Sunday, April 19, 2015

SEL1670 - 2nd try, 2nd fail. / Zweiter Versuch, zweites Durchfallen.

Update 8.5.15: I had the 1670 repaired by Sony and now the blurring has gone. See an evaluation of the 1670 lens performance versus the 1650 and 18105 here.
Well, I already have the 1650 and the 18105. However, recently I got tempted in Ebay to try once more the 1670. My first results some time ago resulted in the blind quiz (several focal lengths at f8) in which the majority preferrred the shots from the 1650, and in me returning the lens.

This time, the price was 570 Euros in new condition so I made another attempt.

There IS a lot going for the 1670: It offers the 16mm wide-angle, some tele, althrough f4, in a still acceptable size and weight and within ONE lens. Its drawback was the initial price of 1000 Euros, that slowly has eroded to below 800, still quite a bit for this lens.

So I made my usual visit to my test location, under fine weather and then evaluated the shots compared to my (good) copy of the 1650 and my 18105. I also put the 1018 into the equation, because it offers both 16 and 18 mm, too.

To summarize briefly:
The 18105 is good to average in the range of 18 to 35 mm. It gets really good at 50 mm and stays that way till 105 mm, from f4 to f8, and excelling the 1670 from 70 onwards in edge performance. Distortion out-of-camera JPG is still visible from 24 to 105, using Raw and Capture One Pro for Sony greatly reduces that. Focal lengths reported by the 18105 are actually much higher. So a "24mm" displayed in the viewfinder is actually more like 29 mm, making direct comparisons a bit difficult. The 18105s strength is more in longer focal lengths with low DOF, though it still is usable as general purpose zoom.

The 1650 is good from 16 to 35 mm, about on the same level as the 1670 when both are stopped down, and gets average at 50 mm. In addition "16 mm" is actually more like 15 mm even after distortion correction, compared to the other lenses offering more WA. So the good range for this lens is clear, too.

The 1018 wipes the dust with the other lenses at 16 and 18mm! Stopped down, it shows what is possible for a wide angle zoom lens.

The 1670 has good performance from 16 to 70 mm, with the edges dropping at 70 mm to good to average. A great lens? Yes it would be, BUT AGAIN this copy of a 1670 is messed up! The right side (about 20 % of the frame) of this lens at 24 mm, f8 is seriously blurred. At 16 mm it is less pronounced, at the other focal lengths no problems.
The same shot with the 1650 shows no such issues. No change to the tripod-mounted camera, OSS off, 10 sec delay, A-mode, single spot focus.
So theoretically the 1670 could be a great lens and I envy everyone who has a good copy of it. Great package in one lens body - but the percentage of bad ones out there seems staggering:
My first copy was not great, but at least not uneven in performance. My second copy has better image quality allover, but messes up the right side of the picture from 16 to 24 mm. Kurt Munger had two inferior copies. Philipp Reeves first copy was decentered. Photozone apparently had a similar one.

Astonishing to me is that this specific lens has this fault only in the wide-angle area. So it could be that at least some who consider their 1670 to be a good one haven't yet stumbled into this hole = focal length. I would have kept the lens otherwise, but the blurring is already visible at normal size.

All in all, I find it pretty frustrating that Sony has designed such a good lens, but seems unable or unwilling to ensure a good Quality control, putting the customer into the position of a guinea pig or gambler taking his lot with chance. In countries with return policies, one might still order several copies to find a good one. But is that really the way to go with an 800 Euro lens?

So to get optimal image quality, I still have to use 1018 for the 10-18 range, continue with the 1650 for the 16-35 mm range, and then go on with the 18105 for the remainder up to 105 mm, and for low DOF (if I don't unpack my SEL50F18).

For all those interested in the good and bad and want to see for themselves, I have uploaded the test images to Google Drive. Remember to download before viewing since the Google viewer messes things up. AWB was customized so ignore colors.

The 18105 directory includes images rendered from ARW with Capture One to illustrate its default distortion correction.

And a small picture to illustrate how big the affected right side is:
Click to enlarge. 23 mm f8. Left side good, right side beyond the red line a mess

If Sony would supply me with a working copy, I'd be willing to give this lens still another try, but for now, I have given up! On the positive side, I can continue to enjoy my 1650.

Deutsche Kurzfassung: Durch ein günstiges Angebot in Versuchung gebracht, habe ich das SEL1670 nochmals getestet. Insgesamt theoretisch ein gutes Objektiv mit breitem Brennweitenbereich, durchgehend f4, Bildstabilisation und noch relativ kompakt. Leider ist dieses zweite Exemplar ebenfalls wieder defekt: Bei 24 mm ist selbst bei Blende f8 der rechte Rand (ca. 20 % des Bildes!) verschwommen. Schade, denn sonst wäre das Objektiv geblieben.
Testbilder sind auf einem Google Laufwerk abgelegt.