First, I have some experience in concert work - I have a *LOT* of experience shooting theater work (I general work as a photographer on 15-20 shows a year). Theater and Concert images have a lot in common when it comes to the lighting situation...
Next, I will be the first to admit, the camera/lens combination is very important to concert work. However, knowing how to shoot in that environment is *far* more important. Experience will produce better images with a cheap camera than a newbie shooting a Nikon D4.
Understanding how to meter and deal with the specific issues of stage lighting are paramount to capturing great images.
Having said that - the D90 is a perfectly good camera for most concert applications. While it may be a generation or two old, it is comparable to the D300 at high ISO and should focus well in that environment.
For a lens, the problem you have is not knowing the exact stage and lighting situation. The 50/1.8 is an outstanding lens, but you are limited to one focal length. I also have a tamron 17-50/2.8 - I use it a lot for theater, very sharp wide open and at all focal lengths. Great for a wide stage shot, but not great if you want a tight portrait of the band members. If I could only bring one of those two lenses, I would go with the Tamron - the zoom is worth the cost of the stop.
I shoot concerts with the 17-50/2.8 and an 80-200/2.8 - I also keep a couple of fast primes in my bag in case the lights are *really* bad - unfortunately, those lenses are likely to be out of your price range.
More than anything, I hope you don't get discouraged if your images don't come out as well as you hope. If you could create great photos by reading a book or two and buying expensive gear then everyone would be able to create great images. Heck, even in this thread you can see multiple ways to deal with the same situation. There usually isn't a right/wrong answer (although there are often better and less good solutions).
Certainly good gear makes it easier - and it is important to study the subject you are shooting, but there is no substitute for experience. You'll learn far more from the mistakes you make than the images you got right.
Ask questions. Post your images for advice. Keep shooting!
If it's an indoor concert I'd definitely go with the 50. More light to the sensor is critical in those situations. The difference between 1.8 and 2.8 makes a difference. Even better if you have 1.4, 1.2 or whatever the Nikon versions are. They would be sharper too.
The Tamron 17-50 F2.8 is ok but for concert photography I think you will find a 50mm F1.4 more useful. I used to have a D90, they create nice images but do not play nice in low light. The images are pretty much unusable after about ISO 400, max 800. Which means the extra 2 stops of light on the 50mm F1.4 will server you VERY well.
What is your budget though? That really is the most important question. There are a lot of options out there.
NocteSilentiFeatured By OwnerNov 5, 2012Student General Artist
I'm calling this an early Christmas present, so the highest I want to go just to be respectable to my father is probably $600- and even that pushes it. Thank you so much. I'm still looking at other options: all I know to do is look at the reviews and what not.
Keep in mind, an older 80-200/2.8 push-pull lens is likely to be in the budget. It may not be a bit slow for sports, but it would be fine for general purpose (not to mention theater/concert/portraits). Still a very sharp lens. The D90 supports Nikon AF (Screw drive) lenses.
That coupled with a 50/1.8 would still be in the budget.