I think you first (and last!) explain the difference in PURPOSE along with the difference in quality. It is not "iPhone camera vs dSLR quality," in my mind. It's, "What is practical and appropriate for me to use today, to get the results I need from the situation?" I use an iPhone 7 Plus and a Lumix GH4. I no longer use SLRs or dSLRs from Canon and Nikon, as I did for 44 years.

Every camera format from smartphone to 100 MP medium format has an intended use case. The use case for a dSLR or MILC is different from the use case for an iPhone. I use what I use for specific reasons, and my reasons are different from others', and that's okay... and as it should be!

Smartphones have lots of artificial intelligence built in. They use tiny little sensors which are quite good in bright daylight, but very noisy at night. Still, under most circumstances, they blow away all the 35mm ISO 400 and higher speed color films of 50 years ago (Yes, I was around back then, pushing High Speed Ektachrome as far as it would go!).

The tiny sensor in a smartphone means it has a short focal length lens (or two or three). That usually leads to deep depth of field. Whether that is good or bad depends on the intended result. AI (i.e.; Apple's Portrait Mode) can mitigate deep depth of field somewhat.

The tiny sensor limits practical megapixel counts. Most phones are 12 MP or less. The trend, now, is to make slightly larger 12 MP sensors with each iteration, to expose more sensel surface area to light and reduce noise/improve dynamic range. But physics is what it is... Larger sensors suck more photons per sensel, which lowers ultimate noise in each processed file pixel.

If you know what you are doing, and work in good light, you can create 20x16 prints from iPhone 5 and later cameras. We have a couple on our walls, and no one, not even photographers, has asked about what camera recorded the images. Would they "look better" if they had been made with full frame? Yes, if you viewed them from one foot. But due to the subject matter, you view these prints from two or three feet. At that range, they're fine, so long as you aren't comparing them to the same exact scene recorded with a larger format.

A huge impact of the smartphone has been the near total annihilation of the "point-and-shoot" pocket camera market. The "snap shooters" first gave up 35mm "point-and-shoot" film cameras for smaller APS film cameras. Then, less than five years later, they gave up those for point-and-shoot pocket digital cameras. Another five years later, along came the practical smartphone camera.

So... John and Jane Public no longer use idiot-proof cameras of any sort. The smartphone, and its choice from two MILLION apps, is the only thing most want to carry. First, bits beat atoms (digital beat film). Then, the pocket supercomputer beat dedicated cameras, at least for most folks.

The term, "image quality," is loaded with ambiguity. Does it always refer to technical attributes? Or... can it refer to decisive moment? Composition? Use of contrast or color? Storytelling? History? Emotional impact? At some level, a camera is a camera, and a good image has MANY quality characteristics.

Cameras are tools. The subtleties of their differences are often secondary to the impact of their users' results. So I would submit that the photographer's knowledge, experience, training, skills, passion, sensitivity, viewpoint, purpose, and understanding of the situation are often far more important than the brand or format of camera in use.

Three key advantages of the smartphone camera are that for most of us:

> It's always with us, whether doing "intentional photography," or just living life. The most important camera you have is the best one you have with you when a photo opportunity arises.

> It's nearly always connected to the Internet, for immediate sharing of audio, video, photos, text... to any location in the free world, and maybe beyond.

> It's both a camera and a photo album, connectable to anyone else's photo album.

Good luck with your students! Welcome to UHH. Enjoy the spirited (and sometimes appalling, sometimes enlightening) discussions.

Gail, a very large number of pictures are not actually printed anymore since people find that sharing on social media is both convenient and a lot cheaper. There is barely a difference between a picture taken with a cellphone camera and a DSLR/Mirrorless/Bridge/Point and Shoot/MILC camera for a vast number of pictures - when displayed on a UHD, up to 4K screen. However, many Luddites here will complain and say that cellphone cameras are ok if you are making small (4x6, 5x7) prints, yet I have printed up to 16x20 with no complaints about sharpness or image quality.

But in driving home the point that cellphone images can be printed large, Apple has an ongoing ad campaign that shows billboard-sized images taken with their 8 and 12 mp cellphone cameras.

I found this great article from among the 1000s of similar articles on cellphone photography:

https://photographylife.com/camera-phone-photography

One day in 2016 I left the house and forgot to pack my batteries. So I used my phone. The first three images below were taken with an iPhone 5S.

I defend the phone-camera, as my previous comments indicate. The fact that a good print was made at 20x30 does not indicate it is as good as a full frame DSLR might have made. It being acceptable, does not mean that shown next to a similar enlargement from a DSLR it would be its’ equal. If so, this defies all logic of what sensor size means. We might as well all have smaller DSLR’s with tiny sensors if that really is true.
Just as with race-car engines, all things being equal, cubic inches always wins. Same with sensors. Some people may have a more steady hand, but again, that should be an issue with and without either or both cameras.

I believe JeffL said a lot very efficiently in his contribution.
I only wish I could obtain the
results some people do with
their cellphones. My wife is
not interested in photography
as a hobby at all. I have tried
to get her cameras and to
get her to do more. Nada. No interest. But, you should see
what she can do with her cell
when we are on vacation. Her pictures are a big hit with her
friends whom she immediate
ly sends the pictures. She is not interested in the bulk of even pocket sized cameras. She
doesn’t enlarge or print much
Sometimes they go on her screen-saver. Why would she ever (really) need more than her cellphone camera?