just started out dslr a while back.. pardon me as im still learning.

however, i noticed when i want to shoot another object(black color) which i put on my desk, it just can't autofocus on it.
image will turn out blur. tried with auto mode and some adjustment on autofocus area but to no avail.
if i use my smartphone, it can autofocus easily.

i tried with d3100 and d5100 with kit lens but same result.
any advise ??

much thanks !

Low contrast + low light might make it hard for your camera to find a point to focus on. Since you mentioned Nikon, pretty sure the Nikon AF assist lamp will be able to highlight (shine on) that black object.

A quick Google search will lead you to various websites with many reasons, read them all with an open mind ( as there are no right/wrong answers but they will lead you to the correct direction, at least ) and keep reading. The more you read the more you'll learn!

This post has been edited by kahtsin: Feb 19 2017, 12:31 AM

how far or close are you to the object.. remember your kit lens is not a macro lens.

The AF points are sensitive to contrast. Black doesn't have contrast.
The shallow depth of field makes it harder to focus precisely, while phone have very large in-focus distance. Anything unable to focus? Infinity will make 90% of thing in focus.

it is not macro object. for instant, im shooting my wallet using my dslr.
it can't really focus and always blurred out, however shooting using phone can autofocus easily pretty fast
that makes me confuse ..

maybe you are too close to the wallet.. try shooting from at least 30cm away?

As I said, phone has extremely large in-focus area, so it is way easier to lock the focus. The focus assist light will help, but in some cases that are infeasible for manual focus, you can resort to focus and recompose. Fix the focus point to be the middle focus point, as the it is the most sensitive among the AF points. Then focus on something that lies on the same plane on the object you want to focus, while holding the shutter, move back to the desired composition. Ideally you would want to set AE lock to off while holding shutter to prevent the exposure being locked on the scene you tried to acquire focus.

This post has been edited by kingkingyyk: Feb 23 2017, 08:27 PM