I’m not too keen on P&S either. If you don’t pay a lot they tend to die all too fast (my experience anyway). And if you’re going to buy a good one, get an SLR instead.

You mentionned that a P&S is good for casual photography, for example. I’m wondering if the P&S will not die out soon. We all have cell phones with better than average photography capabilities, and they’re even giving SLRs a run for their money! I have a Nexus 4 and can do sphere photos, panos and HDRs. Why would I want to carry a P&S too?

I have a Nikon D90 with a pretty good array of lenses, accessories and bags and I’ve had no problems building kits according to destination and needs. I don’t need more. Well… maybe the D7100…

Great show and keep recording!

Ciao,

AC

However, a Canon IS p&s (like my A710IS which i bought used for $80) with CHDK — the Canon Hardware Development Kit has more features than most DSLRs, is only a button click or three away from adjusting aperture, exposure compensation, ISO, multi-exposures, picture size, macro or manual focus with enlargement.

To avoid diffraction or motion unsharpness I almost always use it aperture priority at the maximum aperture, and 8MP is good enough for almost any enlargement — though it limits cropping.

And with CHDK, I have lightning flash detection, intervalometer, raw files, and much, much more!

And small sensor cameras have the advantage of great depth of field, especially for macro shots.
The P&S does need a good lens.

As for diffraction limits, the smaller the sensor, the wider the F/stop you need for sharp-appearing pictures:
Diffraction limits (1/1500 Circle of Confusion)
Sensor/film Diagonal-MM f/stop CoC(microns)
1/2.5” 7.18 3.5 4.8
1/1.8” 8.93 4.4 5.9
2/3” 11.00 5.4 7.3
4/3” 22.50 11 15
APS-C 28.40 14 19
35mm (FF) 43.40 21 29
6x7 92.20 45 61

Unsharpness appears beyond diffraction limits, assuming ordinary eyes, no cropping and a standard viewing distance equal to the diagonal size of the image. (So even a 3MP picture is good for any enlargement size at ordinary (for the print) viewing distances.)  (Note, the diffraction limit F/stop is the same for all focal lengths for a given sensor size. A given aperture like f/2.8 may be wider for longer lenses, but it is further away, so the angle width is the same.)

Of course, if you want it sharper, for cropping, or to take advantage of sensors with more than 1500 pixels diagonally, you need a wider aperture — assuming your lens is good and has few aberrations at wider apertures. For maximum sharpness, you need to  balance diffraction (all lenses) and aberration effects(your lens). Process lenses for printing and chip making are often f/2 for maximum sharpness. It helps that they usually use a single wavelength to avoid chromatic aberrations.

The CoC principle also applies to depth of focus. Stopping down reduces maximum sharpness, but increases what appears to be “sharp enough”.

There is a nice discussion at  http://www.rags-int-inc.com/PhotoTechStuff/DoF/

Also, keeping your P&S at maximum aperture and aperture priority not only means maximum sharpness of what is in focus, it also means a shorter shutter speed for more sharpness & maximises  the  blurriness of other stuff, leading to a sharper-feeling photo, with more concentration on what you focused on.

Do you want your students to make good pictures or make sharp, well exposed ones?
Atget, Bresson & Karsh (I worked for him) did pretty well with comparatively primitive equipment.

Camera controls are just more ways for students to get the image they want.  Like all training, you need to make the camera disappear from the conscious mind. Alas, modern cameras mean a longer training period the more demanding the photographer is. A P&S, though, can  be ideal for seeing.