Camcorders: tips if buying one

A parent emailed to ask for help in selecting a camcorder to buy. As researching the answer took quite a long time I'll share it on both AS + A2 coursework blogs.
Note that my suggestions merely reflect my opinion, which you are quite free to follow or ignore!

FACTORS TO CONSIDER WHEN BUYING A CAMCORDER

You can skip this long list and go straight to the recommended models.

1. Do you need it? Will your still camera or smartphone suffice? (Probably not yet for coursework, but we're not far off that point. You also need to consider tripods etc) This review suggests that an iPhone 4S can compete with a £370 V700 camcorder on image quality, tho' not on image stability or wide angle or zoom.
2. Budget: you can get a good cam for £200, but £300-400 buys you extra future-proofing and should delay the need to buy a new one as technology changes
3. 3D? This is a feature of some new cams; currently irrelevant for coursework, and possibly gimmicky at the budget end. It mostly requires adding a £150-200 3D lens.
4. HD - this seems obvious but there are 3 variants of HD: 720p, 1080i, 1080p. I'll detail this below. Ideally, you want 1080p.
5. Frame rate: the number of frames per second captured (also expressed as Hz). For both 720p + 1080p this starts at 23.976 but goes up to 60fps. Some cameras use software to capture at 15fps but make this equivalent to 24fps. Raw footage is generally compressed to edit, so frame rate perhaps isn't too vital, except for slo-mo effects.
6. Battery life: read reviews carefully, not just the official specs - you need a min 1hr battery life, but probably need to factor in the cost of a spare battery/charger.
7. Memory: internal memory arguably isn't really much use except as a guarantee of recording continuing if your SD card runs out. Some cameras offer dual SD slots, doubling the effective memory. You'll typically want to be able to get your footage off the camera through a removable SD card (put into a USB SD-card reader), not to connect the camera itself.
8. Optical zoom: although 'digital zoom' is getting better, it still leads to a degraded, eventually pixellated image, so optical zoom is the true measure to look for - this varies widely between cameras.
9. Wide-angle lens: if the lens is listed as under 35mm its wide-angle (some claim this if slightly above 35mm). 35-24mm = WAL; below this = ultraWAL. WAL mainly means you've got increased ability to shoot close to a subject; without it you may not be able to get shots in confined spaces that you'd planned. Wiki on lenses. Camcorders.about.com guide. Wiki on aperture. (Bit outdated but this is useful too). For scientists.
10. Lux level: easy to overlook, but this is crucial - the lower this figure the better its ability to record a sharp image in low light conditions. See the table here which breaks down what lux figures mean.
11. Brand: I'd recommend you eschew unknown brands in this case. Furthermore, unless you're buying top end, I'd be cautious about Sony - they're known to often be problematic with Macs. The Media Dept has had 2 Panasonic HD cams running without issue and recording great footage, so I'm going to focus on them below. I'd note here that half of TrustedReview.com's Top Ten camcorders are Panasonic models. (For balance, here's TechRadar's list too; it usefully includes all types)
12. External mic slots: again, this is partially about future-proofing (if you're going to use this cam at uni you definitely want this option), though the Media Dept has a boom mic you can loan out so its a feature you could take advantage of now. Once you've done any work with a boom mic and are able to compare the camera's native sound vs an external mic you'll appreciate the striking difference in quality.
13. HDMI output: this means you can connect your cam to an HD TV.
14. LCD display: 2.7-3.5" has become the norm, some have smaller; just check reviews for issues such as poorly designed menus or difficulty in accessing it because of poor design. You definitely want to be able to flip the viewscreen so you can see what you're shooting from any angle.
15. Image stabilization: this technology has advanced in recent years to smoothen out the flaws that come with handheld filming. Note the Media Dept has a 'FigRig' (a sort of steadicam) you can loan - and that Final Cut Pro X has software tools for improving handheld footage too.
16. Stills capture: just as still cams can capture video, so video cams can capture stills. Check for the MP figure, but also for speed/convenience (some models now offer the ability to snap a still whilst shooting video).

HD VARIANTS
Resolution is expressed at the number of vertical lines that appear on a TV screen. This Wiki is a useful summary of what you need to know, including a table. 720p is the starting point for HD (thats a resolution of 1280 x 720, ie the number of horizontal + vertical lines displayed on a TV). 1080p is full HD (1920 x 1080). This is further complicated by progressive v interlaced (p v i) scanning. 1080p has every line refreshed, 1080i has every other line refreshed (this is the BBC HD standard) and thus can lose image quality.
As noted above, the frame rate is yet another factor here - BUT, when you import footage to software such as Final Cut you are generally compressing the footage into .mov or .mp4 or .m4v formats, so this isn't necessarily a huge concern.
On many cameras you'll find that full HD (1080p) footage is saved on the camera as .MTS files which need to be converted (eg through Handbrake) while 1080i will import without any need for conversion.

RECOMMENDED MODELS
Pricing varies widely: search widely (taking customer service + warranty + postage into account) before buying. All of the below are Panasonic models. Amazon (+ other) user reviews are useful.
The price I give is an estimate from a quick search, but will of course change (+ offers may be available).
The SD cams + the rest all seem to feature Zoom mic: mic zooms with visual zoom.
SD-40/60/80 don't have external mic sockets; SD-90 does. If thats not important the SD-60 is a bargain

SD-40 You've all used these [if I've got the model no. right!]; a good all-rounder BUT not full HD (ie 720p, not 1080p). TrustedReview.com. £200? [de-listed? SD-60 is probably the entry model now] NB: no ext mic socket.
SD-60: The next model up, and a great deal for the price:  TrustedReview.com. £145 from Olimpic-cameras.co.uk. (over £300 on Amazon) NB: no ext mic socket.
SD-80: sounded ok but I found some niggly design flaws: ‘The lens cover opens when switched on, but does not close when switched off.  When using AUTO mode neither the Mic nor the in-built LED subject illumination light can be disabled (low light use).’ About £180 (4* Amazon customer reviews) Detailed review.

This review compares SD-80 + SD-90 (SD-90 replaced SD-60 as its recommended budget buy). Key difference: SD-90 has ext mic socket. 

SD-90: top of the single-CMOS SD- range, 3D option, WAL, HDMI, ext mic socket, circa £400 BUT worse in low-light conditions + over-sensitive zoom switch. TrustedReview.com. TechRadar.com. 2nd hand on eBay £250.
(SD-900 is an example of a new range with 3-CMOS sensors, around £800 though! TechRadar.)

V500 etc may be sold in different memory configurations. These have ext mic sockets.

V500: Full HD and WAL (32.4mm). Good list of tech features. Amazon. £250.
V700: extends V500's WAL capacity. Amazon. Good list of technical details made clear. £320+
HDC-TM80K - best budget cam of 2012 according to this list. Amazon. 720p or 1080i.  £400+

There are many more models out there, Panasonic + others, these are just some you could consider.