As I've documented earlier here, I've been taking piano lessons since the start of this year. There I also mentioned I'd been using a keyboard to learn. Since then, I've switched to a second-hand digital piano for practising.
What I discovered is that a keyboard with velocity sensitive keys (i.e. capable of producing different key volumes depending on how you play) is fine when starting out. Any music you play at first will be simple, but needing to play notes at varying volumes is likely something you'll be doing almost from the start.
If you're planning on trying out piano lessons, if you have such a keyboard already or can borrow one for a few months, that's a sensible initial step. Don't let not having a piano right now put you off starting learning now: it's a substantial commitment to get one. It's probably sensible to ensure that you're likely to stick with learning first, before plunging in.
But, a few months on, once you've made a little progress, the inadequacies of using a keyboard as a substitute for a piano soon become apparent.
One big problem is that the feel of hitting the keys is much different, which is difficult to get used to when playing on a real grand piano for lessons.
Another is that, like the keyboard I used, many keyboards only have 61 keys, not the 88 that standard pianos have. This can be confusing, and can hamper you relatively early on. Even on the simple pieces I was learning, there were occasional cases where you'd just have to miss or mime playing a note out, because it didn't exist on the keyboard. The difference in the number of keys also made orienting myself difficult when sat at the real piano for lessons, and I'd get "surprised" by the presence of the extra keys.
At that point, it felt like that the keyboard was hindering my progress, and a natural juncture to replace it in my practice.
Why a digital piano?
If you're not too aware of digital pianos, and I wasn't before I started looking into this, Wikipedia is a good starting point. There, we learn, digital pianos are really high-end keyboards that are designed to be good facsimiles of real pianos, in both sound and feel of how it plays. (I'd add that sometimes, though not always, they are designed to mimic the look of a real piano too.)
That explains why you might want a digital piano over a keyboard. But why not just get a traditional acoustic piano? Especially when looking around, you can likely find pianos on offer for the literal giveaway price of £0, providing you can collect. Reading on, the Wikipedia entry explains good reasons for this.
Acoustic pianos weigh a lot. It's a considerable task to get one of these to where you live, especially without damage to the instrument. Likewise, if you need to move for whatever reason, you face this problem again.
Likewise, acoustic pianos can take up a lot of room. Some digital pianos can do too (you can even get digital grand pianos, for reasons that aren't that clear to me), but there are digital pianos available that are just the keyboard, and are relatively easy to move. For example, Yamaha's current low end keyboard-like models weigh a little bit more than 10 kg.
Acoustic pianos will also need tuning. That's an ongoing cost and one that's also fairly pricey. Digital pianos could also require repair too, although not likely with the regular frequency that an acoustic would need tuning (pardon the pun).
One downside with digital pianos is that you're somewhat reliant on having local availability of technicians who specialise on those models, and the parts being available to repair the piano; reasons why you might want to opt for a well-known brand.
Almost all (or maybe even all) modern digital pianos, and even lots of older ones, will have some means to use it as a MIDI keyboard. A digital piano in a given price range likely has fewer voices (i.e. types of sound it can play, e.g. piano, organ, strings) than a comparably priced keyboard, but you can always hook it up to a computer and use it to control whatever instruments you have available there in a digital audio workstation.
Digital pianos have headphone outputs, so that you can practice quietly. This is not usually an option on acoustic pianos. I say usually, because you can get hybrid acoustic-digital pianos that allow switching between acoustic and digital modes, though these are very expensive and still suffer from the problems of tuning, size and weight.
Hybrids aside, the downsides with digital pianos are that the feel and sound is a simulation of a real piano. Even with today's technology, they're never going to be quite as authentic as the real thing. But especially when still a beginner, a decent digital piano is probably more than sufficient.
What to look for
It's daunting spending a considerable amount on a piano, if you still feel like you don't know what makes for a good instrument. From reading around, there are some general considerations you can think about:
size and cabinet; as I mentioned above, digital pianos come in different sizes. If you're pushed for space, then you might have to go for one of the keyboard-like pianos. There are also cosmetic choices to make; if a piano comes built-in to a cabinet, do you like the appearance and colour of it?
pedals; acoustic pianos usually have three pedals. I think most electric pianos usually have three too, though lower end models might only have two. Three, then, really is the magic number, so you may want to go for a model with the pedals you'd expect on a acoustic.
voices; this is maybe less important. The main thing for learning here is that the piano sounds realistic. Having other sounds to use is a nice bonus, but not essential.
polyphony; this is the number of notes that can sound simultaneously without earlier played notes that are still sounding just being dropped. Current low end models may have 64 note polyphony, whereas better models will have 128, 192 or even more.
