During the years I used many different mobile phones. I started in 1998 with a Mitsubishi, and I still keep that first Italian mobile number as a backup one. Then mobile phones with cameras arrived, and the first one I ever used was in Japan, around 2001. The one that I remember to be my first official mobile phone with a camera was the Nokia 7650, an amazing device for the time (2002), the grandpa of the modern smartphones. This was the quality of its camera:

And I remember I was very happy with this quality, for quick snapshots with family and friends.

My first iPhone was the 3G, then I had the 4S, the 5, and now the 6. I still keep them all, and this is why I thought to do this quick comparison of their cameras. Apple is going to release the 7th iPhone soon, and this time the camera will see a major upgrade: 2 lenses as the recent Huawei Leica? Or an optical zoom? Both maybe. This is about time, to be honest I don't really see a dramatic difference in terms of quality of the cameras since the iPhone 4S. It's improved, sure, but much less than the rest of the phone.

Let's see some images, straight out of the cameras of the iPhone 3G, the iPhone 4S, the iPhone 5, and the iPhone 6:

The iPhone 3G has a camera that can take only photos, and not videos, and has a more narrow focal length (35mm equivalent) comparing to the later iPhones. I think the widest focal length is about 29mm with the iPhone 6, then 31mm for the iPhone 5, and again 29mm for the iPhone 4S. Though the iPhone 6 feels wider for some reasons, might be an optical illusion because of the bigger screen.

Other photos, this time some macro; again iPhone 3G, iPhone 4S, iPhone 5, and iPhone 6:

The iPhone 3G cannot focus very close. Some other photos:

And a panorama test:

Here the iPhone 3G performs better than the previous tests. Now a test about the dynamic range:

The camera of the iPhone 3G wasn't impressive at the time of its release, but things got better from the iPhone 4, and 4S in particular. In Japan, before buying the iPhone 4S, I used a classic Japanese clamshell mobile phone, a not really fancy Docomo NEC model. I was impressed by the pictures taken with that mobile phone; at the time (2010) it had a better lens than the iPhone 4. In general Japanese cellphone market has always been very keen to mobile photography. A couple of examples here:

I expect the iPhone 7 to bring a significant improvement on the mobile photography, since Apple advertises the ability of the iPhone camera as one of the main functionality of the phone (for instance see the campaign "Shot of iPhone 6/6s").

Mobile photography will continue to grow, as it already replaced the low-level consumer point and shoot cameras. Not only better lenses, optical zooms, sensors, third parties attachments, but also software wise. The post production that users can do directly on the phone is already impressive (I use Snapseed), and new interesting applications also let you have more control of the camera when shooting (like Analogue app). Hardware wise we can expect mobile and dedicated cameras to communicate more and more, like the new instant camera by Impossible Project, the I-1: its functionality can be expanded via bluetooth and its app. Mobile phones can also be used as support of film photography, as showed by several products from Lomography.