Infinity setting on Nikon 18-200 3,5-5,6 VR

[harry_zet]

question to owners of the nikon 18-200 vr - maybe you can check for me: when i focus my lens on the

200mm setting on infinty, the infinity.symbol is on the golden mark, where it belongs. when i do the same

in the 18 mm position, the distance-ring shows about 3 feet. when i turn it on the infinitysymbol, the

picture is unsharp on infinity. Is this normal? also i have to refocus when i focus in the 200 mm position

on some distant subject and then zoom back to 18 mm. is my lens defective?

[Matt Laur]

Harry: I'm a little confused, here. Are you setting the focus manually? Are you using auto-focus to focus on something distant, and camera lands on infinity when it says it's in focus? How is it that you're then focusing at 3 feet? Even something that is quite far away (say, over hundred yards) doesn't usually park the lens at infinity. Try the moon, perhaps, as a test.

 

When I focus that lens on a distant subject, using spot focusing at 200mm, and then zoom out to 18MM, the area (of view) that is now hitting the same spot focus sensor is HUGE by comparison. It doesn't surprise me, I suppose, that the camera wants to re-establish focus since it's now seeing a very different picture.

[harry_zet]

matt, sorry for being unclear, english is not my mother language. the situation is this. when i

focus via autofocus on (say) the moon, the moon is sharp at 200 mm and the moving

distance scale shows the infinity sign.- nothing wrong here.

when i do the same on the 18 mm setting, the moon is sharp, but the distance-scale shows

three feet. when i turn it manually to the infinity symbol, the moon is unsharp. strange. what

i mean is that i get sharp pictures in autofocus mode and also when i focus manually via my

eye, but the distance scale is way off at the shorter settings. also the sharpness varies, when i

zoom back from 200 to 18 mm - kind of a variofocal lens. again: is this normal?

[Matt Laur]

I'll do some testing when I've got a nice infinity-quality target to focus on (I'm having a windy, wet day today... so trees are my target, and I'm getting mixed results). However, my first reaction is to say that my 18-200 does something very similar to what you've just described... though mine shows more like three METERS, not feet, at 18mm. Are you spot focusing, or matrix focusing, just out of curiosity?

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Now, since you've got me curious, I thought I'd try something else. Spot focusing with my 18-70, I saw pretty much the same behavior. When I tried the same thing with my 70-200, not a twitch of difference. But then... what would one expect? The 70-200 isn't trying to do the crazy change from a mid-length telephoto all the way out to a wide angle... the physics of that, for the 18-200 is pretty amazing, actually, so I'm not surprised that the distance scale has to lie to us at one end or the other of that zoom range.

[bsd230]

I just checked mine and it's infinity at both focal lengths.