Even the very best quality teleconverters still degrade the image. The greater the magnification the worse the degradation. This probably explains why they fell out of favor. They do make serviceable paperweights.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
Definitely... Don't take our words for it. Give it a try. Even after my early 70's experience, if one fell in my lap, I'd give it a go. What I now consider a successful image is a lot different than it was then.
One of the acessories was a 3X(!) teleconverter. A vivater, from what I heard 2X are not the greatest optics so I wonder if I use once or twice to see how it works. What sould I except?
Sometimes when your feet can't get the camera close enough for the shot that you want, a teleconverter is a way to leverage a long lens. I have and use a Vivitar 3X with a Vivitar 75-300 mm. zoom on my Canon cameras. That combination will produce acceptable photos if held rock steady with a tripod or braced in some fashion. I try to use a fast film (ASA 400) to get a couple of the lost stops back.
You won't know until you try for yourself, so go for it.
When I purchased my Spotmatic SP ll included along with 3 flashes, a dozen filters and several other items were 2 Kenko Auto Teleplus converters in 2X and 3X. The instructions claimed "even at open aperture there is no softening of focus or deterioration in resolving power so that two TELEPLUS units can be used in combination." A mighty bold statement I think. I never tested their theory, instead I got a small screwdriver, disassembled the innards of the 3X and now I have a 55mm meter coupled extension tube.
Just a thought.