TC 16A

[dak]

I live in the Netherlands. I own a TC-16A and would like to have it modified. My problem is that it's for me not possible to modify it.
Is someone willing to do this for me?

Germany here.  I'd offer to do it for EUR100 plus postage.  That is quite a bit of change.  The mod consists of two parts: rerouting one pin which makes the converter electrically compatible with modern bodies.  However, it identifies then as a teleconverter with F1 or F0 and you need to meter closed-down I think.  That is not convenient.  Also focusing may not work well.  The second part of the mod involves cutting two pins of the CPU (sounds brutal but is more straightforward to reverse than cutting traces).  That makes the teleconverter identify as a 70-210mm/ 1:4 lens at 145mm focal width (which is pretty much perfect for 90mm 1:2.8 behavior but will work comparatively well with a number of other lenses).  This lens has a range of 7 stops and you _must_ close down the aperture 6 stops from the open position to make the body happy.  So an 1:2.8 lens has to be set to 1:22 when controlling the lens via the camera dial. or the camera will protest (the usual FEE).  You can also set the aperture to be controlled via the aperture ring.  Either way metering will happen wide open, but if you close the aperture more than 6 stops from wide open with the aperture ring, the camera will likely not close the aperture more than 6 stops from wide open on the lens (it just goes as far as it thinks it needs to go).  If you use a G lens, the camera will probably only work if the lens has a 7-stop range.

So you are safer off with an aperture ring.  Those are the restrictions, and you better tell your raw processor that it should refrain from any geometric corrections on a "70-210mm/4" lens since those will be inappropriate.

All that being said, this is even surprisingly useful for an AF Nikkor Micro 105mm 1:2.8 because that lens is totally tedious racking even the "limit" range back and forth when it cannot really focus well.  With the TC-16A, you need to prefocus almost correctly (like by using the 1:x scale) manually and the converter will only cater for a rather small distance range which is racked back and forth much much faster.

I've done this mod before and am pretty confident to be able to repeat it, but there is no warranty.  I won't charge when messing up, but the worst case will be a converter that will not talk to any body any more.  Which is close to what you have now…

[dak]

A bit late to the party, but as the original author of the modification, I thought I'd comment:
I originally made this modification exclusively to use on my f/8.0 reflex lens. So don't get talked out of trying it on yours - it works beautifully in daylight, just don't expect autofocus to work well as it gets darker ;-)

PDAF autofocus depends on light coming in from distinguishable different directions to the sensor.  The normal specs are for a circular aperture and a lens that uniformly does not vignette significantly.  I am not sure how the f/8.0 spec works, but I suspect it is more about light admission than outer aperture diameter.  That means that a reflex lens (with its donut-shaped aperture) will deliver light from wider angles than the spec would suggest.  Vignetting due to lens mount diameter issues would make PDAF stop working too far from the center of the image (but often there aren't any AF points there anyway) but again work with larger inclination than one would suspect from the aperture number.

In a nutshell: worth trying out, even if Nikon refuses to guarantee anything working.