Fred Miranda
Offline
Admin
Upload & Sell: On
|
 p.3 #15 · iPhone 17 Pro cameras include a new Telephoto ('100mm f2.8') | |
Steve Spencer wrote:
All three cameras have 48MP sensors, but do keep in mind that the three sensors are not the same size.
The main camera has a Type 1/1.28 sensor. It has a sensor that is 10mm by 7.5mm with a diagonal of 12.5mm. That makes it about a 3.5 crop of a FF 35mm sensor so when they say the main camera that uses this sensor is a 24mm equivalent it really is a 6.8mm lens and that 1.78 aperture will have the depth of field of about an f/6.3 lens. So think of this main camera as a fixed aperture 24mm f/6.3 lens with 48 MP. You can crop it 2X for a 48mm f/12.5 with 12 MP, but the camera has to use a lot of AI to try prevent that from showing how much that is straining the system with a really small sensor size.
The ultra wide angle camera uses a smaller Type 1/2.55 sensor. It is 6.17mm X 4.55mm with a diagonal of 7.36mm. Even though it is 48MP this sensor is pretty tiny. It is a 5.9 crop of a FF 35mm sensor. So when they say the lens is a 13mm equivalent it is really a 1.8mm lens and that f/2.2 aperture with such a small sensor will have the depth of field (and the diffraction difficulties) of an f/13 lens on FF 35mm. So think of this wide angle camera as a fixed aperture 13mm f/13 lens with 48MP. Adding MP to this small sensor isn't going to change things much and the challenges of getting good images out of that ultra wide angle will remain.
Likewise the telephoto camera uses the smaller Type 1/2.55 sensor. They did increase the size of this sensor, however. In the iPhone 16 it was the even smaller Type 1/3.2 sensor. Still the sensor they used is a 5.9 crop of a FF 35mm sensor. So when they say the lens is a 100mm equivalent it is really about a 17mm lens, and that f/2.8 aperture will have the depth of field of an f/16.5 lens on FF 35. So think of this telephoto as a fixed aperture 100mm f/16.5 lens with a 48 MP sensor. You can crop this to a 200mm equivalent, but the results will have the diffraction and depth of field challenges of an f/32 lens, so again they have to add a ton of AI and processing to that image. It may have 12MP, but the challenges are obvious.
So, keep in mind here the lenses didn't change. The sensor sizes mostly didn't change (the telephoto sensor did get a little bigger). Moslty, they just increased the pixel density of the sensors for the ultra wide and telephoto lenses. That isn't going to change things much. In fact, my guess is improvement in AI will matter more than increasing the pixel density of the ultra wide and telephoto cameras. Now increasing the sensor sizes and making new longer lenses should make a lot of difference for the ultra wide and telephoto cameras, but that is not what Apple did and it wouldn't be easy to do. I think it would be easier for the ultra wide, but physically fitting a longer lens on the back of the phone isn't going to be easy and making room in the phone for those larger sensors I am sure won't be easy either. In time I am sure they will do it, but don't expect to get anything at all like even a small all in one camera in a smartphone any time in the next decade....Show more →
This is such a great post. Thanks Steve! 
Photographers used to thinking in depth of field equivalence can think of the iPhone 17 Pro's cameras like this in full-frame terms:
There are only 3 real lenses:
• 13mm f/13 (48MP): Ultra-wide
• 24mm f/6.3 (48MP): Main
• 100mm f/16 (48MP): Telephoto
The app also provides these crop options: (with updated Remaining MP)
• 28mm f/7.3 (35.3MP): Apple outputs a 24MP ProRAW file, despite the higher resolution sensor area.
• 35mm f/9.2 (22.6MP): Apple outputs a 24MP ProRAW file, even though the crop yields a lower raw pixel count.
• 48mm f/12.6 (12MP): Apple outputs a 12MP ProRAW file, matching the cropped sensor resolution.
• 200mm f/32 (12MP): Apple outputs a 12MP ProRAW file, consistent with the heavily cropped sensor data.
Note: These are depth of field equivalences only. Exposure is unaffected. An f/1.78 smartphone lens gathers light the same as f/1.78 on any system. "Remaining MP" refers to raw pixel count after a simple crop. Real world usable resolution will be further reduced by diffraction, noise, demosaicing, and computational processing.
So, that's the real depth of field you're dealing with, no matter what the marketing says about fast apertures. The small sensors force those equivalent DOF numbers, which also means diffraction kicks in earlier than on a larger sensor system.
Everything beyond that is Apple's API computational work:
• Cropping in is just using fewer pixels, then letting AI try to preserve as much sharpness as possible and suppress noise.
• Extra megapixels on the ultra-wide and tele don't create new optical detail, they just give the software more room to denoise, warp, and upscale.
• The real improvement comes not from pixel density but from multi-frame stacking, sharpening, and noise reduction - basically clever processing that hides the limits of small sensors.
|
