hollowing a teleconverter

i would like to ask if somebody knows how to hollow out a teleconverter as i want to use it to act like an extension tube for doing macro photography.

You wil probably need some tools to remove the lens cell without damaging the aperture linkage or electrical or AF contacts.

I have done this with a Tamron Adaptall SP converter where the lens cell came out easily.

Would it not be easier to buy an extension tube?

But:
1) Many T/Cs are optically poor, and their use/sale values are low, so they are not much use anyway
2) Automatic tubes are expensive
3) The satisfaction gained from having used a little bit of time & effort applied to 1) to create a no-cost substitute for 2)!

NB: lots of info on how to do the conversion to be found on the other forum, as well as here

I've done this with a dire Jessops-branded 2x PKA-fit TC. Given I paid about £20 for it over ten years ago I wasn't too worried about value, it works out cheaper than a PKA extension tube. I did test it with my A 200/4 (the best long telephoto I own) and found that images taken with the lens alone and then cropped were better than images involving the same lens and the TC!

You need to look at how the elements are held in. On the Jessops TC they were part of a solid module rather like a loupe, screwed in with a locking nut to stop the module from shifting. I just unscrewed the locking ring and then unscrewed the element module, leaving me with all the auto contacts and aperture lever completely untouched.

Like this one?
http://www.ebay.co.uk/itm/Jessop-2X-Auto-Teleconverter-Pentax-PK-A-fit-case-fits...
(currently unsold @£5 +P&P!)

I did it with a 2x teleconverter. Just used a pair of molegrips to unscrew the element and it just came out clean.

Tried the same thing with a much more expensive vivitar macro teleconverter and totally destroyed it

Yup, just like that one!

If you are planning to do the same you will need a lens wrench to unscrew the locking ring. These have two metal prongs which can be set at different distances apart, the tips of these fit into notches in lens parts to allow you to unscrew them. Also works on some film camera parts.

Re the Lens wrench, I'm told that a set of cheap adjustable metal vernier calipers works as well - and they are a lot easier/cheaper to get hold of, like these:
http://cpc.farnell.com/jsp/level5/module.jsp?moduleId=cpc/278329.xml

I have a set for that purpose, but I haven't tried them yet.

The vernier calipers will work, so will an old pair of normal non
vernier calipers or a set of dividers.

I've filed down one of the adjustable wrenches they use for removing
wrist watch backs. It's adjustable and used to be given away free with
trade packs of batteries, so it didn't cost anything

For a TC you could probably grind down an old piece of
scrap metal.

+1

I've used some carpenters' dividers, and shaped the ends with a file so that they are a good fit in the notches on the ring to be unscrewed.