The club’s digital projector, a Canon SX80 Mk 2, has a native resolution of 1400 x 1050 pixels. (SXGA resolution). This means that in landscape mode there will be a maximum of 1400 dots of light across the screen and a maximum of 1050 dots vertically.
The aspect ratio of 1400 to 1050 is equivalent to 4 to 3. The SX80 will automatically resize any 4:3 image larger than 1400 x 1050 to fit it to that size. So a 1600 x 1200 image will project at 1400 x 1050, as will a 3200 x 2400 image, or a 4800 x 3600 image.
We ask for 1600 x 1200 for competitions, because that is the PAGB / SPF standard, intended for a 1600 x 1200 projector (UXGA resolution). If a 1600 x 1200 image is projected on a UXGA projector, it will fill the screen. A 1400 x 1050 one will only part fill it.
For landscape images, it’s simple. Keep that 4:3 ratio with the file size at 1600 x 1200. It will always be projected at 1400 x 1050, on our SXGA projector but if the file is smaller than that, it will simply not take up the full screen without zooming.
When submitting a portrait mode image, remember that the maximum height is 1050 pixels. So, if you chose 1200 x 1600, the 1600 would be shrunk to fit 1050 and the 1200 width would shrink in proportion, to 788 , so your image would project as 788 x 1050. That’s fine, but you are not constrained to the 3:4 ratio. You can make the image wider if you want, for example 800 x 1050, or 900 x 1050. It depends what edge detail you want to show in the image.
If shown on a UXGA projector , a 1200 x 1600 image will still be reduced, since the maximum height for UXGA is 1200 pixels- so 1600 is shrunk to 1200 and the 1200 width proportionately shrinks to 900.
So, your choice, with portrait mode-For an image which may someday be used in a UXGA projector, like in an SPF inter-club competition, use 1200 x 1600. For an in-club only challenge or competition, you may prefer to set the height to 1050 and set the width to a value greater than 788 which suits the image.
Here is a link to a PDF created by Libby Smith for the SPF on this issue.