While i was writing the previous article about the 500mm mirror lens, I remembered that I had done some tests with the Olympus 2X tele-converter. This turns the lens into a ridiculously small 1000mm lens. Hoever there are some caveats. First of all, Olympus stated that the lens was not compatible with the tele-converter, and that image quality will suffer. Second, you lose another two stops which makes it an f16 1000mm. Better wait for sunny days or long exposures!

However, the tests I did are by no means a disaster, and I think it could be a working solution in certain circumstances.

I shot a scene with the 500mm and 2x teleconverter. (Tripod) Here it is.

500mm f8 with 2X teleconverter

I shot the same scene with the 500mm on it's own, centered on the same spot. I then upsized it in photoshop using SI Pro 2. Here is the result

500mm f8, upsized with SI Pro 2

There isn't a huge amount of difference, but with the 2x tele-converter there seems to be more contrast, but this is just maybe a result of exposure/scanning. You can see a difference in DOF though - the overhead tram wires are definitely out of focus with the converter - it's more obvious in the full size image of course.

To really see any difference we need to do some pixel peeking, So here are two 100% crops. First of all from the upsized image without the converter

500mm f8 100% crop

And now with the converter

I think here you can see that the 2X tele-converter wins over the upsizing technique. It is sharper, and doesn't suffer from the inevitable appearance of film grain in the upsized version, looking smoother.

So what's the conclusion - is it worthwhile trying the converter? If you have one in your bag why not? depends on shooting purpose and conditions, but if you want the reach, and maybe wanting extremely limited DOF it could be a solution. Might be worth acquiring the comverter anyway, becasue it works very will with other Zuiko lenses, particularly the 200mm f4 in my experience