The tiny Sony Alpha 5100 is blowing up online – are folks looking for a smaller, cheaper RX1R III alternative?

The Sony Alpha 5100 has seen a huge uptick in interest recently. This is something that interests me for a number of reasons – not least because I've had four of these cameras on my eBay Watchlist for about a year, and every payday I'm tempted to hit Buy It Now.

On one level, the piqued interest in the Sony Alpha 5100 is due to the same reason the camera has always been popular on the used market: it's an incredibly small, slim and lightweight APS-C camera. In fact, when it launched, it was officially the smallest interchangeable lens camera on the market.

In the broader context of today's camera climate, however, I think the surge in search for the Sony Alpha 5100 is also due to the launch of the Sony RX1R III.

In case you missed it, the RX1R III is an enormously anticipated full-frame compact camera that has finally been released a decade after its predecessor. However, while it ticks the boxes it's supposed to – being both full frame, and a compact camera – it's also extraordinarily expensive at $5,098 / £4,200 / AU$7,999.

As has been well established, the market is ravenously hungry for compact cameras – or, in their stead, supremely small mirrorless cameras with a slim footprint that can be outfitted with a tiny lens to make them just as compact. And this, I think, is why the Sony Alpha 5100 is currently trending.

While the camera is now 11 years old (interestingly launching not long before the Sony RX1R II), the Sony Alpha 5100 was ahead of its time and thus is still quite a powerful photo machine in 2025. Its 24.3MP APS-C sensor still takes a great image, even with a conservative 179 AF points (all phase detect) and ISO25,600 ceiling.

The 3-inch rear screen boasts touch input and 180° tilting for selfies, though at just 920,000 dots it's lacking in fine detail – and there's no 4K , as the video tops out at FullHD 60p.

However, what makes the Sony Alpha 5100 undeniably attractive is its size: at just 109.6 x 62.8 x 35.7mm it's got a smaller footprint than most smartphones – and it makes the RX1R III, still super small at 113.3 x 67.9 x 87.5mm, feel positively obese.

Paired with the positively pocketable pancake, the Sony E 16-50mm f/3.5-5.6 OSS PZ, the Sony Alpha 5100's size leapfrogs its few performance shortcomings to provide a truly compelling option for those seeking a practical everyday carry – or a camera that's smaller, lighter, cheaper and has more focal lengths than the RX1R III.

Yes, obviously in terms of pure specs, Sony's new full-frame compact blows this old APS-C snapper out of the water. It has a 61MP sensor and faster AF, a more detailed rear screen and an EVF… but it's still not really a video device and, crucially, it doesn't have image stabilization. And of course you can't change that 35mm f/2 lens.

So, really, if what you want is an ultra-compact Sony camera that pairs perfectly with small lenses, the Sony Alpha 5100 would be a great shout. Especially since they start at just $344 from MPB in the US and just £234 in the UK!

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Already got a Sony Alpha 5100? Take a look at the best Sony lenses, or if want a bit more firepower then check out the best Sony cameras worth upgrading to.