For most amateurs and beginners, you're probably wondering why each time you bring your fancy new DSLR out to shoot at night dinners your pictures ended up looking grainy and just awful? Well that is because your camera, in fact most consumer cameras have varying difficulties when it comes to shooting in low light.
As such, if you want to improve your low light photography, here are the top 3 essential things you need ranked by cost, the 3rd being the most expensive.
1. Flash/Speedlights
Don't be traumatized by the what the look of a flash gives you based on your experience with your mobile phone camera. You can get really excellence low light pictures just by putting one of these bad boys on top of your camera, of even better, have it directed from the side of the subject for maximum depth and quality. Best of all, flashes are cheap and you can probably get one in ebay or amazon for $50 bucks. That is pretty much as low as it gets in terms of photography electronic gears. This one pictured here, is a Yong Nuo 560IV which pretty much does everything when it comes to lightning up an entire room or people as far as 20ft away and cost roughly $100. You can always improve your photography by adding an umbrella or softbox to bring your work to another level.
2. Fast Lenses
Going up the price scale, is to get a fast lens. A fast lens is any lens with a fixed aperture setting. Generally, the kit lens that comes with your DSLR is equipped with a variable aperture opening that gets smaller as you zoom further into your subject resulting in less light capture. A fast lens will ensure the aperture opening stays the same even if you are zooming in allowing you greater amount of light to work with. A good number to start is a fixed F2.8, followed by 1.8, 1.4, or even 1.2. Remember as these numbers get smaller, the more it will cost you and trust me, it can get really expensive, real fast. A good lens to start would be a 50mm 1.8. I got mine for about $130 and I loved it to bits. I never go on jobs without it. This is a prime lens, meaning that the focal length is fixed at 50mm. While this may seem troublesome for beginners to shoot without the flexibility of a zoom, using a prime lens greatly improves your composition and photography skills. Oh, if you are looking to get those really shallow depth of field (blurry background shots), this lens is probably the cheapest way that'll get you there. A quick note for crop users, you may want to start with a 35mm 1.8 instead of a 50mm. Remember to apply the crop factor to focal length for the actual distance. Nikon(1.5x), Canon (1.6x).
3. Increasing Your ISO
Now you may be thinking, "increasing my ISO won't cost me anything" so why is this ranked as the most expensive? While most modern DSLR cameras do have the ability to shoot at higher ISO's, not all of them perform well doing it. For example, most consumer DSLR's can only shoot comfortably at ISO's of no higher than 1600. If you want to shoot at ISO 3200, or even 12800, though your camera may allow to set those numbers, the results of your picture will be extremely noisy and grainy. So if you really want to shoot at those numbers without suffering losses in quality, then only a professional DSLR camera will get the job done. How do you know if your camera is a professional model or not? Well, a rule of thumb is that if your camera cost you $2000 or more brand new, your camera will shoot at high ISO's well. If it cost you upwards of $4000, then it will do it extremely well. Which is why I put this option at the very end. However, don't be afraid to crank up those ISO numbers on your camera. Every photographer will have a different tolerance of noise levels. Personally when I use my trusty 70D, I never go beyond ISO 1600 in low light before calling for my flash. So the best thing you can do is to keep shooting and experiment to find your camera's ISO comfort zone.
If all else fails, just turn on the lights in the room if you can. If you can't, just take the shot anyway. After all, better to have the picture than not taking it at all.
Happy shooting!