Troubleshoot Kenko Auto Extension Tubes anyone?

After opening the box I selected the 12mm tube.  I do not recall the order in which the tube and 80-400 AFS were attached to this D500.   But it worked.  I lost infinity but I do not shoot at infinity anyway.  I prepared to go outside and test it in the wildflower garden.  

When I got out there the camera would not AF.....AT ALL.  I detached the tube, attached the lens to the body and the camera did AF.  

I tried it again with the tube attached and at the "Infinity to 6 meters" setting and then back to "FULL".  It did not AF.  

Any ideas why this just refuses to work?

Thank you.  

I am going to use a pencil eraser on the copper connectors.

5 minutes later:  Used eraser on those tiny dome-like connectors and that did nothing.

It does move lens elements very slightly, but, very, very slightly.

I cannot even manually focus this lens AT ALL with this 12mm tube attached.  I can with the tube detached. 

As I said, it did work upon attaching it inside the house.  Now I am beginning to question myself on what I really witnessed; i.e. did it really work in the house?  i know it did.   

What could be wrong?  

Thank you.

For the AF to work you have to be within the range that AF is possible with the tube on.  If you are outside the range of focus with the tube in place, it's not going to ever autofocus.  A 12mm tube will give you a small amount of MFD relief at 400mm and will eliminate the possibility of focusing something at a distance, and it will take off a great deal of focus range at 80mm making the total focus range very narrow.  The focus able range increases as you zoom the lens to 400mm.  A zoom can be difficult to work with with extension tubes due to a sliding focus range with zoom length.  it is easier to use if you use it as you would a fixed focal length lens.  For example, pick 300mm as your focal length and then select the tube that lets you focus as close as you need.  The shorter the focal length and the more extension you have the smaller the foucus range becomes.  For example if you go with the longest tube at 80mm, the focus range is likely to be inside the lens with nothing focus able that is actually in front of the lens.  Even with a 12mm tube, at 80mm the focus able range will be very narrow - possibly just an inch or two - if your subject is outside that, it won't even attempt to AF.  Even if it is just in the focus able range but is so out of focus that the PDAF can't determine which way to drive the lens, nothing will happen until you give it a manual assist.

My bet is that you simply selected a focal length and extension combination where there is little or no in focus range at the shooting distance you are desiring.

Very interesting E.J........especially the part where the DOF may actually be inside the lens.  

But if you would ...........  scan this that I found:

http://photo.net/nikon-camera-forum/00CdGl

As I read your characterization of how it works, it did remind me of those days.  Yes, I agree that your scenarios are plausible.  

But I do not think that this is my problem.  I am going back outside now, while there is still direct light and try to work it with your scenarios in mind.

The VR works.  Anyway, I have to get out there as the sun is getting low here in the East.

That whole thread is completely irrelevant since they are talking about the old screw drive 80-400 not the AF-S drive 80-400 that you own which could not get damaged in the way he thinks his lens got damaged.

E.J. Peiker wrote:That whole thread is completely irrelevant since they are talking about the old screw drive 80-400 not the AF-S drive 80-400 that you own which could not get damaged in the way he thinks his lens got damaged.

Oh...ok, sorry about that.  You are right though.  See the next post.

E.J. Peiker wrote:For the AF to work you have to be within the range that AF is possible with the tube on.  If you are outside the range of focus with the tube in place, it's not going to ever autofocus.  A 12mm tube will give you a small amount of MFD relief at 400mm and will eliminate the possibility of focusing something at a distance, and it will take off a great deal of focus range at 80mm making the total focus range very narrow.  

The focus able range increases as you zoom the lens to 400mm.  A zoom can be difficult to work with with extension tubes due to a sliding focus range with zoom length.  it is easier to use if you use it as you would a fixed focal length lens.  For example, pick 300mm as your focal length and then select the tube that lets you focus as close as you need.  

Your above sentences identified the problem and solution!!  I am able to focus quickly if I pick a long focal length and stick with it.  I like the 12mm tube at either 300mm or 400mm.  I think I can change focal length with the tube and the camera on......but only as long as they are long focal lengths, such as 300-400.   At this point, I now am learning how to use it with this lens.  I am not going to keep it on all the time...... because it is a zoom.  In the next few days I hope to discover that I will like this tube more than the 500D, simply because I think the range is much wider....as long as (like you said) I stick with a long focal length.    

Thanks very much E.J.!  I appreciate that.  I thought these things were getting returned  Not for now anyway and I do think they are keepers now.  And I can still use VR.  All the exposures look good, or just as I would expect.  As it is now, I can work with these Kenko tubes and......the build/material quality is very acceptable.  I hope I feel this way tomorrow afternoon and I believe I will.  

