Size and Weight
Manual Everything - mostly focus.
The lens does work, however, in Aperture priority mode on my D610. Since I can control the aperture, and this is fed back to the body, it can still make calculations for exposure. What I've found, however - at least indoors, is that since this lens capture 180º corner to corner FOV (DX crop mode), the overall exposure can be quite wrong - even in spot or center weighted metering. I had to increase exposure compensation 1 2/3 stops to get a decent exposure.
Optics - Performance, Sharpness, etc.
Well, I haven't had enough playtime with this lens to give a real judgement here. But so far, it has room for improvement. That said - I've only tried f/3.5. My main use for this lens would be for stars/astrophotography. So, I went on to my patio to capture a few stars. I live in the city, where we have some nasty high power LED street lights - light pollution is high, but at least white instead of orange. The flare on this lens is quite hideous - I will need to do some further testing out in the fields away from the lights. However - I live in Southern Alberta (Lethbridge), where agriculture is predominent. That means farmhouses everywhere, with several lights per house. In order to capture the horizon with such a wide 180º lens, I will almost always have farm lights in my scenes. Hopefully I can avoid flares.
This lens is design for APS-C sensors, I have a full frame. The following image shows the full sensor capture (including the built-in lens hood):
15sec, ISO 2000, F/3.5, focus set at infinity.
One of the fun things to do with ultra-wide angle lenses is perspective stretching, and this one sure works well for that. Here's a sample of my youngest daughter (hard to focus on her at the best of times, let alone with MF). This was at a very close distance - only a few inches from the front of the lens. 1/400th, ISO 800.
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