Need a faster lens

[mudd]

Hey All,

I'm currently shooting a D90 with the 18-200mm lens. Most of my shots are from my travels, and the 18-200 works great for that application.

However I was out last night taking some photos of a culture show on campus. Most of the photos I captured (with flash) were quite good, but the lens was noticeably slow to focus and I missed several shots I would have liked to get. This leads me to believe that I need an additional lens that will perform better in low light conditions.

I'm thinking the 35mm f1.8 is the perfect answer to my problems. Not only will I add a sharp prime lens to my arsenal, but it'll be quick enough to capture the photos I missed last night. I'm content to crop, so I'm not so worried about having to zoom with my feet.

Does this seem logical? Is there a better non-pro lens that would address my challenge? I'd appreciate any suggestions as well as a correction if my logic has gone astray

Thanks!

[n8]

you may want to consider an sb600.... it's got it's own auto focus illumination, which I think is faster then what the little light on our camera offers. were you using the little light?

edit: just realized you were using flash. built in or external?

[mudd]

I was using the built-in flash. I do have an sb600, but wasn't using it at the time. I would prefer not to blind the performers

[Franglais]

In low light use only the central focussing zone. It's a cross type, more sensitive than the others. If you're using dynamic focussing zone choice the camera is losing time trying to figure out which zone is in focus.

The 35mm f1.8 is my first choice for an available light lens because it's a "normal" view and I can use it in lots of situations. With stage performances, sitting in the front row I can get a good view of the scene with the performers from head to toe. I also have two relatively inexpensive lenses (which I bought second-hand):

- the 50mm f1.8
- the 85mm f1.8

I particularly like the view of the 85mm, which takes me right into the scene with a good view of the performers faces

Without flash probably need 6400ISO. You can use the 35mm and crop but the look of the image is getting a little mushy at this speed due to noise reduction.

[mudd]

Thanks Franglais. I hadn't even thought of changing the focusing zone, but that makes a lot of sense.

[Loupey]

Sometimes you just have to turn off AF and go about it manually.

The lenses Franglais mentioned would be my recommendations as well - although a 28mm f/2.8 would be an inexpensive option as well. These lenses are all much faster (aperture wise) than your zoom so not only will your camera focus faster and more accurately, but you'll be able to shoot manually much more easily.

However, I'd be hesitant to recommend a specific ISO to use without knowing what you mean by "low light" and how fast you need/want the shutter to be.

[Franglais]

The slow-focussing with the 18-200 actually happened to me last Saturday in broad daylight (on the D300). I switched to the central focussing zone and the problem disappeared. I've also had it happen in the studio on the D200. It seems to happen at the longest focal lengths occasionally

[mudd]

The knowledge and experience on this board is tremendous! Thanks everyone for the great advice, I always learn so much from you.