D90 Focus Issues

[umijin]

I bit the bullet and picked up a Nikon D90 with the 18-105VR kit lens. After seeing some shots a friend took of my infant with the D90 on a lark, I was impressed with how easy it was to get great pix.

So, I bought the 18-105 lens b/c I wanted flexibility, and way to determine what focal lengths work well for me. I'll be taking lots of shots of my 2.5 year old and 6 month old (and have already). But I also hope to take lots of nature shots (I'm a biologist), including macros.

So, puttering around with the D90 in the last couple days has me wondering if I'm shooting incorrectly, because I can't seem to get any autofocus in Macro mode. I'm accustomed to shooting very close to my macro subjects with the set of extension tubes I used to use with my old Nikonos V. Part of my problem has been that I'm too close with my D90 and the 18-105. However, moving further away from the subject until the image gets sharp in the viewfinder doesn't seem to cut it either. The autofocus isn't able to focus and the camera won't take a shot. (Yes, auto switch on lens and body, and autofocus mode is set to AF-A). I've shot toys indoor and flowers outdoors with similar results.

I do get shots if I move far enough back, just not what I'm expecting from a macro shot.

Suggestions?

[craigyc]

Could it be that the minimum focus distance of the 18-105vr just isn't small enough for the results you want?

I have the 18-105vr and it isn't great for macro shots compared to my old 18-55mm kit lens which could focus very close for a non macro lens.

If you are going to be doing alot of macro then maybe picking up a specialised macro lens like the cheapish Tamron 90mm Macro will provide better results?

[Prospero]

Can you get the image in focus using manual focus in the cases where autofocus fails?

If you cannot, you are indeed trying to focus on an object which is closer than your lens can focus on. Your lens can focus on objects that are up to 0.45 m/1.48 ft away (this distance is measured from the sensor to the object).


If you can, several things can be causing your problem:

There is not enough light: autofocus may have more difficulty finding focus in low light.
There is not enough contrast: If your subject is entirely the same colour and brightness, with no distinct edges or detail to focus on, you may not beable to get autofocus.
Try using the center autofocus point (if you weren't already), this one is better at finding focus in case of low light or contrast.
Hope this helps.
The lens is indeed not very suited for macro photography. You could try it with extension tubes or screw or magnification filters to get closer, but it won't be nearly as good as a dedicated macro lens.

[K1W1]

I do get shots if I move far enough back, just not what I'm expecting from a macro shot.


You do not have a macro lens. (that was a full stop!)
The minimum focussing distance is 45cm from the sensor or 28cm from the front element of the lens.

[fionndruinne]

Yes, the limitation is with your lens. "macro mode" in a DSLR means nothing, really, since it only gives you a certain combination of aperture+shutter speed. it doesn't let you actually shoot any closer to the subject, as it typically does on a compact camera. You don't need macro mode, you need a macro lens.

[umijin]

Thanks for the replies. I sometimes can manual focus a bit closer, but you are all correct about the 45cm limitation. That's about the closest I can get with the lens.

So, if I purchase a 90mm macro (or other ~100mm macro lens), will I have the same minimum distance issues if I do macro shots?

Thanks for all your suggestions.

[K1W1]

So, if I purchase a 90mm macro (or other ~100mm macro lens), will I have the same minimum distance issues if I do macro shots?

Not if it's a proper macro lens. BTW Nikon call them Micro rather than Macro for some reason.
The 105mm VR Micro will focus to 31cm from the sensor plane at a 1:1 image ratio.

[Shadow13]

BTW Nikon call them Micro rather than Macro for some reason.


Micro makes sense to me since the lens is used to enlarge microscopic details on micro objects as in the function of a microscope. I maybe wrong :D