Sileby Photographic Society

Odds and Ends

Why Having Projectors Capable of 1400 x 1050 Is Bad

Actually, projectors capable of projecting images at 1400 by 1050 pixels are not bad in themselves - ours at Sileby is precisely one of those. The problem comes with competitions that allow images of sizes up to 1440 by 1050 to be entered. Here's why.

Let’s start by looking at how things were a decade or so ago. Most of us were still using slides and these were projected on to a square screen. A 35mm slide is 36mm by 24mm, so we can say that it has an aspect ratio of 3:2; 36 is 3 times 12 and 24 is 2 times 12. As the screen was square, those submitting portrait-oriented slides had pictures that were as big as authors submitting landscape-oriented material. Assuming that the slide was not specifically cropped, it would occupy two-thirds of the screen area regardless of its orientation.

Now we move on to digital projection. The ideal digital projector would offer a square format so that landscape- and portrait-oriented images occupy the same screen area, just like slides. However, in spite of promises from manufacturers such as Kodak, none appeared. Instead, digital projectors appeared with rectangular, landscape-oriented formats. The problem with a rectangular format is that authors of portrait-oriented images are at a disadvantage; their images occupy a smaller area of the screen. At the time when clubs started using digital projectors, they generally had pixel counts of 1024 by 768, that’s an aspect ratio of 4:3. When we bought ours at Sileby, we were one of the first to have a projector capable of 1400 by 1050, also 4:3. In order try to be fair to portrait-oriented images, but at the same time to keep broadly in line with other clubs, we elected to use only 1280 by 1024, yielding an aspect ratio of 5:4, not quite square, but close to it. We project on to a screen that is 60” square and usually we close it up so that the amount of unused screen space around the image in minimised.

Most modern D-SLRs either have sensors that mimic the 35mm film format of 3:2 or and we’ll now look at how landscape- and portrait-oriented images are treated by different projector pixel counts. Before we actually start, a simple explanation of the problem would be useful, namely that as the format widens, the height available decreases. This has a direct effect on the height of portrait-format images. Here’s why.

The table below shows the maximum height, in inches, available in various projector formats based upon a screen 60 inches across. It then goes on to show how a 3:2 portrait-format image size is affected and the percentage of the screen area occupied by such an image compared to a full-size one.

Pixel
Count
Aspect
Ratio
Maximum
Height
(inches)
Width of 3:2
Portrait
(inches)
Area of 3:2
Portrait
(sq. in.)
Percentage of
Screen Area
Portrait
1024 x 768 4:3 45 30 1350 50
1280 x 1024 5:4 48 32 1536 53.33
1400 x 1050 4:3 45 30 1350 50
1920 x 1080 16:9 33.75 22.5 760 37.5

Although HD-format projectors, at 1920 x 1080 pixels, are only just hitting the market and so we're unlikely to come across them in club photography, data for that size is included in the table for a reason that you'll see later. At all pixel counts, with the exception of the HD one, a 3:2 landscape-format image will always be 40” high on a 60” wide screen, so will occupy an area of 2400 sq. in., that’s 89% of the screen at 1024 x 768 and 1400 x 1050 and 83% at 1280 x 1024. This is a “win” on the 4:3 projectors for the landscape-format entrant, so it’s even more of a disadvantage for the portrait-format worker. Of course, there’s nothing to stop anyone entering a full-size image and that would occupy 100% of the screen area. The HD format is wider than the 3:2 of the D-SLR sensors and so a landscape image from such a camera would be limited to 1080 high and be only 1620 wide. The reason for including HD in the table is to show what could happen if the federations start to buy HD projectors and rule-makers decide to make use of the whole width. The 3:2 portrait-oriented image would occupy only 37.5% of the available screen area – this means that you could almost have another copy of your image either side of the one you’re exhibiting. Let’s hope that never happens and that camera manufacturers are not led down the HD-format route – that would kill landscape-format images.

The data in the table assumes that your portrait-style image is using the full available height. If you forget to resize your image to 1050 high or the Competition Secretary decides to take one of your images from a quarterly and put it into a federation competition, the resulting image on a 1400 x 1050 projector would be less than 44” high and on an HD projector would occupy less than one-third of the screen area. In that case you really could place copies of the image on the left and right of your entry - and leave a border between the three of them. Food for thought.

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