Cosina 20mm lens ?
Posted 25/09/2007 - 13:17
Link
I think the Cosina 20mm F3.8 is actually the same lens as Vivitar sell as a 19mm F3.8. If so then I used to own one of the Vivitar versions and here's what I had to say about it in a review written at the time:
Build
Small, light and compact, with a 62mm filter ring, This lense does not inspire a lot of confidence, despite its metal shell. The Pentax KA compatible mount is also metal, but proved quite stiff on my Pentax Z1p camera.
Optical
A 8 group, 9 element design, covering an aperture range of F3.8 to F22, the Vivitar seems underendowed with glass considering it's wide angle coverage. Results varied considerably, depending on the aperture used, with heavy vignetting resulting from wide open use. Don't even consider using this lense with apertures wider than F8 - even then some darkening of the corners of the frame is definitely visible. Colour rendition and contrast are quite acceptable however, as is overall sharpness.
Handling
Despite a sticky and plasticky aperture ring, use of this lense is quite pleasant, mainly due to it's small size and smooth, light focusing ring. Markings are provided on the barrel for depth of field at F numbers 4, 11 and 22, as is an infra-red focus mark. The dark viewfinder image is a bit of a pain though.
Compatibility
Exposures when coupled with my Z1p were off by between 0.5 and 1 stop over (confirmed by the use of a handheld meter, and by tests done using bracketing). I'll reserve judgement on the cause of this until I have the chance to test the lense on a KA mount camera body.
Price
I paid 850 Hong Kong Dollars (110 USD) for this lense, which is pretty much the same as quoted by B&H on their web page. No hood or case is included in that price.
Conculsion
A reasonable introduction into wide angles, at quite a low price, but be prepared to stop down significantly, and to bracket to get decent results
The vignetting will probably not be as bad with the APS-C sensor size however that was the main problem I had with the lens. I also had a cheapo Centon 18-28mm at the same time and it was just about as good optically. That zoom was then replaced with another cheap zoom, a Phoenix 19-35mm and optically that was better than the Centon or the Cosina prime.
Give the Cosina is pretty slow for a prime I can't really see any good reason (other than its small size) for going for it instead of a Cosina/Phoenix/Vivitar 19-35mm which will be better optically and just about as fast.
Build
Small, light and compact, with a 62mm filter ring, This lense does not inspire a lot of confidence, despite its metal shell. The Pentax KA compatible mount is also metal, but proved quite stiff on my Pentax Z1p camera.
Optical
A 8 group, 9 element design, covering an aperture range of F3.8 to F22, the Vivitar seems underendowed with glass considering it's wide angle coverage. Results varied considerably, depending on the aperture used, with heavy vignetting resulting from wide open use. Don't even consider using this lense with apertures wider than F8 - even then some darkening of the corners of the frame is definitely visible. Colour rendition and contrast are quite acceptable however, as is overall sharpness.
Handling
Despite a sticky and plasticky aperture ring, use of this lense is quite pleasant, mainly due to it's small size and smooth, light focusing ring. Markings are provided on the barrel for depth of field at F numbers 4, 11 and 22, as is an infra-red focus mark. The dark viewfinder image is a bit of a pain though.
Compatibility
Exposures when coupled with my Z1p were off by between 0.5 and 1 stop over (confirmed by the use of a handheld meter, and by tests done using bracketing). I'll reserve judgement on the cause of this until I have the chance to test the lense on a KA mount camera body.
Price
I paid 850 Hong Kong Dollars (110 USD) for this lense, which is pretty much the same as quoted by B&H on their web page. No hood or case is included in that price.
Conculsion
A reasonable introduction into wide angles, at quite a low price, but be prepared to stop down significantly, and to bracket to get decent results
The vignetting will probably not be as bad with the APS-C sensor size however that was the main problem I had with the lens. I also had a cheapo Centon 18-28mm at the same time and it was just about as good optically. That zoom was then replaced with another cheap zoom, a Phoenix 19-35mm and optically that was better than the Centon or the Cosina prime.
Give the Cosina is pretty slow for a prime I can't really see any good reason (other than its small size) for going for it instead of a Cosina/Phoenix/Vivitar 19-35mm which will be better optically and just about as fast.
Posted 25/09/2007 - 14:00
Link
Thanks for the quick reply, and the very detailed review.
I guess it's another case of you get what you pay for. I think I will keep my eyes peeled for the lesser spotted second hand smc-a, 20mm 2.8 and stop drinking beer for a while to help pay for it !
Cheers again,
/Ian
I guess it's another case of you get what you pay for. I think I will keep my eyes peeled for the lesser spotted second hand smc-a, 20mm 2.8 and stop drinking beer for a while to help pay for it !
Cheers again,
/Ian
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271 posts
19 years
Stockholm
Anyone ever used or have any opinions about the Cosina 20mm ? I'm after a manual focus 20mm prime, that does not cost the earth. Would love the smc-a 20mm, but the ocasional ones that turn up on ebay always end up well over my budget.
Cheers,
/Ian