9 replies to this topic

[Admin]

The objective of this thread is to gather the opinions of our members on the lens in the title as well as provide a poll for opinion reference.

Please read the guidelines in the sticky before you post in this thread, so that you get a good idea of the kind of information we are looking for. Also note that all messages posted to this board are screened before being published.

[JBPhoto]

My copy of this lens was not great. Soft corners even stopped down to F5.6 and centre sharpness was meh, so I parted with it.

[Airy]

I bought a second-hand one and tested it on my D800.

This lens is small, light and compact. Focussing ring is a bit too loose for my taste, and feels like an AF lens.
Performance is rather good : distortion is not bothersome ; vignetting is reasonable. CA is noticeable, but easily corrected using LR4 for instance.
Contrast is only average and sharpness is OK when stopped down. One should really try to remain in the f/8-f/11 range. Below, you will get mushy corners. Stained glass windows never look good, as the bright pieces of glass seem to "bleed".
Nevertheless it is quite usable, though no match for the big 14-24. I gave it a 3, although on D700 it may have got a 4.

Below a sample picture, shot at f/11 and benefitting from PP in LR4 :

[Airy]

A bit more of that lens in a real-world situation. First the overall picture, at f/8, focus on the organ pipes:



Now a central 100% crop :



For comparison, the Zeiss 35/2 at f/8, cropped and downsampled :



Now the 20/2.8 again, but off center and still at f/8 ; part of the blur may be due to the focus :



The Zeiss again, cropped corner downsampled to match the previous pic :



All pictures were corrected for CA, but no sharpening was performed. The Zeiss has definitely more contrast, and a more neutral rendering (the 20/2.8 is rather warm). The 20/2.8 is not quite as good in the centre, and gets somewhat worse towards the corners, even at f/8. Diffraction gets quite visible from f/16, mostly in the form of diffuse light near bright parts.

So, overall, we can say that the 20/2.8 can deliver sharp pictures from corner to corner, provided 1) you are not too picky, and 2) you use a tripod, LiveView for focussing, low ISO and f/8 to f/11. And careful not to knock the focus ring, because it offers little resistance.

Among the cons, the focus throw is ridiculously short, resulting in the "infinity" and "2m" engravings to be very close with nothing in between. In fact, one cannot set the focus by evaluating distances and, unfortunately, infinity is not suitable if the subject is at eight meters. Given that the green dot lacks accuracy, only solution is LiveView. Also be careful that the infinity focus stop may be off, and on the wrong side (i.e. not on the side of the hyperfocal, but "beyond infinity"). So be very careful before disqualifying this lens. This happened to me, as the infinite stop was really badly off (and still is, but now I am careful...).

That being said, I only gave it a "3" because of the difficulty to get the good images which are intrinsically possible. The focus ring and the weak corners wide open are the main reasons for this difficulty.

Note : the "test protocol" can certainly be criticized, as I am to some extent comparing apples with oranges. For instance, DOF was not the same (DOF is proportional to the quotient of distance by real aperture, and the relative aperture being the same, i.e. f/8, the Zeiss was theoretically at a disadvantage). I made another series with the Zeiss at longer distance to frame about the same area, but this resulted in very different pictures with different lighting - through the stained glass window - making comparisons impossible. Anyway, my purpose was to judge from real pictures, and the kind I am often shooting, rather than from brickwall evidence. In that sense the test was absolutely honest, and the results are significant to readers envisaging similar usage. My main conclusion would be "OK outdoors, but indoors with a tripod, period, otherwise carry the 14-24 instead". Using the downsampled Zeiss crops as a "reference" raises the bar very high, and the 20mm being worse is no suprize; but the difference is not massive and speaks for the quality of this lens.

Edited by Airy, 16 June 2012 - 20:10 .

[davepaterson]

The attached 100% crop was not, in any sense, from a test - it is merely a closer look at part of a casually-taken image (at f5.6). I think it shows some of the quality of the 20mm in close-up situations; and also why the Zeiss 21 which I am expecting delivery of tomorrow will have to be a bloody good lens to be a real keeper. View large to see the detail.

Attached Images

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Edited by davepaterson, 17 March 2013 - 15:24 .

[nfoto]

In fact, shooting up close is what really makes the 20/2.8 sing sweetly. For more distant subjects there is a lack of detail mainly because the small magnification of detail. In that respect, the 35 will have a "built-in" advantage.

I keep the 20/2.8 more or less permanently attached on my D700 in underwater housing, An excellent combination.

[davepaterson]

I keep the 20/2.8 more or less permanently attached on my D700 in underwater housing, An excellent combination.

Having been without my D800 for ten days or so, I am beginning to think that the 20/2.8 and the D700 sensor are a particularly good match. And I agree about distant detail; not so much the lens's strong point.

Edited by davepaterson, 17 March 2013 - 16:11 .

[Ron Scubadiver]

I have the AF (not D) version of this lens and I like it. With distortion control in ACR and shooting at f/5.6 or f/8 the results are nice. Nfoto, I did not know you were a diver.

[nfoto]

Ex. From days long gone before asthma became a major issue. So these days only in the shallows.

[ozone]

For me, this lens is only usable for group portraits at 1-3 metres, where I need wide background coverage. 

Medium and distant scenery renders flat and with little contrast and detail. Corners are still mushy even at f/8-11!

 

All in all it is not any better than the 18-35mm f/3.5-4.5D, without the advantage og the possibility to zoom, so in my mind the 20mm f/2.8 is not viable any more.

 

Besides, my 20mm f/3.5 is much sharper on all distances, and WAY better on ghost/flare (but alas equally bad in the corners...)