Hello all,

I'm a bit of a newbie when it comes to this SLR business, so I figured I should post my question here.

I've been shooting around with a Nikon D50 and Sigma 28-300 lens, and have noticed that the setup has to "hunt" for focus quite a bit in low light on AF mode. Especially when shooting in really poorly lit indoors locations or landscapes at night, this can get so bad that the camera is unable to acquire an AF-lock at all! I notice that the camera has an AF-assist light on its side, but it only seems to function in full auto exposure mode.

Are my AF woes to be blamed on the camera, the lens or my own inexperience?

Hi Joshua,

Nikon is one of the best camera makers in the world. Perhaps, it is more on getting accustomed to your camera that can help you in shooting in low light conditions. First of all, the lens that comes with your camera is the 17-55mm AFS-DX Lens and it only has an aperture opening of f3.5-5.6. It is said that the metering system of Nikon is not that accurate, it is best that you shoot using aperture mode in low-light conditions and use the biggest aperture opening of your lens. With regard to focusing, you can do it manually by shifting the M/A switch of the lens. Third, you can also focus more on your subject depending on your shooting preference by adjusting your shutter speed. Hope you try shooting with your camera using your basic knowledge of photography and not merely rely on the auto-focus functions since our experience and brain performs better than the microchip inside the camera :-). Until then. Best Regards and Happy Shooting.

plus the Sigma 28-300mm is known to hunt in low light :D if you have a fast lens with fast focusing speed, you'll be amazed with the focusing of your D50.

@ eric

it's an 18-55 lens po... ;-)

@joshua

another quick option would be to use a tripod... or a flash unit... or get a fast lens...

@ joshua

have you tried turning on the assist lamp of your D50? this could address your AF concern. Good luck!

AF relies on contrast to focus, no matter what camera model you have matched to a very fast lens, if what you are focusing is white on white, it will just keep hunting. On the other hand if the scene seems to have relatively good contrast, but you are using a slow (dimmer) lens, contrast is reduced and focusing would be difficult. What you can do (as Dindin suggested) is trying to put more light on the subject, either by using a faster lens or focusing assist lamps. An external flash like the SB600 or SB800 has a better focusing assit lamp, which projects a grid on your subject helping the focus to lock on faster. Though I don't see the tripod helping in the focus department, though it will help keep your image sharp in low-light situation.

Sigma 28-300 is one of my favorite lens (tho for Canon)...while you are half pressing your shutter, try to focus and lock on the edge of your subject (or maybe on lighted portion) then re position your aim to your desired framing, then click...

ross' suggestion is probably your best bet. I had a D50 before and i don't recall having difficulty in focusing but maybe because i knew then that I had to look for contrasty elements in my shots to lock on.

focus-recompose :)

Hi Din Din,

Thanks for the correction. I also tried shooting with the new Sigma 70-200mm f2.8 APO HSM Macro Zoom lens and it had difficulty hunting with my Nikon D70 but when I tried shooting it with the Nikon D200, I didn't have any problems. It was fast and performing like a Nikkor lens. The Nikkor 80-200mm f2.8 zoom lens is now cheaper than the Sigma 70-200mm f2.8 lens so it's better to invest in a fast lens that has system compatibility with one's camera.

Joshua,

I think that some of the bugs of Sigma is not yet fixed, they still have to update their software and you have to bring your lens at JT Photoworld for Calibration update.