Found

[Grahame Hamblin]

Found in a box unused in garage from years ago a 2x macro vivitar. put it on the 300f4  image full frame un cropped is it worth carrying on with did take a few others rubbish but i think that was me

[Grahame Hamblin]

Should have added manual focus hand held auto does not work
Grahame

[pluton]

Would this be the macro focusing teleconverter, that has a 2X converter and a focusing helicoid? 
Shoot a few more test shots with the camera locked down or on a tripod.  Then do a few w/o the converter on the same setup. Then you'll see what the converter does to the image quality.

[Oskar O]

Those make for excellent extension tubes when the optics are removed.

[Grahame Hamblin]

yes it is helicoid will test on lockdown.
had not thought of removing glass have done this to old zoom lens works great
Grahame

[Steven Paulsen]

I'd test your converter on a few other lenses B4 removing the glass. Depending on which/what version you have.....(I've found that many old vivitar products, are or can be,.......really great performers.)

[Matthew Currie]

I'd test your converter on a few other lenses B4 removing the glass. Depending on which/what version you have.....(I've found that many old vivitar products, are or can be,.......really great performers.)

It seems to depend on various factors. Some converters are most at home with some specific lenses.  I had a pre-AI Vivitar 2x converter that was never very good, but I had a Vivitar 2x AI converter that mated to my old 80-200 F4 with surprising sharpness at the long end, though not so well with anything else.  I'd definitely try it in a few places just to check.  There may be a sweet combination.

[Grahame Hamblin]

Thanks Matthew it is in my to do box.
Grahame

[Grahame Hamblin]

Had a bit of a play not bad  but not perfect would love comments
300mm pf plus 2 times macro (old) 25sec no idea on aperture 64 iso

Fucia stamen

[Grahame Hamblin]

This time using the zeiss 135 apo f2

[pluton]

The second one (w/ the 135) shows a useable quality.  The first one is either out of focus, or the 300PF is not a good candidate for this converter. 

[Grahame Hamblin]

Thank you Pluton will do some more testing but agree the 135 Will try the 70-200 The hardest part is focus.but grew up with that
Grahme

[Roland Vink]

The first one is either out of focus, or the 300PF is not a good candidate for this converter.

The first one looks more in focus towards the back of the stamen, if it had been focused a shade closer it would look sharper.