equipment recommendation - What are the properties of a camera that affect taking pictures in poor lighting?

I had recently bought a Nikon CoolPix L110, which was stolen a few months later. In searching for a replacement, I'd like to get something that takes better pictures in poor lighting. The zoom on the L110 seemed to be overdone, as zooming would reduce the quality of the images. I don't know much about photography, so could you tell me:

• what settings/properties of a camera affect how it takes pictures in poor lighting (avoiding blurriness and not too grainy)



• what kind of price range am I looking at?

I think I let myself be sold on the L110 for its zoom (my previous camera only had 3x zoom), and then was constantly disappointed with the blurry indoor pictures.

Answer

What settings/properties of a camera affect how it takes pictures in poor lighting?

1. 
   

   Size of the sensels, not the size of the sensor itself.

   
   
   

   Sensel size depends on the sensor size, the number of pixels, and some physical aspects of the sensor design. For a given format--that is, sensor size--as the number of pixels goes up, the sensel size goes down, making low-light pictures (and dark areas of other pictures) grainier. Somewhat counterintuitively, then, one thing to look for here--all other things equal--is a lower number of megapixels, not a higher number.

   
   

   The maximum ISO (sensor "speed" or sensitivity) can be a crude surrogate indicator of better low-light sensitivity.

   
   


2. 
   

   Best lens f/stop. Larger apertures let in more light. Large apertures are indicated by small f-stop values. A value of 2.8 or less is often considered good for lower light, but there's no definite threshold. F-stops are measured on a squared ratio scale, so f/1.4 is four times as good as f/2.8 and f/2.8 is four times as good as f/5.6 (even though it would seem 1.4 is pretty close to 2.8).

   
   

   Watch out, though, in the point & shoot realm with long zoom lenses: typically, their best f/stop is achieved at wide angles and rapidly gets worse as you zoom into the telephoto range. The Fuji FinePix 300 is a good example: its best f/stop of 3.5 isn't too bad but it quickly changes to f/5.6 as you zoom.

   
   

   For cameras with interchangeable lens systems you can often buy a lens that has a better maximum f/stop. This can be costly (thousands of dollars instead of hundreds once you get below f/2.8 with good optics; notable exceptions are some 50mm and 85mm lenses for SLR cameras, where great optics at f/1.8 can be had for $100-$400 [plus the cost of the camera body]). Lenses that let in lots of light have to be larger and heavier.

   
   


3. 
   

   Image stabilization. This is found on some SLR and SLD bodies, and on some SLR and SLD lenses, but increasingly it is also available on P & S models like the Canon Powershot S95.

   
   
   

   IS inhibits certain forms of camera shake for hand-held pictures. This lets you take longer exposures, letting in more light, improving the picture. Typically it lets in 5 - 15 times as much light. (The latter is the difference between, say, f/5.6 and f/1.4: that's huge.) However, obviously IS cannot stop your subject from moving. It's great for landscapes, still portraits, and the occasional candid shot, but not for sports and action.

   
   


4. 
   

   Auxiliary light sources, like a flash. On-camera flashes typically do not illuminate much beyond 10 - 20 feet. A camera that has a hot shoe or otherwise can connect to an external flash will be capable of providing enough light to illuminate any nearby object (and do so very well if you move the flash away from the camera with a cable or wireless device).

   
   


5. 
   

   Size, mass, and shape. A larger, heavier body that you can grip well will often be steadier and reduce blur. Such bodies usually appear in professional camera lines starting at $1000.

   
   


6. 
   

   Noise reduction algorithms. Most digital cameras can process low-light pictures to reduce noise and increase sharpness. Some do so better than others. Some give you an option to turn this off; some do not; some let you take "raw" pictures where you can apply the noise reduction in the computer later. With a few, the noise reduction is not optional and is so aggressive in low light that you can lose a lot of detail.

   
   
   


7. 
   

   Other vibration reduction capabilities. These include a socket for mounting on a tripod (most cameras have this), remote-control triggers, and mirror lock-up (for SLRs). To take advantage of these you need a tripod or equivalent stabilizing device.

   
   

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Detailed, comprehensive reviews often cover the low-light capabilities of a body or lens. Even some of the cheaper P&S models get reviewed. They are worth studying.

Overall, IS and a good flash may do the most per dollar to help you acquire good low-light pictures. As others have mentioned, better sensors rapidly get expensive. Better lenses do, too.