Apple on Tuesday unveiled its next generation of iPhones - a lineup that will boast better cameras, faster processors, a new charging system and a price hike for the fanciest model.

The showcase at Apple's headquarters in Cupertino, California, comes as the company tries to reverse a mild slump that has seen its sales drop from last year in three consecutive quarters. The malaise is a key reason Apple's stock price has dipped by about 10% since mid-July, dropping the company's market value below the $3 trillion threshold it reached for the first time earlier this summer.

MORE: Update your iPhone - Apple just pushed out a significant security update

Investors apparently weren't impressed with what Apple rolled out Tuesday. The company's shares fell nearly 2% Tuesday, a steeper decline than the major market indexes.

As has been case with Apple and other smartphone makers, the four types of iPhone 15 models aren't making any major leaps in technology. But Apple added enough new bells and whistles to the top-of-the line model - the iPhone 15 Pro Max - to boost its starting price by $100, or 9%, from last year's version to $1,200.

Apple is holding the line on prices for rest of the lineup, with the basic iPhone 15 selling for $800, the iPhone 15 Plus for $900 and the iPhone 15 Pro for $1,000.

Although maintaining those prices are bound to squeeze Apple's profit margins and put further pressure on the company's stock price, Investing.com analyst Thomas Monteiro believes it's a prudent move with still-high inflation and spiking interest rates pinching household budgets. “The reality was that Apple found itself in a challenging position leading up to this event,” Monteiro said.

And the price hike for the iPhone 15 Pro Max could help Apple boost sales if consumers continue to gravitate toward the company's premium models. Wedbush Securities analyst Dan Ives expects the iPhone 15 Pro and Pro Max to account for about 75% of the device's total sales in the upcoming year.

All the new models will be available in stores Sept. 22, with preorders beginning this Friday.

One of the biggest changes that Apple announced is a new way to charge the iPhone 15 models and future generations. The company is switching to the USB-C standard that is already widely used on many devices, including its Mac computers and many of its iPads.

Apple is being forced to phase out the Lightning port cables it rolled out in 2012 because of a mandate that European regulators plan to impose in 2024.

Although consumers often don't like change, the transition to USB-C ports may not be that inconvenient. That’s because the standard is already widely used on a range of computers, smartphones and other devices people already own. The shift to USB-C may even be a popular move since that standard typically charges devices more quickly and also offers faster data transfer speeds.

The basic iPhone 15 models have been redesigned to include a shape-shifting cutout on the display screen that Apple calls its “Dynamic Island” for app notifications - a look that was introduced with last year's Pro and Pro Max devices. The basic models are also getting a faster chip used in last year's Pro and Pro Max models, while the next generation of the premium iPhone 15s will run on an even more advanced processor that will enable the devices to accommodate the same kind of video games that typically require a console.

The iPhone 15 Pro and Pro Max also will be equipped with what Apple maintains is the equivalent of seven camera lenses. They will include periscope-style telephoto lens that will improve the quality of photos taken from far distances. The telephoto lens boasts a 5x optical zoom, which lags the 10x optical zoom on Samsung's premium Galaxy S22 Ultra, but represents an upgrade from the 3x optical zoom on the iPhone 14 Pro and Pro Max.

In anticipation of next year's release of Apple's mixed reality headset, the iPhone 15 Pro and Pro Max will also have a spatial video option designed for viewing on that headset.

Apple is encasing the premium models in titanium that the company says is the same alloy used on some space ships.

Besides its new iPhones, Apple also announced its next generation of smartwatches - a product that made its debut nearly a decade ago. The Series 9 Apple Watch, available in stores Sept. 22, will include a new gesture control that will enable users to control alarms and answer phone calls by double snapping their thumbs with a finger.