Olympus digital camera question

I was wondering around this guy's website and noticed his talk about

the attachments he puts on his Olympus E-10 digital camera. Here

is a quote from his site. Someone explain this to me. "By

combining together two lens attachments from Olympus: the 3x TCON-

300 and the 1.45x TCON-14B, you can bring the 35-mm equivalent

length of your lens to 600 mm.

More, the lens still will have the effective aperture of F/2.8!"

Ya. . .But does it really keep the 2.8 f-stop. I find that

extremely hard to believe. Someone explain this to me. The way I

understand it is when the focal length extends so does the f-stop.

http://www.wrotniak.net/photo/e10/tcon-300-14b.html

Optical attachments on the front of a lens, whether close up diopters, wide angle or tele converters, do not cut down on the effective speed of the original lens in the same way as devices placed between the lens and body, like teleconverters and extension tubes.

However, the more glass in front of the original lens the more interference there is with light transmission. Even a protective filter (haze, UV, skylight) cuts down very slightly and insignificantly on the effective light transmission - probably no more than a tenth of a stop.

But the combination of optical attachments described above will probably cut the effective light transmission considerably, probably at least half a stop. Since the camera's TTL AE metering takes care of the rest the user probably doesn't even notice the slight loss of effective speed.

And while Olympus makes some very fine optical attachments, stacking 'em like this will probably also cut into resolution and contrast.

I've long been a fan of the Olympus (and earlier Chinon) "ZLR" (zoom lens reflex) format - a good quality noninterchageable zoom on a very capable body. Most casual photographers who want good photographs don't really need interchangeable lenses. But this is an example of trying to make rock soup.