Size
Smaller cameras are more likely to be with you when needed unexpectedly - that role tends to be filled by mobile phones nowadays, although the usual lack of optical zoom is a big limitation. Bigger cameras tend to have better flash range and take much better pictures. There are some quite reasonably priced cameras in jacket rather than shirt pocket sizes. Or why not have a little camera and a bigger one for special? I take that to extremes, with six cameras, all bought at bargain prices (two were free to review), for different roles.Most mobiles take decent photos in good light nowadays, but even if they have lots of megapixels the lenses and sensors are so small and the lack of optical zoom so restricting that you cannot expect too much from them, especially in poor light. And going round flashing at people to overcome this is regarded as intrusive in most situations and doesn't work anyway with subjects over a couple of metres away. But top end phones are pretty good nowadays for anything but telephoto shots. My newish Pixel 6 Pro is pretty fantastic, even in low light, and has 5x of zoom.
I will sometimes choose my Pentax K50 SLR (top right) if I want the best quality, eg on safari. But in low light social situations I mostly prefer my Olympus PL9 or M10 II or Sony ZV-1 II - less obvious but still very capable. They are also all excellent video cameras, unlike the K50. For distant subjects it's got to be my little Canon superzoom, compact enough to be an all rounder in my messenger bag. Or for better shots I have a super 24-400mm lens for my Olympus cameras. If I don't have a camera with me my Pixel 6 Pro phone's amazingly good in all sorts of light and is excellent for videos if you don't need smooth zooming.
Megapixels
Doesn't really matter nowadays. 4MP (impossible to buy) would be more than enough up to 7x5" prints, even with cropping, and plenty for screen displays. No point in chasing past 20MP unless you want to print really big enlargements. In fact, more megapixels can often mean worse low light pictures with more noise on them (speckly) because they cram more pixels onto the same sized sensor. It also means huge files clogging up your computer if you don't process them. My Pixel 6 Pro phone has three cameras, 2 of them 48 or 50MP but downsamples images to 12.5MP to achieve excellent results.
Sensor size
This is much more important than megapixels yet manufacturers try very hard to keep us confused with sensor size 1/2.3" or similar (a typical smaller digital camera size) and never seem to state the sensor area - which is what matters. 1/2.3" actually means a tiny sensor package with a sensor area of 6.17 x 4.55mm or a minute 28 sq mm. No wonder low light performance is so poor! Most smartphones are even worse, some with a sensor size of just 15 sq mm as well as minute lenses. At that size the attempt to pack over 40 megapixels onto such a tiny sensor means the pixels are almost as small as the wavelength of red light - physics decrees there's no point going any smaller. There's a superb article on this at Gizmag. Newer smartphones may have bigger sensors and use computational tricks to mimic real bokeh.My Olympus PL9 and M10 II both have a sensor of 225 sq mm, very significantly bigger. Hence their much better picture quality. My Pentax K50 SLR has a massive 370 sq mm. That lets you really control depth of field, eg to produce shots where the subject is sharp but the background out of focus - just like our eyes work. See a good article at Wikipedia.
DSLRs all have big sensors, eg APS-C sensors are 320-370 sq mm and the expensive ones go up to 35mm film size (860 sq mm). That's why DSLRs have such good low light performance and depth of field (in-focus zone) control. But it does mean the lenses are big. Micro Four Thirds cameras have 225 sq mm sensors so the lenses can be quite a lot smaller. There's an absolutely brilliant site that lets you simulate the depth of field achievable with different sensor sizes. I put in the sensor sizes for my 4 cameras (1/2.3", MFT and APS-C) and had fun with the sliders.
Low light performance
Most small digicams are not too good in really low light conditions, apparently because of their small sensors as well as their little lenses. Photoshop Elements has a filter which helps de-speckle low light pics and the Nik Collection has some good filters too. Small digicams generally have a weak flash and produce far more redeye. With a good, bigger sensor camera you have much more chance of getting good results in low light, especially if it's a modern one that can go up to 6400 ISO without the image quality deteriorating too badly. The image on the right is pretty speckly close up, as it was taken through glass with a pocket Fuji camera at ISO 12800 (extreme measures!) But it's atmospheric. Many phones are getting pretty good in low light conditions.Screen size
Resolution matters too as does sunlight and night time performance. 3" or bigger should be fine. 250,000 pixels or better makes it reasonably sharp. A 3" 460k screen will be much better. My Olympus cameras both have super sharp 1040k touch/tilt screens and the Sony has a fully articulated screen, great for movies.Viewfinder
Left out on most small cameras. Can be useful in low/bright light and also saves on battery consumption if optical. It's also easier to hold a camera with a viewfinder steady. My SLR has a good optical viewfinder. Electronic viewfinders are much better if they have at least a million pixels. My Olympus M10 II has a brilliant 2.36m dot OLED EVF. That makes tracking moving subjects so much easier than a rear screen. But with its big 24-400mm lens it looks far to 'Pro' to take to football matches.Zoom lens
Ignore digital zoom - that just crops the edges of the picture in the camera, which you can do later (and much better) on a computer.The wide angle end of the zoom is important. The Sigma lens on my SLR has a lovely 27-300 zoom and I wouldn't be happy with, say, a 36-400 range (no wide angle). I've also got a second hand SLR 105-450mm zoom for long shots, eg on safari. Note that all the zoom figures I've used in this guide are 35mm equivalents.
