I'd definitely go for the lens over another body. Lenses are the key, bodies come and go and what is current technology now will be obsolete in a couple of years and much cheaper, but the lenses won't. One of my L series lenses is currently selling new for £200 more than I paid for it (new) 3 years ago!

If you are going to stick with crop bodies for a while, the EF-S 17-55mm f2.8 is a very good lens, and one I wish I'd bought for my 40D a few years ago. But obviously it's EFS not EF so won't work on full frames.

I've got quite a selection of lenses, I like my f/4 17-40L for group shots, but I don't think it's up to the sharpness of my f/4 24-105L which is my favourite walk around lens, and the IS with the latter is fantastic in low light, often removing any need for a faster aperture at all. With a lot of the things I'm shooting anything faster than f/4 at those focal lengths would lead to much of the key subject being out of focus. I'm toying with the idea of the 70-200 L IS f/2.8 but it's so much heavier than the f/4 version that I'd need to ensure the 2.8 was worth it.

The "nifty 50" f/1.8 is an ok lens (was a bargain at £50 a few years ago, it's £90 at the moment), but it's very poor build quality, it's not something I'd buy or use personally because I like the quality and build of the L series, also the bokeh isn't very good, giving harsh 5 sided blur, it's also slow to focus. IMO the f/1.4 is well worth the extra money (currently £290), the build quality is much much better, it's faster, (some say sharper than the L series in tests at some apertures) the blur is better, although not up to that of the f/1.2, but it's a fraction of the cost. I can't see how the L f/1.2 is worth the extra money (£1260), the related Sigma gets good reviews, but I'd need to know the evaluative metering was perfect for flash work. I do think the f/1.4 is worth a couple of hundred over the f/1.8. I guess it depends what you expect. I'm happy to pay a bit more for something that'll last years and years.

Silly question, I know but do you guys think there's any advantage in buying a 50mm when I already have...

Nikon AF NIKKOR 28 - 100mm. LINK

As the wife has actually said she thinks I should get one, (although she knows nothing about cameras except how to press the button on "auto everything" mode...

It all depends on aperture John. A dedicated 50mm would likely be considerably faster than the lens linked to above, which means much more DoF control in more varied lighting conditions.
It's all about what your intended use is and the situations that usage is likely to be.

Mark

Well, this is where my opinion differs from that of the wife... for her it would be for "happy snappy family do" type pictures which, as I may have mentioned elsewhere she takes with the camera set to "auto everything" mode, and being brutally frank she really doesn't have much of a clue when it comes to composition... bless her!

I, on the other hand, am actually rather keen to have another bash at portaiture, having last tried about 12 years ago with a fully manual Praktica.

You may get frustrated with the settings on the lens you already have so, I would suggest that if you do go for a dedicated 50mm you get a fast one, say f/1.8 or so.

Mark

That's what I thought... but let's not mention the head kit that I would definitely need just yet, eh? :etc:

As Mark mentioned the 50mm will be much faster. However, one consideration is that if you intend it to be useful for shooting indoors with available light then 50mm may be a bit restrictive and 35mm could perform better. One thing you can do is use one of your lenses on 35mm and 50mm and shoot a few test photos to compare what you'll get.

One real benefit you have from owning a D90 over a lower spec body is that it can autofocus the older AF lenses in addition to the newer AF-S. This means the money saved on buying an AF lens rather than the AF-S equivalents is quite significant and will probably equal the amount of money you paid for the D90 over the D5000, which cannot autofocus the AF lenses. There are other factors to think of as well, as the 50mm AF-S lens allows autofocus with manual tweeking and the 50mm AF-D does not.

I think I mentioned at the time of purchase that this was the main reason I chose the D90 over the D5000, and just for once I think I actually made a wise choice

Good idea about the test shots though. I'll try that out when I get home. Thanks.

Thinking about it... I already know that I will get a "nice" picture using my existing lens, but, (and this might sound stupid, but sounding stupid is something I'm used to) how will I know if I would have gotten a "better" picture from a dedicated 50mm?

Previous to getting my 50mm I was using the kit zoom (and the Pentax/Samsung was considered to be a decent kit zoom compared to some of the competitors) and the 50mm makes it look stupid IMO. Some of the baby pics I have taken would simply not be possible with the 18-55 and the DoF in the close up shots its insane. I love it. And mine is 'only' an f/2.8

Some zooms are somewhat 'wobbly' particularly when extended. Much the same as some people use remotes or take shots on the time to reduce the vibration or movement from pressing the shutter, most zoom lenses also move a bit. If it is noticeable is debatable, but just one more thing in favour of a prime. That isn't to say that a cheap prime would always be better than a Zoom of course.

On a DSLR it's not the lens that wobbles, it's the pressing of the shutter button with a finger.
When a telephoto lens is at it's longest range the physical act of pressing the shutter is enough to create just a little bit of movement on the body of the camera, which in turn travels down the lens. That's what the movement on the image is, and that's why you should use a remote shutter release or even timer mode.
Of course, if you have a cheap-as-chips zoom there's every possibility that it would 'wobble' when extended, but then you get what you pay for. (8+)

Mark

Well I mean, some lenses actually, when holding the camera body by hand, move. Can think of some Pentax kit lenses in particular.......they slop in the housing ! If you were panning, it wouldn't help.

I have a remote control and I'm not afraid to use it... I also had an interested little experiement with a home made flash diffuser last night, but that's for another thread!

The Nikkor 50mm F1.8 AF-D is my default lens now, it's fantastic - fast, controllable depth of field and ready for a full frame camera when I get one!

FWIW John, I have the Nikkor 28-80 version http://www.kenrockwell.com/nikon/28-80mm-g.htm of your zoom and the 50/1.8 http://www.kenrockwell.com/nikon/5018daf.htm. The zoom is a very handy general lens but the 50 allows the shutter to be 3X as fast, allowing me to get the same shot in less than half the brightness of available light. The image quality of the zoom is good but it can't match the distortion-free, sharpness and contrast of the 50.

IMHO the 50 is excellent value for money and if you compare the 50 with your zoom, shooting kids (!?) without flash in domestic indoor lighting, you'll soon see its merits. Sure, you don't have the wide-angle end, or, perhaps less of an issue, the short-telephoto end of your zoom, but if the light is so low that your shutter speed becomes unusably slow, you can't use that zoom range anyway.