that the texture of the glass panes was weaker in the image than what I recalled at the scene. I realized the glass was weak on film because so much light filled the inside of the greenhouse that the dark and middle tones of the panes were brighter than I anticipated. It was clear that their dark and middle image tones needed darkening to achieve adequate texture.

I used PhotoShop’s Magnetic Lasso tool to select shaded areas in the upper half of the photo and modified the curve for the selected areas. The curve was bent downward substantially for dark tones, bent downward less for midtones and bent downward only slightly for bright tones so darker pixels were darkened progressively more than brighter pixels. This strengthened the texture of the glass considerably and added some “weight” to the wood frames around the glass panes.

Local retouching using PhotoShop’s Burn and Dodge tools was performed next. A few large shadowed areas of the concrete blocks were so dark that they pulled the viewer’s eyes off of the glass panes. Those areas were lightened by dodging to reduce their weight and help keep viewer’s eyes on the textured glass. This was important because a key editing goal was to contrast bright, sunlit areas with soft, shadowed areas and the interface between these two areas was located on the glass panes above the concrete blocks.

Next, I wanted to direct viewer attention more strongly to the interface between bright sunlit areas and soft, shadowed areas. This was accomplished by increasing contrast at the interface in a way that could be viewed loosely as edge enhancement on a macro level. Shadowed areas near the interface were burned slightly darker whereas sunlit areas near the interface were dodged slightly brighter. This emphasized the interface in a way that is similar to enhancing edges during image sharpening by darkening and brightening pixels at the edges. My edit was applied manually with local burning and dodging over areas that included several hundred pixels on both sides of the interface but its effect was analogous to edge enhancement using ordinary image sharpening.

Comparing my edited and unedited images showed that the edit increased contrast at the interface and effectively pulled viewer’s eyes toward the interface.

Small sunlit portions of the pipe were brightened by dodging to enhance the feeling of blazing sunlight reflecting off of the pipe. Light also was added to the pipe’s shadow on the concrete blocks to further increase the feeling of strong light in the lower half of the photograph. Several small areas of the concrete blocks also were brightened by dodging to strengthen the feeling of strong, bright sunlight.

Finally, I identified a few small areas of high contrast near edges of the photograph that pulled the viewer’s eyes off of the image. The contrast in these areas was reduced by burning and/or dodging.

Today’s image feels right to me when printed to a small size that can be held in the hand (e.g. 11 inch x 14 inch).


The subject of this photograph was the presence of an enormous amount of sunlight falling on a greenhouse wall. For me, the final image successfully captured the feeling of bright light flooding the wall which I experienced at the scene. Any comments you might have about the image, the photographic approach used for it, its composition, or image workup will be appreciated.

Randall R Bresee

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