Wesley's Tool-Box

One of the things I've noticed about the iPhone's camera is that its field of view seemed to change with each generation, especially in the early days. This meant that the focal length was different. While the EXIF data does show the 35mm equivalent focal length, I wondered if this was really accurate. I wanted to check this out before doing deeper comparison.


By taking photos of a tape measure from a set distance and calculating the focal length with a formula, this is what I got. The last three generations have been stable - they all report 29mm, and the actual measurements are nearly the same at around 30mm. For the three generations before that, the measured values are around 32 to 33mm, although the reported values exceed this by a mm or two.

Interestingly, 3GS has the longest focal length of all at about 37mm. It isn't particularly good for selfies or group photos, and since it didn't have a front-facing camera, this was doubly unfortunate. As the selfies and wide-angle lenses became popular, perhaps Apple saw this as a problem and kept reducing the focal length until iPhone 5S in addition to adding the front-facing camera.


Now I decided to figure out the optical resolutions of the iPhone cameras. This is done by using the ISO 12233:2000 chart and looking at the test lines to see how far each of the lines remain distinguishable. I've done this test five years ago with 3GS, and I had promised to revisit it with newer iPhones. It's rather long overdue, but it's definitely worth it.

Considering the processing done to the output photos, conventional sensors would be alright with Lines per Picture Height (LPH) being 65% or greater of the sensor resolution. Let's see how the iPhones have progressed throughout the years. The photos were taken in a sufficiently well-lit room so that the lowest ISO setting would automatically be chosen by the default camera app.


Sharpening applied to the image processing during the iPhone 4 to 5 eras have apparently enhanced the percentage slightly, while the more recent ones have toned this down and still maintained the numbers in the high 60s. So it seems that the optical resolution has been kept up with the increase in the sensor's pixel count more or less. It does seem that, to go beyond 12 megapixels used in 6S Plus, Apple may need to opt for a sensor size increase to avoid degradation in quality.

Apple Watch's Korean launch is just a few days away (June 26) and I'd like to offer you a nicely consolidated list of all my reviews for your convenience. I hope this will help you get some idea on whether you should get one and how you should use it if you do.

Preview	Summary
	1. One of the first Apple Watch in Korea
	Sent three days after the official release in the US and arriving about a week later, one of the first Apple Watch to land in Korea gets prompt unboxing and gets ready for a full review.
	2. Getting the Apple Watch up & running
	I have the bands installed in place and the battery wirelessly charged up, so that I can pair the Apple Watch with my iPhone 6 Plus and make it work.
	3. Basic screens & buttons of the Apple Watch
	Apple Watch's many screens are explored, including the watch face, lock screen, home, and favourites. I also try out the digital crown and the side button.
	4. Notifications & contacts on Apple Watch
	As one of the primary functions, I took a look at how the notifications appear and interact. Then I tried contacting someone with Apple Watch, either through text or voice.
	5. Apple Watch's daily life tracking
	Fitness tracking with Apple Watch is explored, including the heartbeat measurement with an integrated sensor and the daily activity logging through a three-ring system.
	6. Running, swimming with Apple Watch
	I had both Nintendo Wii Fit Plus and Apple Watch record indoor running sessions to see how they compare. Then I went swimming with my Apple Watch to see if it'd actually work.
	7. Apple Watch as an extension, stand-in
	I tried using Apple Watch as a replacement for membership cards. Then I remote controlled my Apple TV and iPhone 6 Plus camera with it, as well.
	8. Battery life of the Apple Watch
	I recorded my Apple Watch's battery life for three weeks, through international travels and all sorts of exercises, to see if Apple's claims stood up.
	9. More Apple Watch observations
	I took a look at how fast the Apple Watch charges up and how step counting data are consolidated. Also, I have some more tips and observations on its daily use.
	10. 45 days with Apple Watch & watchOS 2
	Seven weeks later, the hardware of Apple Watch Sport is still standing up quite well. But early watchOS 2 and iOS 9 betas are incredibly rough to use.