Cannot increase aperture in some instances

[newPerspective]

I'm a recent graduate into the wonderful world of DSLRs. And I'm practising with Nikon D70s and mainly shooting in Manual mode and using a Nikkor lens: 18-200mm F3.5-5.6. In certain circumstances I cannot seem to increase the aperture beyond 5.6. I can keep turning the wheel, but the setting wont change.

I can make the aperture smaller and get crisp and sharp pictures. But cant seem make it any bigger for a good bokeh affect.

I do understand that disctance between camera & subject is important so I tried zooming in and out, but that didnt do much. (I'm not sure if I actually tried moving back and forth with my feet. I also tried altering the ISO (since it forms a part of the Exposure Triangle), that didnt help either.

What am I missing?

[smc1377]

On that particular lens, the f3.5-5.6 means that it can open up to 3.5 at the 18mm side of the lens and only up to 5.6 on the 200mm side. So if you're zoomed in all the way, or even remotely close to being zoomed in, you're only gonna be able to open that up to 5.6.

[stitchbug]

Originally Posted by smc1377

On that particular lens, the f3.5-5.6 means that it can open up to 3.5 at the 18mm side of the lens and only up to 5.6 on the 200mm side. So if you're zoomed in all the way, or even remotely close to being zoomed in, you're only gonna be able to open that up to 5.6.

yeah, that.
but im confused if you said you tried zooming out and the still couldnt get a wider aperature? or did i read that wrong?

[newPerspective]

Originally Posted by smc1377

On that particular lens, the f3.5-5.6 means that it can open up to 3.5 at the 18mm side of the lens and only up to 5.6 on the 200mm side. So if you're zoomed in all the way, or even remotely close to being zoomed in, you're only gonna be able to open that up to 5.6.

Thank you smc1377. That makes complete sense.

Originally Posted by stitchbug

yeah, that.
but im confused if you said you tried zooming out and the still couldnt get a wider aperature? or did i read that wrong?

Thanks stitchbug. Now I remember, I'd encounter the problem mostly when I was trying to shoot macro style shots zoomed in fully @ 200 mm. I did try zooming out, but I dont think i took it back all the way to 18mm. And smc1377 response explains why I wasnt't getting what i wanted.

Thanks guys, you are awesome.