Here's a few very quick sample shots. All with K10D in manual mode:
First Vivitar 2x at full extension with an FA50mm/1.4. 1/6, f9, MF, ISO 400
Second the FA50mm/2.8 macro on it's own. 1/8, f9, MF, ISO400
Third the FA50mm/2.8 macro and Vivitar 2x at full extension. 0.6 sec, f5, MF ISO400. I think this has a touch of motion blur and could be sharper with a bit more light but the 2 together are tough to get a perfect focus only because the DOF is very small.
Last the FA50mm/2.8macro and Vivitar 2x both set as a 'prime'. 1/80, f9 MF ISO400
There was no cropping or retouching, just some resizing of the images to fit here. As you can see with careful use the Vivitar and a fast 50 can give similar results to the FA50mm/2.8 dedicated macro. I would suggest that an A SMC 50mm f1.4 or 1.7 would be the best lens to use. Simply because the focus ring on that lens is better than the FA50mm/1.4. I used the Vivitar at full extension and the FA50/1.4 was used to get focus ensuring the macro ratio was at 1:1. All these were taken with a tripod.
Finally here's a 100% crop of the 4th image. A bit soft but overall not bad for a TC. But there's no real highlights in the shot so CA/PF's are relatively well controlled. Shoot at a tree branch in the sky and you will delete the image much of the time.
Last edited by Peter Zack; 05-11-2008 at 01:19 PM.