[Leica] extension tubes for long Telyts

[Douglas Herr <telyt@earthlink.net>]

I have struggled with extension tubes for my long Telyts for quite a long time.  The minimum focus distance of the 400mm, either the f/5.6 for Televit or the f/6.8, is a reasonable 11', and the 560's MFD is about 20' ... good for many subjects but when I want to get closer to the smaller birds I often run into the MFD.

The 14182 extension tube was made for the f/6.8 Telyts - it fits between the lens head and camera mount tube for 60mm of extension.  It's a lightweight extension tube allowing me to focus as close as 6' with the 400mm lens, but it's a pain in the a$$ to add to/remove from the lens, particularly if I'm in a blind.

The Macro-Adapter-R in its various forms (14198 for 60mm Macro, 14256 for R3 or later, 14299 ROM) can be used for 30mm of extension, but these extension tubes have linkages for auto-diaphragm and metering stuff that constrict the throat of the tube, causing vignetting with lenses whose exit pupils are a long way from the mirror box, as with the two-element f/5.6 and f/6.8 Telyts.

Another option is the 14159 ring combiation for 25mm or 50mm of extension.  These are dumb extension tubes without any throat constrictions, but I'd be concerned that they'd come unscrewed while turing the camera from horizontal to vertical and back.

Here's what I've done:  I modified an old 14198 1:1 adapter for the 60 macro <http://www.wildlightphoto.com/leica/14198.JPG> by removing its guts.  This gives me a dumb 30mm extension tube with no vignetting problems when used with the Telyts.  The modification starts by removing the bayonet flange at the rear.  From here, the aperture ring slides off revealing two pins that hold the inner diaphragm ring in place  These pins are unscrewed, then the inner diaphragm ring slides out.  You'll have to remove the screw holding a diaphragm spring in place; kinda tricky but not a big deal since any parts that go "sproing" and get lost are parts you're getting rid of anyway.  There are light baffles at the front of the tube and attached to the bayonet flange.  The one on the flange is removed by unscrewing 3 tiny screws, the one at the front of the tube is glued in place.  Just push it out the front.

Re-assembly:  you'll have to use the faux diaphragm ring otherwise you'll get light leaks.  Just put it back on the tube where it came from, and put the bayonet flange back on.  You'll notice some shiny surfaces inside the tube where stuff was removed; I used my daughter's cast-off blank fingernail polish to fix this problem.  The fingernail polish also serves to glue the faux diaphragm ring in place so it doesn't spin around.  At this point the modified tube is usable on the Telyts, but in case you want to use the tube with other lenses that would interfere with the tube's collar that covers the 60's aperture ring, take the collar off.  It's held in place with a set screw and glue.


Doug Herr
Birdman of Sacramento
http://www.wildlightphoto.com
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