[davidmanze]

When you have a pouch that hangs vertically it seems natural not to put it in the case lens side down.  Also when stored with the base down, you naturally make the lens it shortest physical length. 

But with lenses that don't change length, I haven't really been thinking about it.  In fact my prime macros are pretty nearly always close the their closest focus when I put them in a pouch.  If the lens is front up the elements are working against the strain of gravity.

Everyone loves their 70-200mm zooms.  Here is the thing, mine is almost always set at 200mm (longest physically --- well I guess at least, it is a design decision, but very often longest zoom has the furthest position of the front element from the base of the lens). 

It is a little embarrassing to have to come and ask the experts about something I have been taking for granted.  Just assuming I could drop my IF focusing lens in the bag without a care in the world.

The reason I am finally thinking about it is my usual one.  Something went wrong with the focusing of my EF 70-200 F/4L (i) IS USM lens.  It is not completely broken.  But sometimes when I turn the focus ring in MF, or even the camera attempts the same feat in AF, it will not make it to the MFD.  Sometimes getting only as far as 2.5m.

The are some rituals which can help.  For instance, hold the lens horizontally, and talk to it in a soothing voice.  You see the connection?  The elements do not have to work against gravity. 

Aside from the inevitable, 'Send the lens to be repaired', I was hoping to hear what you, who have handled this type of lens for years have any advice on "Best Practices" for carrying your IF/IZ lenses vertically in a case or camera bag.

Please be kind.  Most of my experience is with less modern lens designs.  I somehow thought this type of lens was bullet proof!

Thanks in advance!  I come here for advice because you guys know a universe of information.  But even if you don't know, I can still learn from your experiences.  What works for you?

-Arthur

Hi Arthur nice to hear from you again!

    Having delved into the interiors of a few Nikon lenses and had a similar fault with the AF-S 28-70mm where the lens would give up focusing near infinity...........I give you a few thoughts.....

      ......a common reason for this are the "ribbon connectors"....they are thin, robust and are self adhesively attached often in areas where "man has trouble going"...ie.  down the sides of the inner front barrel etc.
  Over the years they can become detached often lifting a corner which then rubs or catches the AF mechanism and then the fun begins.  Your gravity theory could well be caused by a ribbon connector hanging where it shouldn't be hence the orientation of the lens.
  I've also found that once the AF motor's movement is restricted a protection circuit switches it off (some Nikkors) which can throw up an error message, requiring the camera to be turned on/off to get restarted.
   
  It's worth confirming your AF sensor prism under the mirror is clean, a speck of dust can often give one the run around!

  Maybe your lens needs a visit to the lens doctor, it's a great lens after all..........

    All the best Dave