On my d90, under M (manual mode or aperture priority), the aperture on the readout goes beyond the actual aperture range; i.e. f3.5 - 5.6; readings will show aperture range of 5 - 29 when I scroll with the sub command dial; sometimes when i remove the battery it returns to normal; how can i fix this problem permanently?

Either too low an ISO or too narrow an aperture.

A 500 mm mirror lens is a fully manual lens (manual focus no aperture change) using a T mount adapter to your specific camera. The T mount costs some $15. It depends on your camera how to turn off the auto focus and go to aperture priority mode. The aperture on a mirror lens is set, usually at F8, so the shutter is the only item that can be adjusted to get a correct exposure. A digital camera (set in adjustable ASA setting) can change it's ASA to help with getting a correct exposure. Manual for digital camera are usually on the companies' web site.

You have not stated which model camera body you have so I can only give you general Nikon information. There is a range over which the automatic settings will work for each camera. In addition, Nikon bodies have multiple sensitivity ranges. On the D90 for example, go into the "Shooting Menu" and open the "ISO sensitivity settings." You will see "maximum sensitivity" and "minimum shutter speed" menus along with the "ISO sensitivity auto control" options. Turn off the auto control option and manually set the maximum (ISO) sensitivity and minimum shutter speed. Also, the Shooting Menu also has "High ISO NR" settings that can be used to accommodate most lighting situations. You need to look in your camera's manual for all the details. The Nikon website has manuals available for all the Nikon products.

In all modes the aperture ring on the lens should be locked at the smallest aperture. In the M and A modes you control the aperture by turning the command dial on the front of the camera. In P and S modes you control the aperture indirectly by turning the command dial on the back of the camera.

The error code means that you have mounted a lens with a manual aperture control and have failed to set the control to the minimum aperture setting (highest number). By setting the control to the minimum aperture, the camera can then automatically select any aperture between the maximum and minimum settings when taking the photo. The actual aperture selection is either set automatically by the camera body (if in shutter priority or auto/program modes) or is done using the camera body controls when in aperture priority or manual modes.

If you have done so and still have the problem then add a comment and we'll explore further possibilities which all involve a fault with either the lens or the camera body.

If I have resolved your problem then please take a moment to rate my answer.

Hello,
The 50mm lens is fairly old and uses a different system to the later lenses. On the D90 and other later cameras you should rotate the ring to 22 and lock it there using the lock just above the aperture ring.
To adjust the aperture you use the front dial by the on/of switch.

Try it out in A mode. Rotate the mode dial on the top left of the camera to A (Aperture Priority mode) then lightly press the shutter button to turn the meter on. Then rotate the front dial and you will see the aperture reading changing.

The older Nikons changed their apertures using the ring but the later Nikons use the camera controls.

Yes. You pick the apature (the 3000 keeps it aorund the setting you pick) and then it automaticly adjusts the speed for you.

In addition to the "quirks" of the Landscape and Aperture Priority Modes (neither mode works as documented!)..... The camera also behaves differently in full Manual Mode (it changes the settings, whether you want it to or not to compensate for available light)... At lower Zoom Levels, the camera will adjust the Shutter Speed Only, to try and compensate for available light... For example: with the Camera preset to F5.6 Aperture, and 1/48 sec. shutter speed, the camera will adjust the shutter speed between a range of 1/30 to 1/291 sec, to try and "auto expose" the shot for lower or higher light levels, even though you're in manual mode. At an Aperture Setting of 2.8 and 1/48 of a second, the number of internal steps in shutter speed the camera is willing to take, increases dramatially - for example: shutter speeds up to 1/600 of a second, even though you have the shutter set to 1/48 in manual mode. The camera WILL NOT attempt to adjust the Aperture to compensate for proper exposure in available light (OR WILL IT??).... It depends on your Zoom settings! It won't if your're near to full wide angle, but IT WILL if you are using the Zoom. Once you cross some unknown zoom threshold (it doesn't have to be at full zoom), then the camera begins to change both the Aperture and Shutter speed to compensate for available light, even though you are in "Full Manual", versus Auto Exposure Mode. In Manual Mode, (as in Aperture Priority Mode), the amount of change the camera is willing to make to your settings, appears to be related to a preset number of internal steps, with the number of steps dependent on both Aperture and Zoom Settings, before it gives an EV Warning for Over or Under Exposure conditions.... The type (shutter speed only for wide angle, shutter and aperture for zoom) and amount (number of internal "steps" it takes to increase/decrease shutter speed and increase or decrease aperture), is dependent on the amount of zoom you are using for the current shot.

MTF stands for "Modulation Transfer Function" ... It's a somewhat arcane name for one type of testing methodology used in modern lens analysis. The *ist D's MTF priority program mode sets the "best" aperture to use for a given ISO setting and meter reading based upon lens information encoded in the latest FA series lenses. Earlier series lenses do not include MTF information in their communication with the camera so I suspect it defaults to Normal program mode when non-FA lenses are used.