John,

There were no fewer than five different versions of the old Vivitar Series One 70-210 lens. The first three versions were superb. I was lucky enough to get hold of what many regard as the best - made by Komine- for not much money.

http://www.robertstech.com/vivitar.htm

In my subjective view, the mechanical quality of the lens is similar to the Pentax K lenses, and optically it is just as good, perhaps better, than the famous SMCP-F 70-210 (which I have and love). It is certainly bigger and heavier than the F, but it's a stop faster, so fair enough.

For people who prefer manual focus cameras, this lens is a real cracker. It is the only independent lens I use (though I have a few discarded Sigmas at the back of the cupboard).

Of course, I cannot speak for other versions, which may, as you say, be made to lower standards.

So, if you see a Vivitar S1 70-210 with a serial number starting with 28, my advice is: snap it up!

G

But to answer the question.

In general, the wider the zoom range, the more the compromises that have to be made. It is theoretically possible to make a good 50-500mm zoom, but to be any good it will be huge and expensive and heavy.

70-200, however, is a zoom ratio of under 1:3, and it is possible to get excellent results much more easily.

Since you will inevitably have to use a tripod at 500mm, the only argument in favour of the 50-500, that of convenience, is already dead in the water.

In these days of great image quality from ISO 800 DSLRs, you have to have a pretty good reason for committing to the weight and expense of a 2.8 zoom.

In your place I'd buy either an FA 80-320, like Matt, or an F 70-210 plus a longer prime lens and a 1.7 converter. High quality, plus low weight and low cost. And a lot easier to sell again than a Sigma.

G

John,

Do we deduce from this sale that you have bought or are buying a piece of new Pentax DA glass? 12-24mm, 14mm, 16-45mm?

Pray tell.

G

You seldom see the A 20mm, and like the optically similar FA, which I have, it is therefore a bit pricey. But very nice.

However, the 31mm (which of course isn't wide on a DSLR) is perhaps the greatest bayonet lens of all. Big but beautiful. If I were only allowed one prime lens, that would be it. (Unless I could have a bayonet adapter fitted with a stop-down lever. Then I might choose an SMC Tak.)

G

Kim can explain this better than me, but there are two springy strips of steel behind the aperture ring, which relate to the A button. They are attached at one end by plastic passing through a small hole in the steel. Of course, they should have been attached with screws.

I'm going to try a bit of epoxy and see what happens.

G

I hope it's better made than the 1.7. Mine seized up recently, and I discovered that it has a spring attached by a sort of plastic rivet, which had given up the ghost. Not impressed.

G

Very philosophical, Don, but tell me one thing. What use is a million whatevers in a hundred years time when you're dead and gone?

G

All the SMC Pentax 1:4 100mm macro lenses are superb.

Just make sure you don't buy the one called the "bellows macro" because it is designed to be used on a bellows, and has no other means to focus it.

In the UK these lenses go for anywhere from £75 to £150 on-line (and more in the shops). They are very usable as ordinary (but extremely sharp) 100mm lenses.

For the money, there is nothing better - except an SMC Pentax 1:2.8.

The 1:4 aperture is not much of a disadvantage for macro (except that it's easier to focus a 1:2.8 because it's a bit brighter). Macro nearly always demands a small aperture to increase depth of field.

On balance, 100mm is a pretty good focal length for macro. 50 is a bit short, and 200, whilst better, is much more expensive.

Go for it.

G

Think in terms of about 20 metres. You can't extrapolate when using long lenses because most of the flash power is wasted on the area outside the image circle of the lens. Set at max, the 360 zoom covers the image circle of an 85mm lens on film - ie a 55m lens on digital.

G

Kim's right.

The Pentax 300 mentioned is a * lens. No Sigma zoom will come close.

G