[Markulous]

Whilst not a solid endorsement, the suggestion is that it's not a bad lens - but £100 would appear to be on the high side

Vivitar, Cosina, and Phoenix are all actually the same.

It is the cheapest zoom of 100-400mm focal length I can find in the market. Especially since I got a mint used one at $80. Summarily the quality is below par, but at this price, I would say it's a good deal.

It is a push-pull type of zoom, sometimes called a pump-zoom.

SHARPNESS: Not too bad at 100mm stopped down, surprisingly sharp from 135mm to about 300mm (especially at f/8 to f/16). From 300mm to 400mm it gets soft very quicken and very soft at 400 end at any aperture. I would say it's about as sharp as Canon EF 100-300 5.6L (not the 4.0-5.6L) from 135 to 300.

CONTRAST: Not very good. I almost always have to boost the contrast in Photoshop. Lots of light will help.

Terrible flare. One of the worst that I have used. A good hood may help but I haven't tried.

Not very good build quality. At the maximum zoom, the front element seems to be shaking a little bit, results in very soft image at 400mm even on a good tripod. It seems that winds or flipping mirror on the camera while taking the shot will cause the front element to vibrate a bit.

The zoom is also too loose, it means that the zoom will move when you tilt the lens up or down, even in a small angle.

Manual focusing is not full-time, you will have to manually switch from AF to MF. Autofocus is acceptably quick

Certainly not a good value for money at $200. Only buy it if you can find a used one in good condition at less than $90.

A decent 100-300 F4.5-5.6 Lens, 400 is barely usable unless you print only at 4x6 or 5x7 at most.