DSLRs often come with very limited zooms, eg 28-80mm. I'm not sure they're worth getting unless you spend the extra on a decent long zoom lens. Even then you have the bother of changing lenses - I really like having a wide to long zoom always available. When I did finally get an SLR I replaced the 27-80mm lens that came with it with a bigger, heavier 27-300mm Sigma. Far more useful. I've also got 52 and 75mm non zoom 'prime' lenses for when I want maximum quality and light and don't need a zoom. For my Olympus cameras I've got a compact 28-84 lens, a much bigger 24-100 one, my favourite, and a 24-400mm superzoom one which is very useful if a bit big.
Some quite small digital cameras now have very impressive zoom ranges, eg my old Canon SX510, which goes from 24-720mm. Its tiny sensor allows that amazing zoom range without too much bulk.
Anti-shake (image stabilisation)
Very useful in low light or for long zoom shots. Check it's real (moving the sensor or lens elements, not merely stepping up the ISO setting and opening up the lens aperture - that just doesn't count). Anti shake doesn't help, of course, with moving subjects. A tripod or monopod (like my hiking pole) can really help too. Bigger cameras are much easier to hold steady. I've always avoided cameras which have no sensor anti shake as you then have to buy it again and again in each lens. So no Nikon or Canon SLRs for me. That's also why I went Olympus, not Panasonic, for my medium cameras. All the camera manufacturers now seem to be going for IBIS (In Body Image Stabilisation). Strangely my Sony ZV-1 II has no anti shake on still images, but it's got a very wide zoom lens, 18-50mm.Controls
Automatic mode is often fine but it's much more fun and produces better results controlling aperture, shutter speed and ISO yourself. I generally use Aperture Priority mode on nearly all of my cameras. That gives you good control over depth of focus and puts you in charge of shutter speed, by varying the film speed and aperture. I've never found the scene modes you get by the dozen on modern cameras very useful. I think it's really unfortunate that manufactures are so dumbing down their less expensive cameras and would not lightly buy any camera lacking aperture priority mode.On the right are the controls on a compact Sony HX60 camera. Set it to A(perture) mode and you can quickly change ISO via the Fn button then vary lens aperture with the ring round the lower rotary controls. There's even a separate dial for exposure compensation (to make the pics lighter or darker).
Movie mode
Most digital cameras will now take quite good movies. They are not going to be of top camcorder quality unless expensive (eg Lumix GH5) but if it's important to you, make sure a camera you are interested in takes reasonable movie clips. It helps if you can zoom in and out mid clip but that may introduce electric motor noise. Many cameras now offer HD movie recording and some 4K. I find the video clips from cameras tend to be huge and that processing them (I use Magix Movie Studio Platinum 17) can squash them to 50% of the size or less with no obvious loss of quality if I output as mp4. I'll often render clips as 720p, so much smaller than full HD.Reviews
Do check out any camera you're thinking of. There are lots of sources, for example:imaging-resource.com
dpreview.com (user ratings per camera and some excellent full reviews)
trusted reviews
Suppliers
Amazon are good but do look around. Some suppliers, such as Clifton Cameras can be very competitive. If you put a supplier name into google with words such as 'problem' that should show who's unreliable. Beware too good to be true deals - they might involve a camera shipped from Hong Kong with you liable for the duty if Customs check it.Cameras types to check out
Do research the options thoroughly - prices zoom up and down alarmingly
and models are often replaced at a frantic pace. Good ones that have
been around a while often seem the best choice. I find the
Camera Price Buster
site inaccurate at the edges but good at showing when a camera's price has dropped,
maybe because its successor model has just been released. The screen-shot shows
how my Olympus M10 II has often been near £450 (body only). I grabbed mine
during the few days it went under £300. The blue line is average price (you
can pay more!) and the red lowest price, showing how important it is to
look around. But do read the reviews too before choosing. Zoom range has increased
usefully but sensor size seems stuck at minute sizes for digital cameras that
don't cost a fortune.I haven't suggested any particular models as they tend to be superseded so often.
