Apple's iPhone 4: Thoroughly Reviewed
by Brian Klug & Anand Lal Shimpi on June 30, 2010 4:06 AM EST- Posted in
- Smartphones
- Apple
- iPhone 4
- Gadgets
- Mobile
Screen - Retina Display
Right out of the box, the iPhone 4's new 326 PPI, 960x640, 3.5" display is arguably the single most striking change the new iPhone brings. In a word, it's dazzling. Text and high res images look amazingly sharp on the iPhone 4’s retina display. It’s an improvement over the 800 x 480 AMOLED screens that have been shipping on most Android phones. But if you’re comparing it to an iPhone 3GS the difference is huge.
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iPhone 3GS
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iPhone 4
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Text on the Google Nexus One
Text on the iPhone 4
The dot pitch is truly remarkable, so much so that Apple makes the claim that their display outresolves the human eye; its advertised ability to do so has earned it a new Apple tradename, "retina display."
Text on the HTC EVO 4
Text on the iPhone 4
AnandTech Logo on the EVO 4G
AnandTech Logo on the iPhone 4
Immediately after hearing Apple's claim that the Retina Display outresolves the human eye, I snapped into optics mode and crunched the numbers, and tweeted that the results were valid.
In the days that followed, there was considerable debate about the validity of Apple's claims. However, nearly all of the debate really just hinged on a debate over angular resolution of the human eye, and a little more over viewing distance. They're both entirely conventions.
As you've probably discovered by now, the human eye resolution can really only be characterized in angular subtense. Hold something closer to your eye, and you can see smaller features better (in theory), move it further away, and you can't make out small spatial details. The minimum angle visible with the human eye is the angle at which features (for the most common definition, a black and white square wave) stop being visible, and are indistinguishable from each other.
Most measures of visual acuity test with this implicitly - the Snellen eye chart's use of the capital "E" is literally a perfect example, which has given rise to a "tumbling E" eye chart. At twenty feet, the capital E subtends 5 minutes of arc, and conveniently has five half cycles of white to black (from top to bottom). So 20/20 implicitly implies an angular resolution of 1 arcminute (1/60 degrees).
As an Optical Sciences and Engineering undergrad, I've had 1 arcminute drilled into my head more times than I can count as being the "normal" angular resolution of the human eye system. In practice, this is 20/20 vision, which is "normal," yet not perhaps the absolute maximum for human perfection. We can play games of course and argue that a small subset of the population has better than normal uncorrected vision, and thus an angular resolution of below 1 arcminute. I have above average uncorrected vision, which I've measured to be 20/15 on average, giving an angular resolution of approximately 0.75 arcminutes. Of course, the definitions stem from the spacing of cones in the fovea, the highest resolution part of the retina.
The other informational quantity needed to test the Retina Display claims is viewing distance. Again, there's a commonly agreed upon convention - standard viewing distance is considered to be 1 foot. This is another drilled into my brain number tossed around for comfortable viewing and reading. In practice, you can focus on objects much closer to your eye - this is called the near point and is often given as 10 inches, though as you get closer you increase strain aren't likely to keep it here.
Maybe not exactly the limit, but close enough.
Given the two most common standards tossed around, 1 arcminute and 12 inches, do the math out and you'll arrive at around 286 pixels per inch as the limit for eye resolving power, comfortably below the 326 on the Retina Display. Move to 0.75 arcminutes at 12 inches, and it's 382 pixels per inch, higher than the Retina Display. Honestly, I can't see the pixels at 12 inches.
Of course, the real story is even more complicated. Remember how the definition comes with the implicit assumption that we're dealing with a square wave pattern from white to black? That's a factor too - the contrast of the two pixels. Lower the contrast, and the eye's ability to pick out features decreases even more. So far, everything we've talked about has been first order, and without aberrations. Toss in spherical and astigmatism, two aberrations common to the eye system, and eye performance drops way more.
The human eye system is actually pretty poor, and shockingly easy to outresolve. In fact, if you saw the image your eye forms on your retina, you'd likely be appalled; it's your brain that makes the system usable. But at the end of the day, Apple's claims that the display outresolves the human eye are good enough for us.
