which lens should I buy to make shots like this better?

Depending on your budget:

85 1.8
100 2.8 Macro
135 2.0 (maybe a little long on your crop body though)

It needs some point of real sharpness. The unfocussed look makes it seem just out of focus.

I'll bet the experts here would like more information to give you some advice regarding your query, such as:

What were the exposure and conditions of taking the photo?

What lens are you currently using?

How would you like to improve the image?

In addition, there may be other issues such as composition/cropping and postprocessing to enhance such portraits. I'm certainly not an expert in these areas, but there are many others on this site that can assist.

Regards,

.....Dennis

my budget is veerry verry low. I work on a 20€ an hour basis and work is slow. so the cheapest stuff would be good! haha. I used the standard lens that came with the canon (I know, I know, this is awful, but I am not very good at using the focus on my other lens which is a f/1.8 55mm and I wanted to get the most good images possible). I have 2 lenses, (standard and the f/1.8 which I'm completely in love with, if I could ever get the focus right every time), both were reasonably cheap (this photograph probably shows that haha) and I really wanted to get the Canon EF 85mm /1.8 USM but its over 200€. What does everyone think?

That shot does look a bit soft to me, but I'm not sure how much of that softness is due to the lens you were using? As Dennis said, there are other factors that can introduce softness into an image too.

Chris' suggestions are all good Canon portrait lenses. The 135mm f/2L is my favourite lens for longer portraits, indoor sports, and performance photography. But it is the most expensive of the three and fairly long on a crop camera. I find it is sometimes a bit of a restrictive focal length, but if you manage to frame a nice shot this lens can make it look amazing.
I more recently bought both the 85mm f/1.8 and the 100mm f/2.8 macro lenses. Both are really great but if I were shopping for a portrait lens then I would definately choose the 85mm over the 100mm. Of course if you need a macro lens then the 100mm is the obvious choice and it does make a great lens for other subjects as well... but personally I find 85mm a more versatile focal length and f/1.8 a lot more useful than f/2.8 max aperture. And the 85mm is the cheapest of the three lenses too - for the image quality you get it should cost double what it does.

I've got a bunch of photos from a recent trip to Bali which I haven't got around to posting here yet which feature all three of these lenses pretty heavily. I'll post them up soon.

Be patient and save up for the EF 85mm f/1.8! It's really worth it.
There isn't much else available that is cheaper than the 85mm f/1.8 and in the same league as it optically. If you are after good optics then save save save... Unfortunately great lenses don't often come much cheaper than this.

If you enjoy your 50mm f/1.8 then you'll fall in love with the 85mm. Everything the 50 1.8 does, the 85 does much better. Better build quality, better bokeh, more bokeh, sharper at wide apertures (I can shoot the 85 @ f/1.8, but my old 50 1.8 was useless below f/2.5), MUCH better autofocus, just better everything.

Of course you could choose the 50mm f/1.4 lens instead which is optically great and a bit cheaper than the 85mm f/1.8. But I wouldn't if I were you. The 50mm f/1.4 is a LOT better than the 50mm f/1.8 that you currently have, but I think the 85mm is a bit better again and not much more expensive. Seeing as you already have 50mm covered with your 1.8, it also makes sense to pick something a bit different.

btw, the picture you posted is great. I like where you're heading with the lighting in your shots.

Maybe look around for a second hand 85 1.8.

>I am not very good at using the focus on my other lens which is a f/1.8 55mm<

Do you mean 50mm. If so why can't you get the focus right . It is both auto and manual focus.
Bear in mind that if you use it wide open,(at f1.8) then the DOF is much narrower (when close to your subject), than when it is stopped down. That could be your difficulty.
If not the lens may be duff. Mine is pin sharp.

Thanks for all your feedback! It's really really helped me. I'm planning on bugging dad to get me one and hopefully the lens will pay for itself in the future!

Any tips on doing an event shoot? (apart from the obvious camera settings. I'm talking flash, lenses and things like that) The place will be dark because it's a club. I've got several jobs coming up for the summer and I don't want to cock it up!

Thankyou!

There are lots of people here that hate flash for events - but it really matters what you are shooting. If the light is decent or the subjects fairly still, you should try to use high ISO and available light as much as possible - but that is not always possible. I shot a fast moving heavy metal band in a very dark club - and if I had not used flash, there would have been no photos. Check with the venue to see if they have restrictions on photos / flash.

they dont, they have told me to do what's best, but I haaaate flash, and I only have the flash that comes with the Canon EOS 400D, I realise I'm going to have to buy another flash, aren't I?

I don't like flash either but if I have to use it (the onboard camera flash- Canon 350D) I set it to 1/200th sec and adjust the strength by stopping down or opening up, relative to the distance from the subject. (If you stop down or move away from subject the flash is not as bright. If you move closer to the subject or open up lens, it gets brighter.)

A little trial and error to start with will give you passable results without a light meter.
Other than that it is a dedicated flash.

Can you control the DOF while using a flash, anybody?

I agree that direct on-camera flash really is horrible, and good on you for resisting the urge to use the built-in flash.
But once you get that light source away from the camera the situation gets much MUCH better.
There are a million different things you can do with lighting; some very cheap and some very expensive.
The best resource by far I can recommend is http://www.strobist.blogspot.com

Given your scenario, if your venue really is too dark to shoot with just ambient light, and you have unrestricted access then I might suggest putting a bare strobe with a snoot on top of a lightstand and hide it in the wings off to the side of the stage with a remote trigger. This way you'd get a hard side-light on the performers which would really define their outline and look like part of the stage lighting without the flash ruining the atmosphere or illuminating much else in the scene. Although it might sound complicated and expensive, a little setup like this could actually be quite cheap if you used a generic manual strobe (ie a Vivitar 285 instead of a Canon 430 EX) and used Gadget Infinity triggers (they have just released a new v4 which are apparently much better than all the earlier cheap triggers). You might be looking at around US$200 all up for this kit, and it would be useful for all sorts of things.

If you aren't sure what a snoot or a strobe is or how this setup might work, then check out the FAQ at the Strobist blog and start reading up!

If you want to be really cheap and don't mind 2nd-hand gear then PM me because I have some old Strobes and Gadget Infinity triggers floating around, but even if you buy new gear it need not be expensive if you're smart and don't mind losing a few little conveniences. Again there are loads of great project ideas on the Strobist website, many of them for learning photographers on limited budgets. This stuff will also be extremely useful for your portraiture as well.

Without fast lenses you will need to use flash - Kombi's suggestions were great and the Strobist site is wonderful.

How about talking to the venue and seeing if you can go there on a night when you are not booked to shoot and try it out without the pressure of stuffing up a paying job.

The 85 1.8 would be an ideal lens for that type of venue/event.

I agree the 85mm sounds awesome for portrait shots.

If you're not sure, I would recommend walking round with your zoom lens "fixed" at a particular focal length for a day or two just to make sure you're comfortable with the working distance and field of view.