Let's talk about print ratios for a moment. They are weird. Some of them are very weird. A standard “snapshot” on 35mm film was generally printed on 6 x 4 inch paper. There's quite a good reason for that - a full frame film sensor is 1.5 times as wide as it is tall. If you print the entire negative to a suitable size to hold in your hand, you're going to come up with a 6 x 4.
Next size up was a 7 x 5 and this never really made sense to anyone. My guess is that the labs had 10 inch wide rolls to print 10 x 8s and could slice it down the middle to make 5 inch wide paper. A full frame print would be 7.5 inches x 5 but regular print size are always 2 inches wider than they are tall (or 3 inches once you get to 11 inches tall) so 7 x 5 it is and to print this you have to crop half an inch from the long side of a full frame.
The really odd one is 10 x 8. This dates back to large format film which was often in a 4:5 ratio (or close to a 4:5 ratio - there has always been cropping in printing). One common size of large format film was 4 x 5 inches and this fits beautifully on 10 x 8. All other sizes such as 6 x 4.5 centimetres and 6 x 7 cm (and no, I have no idea why film was always traditionally measured in cm and prints in inches!) had to crop their image.
Basically - no print sizes make sense. This is particularly true in the digital age. Many dSLRs have a 3:2 ratio but lots of compacts have a sensor size which is 4:3. Printing's a mess. If you want to fill a sheet of traditional sized paper with your picture then you are going to have to crop bits off it.
It won't have escaped some of the sharp eyed readers here that the 4:3 sensor size of a compact digital camera exactly matches a “traditional” TV. Shoot full frame on a 4:3 camera and your pictures will look great on a TV but to print them you will often have to crop.
But then of course widescreen TV took off. This has a ratio of 16:9. All of a sudden your pictures don't look right either on TV or printed. Even worse widescreen TVs often stretch the images to make them look like they fit - and make everyone gain a stone or two in the process. Camera manufacturers haven't been slow to catch on to this and many compact are now being built with 16:9 sensors. This is one reason why 7MP cameras are becoming common. If you take a 6MP 3:2 sensor and “stretch” it out to 16:9 then you need 7 million pixels to fill it.
Great for showing your pictures on TV - but what about printing? If you go back to our 6 x 4 print you will have to crop well over an inch off the long end to make your widescreen camera fit. If you want to print a borderless A4 on your inkjet then you'll need to lop over 3 inches off the long end just to make it fit.
Well, those nice chaps at Epson have thought about this and come up with an answer - 16:9 ratio paper. Their new 16:9 premium glossy photo paper measures 101.6mm x 180.6 mm or roughly 7 x 4 inches. Apparently this works really well with the 16:9 sensors on all Panasonic cameras (or so the joint press release from Epson and Panasonic says - I'll bet it will work great with any 16:9 sensor). Expect to pay about £5.50 for a pack of 20 sheets. Now if only the labs will catch on I could stop ordering 7 x 5s and trimming them by hand…
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