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Latest Review Posted Cosina cosinon-w ( Petri ) 28mm F2 MC
You may have noticed that I've given this lens a high overall rating, but lower for everything else; this is because the lens is more than the sum of its parts.

First off, I've no idea why but when I got it the auto-aperture wouldn't function either side of F5.6-8. I took apart the mount and put it back together, not really having any idea what I was doing and losing a screw in the process. Now the aperture works, but as a preset. This doesn't really inspire confidence in the build quality, but hey-ho, I paid only 40 for a 28mm F2 so what can be expected? Like the other Petri lenses I own, the aperture ring also only does full stops.

Perhaps having something to do with my bungled mount job, the lens also judders when I take photos with it. I think this has occasionally thrown my focus off, and means it tends to work best in Live View, or with the 2s timer.

Edge sharpness is pretty dire until stopped down to F8, but then it's pretty fine - on the crop sensor at least. Centre sharpness is surprisingly good all the way from F2 until diffraction sets in. Though of course the centre is sharper at F5.6, you're splitting hairs unless trying to print larger than A4.

Flare resistance is minimal, so in most circumstances a hood is highly recommended. There is also noticeable chroma at high contrast edges, though we do have the modern advantage of software CA correction.

So why would I rate this lens 8/10? Sounds pretty crap, right? Yeah, but now we're coming to the go...

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