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Griswold - Wednesday, June 30, 2010 - link
Lets be honest, he has only very limited means to meassure the problem. To get to the bottom of this, it needs to be meassured in a HF lab.samspqr - Wednesday, June 30, 2010 - link
"The fact that Apple didn't have the foresight to coat the stainless steel antenna band with even a fraction of an ounce worth of non-conductive material either tells us that Apple doesn't care or that it simply doesn't test thoroughly enough."I find it really funny that they would never catch this specific problem because of them just being apple: if their engineers are not as good as anand is (as in thinking "that's gonna be a problem" right after hearing the description of the antenna), and if THE FIELD TESTERS HAD THEIR PHONES DRESSED AS A 3GS BECAUSE OF PARANOID ISSUES, this kind of problem can only slip through
The0ne - Wednesday, June 30, 2010 - link
I think Anand was a little light on this topic. As an multi-discipline engineer myself this type of problem with the Antenna SHOULD NEVER had happened. It can only happened due to decisions that did not properly address it. This is not rocket science to engineers. If anything, testing WOULD HAVE discover the problem and yet it's in the finish product. Quite sad if you ask me.For example, why put a ferrite clamp on the end of the cable instead of designing it into the PCB . The only reason I can see why we did this was due to lack of time and we severely paid for it by having products become defective because the ferrite would pull the cables loose from the connectors.
deppbv78 - Wednesday, June 30, 2010 - link
I'm really disappointed at the lengths taken by AT to justify that iP4 losing signal as not a big deal...If it was any other product from any other manufacturer, I'm sure you'd not have gone to such lengths to justify the signal drop and just concluded that the phone has serious antenna problems. I'm not understanding why is it so difficult for anyone just provide an unbiased view of the product.I have HTC Hero & Touch Pro both of which lost a bar or two (with fluctuations) when cupped tightly. However, it was always just 1-2 bars and never went down like iPhone 4 does from 5 bars to 0. This continuous loss of signal is the problem. Justifying it telling that all phones lose signal is not right, as every other phone (including 3GS) loses signal temporarily and then stabilizes unlike iPhone 4.
No wonder the iPhone 4 is engineering marvel, but that set aside it is also true that the design has created issues as well and the reviews need to acknowledge it and not justify it
geniekid - Wednesday, June 30, 2010 - link
HTC Incredible owner here. I think AT successfully showed that the antenna issue is NOT a big deal and their methods for doing so are sound. I share your suspicion that maybe they wouldn't have made such a significant investigation if it had been another phone, but let's not accuse them of mistakes they haven't made yet.bplewis24 - Wednesday, June 30, 2010 - link
I have a sincere question though. Does this test really successfully show the antenna issue is NOT a big deal, or does it simply show that it's not a big deal in the utmost ideal conditions?Sometimes the article is difficult to decipher in terms of understanding who is saying what, but upon my initial reading I take it Brian did the testing of the antenna in Arizona. By his own admission (from my understanding), he lives there because the reception is absolutely stellar and about as good as it can possibly be.
Again, from what I can tell, it is under those conditions that he conducted the attenuation signal loss comparisons. If it still drops down to 1 bar and comes reasonably close to dropping calls under the best possible conditions, how does it react under "average" conditions? Other people are reporting dropped calls for a reason. Is Brian's test the norm or an outlier?
Please correct me if I've read this article wrong.
Brandon
anactoraaron - Wednesday, June 30, 2010 - link
My understanding is you are partially correct in assuming (which is what I interpreted from your post) that under "normal" or "average" conditions you will go to one bar - which with the improved reception even at 1 bar you are still fine - OR will drop signal completely.This is also the reason why they say "At the bare minimum Apple should give away its bumper case with every iPhone 4 sold."
Again, fantastic in-depth review.
strikeback03 - Thursday, July 1, 2010 - link
Well, he said the location he lives in has stellar reception. But he also said he drove around for a day testing, which implies to me that he found somewhere with a stable, "average" signal and did some testing there, then probably went somewhere with a "poor" signal and did some more, etc.bplewis24 - Friday, July 2, 2010 - link
@strikeback03Correct. And in driving around to the less-than-stellar areas showed the phone dropping down below -107dB for reception when showing less than 2 bars. And this is on the low end of the reception spectrum as described earlier in the article. So it's pretty clear that the antenna does INDEED show poor signal strength in average or less than average areas when the "death grip" is applied.
That is the determining factor. That determines that the design is defective and flawed. If it was not designed that way, when in average or below signal areas, the reception would still be average or below, and not well below because of the way you hold the phone.
However, the article skirts this and attempts to present it in a way that shines the best possible light on Apple and their defective design. Big disappointment in terms of an objective review.
Brandon
geniekid - Wednesday, June 30, 2010 - link
The article made it clear that bars are a misleading way of measuring call quality/reception. In practice, it was noted that call quality/reception is improved/equal to the 3GS on the 4, regardless of bars (raw signal power).Who cares if you have 1 bar all the time if you're still making calls better than someone with 4 bars?
HTC Incredible owner here.