can anyone tell me why in 'a' mode and in manual, my d90 will not go below f/5.6? i hope this is just some stupidity on my part and not something wrong with my recent purchase.

What lens do you have on it? What does it say on the lens? I suspect that you have a zoom lens which aperture is 5.6 at the long end of the zoom. Could this be why the camera can't "magically" enlarge the lens opening?

that's what i checked first. it's an 18-55/1:3.5-5.6. i have changed the iso to 640, and now the f stops change like this:f/4 up to f/25. i don't get it. but i guess i'll figure it out.

i have changed the iso and shutter speed all around. now it is back to not going below 5.6. i really am so confused.

omg.i'm really stupid. i just figured it out. thanks for laughing behind my back and not in my face. derrrrrrrrrrrrrr.

Don't be so hard on yourself! At least you took the lens cap off!

Laugh and enjoy it. It won't be the last stupid mistake you'll make.

Yeah mate, we've had at least 1 Deeerrrrrrr moment, Lens caps, wondering why the camera won't take a photo when the memory card is still in the card reader or on one very tired and emotional night, with my good friend Jack Daniels, managing to put the batteries not once, not twice but three times the wrong way round into my old Fuji. LOL

Mistakes teach experience! LOL glad you got it sorted

As Pete said, don't be too hard on your self, I've been at it over 35 years & still have to refer to the manual especially about zoom lenses & yes some of my best pictures are of the inside of my lens cap.

A couple of weeks ago I had the opportunity of driving a truck to Denver from Vegas. I took my camera with me just because if by chance I might see something worthy of a snapshot. This was a fast trip and had no time to stop and get some good pics. While driving east on I-70 the scenery was just spectacular so I took out my camera and and tried to grab a few pics while driving 70 mph. I know, I know very unsafe. I tried to look at the previews of the shots and nothing but black. Finally figured out that the lens cap was still on the lens. should glad I was by myself.