Sigma 170-500mm F5-6.3 APO Aspherical A-mount lens review by roo
|roo#11730 date: Mar-17-2014|
flare control: 5
|ownership:||I own this lens|
|compared to:||- Minolta AF 100-300 Xi|
- Minolta AF 75-300 Big Beercan
- Sony AF 75-300
- Cosina 60-300
- Tokina AF 400mm F5.6
|price paid:||270 GBP used ebay|
|positive:||- Very sharp from 170 to maybe 400mm.|
- Pretty sharp at 500mm if stopped down and focused correctly.
- Low CA if focused correctly.
- Can AF on birds on flight.
- Light enough for hand holding and walking around for a day.
- Good image quality on A580.
- Zoom creep can be used as push-pull zoom.
- Cheap for 500mm.
|negative:||- Low image quality on A700.|
- Focus ring is heavy and not smooth making MF quite difficult.
- No focus limiter.
|comment:||People complain about the zoom creep but this problem can easily be avoided using a band, string etc. The zoom creep can actually be utilized as push-pull zooming. This is quite useful to capture small objects like birds and insects in the finder, which are not very easy to capture at 500mm, on wide end and zoom in by pulling the end of the lens. This is actually a varifocal lens and not strictly a zoom lens in that the focus changes (a little bit) with zooming in or out. But once you capture an object and focus on it, zooming in with AF-C will keep it in focus. Pulling action will help keep the axis of the lens straight to the object while rotating zoom ring tends to misalign the lens.|
Optically, I think this lens is pretty good. At 500mm it produces lots of rubbish but it creates some of decent images as well when stopped down to F9-11. I think that means the lens is optically good and something other than optics is wrong in those low quality images. It is very likely slight out-focusing.
There is CA (color fringing) in out-focused images but almost no visible CA in correctly focused images. IMH, for a telephoto lens, low CA is almost as important as being sharp. This lens is good in this regard as well.
With A700 this lens required very good light to produce a good image but with A580 I feel like the lens has a new life. A better sensor definitely help in not-so-good light situations.
AF is not fast but my A580 manages to focus birds in flight with simple background like sky or water. On the other hand, focusing on bird on a branch of a tree can be a nightmare. AF locks on branch almost all the time, and without DMF on camera side, switching to MF cannot be done in a smooth&quick action. On my copy focus ring is not smooth and heavy at some places so MF is very difficult.