Hi, When i turn on my camera attached with my 18-135mm lens, it says F-- . I've tried change with another lens, then it became normal and it seems like no problem at all. What is the problem actually with my lens?

Try these procedures.

Hi,

Is the lens totally stuck? Does it even move a little? Did you try to power cycle the camera?

I had an issue with my Sigma 1.4X TC where it became loose after several years of use. I fixed min as follows:

On the camera-mount side (where TC attaches to camera) I removed the tiny four screws. Then I very carefully lifted up the metal mount being careful not to damage the ribon cable which is attached to it. I DID NOT complete remove it, I just tilted it up so as not to damage the cable. I then tightened the 3 screws that I found below that as all three were loose. I think that there may be four screws, but I could only see 3 of them without removing the plate further. after tightening the screws and replacing the metal plate and the four screws holding it, the mount was again tight and the attached lens functioned normally.

Hi,

Here is a tip that I wrote about How toget a Digital Camera Lens to work again

Steps toRepair a Digital Camera Lens
heatman101

This may be something you've already checked, but there's a small dot both on your lens mount, and on your lens that must be lined up for the lens to mount onto the camera - if they are not the lens will seem to not fit.

hi dear alexanderesma, your lens have the pin roller's out of cylinder helicoid,some case maybe repaired, otherwise change of lens unit become necessary.
Please send to Nikon service.
Regards

Hi mom_0809, According to the manual page 132, it says F- - blinks means No lens attached, non-CPU lens attached. Solution is to attach the lens, select mode M. If the camera sustained a violent drop maybe the lens internals became damaged. Remove the lens then put it back on. Turn to page 129 for how to reset the camera. Does the F- - blink with another lens. If so then the camera should go to Nikon for a CLA

Hello. Check the area around the lens mount carefully - specifically the contacts. Make sure all are clean and protruding the same. If one is lower than the rest, try 'flicking' it with a fingernail (lightly) to see if it will pop up to the height of the others. It may have dirt or a particle of dust lodged. If this doesn't help, get the lens to Nikon for a check-up.

Take the lens off and continue pressing the shutter untill it doesn't react anymore, you should then have a normal menu without the error message.Put your lens on and you're all sorted.Cheaper and less hassle than sending it to Nikon.
olly

The setting should be the the other end of the scale, I.E. f16,f22. The lens needs to be at the smallest aperture opening size, not the wide open setting. The lens does have a small tab that will lock the ring in that position.