modern 200mm zoom v old 500mm mirror?

I have had some interesting results when comparing my old prime lenses with the cheap Sigma 18-200mm lens. Generally, the speed advantage of the old primes (f1.4 or 2.8 compared to 3.5-6.3) is nothing to be sniffed at, but neither is the usable high ISO of the Kx. Most of my primes are about 30 years old, but all are well regarded in the on-line community, but still lack sharpness and local contrast. So would I carry them on a photo walk? Probably not. Would I take them in case I wanted to do some hand-held low light shooting? Yes, except that the 50mm proved to be too limited for framing when I used it with the flocks of starlings in Brighton this week. Image quality was good and focus was not too much of a problem.

So I have a range that covers fisheye to 200mm in modern zooms. For prime lenses, it is the 24, 50 and 135. Not convinced by the sharpness tests from these, I decided that what I *really* needed was a bit of reach! I was in Arundel yesterday and had a quick play with a Centon 500mm on a Nikon body. In the shop it is dark and not that easy to see, despite reservations I thought £45 was OK for a punt. With a couple of lens caps and a hood or two thrown in, so I am now the proud owner!

It is not as awful as I expected. For range, it is competing against a £7-900 sigma zoom that I would never justify buying. I have had a couple of reasonable shots so far, it is tricky to get focus and it really needs the heavy tripod. This morning some obliging bunnies served as a subject for a comparison. Which is better, cropping the Sigma super zoom, or straight out of the Centon?

Both lenses were at f8. The Centon was ISO200 at 1/125 second. The Sigma was ISO800 1/250 second. Both used 2 second mirror lock-up and no shake reduction. Sadly, the Sigma wins again. Well it is not that sad really, at least I know that I can reduce the weight in the bag!

Centron 500mm mirror lens 1/125 ISO 200
Sigma 18-200 f8 cropped to approx 500mm equivalent ISO800