Harry Rose

This post will briefly introduce Bitcoin — a new online currency that I’ve decided to play with. It’s composed of a number of sections, so if you’re particularly interested in a single aspect, go and jump right to it. Thanks to Mark for his helpful comment (which can be found at the bottom of this page). I’ve updated this post to reflect his feedback.

What is Bitcoin?

Bitcoin is a (relatively) new online currency, which I’ve decided to experiment with. It’s transactions are distributed over a peer-to-peer network, where users can earn coins by ‘mining for bitcoins’. My understanding is that this mining involves computing computationally hard problems, which, when complete, earn us some coins! As time progresses, the size of the problem that is to be computed by each user increases, this way, the rate (and ultimately, the number) of bitcoins being made available decreases, giving the coins their value.

If you’d like to get started with bitcoin, the first thing to do is to go to the bitcoin website and download their client. When you install this, you’ll get a unique wallet address for receiving coins (in my case, 1CWtz5R2bDjMwi4wp2qpFC4nG5BDd3kHpb ). When users make payments to you, they simply paste your receiving address into the pay to box of the bitcoin client.

It is thought that bitcoin transactions are anonymous; receivers only see your long bit-coin address (of which you can make as many as you like — e.g. one per transaction). Having said that, this anonymity has been called into question, although identifying a user still takes a fair amount of work.

Getting Started

As I said above, first you should download the bitcoin client. Next, once you’ve run the client, you’ll see something like the following:

GUI of the main, official Bitcoin client

Now, to get some free bitcoins, you can enter the address under “Your Bitcoin Address:” to websites such as the Bitcoin Faucet. Note that, you can create as many receiving addresses as you like. So far, I’ve been creating new addresses per location that I’m using them (whether or not this is a good thing to do I’m not sure). If you go to the address book from the bitcoin client, you will be presented with a window similar to:

Bitcoin GUI Address Book

Note the new address button that you can use to create new receiving addresses.

In order to begin mining you’ll need to get some mining software. The software I’m currently using is Kiv’s GUI Miner, which will offload the mining computation to your graphics card, (which is particularly good at these problems) using CUDA or OpenCL. The image below is the UI of the gui miner:

Kiv's GUI Miner for Windows

As I said, mining for bitcoins isn’t designed to be easy; it’s a computationally expensive procedure. To try to obtain a constant flow of income, people have set up mining pools, in which users all individually mine for bitcoins, but when found, coins are entered into the pool, which is then distributed among the users participating in the pool according to their individual computational contributions.

Safety – Keep backups!

Of course, it goes without saying, the ability to make anonymous transactions online might be abused by certain people, so tread carefully. Another issue, which, alas, I fell victim to, is to make sure your bitcoin wallet key is backed up (see Mark’s comment below)! I had a number of bitcoins stashed away a couple of months ago. However, they were on a machine that is no longer among the living, and shamefully, my bitcoins shared the same fate. The lesson: make sure to keep a regular backup of your wallet bitcoin keys, which seems to be located (under windows) at C:\Users\[Your Username]\AppData\Roaming\Bitcoin.

Finally

I hope this has been a useful introduction to bitcoin for you. If you’d like to know more, please leave a comment and I’ll try to answer any questions, or maybe make a future blog post. If you’d like to donate any bitcoins to me (which will be very gratefully received), please send them to the address below:


My Bitcoin Address: 1CWtz5R2bDjMwi4wp2qpFC4nG5BDd3kHpb


When I was younger I used to have a small collection of cameras. Now, however they have been relegated to a loft somewhere. Last year I was gifted a Canon Ixus 95 IS, and since then my interest in photography has been rekindled.

In December last year I bought myself a Canon EOS 500D, digital SLR with a basic kit lens, and yesterday I decided to purchase a faster, 50mm prime lens – the Canon EF 50mm f/1.8 II.  This is the cheapest of the 50mm lenses currently offered by Canon, it can be found for as little as £89, compared to £250 for the f/1.4 USM, and which is less than a tenth of the price of the 50mm f/1.2 L lens that Canon sell.

I’ve had this lens for only a day, but I thought I’d give my thoughts so far.  The fact that I’ve not gone back to my kit lens might be sufficient evidence to show that I believe this lens to be of very high quality despite the price tag.  I decided to purchase it from a Canon specialist high-street store, and in comparisons between the f/1.4 USM lens didn’t seem to show a huge amount of difference to me.  The only real disadvantage I found with the cheaper lens was the focussing motor — it can be a bit loud, although in my experience it doesn’t seem to be as noisy as the 18-55mm kit lens supplied with the 500D.

The lens takes 52mm diameter filters, and the lens does not rotate when focussing, which is great for gradient or polarising filters.  It doesn’t use internal focussing, so the front of the lens can extend slightly while focussing, but this isn’t really a huge problem for me.  The lens supports manual and auto focus, and the manual focus ring could do with being a bit wider in my opinion.  The switch to change between auto and manual focus is incredibly stiff on my lens, and when switching to manual focus mode, the focussing ring can be a bit sticky at first — as if it is caught on one of the auto-focus cogs.

There is no IS on the f/1.8 lens, but to be honest that hasn’t been a huge problem for me.  At f/1.8, the lens is fast enough to use fairly quick shutter speeds (1/20 and faster, although you might need to use a higher ISO in particularly low light), so hand shake isn’t very noticeable unless it’s particularly severe.

Below are a couple of photographs taken using this lens, they show the difference in depth of field you can get with this lens, more will no doubt come soon as I blog about trips and holidays, but I thought I’d give you these as a taster of what this lens can do.

OK, well that’s all I have to say for the moment. To summarise, I think this is a pretty good lens, great for people like me who just want to take casual photographs without spending a fortune. This lens would be particularly good for portraits because of the fast aperture. If you have any questions, or you’d like to see photos of other settings that I might be able to shoot, feel free to leave a comment below. Also check out my Flickr account, as I pretty regularly upload photographs to that, and I plan to use this lens a lot in the near future.