Small digital cameras
I always have my phone with me, with its 5x stepped zoom range and excellent picture quality. Also I often take either my Sony ZV-1 (1" sensor) or a small 'travelzoom' camera.Bridge cameras
These tend to have big lenses with a wide zoom range and decent control over taking shots, eg aperture priority mode, although some have been dumbed down (ie made useless) with the semi manual controls left out. The other thing they need, a larger sensor to improve low light capabilities, is very hard to find (because it would make the lenses much bigger). The useless chase after more megapixels and even longer zooms goes on and sensor size, so crucial to image quality, is what seems to suffer. So bridge is a misnomer - they are mostly chunky small sensor cameras with big zoom lenses.Panasonic, Canon, Nikon and Kodak are among the suppliers offering bigger non-SLR cameras - do the research! This category is now feeling the squeeze from compact system cameras (bigger sensors, most with interchangeable lenses, far more expensive).
If money is no object the Sony RX10 IV looks superb if its considerable bulk doesn't scare you off. It has a fast 24-600mm lens, EVF, 1" sensor and takes 4K video. A great beast of an all-rounder.
Compact system cameras
An interesting alternative to traditional DSLRs are cameras with interchangeable lenses but smaller bodies because they have no mirror (and often no viewfinder either). Micro Four Thirds cameras are an example. They are not at all cheap but they and their lenses are much smaller and lighter than DSLRs and they are quite close to APS-C DSLRs in performance. Olympus, and Panasonic have a variety of models and lenses to choose from. Don't assume lenses are fully interchangeable between manufacturers as Olympus uses sensor movement image stabilisation and Panasonic often puts it in the lens.I was leaning towards Olympus but then the smaller, twin lens Nikon 1 J5 system (with a fairly big 116 sq mm sensor) was suddenly very cheap when Nikon lost interest so I got one. Excellent low light performance, incredible focusing speed and accuracy, superb 1080p videos and packs into a slim bag if you detatch the lens(es). Here's an example image in extreme high contrast lighting conditions:
Then I got a free Olympus PL9 with a compact 28-84 lens to review and was smitten. Much bigger sensor and sensationally fast next shot interval. I gave the J5 to my daughter, got an M10 II body as well plus 24-100 and 80-300mm lenses, later a 24-400mm superzoom. Now most of my still shots and videos are taken with my Olympus cameras.
Sony and others are offering an expanding choice of APS and even full frame mirrorless cameras with fairly small bodies. But the laws of physics dictate that the lenses are still big so I don't really see the point. Micro Four Thirds is the sweet spot for me.
DSLRs
I wouldn't presume to suggest any models here - if you are considering a DSLR then you're going to do lots of research yourself before deciding. Canon, Nikon and Sony are the main brands. They are more expensive than prosumer cameras, especially with a good range of lenses, but they can take astonishingly good shots, especially in low light because of their larger sensors. They can also be much cheaper than compact system cameras, especially if you get some second hand lenses. But a cheapish DSLR with an "18-55" zoom lens (this really means something like 27-82mm) is pretty limiting if you're used to much better, eg 24-720 on my Canon mini bridge camera. So you really need to get two lenses - expensive and heavy to lug around - or a superzoom lens. When I finally did go for a DSLR I got a Pentax k-r and have now upgraded the body to a K50. It is superb in very low light and the anti shake is on the sensor like Sony, making extra lenses smaller, lighter and potentially cheaper than with Canon or Nikon. Instead of the 28-82mm lens that came with it I mostly use a 28-300 Sigma superzoom plus fast Pentax 52 and 75mm prime lenses. I also have a used Sigma 105-450mm (nominally 70-300) telephoto that cost a mere £75 - an excellent safari zoom.
Accessories
A printer is essential. I've got an Epson that will print high quality images up to A4 borderless. But with thousands of photos on our computers and on my phone and tablet via flickr I rarely get any printed nowadays (other than Albelli/Bonusprint photo books). I also now crop to suit each image, not to a print format.One thing I found incredibly useful on safari was a £2 OTG cable. This let us connect a card reader to an Android tablet so we could review and delete images on a much bigger screen (than on the cameras) then make backup copies on the tablet and a memory pen. But make sure your Android device is OTG enabled.
If you have a lens that will take one, put a UV filter on it - that protects the lens and improves sky shots.
You'll also need software for processing your images - see my post processing guide.