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Sigma 180mm f3.5 EX APO Macro IF HSM

Review Date: May 2, 2009 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: Very sharp and contrasty even at f/3.5, high build quality, very good macro performance (as good as tele).
A bit heavy and big for my taste, not easy to focus correctly at f/3.5 which results in "nervous" performance wide open: either excellent or way off.

I bought this lens second hand at half the price from some guy that thought the lens was very difficult to use and produced inconsistent results. Well... I understand him: this lens is hard to focus correctly when wide open! Even a very small movement and you're way out of focus. Of course for macro work this is not so important because you tend to stop down a lot, but for tele it's a real problem.

The solution for tele is using autofocus or being patient while manual focusing. Also this lens is very sensitive to camera misadjustment: if your autofocus sensors or your focus screen position are not well calibrated and coplanar with the sensor you will get misfocused shots all the time.

When properly used it performs quite well even wide open as you can see in this two test shots (no sharpening applied):

In macro usage the performance is just as good, but of course the depth of field wide open is close to zero. Stopping down you will notice improvements in contrast up to f/8 or so, and then degradation as diffraction takes it's toll.

For tele usage the contrast does improve somewhat up to f/5.6, but not the sharpness, which is already excellent wide open. Performance degrades over f/8 due to diffraction (this is not a lens problem, of course).

There is some residual chromatic aberration visible, but it's easy to correct in photoshop, although I end up not correcting it most of the time since it's not noticeable in most shots anyway.

Sigma 30mm F1.4 EX DC HSM

Review Date: May 2, 2009 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: High contrast, very sharp in the center, easy to focus manually and fast to focus automatically. Nice bokeh.
Some chromatic aberration. Performance does not improve when stopped down: lens clearly optimized for wide open shooting. Infinity mark is not correct.

First of all you might want to look at 2 test shots:

So... what do I think? For a f/1.4 lens it performs quite well. It's very sharp and contrasty even wide open in the central region. This is a lens for portraits and street shooting, so corners are not important, but even there the lens performs quite reasonably wide open, as you can see. Please take in consideration I applied no sharpening whatsoever (SPP sharpening = -1).

This lens is optimized for wide open shooting, so the performance will not improve when stopped down. Has some chromatic aberration wide open, gets worse when stopped down. The maximum sharpness all over is probably attained at f/2.0 or so, and from there on it degrades! At f/2.0 the sharpness in incredible, there is moiré all over the central zone, the resolution being well above the sensor.

The build quality is quite decent for a ~€400 lens, but my lens has a problem: the infinity mark is way off infinity. This doesn't affect performance of course, and anyway could easily be corrected be opening the lens and relocating the ring with the marks.

One final comment: this lens requires a well adjusted camera! Otherwise it will backfocus/frontfocus. This is never a problem of the lens, contrary to popular opinions: lenses focus to the position the camera commands them to. The AF sensors must be coplanar with the sensor and the focus screen, this can be adjusted in most SLRs with a few screws inside the mirror box.

Some usual shots with this lens:

PS: I just did some comparisons and contrary to some reports this lens is really a f/1.4 in the central zone, but there is some vignetting outside the center (normal at such apertures), so the real aperture in the corners is something like f/2.1 or so.