State of ultrawide

Started 7 months ago | Discussions thread
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Vasyl Tsvirkunov
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State of ultrawide
7 months ago

Finally got a couple hours yesterday to do some testing on m43 ultrawide options. The common opinion is that m43 is not very good in that area because of the crop factor. Let's see if that opinion actually holds. I could not upload the chart to dpreview galleries (too large) so here's the flickr link: Test chart. Please view the image at the original resolution.

Don't judge the image or location - I just picked some small local park as it had a convenient bench and not too many people asking questions. All shots are done from the same point in the same direction, handheld. Developed in C1Pro at default settings. I did not try to defish fish-eyes as that would compromise edge sharpness.

Contenders: Panasonic 7-14, Rokinon 7.5 (aka Samyang, Bower, etc.), and three Canon-mount lenses - Peleng 8, Lensbaby FE 5.8, Sigma 8-16. I've used two adapters for Canon lenses - Mitakon focal reducer and some off-brand simple adapter. As none of those adapters support electronic control (and Metabones is still AWOL with their SpeedBooster for EF), Sigma is stuck wide open.

Immediate comment on adapters. As simple as straight mount adapter is, off-brand adapters often don't work well. Mine allowed to focus way past infinity (better than the opposite problem, I guess) and has significant play. Mitakon adapter may not be up to Metabones optical quality but works well - I haven't seen any issues that I could attribute to the adapter.

The first obvious thing is that how good both Panasonic 7-14 and Rokinon 7.5 are. The sharpness kicks in at wide open, increases for one stop, and then stays very high until refraction takes its toll. Panasonic is good until f/10, Rokinon pulls slightly better with usable f/11. The edge is actually better with Rokinon, that's expected of a fish-eye.

Peleng 8 shows its age but still quite good at 5.6. Center may be even comparable to Rokinon at that aperture but the edge suffers from CA.

Sigma got punished by being stuck at the wide open. The center is actually very good but the edge is not very usable.

Lensbaby is a special lens so it gets same handicap. Sharpness seems the best at f/8 but it's obviously not in the ballpark of Pana or Rokinon.

Mitakon adapter appears to improve the overall sharpness making both Peleng and Lensbaby very usable around f/8. It does help Sigma but continue reading.

Now, let's consider FOV. Panasonic and Rokinon are known quantities. Peleng with a simple adapter is pointless - Rokinon is better in every respect and wider. Lensbaby with a simple adapter produces very strange view, not practical. Mitakon adapter does not help Peleng that much - the edge on that lens has some problems beyond sharpness. Lensbaby, on the other hand, becomes what it is supposed to be - full circle fish-eye. It's a special purpose lens, somewhat of a toy, but it has its place.

The last is Sigma. This is a disappointment. First of all, I don't believe it is 8mm anymore. With Mitakon adapter that should've been 5.7... It is barely wider than Panasonic's 7. And it does not cover the entire frame so it needs to be cropped at least vertically. Should I even point the vignette? Or the weight of that lens? I would expect the sharpness to improve with aperture but even if it gets to the level of Panasonic it's still not enough to redeem that lens.

So, the conclusions. If you need ultrawide - get Panasonic 7-14 and Rokinon 7.5 and you are all set. Both are excellent and you are not going to get anything better or even that different if you go into contraptions. For its purpose, Lensbaby is usable but factor in an adapter. The m43 crop factor does not put it at a disadvantage compared to other crop or FF systems (Sigma 8-16 has practically identical FOV to FF 12-24 which is the widest corrected lens you can get).

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