Jump to content

Random backfocus after lens change?


jpk

Recommended Posts

Advertisement (gone after registration)

I have the feeling that my lenses all focus correct, only sometimes after mounting a lens I can detect wrong focus (live view vs. focusing through viewfinder). If I remove the lens and mount it again it will usually focus fine.

 

Do you have similar experiences? How can I avoid this?

Link to post
Share on other sites

mmmm......

 

Before doing anything further I would check things carefully using a tripod to avoid user error ....... :rolleyes:

 

The only other possible explanation is that you have some crud or issue with the roller on the cam that moves when the lens is focussed..... it is designed to rotate ..... and if one area is flat ..... or raised due to something stuck on it.... it might account for the random variation. It is spring loaded so it is unlikely to be 'sticking'

 

It is also possible that the arm is bent and is not completely in contact with the lens at its extreme extension .....it is factory adjusted to allow a certain degree of movement that should lie between infinity and 0.7m plus a bit of leeway ...... there is a second arm to the mechanism that contacts an eccentric 'stop' screw ......but that would give you a repeatable issue and may be lens specific.....

 

The RF mechanism is crude in construction but delicate in function .... it doesn't take much to cause very subtle problems like this ......

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...