Do you like crisp photos and great low-light? You want to upgrade to the iPhone 6s or 6s Plus.

After a few hard-core days of camera tests here at iMore, I wanted to share some of our 5s comparison shots for people who may be on the fence about upgrading this year.

The iPhone 5s's rear camera is pretty good for a two-year-old smartphone: It offers an 8MP back-side illuminated sensor, 1080p HD video, 720p 120fps Slo-Mo video, a TrueTone LED flash, an f/2.2 aperture. It was one of Apple's first cameras to offer automatic digital image stabilization, and it continued to improve on the low-light conditions of its predecessor. The iPhone 5s's front camera, a 1.2MP sensor with options for HD video and burst mode, is less impressive two years in, but still respectable for the occasional selfie.

But the iPhone 6s cameras both offer a huge leap forward: The 12MP rear camera is great on specs alone, offering further improved low-light conditions, a 4K video option, and both digital and (6s Plus only) optical image stabilization. The front-facing camera, too, takes a big step into big boy camera land, offering both a 5MP sensor and a "Retina flash," which lights up the pixels of the screen to help aid in the taking of dark selfies.

We've been testing the new iPhone models over the last few days alongside their older counterparts using the stock Camera app, with no post-production or extra stabilization added. In our tests, the iPhone 5s held up remarkably well against both the iPhone 6 and iPhone 6s cameras in certain areas: Daytime shots look similar across the entire iPhone line of the last two years, with the 6s and 6s Plus grabbing extra texture and detail in shots thanks to their bigger sensors.

(In all galleries below, sorting is as follows: top left iPhone 5s; top right iPhone 6; bottom left iPhone 6s; bottom right iPhone 6s Plus)

Macro photos, too, look about the same across all devices; Apple's fixed aperture prevents the camera from being particularly fancy in that department. (Of course, that's what third-party lens add-ons are for.)

When it comes to low-light details, however, the 6s and 6s Plus exited the tests as our clear winners. Details are sharper, there's more color in the scene, and the overall light balance is much better.

And though hard to show in these photographs, the 6s series takes markedly crisper shots when firing off a burst or attempting to snap pictures freehand in low-light conditions—for example, when shooting 15 quick-burst pictures of my cat, the 6s and 6s Plus had about 7 blur-free pictures to the 5s's 4, though the 5s did have better coloration (in part due to poor exposure tapping on my part).

When it came to the front-facing camera, there was no competition: Those 3.8 extra megapixels do a lot of work to flesh out front-facing selfies and photos, especially in lower-light conditions. And the Retina flash, while weaker than your standard TrueTone rear flash, still provided nice overall fill for the photograph.

I didn't do a lot of rear-facing TrueTone flash testing, because frankly: I hate using the flash in most photographic situations and the more people I can convince not to use flashes on a daily basis, the better. I will note, however, that both the iPhone 6s and 6s Plus routinely took a few milliseconds longer than the 5s or 6 before snapping and saving the image. The iPhone 6 in general has a cooler-colored flash than either the 6s or 5s, while the 5s's flash is slightly dimmer than its newer counterparts.

We'll have even more photographic comparisons coming soon, including matching up the new iPhone cameras against the latest Android tech and a lowlight, late-night test across the streets of New York City. Until then: How are you liking your new iPhone 6s camera? If you don't have one yet, is this enticing you to upgrade? Let us know in the comments.