A Monarch came through VERY quickly several days ago.  Did not see what it wanted. I know what that was and I know it is coming back to recheck in the days ahead.  These Common Milkweeds are spreading somewhat (not so that they are a problem) and the Monarch did not see the flowers yet....because they have not popped yet. It will check back, and I am going to be shooting that Monarch with one of these tubes at 300 to 400 mm!\

Yippee!  :)     

E.J. Peiker wrote:The shorter the focal length and the more extension you have the smaller the foucus range becomes.  For example if you go with the longest tube at 80mm, the focus range is likely to be inside the lens with nothing focus able that is actually in front of the lens.  Even with a 12mm tube, at 80mm the focus able range will be very narrow - possibly just an inch or two - if your subject is outside that, it won't even attempt to AF.  Even if it is just in the focus able range but is so out of focus that the PDAF can't determine which way to drive the lens, nothing will happen until you give it a manual assist.

My bet is that you simply selected a focal length and extension combination where there is little or no in focus range at the shooting distance you are desiring.

I would suggest that you try the 36mm Kenko ext tube on the 80-400 AFS VR lens indoors and become familiar with your focus range on say a quarter, which is extremely close to the height of a 35mm frame. See how close you can get for closest focus, set the lens for it's minimum focus and then physically move closer to your subject until it's in focus. Then do the same for maximum focus distance. Check out your distances and make a mental note of them. Then in the field you can apply your range of focus when trying to shoot non-stationary subjects. But for doing close-up or macro, you really aren't usually trying to shoot from a distance anyway, so the closer range of focus will be what you are primarily interested in with ext tubes. For stationary subjects, just go for the magnification and focal length you want, and of course auto focus won't matter as much then.

Have to say that I am very impressed with these Kenko tubes

Mark Picard suggested these to me a couple of years ago but I was very skeptical.  Back in the 80's I had been accustomed to the Nikon auto extension tube series (PK?).  Anyway, I was disappointed that Nikon had discontinued their tubes and also, at some time in the past, I was told that the Kenkos were plastic. 

As I use these I realize now that I should have bought the Kenkos back when he first recommended them.  

Build-quality:  Two nights ago I set the 12mm tube on the half-wall at the top of my stairs. When I reached for it, I accidentally knocked it off and it fell to the first floor and bounced off the oak floor...not down the stairs, but straight down through nothing but air.....to the oak floor.   The body of the Kenko does appear to be made of a plastic composite.  As I walked down to pick up the tube, I made up my mind that I would just buy another set.  It had to be cracked.  Nope!  No way of knowing how it hit, but there was no damage at all!  

These tubes are tough

Robert wrote:I took your advice immediately.  Seems the 36mm tube at 80mm focal length is the closest combination, with a quarter filling the frame.

I would suggest that you try the 36mm Kenko ext tube on the 80-400 AFS VR lens indoors and become familiar with your focus range on say a quarter, which is extremely close to the height of a 35mm frame. See how close you can get for closest focus, set the lens for it's minimum focus and then physically move closer to your subject until it's in focus. Then do the same for maximum focus distance. Check out your distances and make a mental note of them. Then in the field you can apply your range of focus when trying to shoot non-stationary subjects. But for doing close-up or macro, you really aren't usually trying to shoot from a distance anyway, so the closer range of focus will be what you are primarily interested in with ext tubes. 

When shooting closeups of fauna, I stay as far away as I possibly can.

For stationary subjects, just go for the magnification and focal length you want, and of course auto focus won't matter as much then.

It is becoming clear that there is an array of tube/focal-length combinations that one can use to achieve the objective.   This is what E.J. was referring to.  

Thank you for your input.

Also what you will find, is you can get the same maximum magnification at the short end and the long end of the zoom with the same ext tube when using them at their respective minimum focusing distances. The difference is a closer minimum focus with the short end of the zoom and greater working distance at the long end of the zoom, as well as the angle of view difference due to different focal lengths.
I know this from my own testing of the Kenko ext tubes out on the 70-200 f4 Nikon to see what kind of magnification and working distance I would have with the various ext tube/focal length set ups. Now, whether that is different for other lens, I don't know, but I suspect not.

Robert wrote:Also what you will find, is you can get the same maximum magnification at the short end and the long end of the zoom with the same ext tube when using them at their respective minimum focusing distances. The difference is a closer minimum focus with the short end of the zoom and greater working distance at the long end of the zoom, as well as the angle of view difference due to different focal lengths.
I know this from my own testing of the Kenko ext tubes out on the 70-200 f4 Nikon to see what kind of magnification and working distance I would have with the various ext tube/focal length set ups. Now, whether that is different for other lens, I don't know, but I suspect not.

