600mm Mirror Lens

[Rob Williams]

I am thinking of a new lens for my 20D. I currently have the 75-300 but want something longer (I knew I would when I bought it). I have seen that Sigma do a 600mm mirror lens. Is this worth considering or should I stick to their zooms?


Rob

[redshift]

I am thinking of a new lens for my 20D. I currently have the 75-300 but want something longer (I knew I would when I bought it). I have seen that Sigma do a 600mm mirror lens. Is this worth considering or should I stick to their zooms?


Rob

Beware of mirror lenses - the boket is horrible. Boket is what the out of focus background looks like, and thanks to the central obstruction in a mirror lens, every dot of light or point in the background will turn into a blurry ring. Ghastly.

I suggest you think about the Bigma (Sigma 50-500) - because everyone else will suggest it - but a better bet may be the Canon 400mm F5.6L prime with a 1.4x extender.

Consider:

1. If you buy a zoom you will find you are using it fully extended 95% of the time. Why not just get a prime? It is lighter and smaller than the Bigma.

2. The 400mm prime is much sharper at full aperture than e.g. the Canon 100-400mm L zoom. Characteristically of superb lenses, it is as sharp full open as stopped down.

3. You will not really miss IS. To get sharp photographs of birds you need fast exposures. Birds move, feathers ruffle in the wind.

4. The 400mm F5.6L autofocuses like a demon - it is REALLY fast, way faster than any of the zooms.

5. With the extender you have a choice: if you opt for the cheaper Kenko model (not the Pro), then the lens aperture information does not get fed back to the camera body. This means that the lens will continue to autofocus like a demon even with the extender fitted.

6. The 750-300 Canon lens is, to be frank, awfully soft at 300mm. Anything you get will be an improvement!

[mad]

hi rob
i did all the reasearch for a lens for my 350d it seem's the bigma (50-500) or 400mm f5.6 canon if u will use the zoom at any time ie prohaps at an airshow or the zoo then it can be very useful if not then the canon for the price so ive heard u cant get better.
the image is taken with the bigma dg im no pro only had this set up for about 4weeks .been digiscoping for 18months. when u get used to the distane from u and the object the image quality is a1.
many thanks
mad
http://i11.photobucket.com/albums/a166/madas/coaltitwebcopy.jpg

[cfagyal]

I agree with mad and redshift, the 400 f/5.6 is a superb lens. I've been using one for a bit over 2 years, and it is a far superior lens to the 50-500 mm Sigma lens. I'd majorly avoid mirror lenses for all of the reasons redshift mentioned.

[adrianf]

I've got both the 600mm mirror and a Bigma. The Bigma wins hands down. The mirror lens produces dissapointingly soft images almost all the time.