It's not quite as simple as the number of notes you play simultaneously, since, for example, using multiple voices (e.g. piano and strings) at once, or using the sustain pedal to prolong the sound of non-held notes will eat into this note "budget". More is better, especially if using multiple voices simultaneously. But given that 64 note polyphony seemed to be a satisfactory standard in the past, anything above that is likely very good for a beginner piano.
headphone noise; after I had an experience with a keyboard's headphone output being distractingly noisy, I knew I should check this on any piano I bought. Just remember to take the pair of headphones you use with you when looking at a piano to test this. Trying to concentrate with a distracting buzz in your ears isn't a great feature to have.
the feel and action of the keyboard; I can appreciate that higher end pianos aim to more realistically replicate the feel of a real piano. For instance, the weights of the keys, and the texture. And if you've experience of several pianos, this is probably easy to discern. For me, having played on one acoustic piano, this was far less easy for me to know what was good and bad. More expensive digital pianos tend to use different hardware than cheaper variants, whether you can tell much of a difference as a beginner is difficult for me to know.
branding; common brands are those you might expect, the likes of Roland, Korg and Yamaha. There are also no-name branded pianos available, but I suspect the quality of these can vary wildly. I'm not always one to go for big name brands, but I think in cases like this, where there's likely much expertise gone into the research and development, it's probably easy to cut corners and end up that might look the part, but is in fact considerably inferior.
And with used pianos?
My teacher's advice was to stick to a low budget and pick up a used model (given that it would be almost certainly an improvement on the keyboard I was using), rather than a brand new, but low end model. When I was looking at the market, digital pianos seemed relatively mature. The manufacturers continue to churn out regular updates to their product lines, but, much like mobile phones now, it doesn't seem that there are any real technological revolutions that have happened over the past couple of years. Buying used seems like a good way to get more for your money.
When buying used, the condition of the instrument is important. Spares may be few and far between and expensive if anything does break. That's another reason not to maybe spend a huge amount on old kit: the repair costs may also be very expensive or repair may rely on you getting hold of a second broken model for spares. (This also is another reason why no-name digital pianos may not be a good investment, if there are no parts available or indeed anyone who knows how to repair those models.)
Bearing all that in mind, the most I wanted to spend was the cost of the current low end Casio and Yamaha electric pianos, and I didn't really want something more than about a decade old.
Buying a used piano
In the end, after a week or two of searching on eBay and Gumtree — if you're in the US, Craigslist is probably a good substitute for Gumtree — I managed to find a Yamaha Clavinova that seemed ideal. It was within driving distance to collect, seemed reasonably priced, was in my budget, and claimed to be in good condition.
When looking around, I found that used digital pianos were generally claimed to be well cared for. My hunch is this is because these are reasonably expensive bits of kit new and therefore buyers want to look after them. Another reason is that a lot of sellers are getting rid of them because the piano is no longer in use, either because they have bought a newer instrument or have given up learning. Not in use means not becoming worn.
This was much the case for the piano I ended up buying. The seller never really took to it, was looking to replace it with a synthesizer and so it looked almost brand new. There was plastic wrapping still on the pedals, hardly a visible scratch on the cabinet, all the manuals were present, and even a catalogue of various Clavinova models that the original purchaser had been given while they were originally deciding which one to buy. All a good portent for the piano being treated well.
Some other tips on buying used
Make sure you try as much as possible before handing over cash. Do all of the buttons work? Does every key plays smoothly? As mentioned above, I took my own headphones to test the headphone output too.
Don't be afraid to haggle a little. Prices of pianos vary a lot as there are lots of different models and often relatively few sellers around (although major cities will tend to have more). Unless someone has expressly stated the asking price is the final price, even if the asking price is reasonably sensible, I don't think there's any harm in offering something like 10-15% below to give them room to counter-offer, and maybe give you a small discount. Since pianos are big, and sellers may well want to get rid of them quickly, if they sense a possible sale, they may well be happy to negotiate a little.
Make sure you're clear on what's included for the price. Sometimes sellers will sell piano stools or stands separately from the piano itself.
Going to a manufacturer's website and getting hold of a PDF copy of the manual, if available, is a good way of answering questions you may have prior to purchase (e.g. is the MIDI via USB? does the piano need drivers for connecting to a PC? are they available?) or finding detailed specifications. You can usually find these in the support section of a manufacturer's site.
Similarly, if you're intending to ever use your piano as a MIDI keyboard, make sure that drivers are available for the piano for your operating system from the manufacturer.
Don't be too set on going for a particular model or brand. The market depends on what's available in your area, so I'd just stick with a budget and features you're not willing to compromise on. Most sellers want you to arrange collection, which likely means you travelling there to collect in person (unless you pay someone to move it, which will probably cost you a fair bit).
Three months on
In the end, I went with the first Clavinova I looked at, and have been very happy with it since. While a little unusual to switch from the previous keyboard initially, it didn't take that long to adjust. Since then, it has made a noticeable difference in my confidence going into piano lessons and being sat at an acoustic grand piano. It now feels much more a natural transition to go from playing at home to playing in lessons.