Last month, iPhone 15 line up had been released. Especially for iPhone 15 Pro Max, it came with 5x optical zoom using tetra-prism setup which would be similar to periscope lens on S23 Ultra. However, when I tried them at the store, the image quality at the tele range is not very impressive. Looking at the specs the Pro Max line up have the following
- Main
- 48 MP 1/1.28" (10 x 7.5 mm), crop factor of 3.46
- 24 mm f/1.78
- True focal length 6.94 mm
- DoF equivalent f/6.15
- Wide
- 12 MP 1/2.55" (5.6 x 4.2 mm), crop factor of 6.19
- 13 mm f/2.2
- True focal length 2.10 mm
- DoF equivalent f/13.62
- Tele
- 12 MP 1/3.5" (4.5 x 3 mm), crop factor of 8
- 120mm f/2.8
- True focal length 15 mm
- DoF equivalent f/22.4
It make sense that for tele, it need to have smaller image sensor to reduce the focal length. But this also decrease amount of light the sensor can capture. Thus, the noise is increased. So in low light, to have any usable telephoto, heavy noise filtering is applied. This caused a lot of detail to be lost
Last year, LG innotek teased 4x - 9x optical zoom. But it is likely a trade off between continuous focal range, and aperture, and I do expected smaller on 9x end. Assume best case, where we use the same camera lens specs of Sony RX100 VII of 24-200 mm f/2.8 - 4.5 then we will lose the light about 1.33 stop. So either they make the sensor area larger by 2.5 times, or they need to better design their lens
Let’s take a look at S23 Ultra camera telephoto setup. They have 3x f/2.4 (69 mm), and 10x zoom f/4.9 (230 mm). They did this to combat the aperture problem by using prime lens. But anywhere in between 3x, and 10x it will be a digital crop of 3x sensor. So at 9x zoom, your image is probably look like garbage before snap back to acceptable image at 10x
But since the smartphone chassis space is at a premium, they probably can’t realistically have better low light performance with the small compact camera design. The most camera on a smartphone is 16 (by Light L16 Phone). But that one is non-practical anyway, and they can’t just keep adding camera. So what they can do to improve the telephoto performance on a smartphone?
I have a few ideas that came to mind
- Xaomi 12S Ultra Concept, which just expose their main camera with a lens mount. Basically convert it to a mirrorless camera
- Third party lens, Moment lens is a good example of this. They have 58 mm zoom over original 24 mm main camera. So it might be possible to engineer a zoom lens version for this. But I would not imagine the lens size
- Minolta RD-3000 has a dual chip sensor by splitting the image into 2 parts at 90 degree angle. This has the potential to have a larger sensor in a small enclosure. But I don’t know the practicality of this
Look at the lens… how do you expect to get a quality image with tele glass like that?
Eventually you just don’t have enough information to start with to make processing and up scaling not look like ass. You reach a limit.
Lens size + sensor size.
It’s like trying to fit an entire high school inside a van for a field trip, they won’t fit (unless you make something similar to a milkshake for better space management but then the parents might be slightly upset).
It’s the sensor size. Phones will probably never have a sensor large enough to be able to translate a zoom magnification of any decent proportion.
50 mp on a 35mm equivalent sensor, even stacked sensors, is hard to process into a viable noise free image. The sweet spot is somewhere between 24 & 36 mp.
Imagine trying to cram that info into a sensor the size of a literal fingernail. Now, put in a processing system that can sift through that info and compile a viable image in nanoseconds, and still do everything else your phone does.
Yep, sensor size is the issue, and because people want their phones to be of a certain size/weight/thickness, there are limitations to what sensor size a phone can have. And, not only that, but when you make the sensor larger, you have to optimize the lenses to cover that sensor too, usually they’ll have to be larger, thicker, maybe more groups of lenses in various shapes in order to produce a correct image.
Hence why companies like Sony originally had the idea of basically strapping what was basically a DSLR sensor to the back of a lens and give it electronics to communicate with a phone to make it be able to make your phone have a more “pro” camera, theDSC-QX100 which in my view was a good idea in concept, but really didn’t have much of a need to fill, and it was bulkier than what people were generally willing to carry around if they just wanted to have better photos taken with their phone. Didn’t sell very well.
I wonder though if someone were to explore the idea again if it couldn’t be done better now? Maybe make the whole thing more rectangular in shape and utilize a larger periscope-type lens system but be able to put a much larger sensor at the end of the periscope? So basically shaped like say, one of those thicker battery-bank cases, but just with the guts of a higher quality periscope lens camera in it?
iPhone pro also auto-switches the lens (usually in low light or bad focus) EVEN if you choose tele, there’s no setting to override this
The pro will auto switch to the wide angle lens if it detects your focusing close (macro). When the macro mode was first released you couldn’t disable, but they updated the camera app a month or two later with a macro button that allows you to disable the auto switching. So, yes there is a way to over-ride it.
If you want additional control I recommend the Halide camera app which has a lot more photo/camera focused controls including manual focus.