Nikon D40 auto focus help

[westy79]

After a day or so with my first DSLR (nikon D40) i have noticed a problem, either me or the camera? the auto focus seems to be hit and miss. So many times it focuses on either side of the centre box whatever setting i use.

Also today as dusk was setting in the sky was blue and clear and the moon was very bright. If the moon was off centre of shot the camera would only focus on it in full auto mode. i tried every setting but it would not auto focus on the moon. The moon would also not focus at all when zoomed in, again only on auto. The only other thing i can think is the iso was reading high on auto but set to only 200 on the other modes, p,s,a etc.

Im still new to DSLRs and im finding it tough to take pics, i seem to be getting wrapped up in settings

[r3g]

What other things are you trying to focus on? The camera wont focus on flat surfaces that have no detail such as plain walls and the moon. From what I understand the camera AF system uses contrast to determine focus so next time try focusing on the edge of the moon and it should work then.

[lorilu]

I have a d40 and have had similar experiences. To me, it sounds as if there wasn't enough light for the camera to auto focus on the moon. Did you try manual focus? Flip the switch on the side of the lens to M. Watch for the green light in the lower left corner of the viewfinder - when it glows steadily, you're in focus. Also, you can move that focus point back into the center by hitting the info button on the top of the camera and then use the left arrow or right arrow to move the focus spot back into the center. Hope this helps!

[K1W1]

The moon is to far away to use as a test. It's beyond the hyperfocal length of any lens and you should really manually focus on it if you actually want to take photos.
Try focusing on something closer like a street light or similar if you just want to do tests.
If you do want to take photos of the moon you will need a tripod with the kit lens because the exposure required will be too long for a hand held shot.
With regards the focussing either side of the centre box it sounds like you have AF-A (As in Auto) mode and maybe closest subject turned on. In this mode the camera will select the closest subject and it will make a decision about what it wants to focus on which may differ from what you want. Advice - read the owners manual section about the different focus options (AF-A, AF-C, AF-S).

[westy79]

yes to be fair its asking alot of the camera and the moon was quite distant. Also auto mode seems to produce a focus and shot everytime but i dont like how some of the photos come out. Whats the difference having the auto focus in the camera, which i believe the D40 does not. Am i right in thinking the kit lens which comes with the D40 has the auto focus lens, because it does auto focus on most things.

[Rooz]

westy, best to post some examples. hard to diagnose a problem like this.

the d40 does not have a lens focus motor, (neither does any canon eos camera), so relies on the lens itself to drive the AF. in other words, if the lens does not have an AF motor inside it, (eg: af-s, HSM), then there is no motor turning the glass insie the lens to focus cos the camera itself has no motor.

the kit lens is an af-s lens, you will see it marked so on the barrel. so if you buy an afs lens then you;re fine. like i said, post sopme examples and we'll try and help out.