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Cosina Cosinon 40mm F2.5 Auto MC

Reviews Views Date of last review
2 14,764 Wed May 16, 2018
Recommended By Average Price Average User Rating
100% of reviewers $85.00 8.50
Cosina Cosinon 40mm F2.5 Auto MC

Cosinon's Answer to SMC-M 40mm f2.8. An Ultra Compact pancake style lens.

Max Aperture: f2.5
Min Aperture: F22
Increment: Whole stops.
Min focussing distance: 0.6m/2'
Filter thread: 49mm
Mount Type:
Price History:

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Registered: March, 2018
Posts: 96
Lens Review Date: May 16, 2018 I can recommend this lens: Yes | Price: $80.00 | Rating: 9 

Pros: Size, weight, speed
Cons: Manual only, no autofocus, not as sharp as a fifty
Sharpness: 9    Aberrations: 7    Bokeh: 8    Handling: 10    Value: 10    Camera Used: K3, K5   

Just got this from an auction site, 60 or approx $80. I bought it on a whim really, it's a pancake, it's rare. Serial number is 781520, badged Cosinon.

It really is tiny, on the K3 the lens protrudes only a centimetre or so forward from the mirror box. The focus ring is easy to find though, and easier to operate than many "thin" focus rings found on more modern lenses. If you just put a plain 49mm hood on there you'd need to look twice to see if a lens was even mounted.

In use it's a pleasant experience, focus ring is smooth and damped, the aperture ring is positive and it operates as any other manual lens. Sharpness at centre is pretty good throughout although obviously improves with stopping down. It's easily on a par with an 18-55 kit lens.

No hood supplied but a filter thread, so will be fitting a short metal hood with a 49mm mount and a 52mm end thread, so I can put a 52mm cap on it. I already have a few manual lenses and all are 49mm thread so the few filters I use will fit.

Haven't had much of a play yet, but I'd say for walkaround shooting this will give me as good results as any 50mm lens in this price bracket & max aperture, the 40mm length is a nice "standard" for me on APS-C (35 is slightly wide to my eye), and the short length/diminutive size mean I can cart it around without it banging into things and generally getting in the way.

I wouldn't scour the internet for one, but if you see one at a reasonable price, my advice is buy it. Even if you don't like it, you're most unlikely to lose out on resale.
Forum Member

Registered: April, 2011
Location: Gwynedd
Posts: 93
Lens Review Date: June 7, 2011 I can recommend this lens: Yes | Price: $90.00 | Rating: 8 

Pros: Small Size
Cons: Close Focus, Build quality.

I bought this lens on a whim, as a stupidly small normal prime. Having read up on what limited resources could be found for this lens I was pleasently suprised when I finally got to try it.

It is really small! About half the length of a 50mm f1.7! Some people find it too small, I do not.

One of the compromises undergone to make it so short is the cutting of the closest focus to a measly 2 feet, which isn't all that close, which is a shame.

How does it perform? Pretty well I think. It's often criticised for not being as sharp as a 50mm, and that may well be so, I haven't tried a 50mm to compare it too, however I am a bit of a pixel peeper and I am happy with this lens, even wide open. I should in fact say especially wide open, on account of it's bokeh. It's not perfectly smooth, the outlines are slightly harsh, but I quite like it.

Some real world samples:

@ f2.5 on XP2
@ f4 on XP2
@f4 on Fuji Pro 160C
@f5.6 Fuji Pro 160C (closest focus)

Size comaprison - SMC-M 50mm f1.7, OM Zuiko 50mm f1.8 on 2x macro TC, Coisnon 40mm

Update: Tested against SMC-M 40mm f2.8. SMCM is sharper wide open but slightly slower. Cosinon has 6 aperture blades, SMC M has 5. Cosinon is slightly less well made. More samples here.
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