That very much depends on the lens and the length of the extension tube.  Not all lenses and lens/tube combinations will respond that way - it's often true for the telephoto lenses with a moderate amount of extension but something like a 24-70 will never behave that way since the MFD on the short end will likely be inside the lens with any tube you can buy when used at the wide angle part of the range.  Put a longer tube on that 70-200 like a 35mm or 50mm tube and you will find this not to be true on that lens either.  Then add to the complexity of all of this whether or not the lens is internal focus or not and how much focus breathing the lens has even before you put on the tube and you end up with a ind boggling set of equations that tell you that quite often, more often than not, the maximum magnification achievable with a zoom/extension tube combination is actually highly variable for even lenses with the same focal length range but different optical designs.

I have a set of Kenlo tubes and they will not work in Autofous.  Purchased a set of Phottix tubes that they sell on this site and they work with all the lens that I have tried them on.  hcarl

E.J. Peiker wrote:

Robert wrote:Also what you will find, is you can get the same maximum magnification at the short end and the long end of the zoom with the same ext tube when using them at their respective minimum focusing distances. The difference is a closer minimum focus with the short end of the zoom and greater working distance at the long end of the zoom, as well as the angle of view difference due to different focal lengths.
I know this from my own testing of the Kenko ext tubes out on the 70-200 f4 Nikon to see what kind of magnification and working distance I would have with the various ext tube/focal length set ups. Now, whether that is different for other lens, I don't know, but I suspect not.

That very much depends on the lens and the length of the extension tube.  Not all lenses and lens/tube combinations will respond that way - it's often true for the telephoto lenses with a moderate amount of extension but something like a 24-70 will never behave that way since the MFD on the short end will likely be inside the lens with any tube you can buy when used at the wide angle part of the range.  Put a longer tube on that 70-200 like a 35mm or 50mm tube and you will find this not to be true on that lens either.  Then add to the complexity of all of this whether or not the lens is internal focus or not and how much focus breathing the lens has even before you put on the tube and you end up with a ind boggling set of equations that tell you that quite often, more often than not, the maximum magnification achievable with a zoom/extension tube combination is actually highly variable for even lenses with the same focal length range but different optical designs.

I remember you saying this before EJ. But when I got the Kenko ext tube set of 12-20-36 tubes, I found what I said above to be true on the Nikon 70-200 f4 VR lens with the 36mm tube or stacking all three tubes (12, 20, and 36) together.(And I was using an FX body.) That is, the maximum magnification amount was the same at 70mm focal length and at 200mm focal length when using the same ext tube, but the minimum focusing distance was different. In my testing I was simply trying the ext tubes out to see what they could do and how I might want to best use them when in the field for maximum magnification. I remembered you saying that the ext tubes would yield greater magnification at the 70mm end of the lens, but I found it to be the same as at the 200mm end with the same ext tube on this lens (70-200 f4 VR).

Good point about ext tubes on a 24-70mm lens and all the other lens variables variables. Certainly more than I can calculate too. 

I have owned and used the Kenko tubes for over 10 years now. For me they are just okay. I find if I try to use more than one tube the AF and connectivity is spotty at best. Even with just one tube, the connectivity and AF can be intermittent at times. I find that I pretty much only use them with manual focus.

I don't use them very often but my Kenko tubes work just fine singularly or in combination with my 300 f2.8 or 500 f4 (Sony).

The Kenko tubes definitely seem to fit a little loose, even though I bought new maybe 1 1/2 years ago (as opposed to used that had already been well worn). The loose or sloppy fitting seems multiplied when stacking them. No electrical contact issues for me with just one or two tubes, and occasional electrical contact issues with all three stacked. When that happens I unmount and remount them and the contact issue goes away. They're not perfect, but the only autofocus ext tube option for Nikon (unless you want to buy a used 1.4 AF TC and remove the glass like some have). Like much in photography, there is some compromise with this tool.

Robert wrote:The Kenko tubes definitely seem to fit a little loose, even though I bought new maybe 1 1/2 years ago (as opposed to used that had already been well worn). The loose or sloppy fitting seems multiplied when stacking them. No electrical contact issues for me with just one or two tubes, and occasional electrical contact issues with all three stacked. When that happens I unmount and remount them and the contact issue goes away. They're not perfect, but the only autofocus ext tube option for Nikon (unless you want to buy a used 1.4 AF TC and remove the glass like some have). Like much in photography, there is some compromise with this tool.

The Phottix tubes I have work very well on my Nikon gear.  hcarl

Robert wrote:Like much in photography, there is some compromise with this tool.

I haven't used them myself, but my understanding is that the Canon tubes do not suffer from these same issues. Once again, Canon knows how to make a good product, when Nikon falls behind. I wonder why Nikon refuses to make their own tubes? I actually still have a Nikon tube set from the 80's, but they are manual only. If I needed or used them more, I would look into those Phottix tubes

Here is a link , for each auto extension tube brand, showing the ratings and numbers of users doing the ratings.

It has been my experience that there is much value in how close that rating gets to a full 5 stars and the number of raters.  Also, before I bought this set, I did not know that they are made by the same company that makes my Tokina 11-16 2.8 DX Pro lens.  I like that.

Robert