Optical zoom resolution on iPhone Pro 17's 48MP camera

What do you mean by optical zoom vs. mechanical zoom?

Here is what Apple says in the Technical Specifications:

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48MP Pro Fusion camera system

• 48MP Fusion Main: 24 mm, ƒ/1.78 aperture, second‑generation sensor‑shift optical image stabilization, 100% Focus Pixels, support for super‑high‑resolution photos (24MP and 48MP)
• Also enables 12MP optical-quality 2x Telephoto: 48 mm, ƒ/1.78 aperture, second‑generation sensor‑shift optical image stabilization, 100% Focus Pixels
• 48MP Fusion Ultra Wide: 13 mm, ƒ/2.2 aperture and 120° field of view, Hybrid Focus Pixels, super‑high‑resolution photos (48MP)
• 48MP Fusion Telephoto: 100 mm (4x), ƒ/2.8 aperture, Hybrid Focus Pixels, 3D sensor‑shift optical image stabilization and autofocus, tetraprism design
• Also enables 12MP optical-quality 8x Telephoto: 200 mm, ƒ/2.8 aperture, Hybrid Focus Pixels, 3D sensor‑shift optical image stabilization and autofocus, tetraprism design
• 8x optical‑quality zoom in, 2x optical zoom out; 16x optical‑quality zoom range
• Digital zoom up to 40x

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To me, this says that there are five optical zoom stops, among which the phone can select by changing the camera and the portion of that camera's sensor that it uses.

• Ultra-Wide (0.5x) – 13mm f/2.2, using the full sensor (24 MP or 48 MP)
• Main (1x) – 24mm f/1.78, using the full sensor (24 MP or 48 MP)
• Main (2x) – 48mm f/1.78, using 1/4th of the area of the sensor (12 MP). (This is a type of digital zoom, but since it's exact, it's equivalent to optical zoom.)
• Telephoto (4x) – 100mm f/2.8, using the full sensor (24 MP or 48 MP)
• Telephoto (8x) – 200mm f/2.8, using 1/4th of the area of the sensor (12 MP). (This is a type of digital zoom, but since it's exact, it's equivalent to optical zoom.)

twentworth wrote:

My previous post was removed, so I'm going to try again to get some information. My question is simple:

For the iPhone 17 Pro, what is the maximum optical zoom available at full 48mp resolution?

I would have thought you could have worked that out yourself, from the Technical Specifications, or from my post.

4x, using the Telephoto camera.

The 8x setting uses the Telephoto camera, but crops off 75% of the image (and 75% of the pixel values) captured by the sensor, so the maximum resolution available at 8x is 12 megapixels.

Gatorowl wrote:

Very helpful reply, although I wouldn't call the 48mm and 200mm FL digital since they are using actual pixels rather than digital extrapolation. Rather, I think that the OP's terminology of "mechanical zoom" (terminology that is new to me) is a more appropriate description of what is going on behind the curtain.

I don't believe that mechanical zoom is an appropriate description.

On standalone cameras like film SLRs, digital SLRs, and mirrorless interchangeable lens cameras, a zoom lens is one that typically has a continuously variable focal length. As you mechanically zoom the lens from the wide end of its range to the telephoto end, or vice versa, you get optical zoom at every setting.

Smartphone cameras typically do not work in this way. Instead of having zoom lenses with continuously variable focal lengths, a smartphone may have multiple cameras, each with a fixed-focal-length lens. So there are only a small number of optical settings.

E.g., on the iPhone 17 Pro and Pro Max, the only optical settings are 13mm, 24mm, 48mm, 100mm, and 200mm. For a continuously mechanically variable zoom, you would need extra space for multiple lens element groups and for motors to adjust their relative position.

It must crop off 50% of the horizontal pixels and 50% of the vertical pixels. So the 8x telephoto image is based on only (0.5 x 0.5) = 0.25 = 25% as many pixels as the 4x telephoto one. 25% of 48MP is 12MP.

Pretty sure it’s only 4x if you want the full 48MP.

Between 4x and 8x you get digital zoom which will decrease the resolution. All the way down to 8x at which point you’re getting what Apple calls optical again, as it’s just using exactly the 12MP in the middle of the sensor.

100mm at 48 mp, only if you are shooting RAW. You have to go to Settings/Camera/ Formats

Very helpful reply, although I wouldn't call the 48mm and 200mm FL digital since they are using actual pixels rather than digital extrapolation. Rather, I think that the OP's terminology of "mechanical zoom" (terminology that is new to me) is a more appropriate description of what is going on behind the curtain.

I don't understand the above calculations. if 4x is equal to 100mm at 48mpx and the 8x is double the 4x,ie, 200mm than it only has to crop 50% of the 4x image which would make it equivalent to 24mpx.

According to Apple:

8x optical-quality zoom.

All the best! 👋🏼😉

And more precisely Apple ProRAW. Many third party apps are now using a 12 MP Raw file format. It’s not as heavily processed as Apple ProRAW. Both Raw formats produce a linear DNG file.

My previous post was removed, so I'm going to try again to get some information. My question is simple:

For the iPhone 17 Pro, what is the maximum optical zoom available at full 48mp resolution?