Friday, 23 September 2016

SMC Pentax-M 1:4 20mm Asahi Opt. Co.

Cost: 0$ (average market price $273)


Another decent, impressively compact, lens from Pentax. This lens was owned by my girlfriend who use this lens in previous years on her Pentax K1000 (she uses a Nikon D800 now). So another favorite!

As most old Pentax lenses, it's good old quality with a solid metal build, and butter smooth focus and aperture. It has small profile, so combines well with the Sony a6000, even with an adapter. With the APS-C crop factor of 1.5 (resulting in 30mm), it still makes a decent landscape portrait lens. Good sharpness and color rendition, but as it is a slow lens, it is advised to use a tripod if you use a camera without stabilization such as the Sony a6000 (or shoot in bright light). The lens was more compact than its K predecessor.

The lens does seem to suffer from the "blue dot" caused by flare. I had a good bunch of pictures with this problem when photographing a sunset. So a hood might be advised.

Again proof that an old lens might still be worthwhile and compete with the latest lenses out there. I will definitely use this lens more often. Fully recommended and a pleasure to use!

To combat partial reflection, Pentax developed chemical coatings for the lens surfaces with minimum light loss. SMC is "a remarkable seven-layer lens coating process that cuts the reflection ratio down to just 0.2% per lens surface. The result is a dramatic improvement in both color fidelity and brightness and the elimination of flare and ghost images."
SMC was patented and first applied in 1971, when Pentax was still making screw mount equipment. The multi-coated lens lines changed from Takumar and Super-Takumar to Super-Multi-Coated Takumar and later on to SMC Takumar. SMC Pentax was used for the newly introduced K-mount lenses. Pentax's SMC is still today considered as one of the best lens coatings on the market.

  
Lens Specification:

Focal Length: 20mm
Maximum Aperture: F4
Minimum Aperture: F22
Image Format: 35mm
Lens Mount: Pentax K
Optics: 8 elements, 8 groups
Blades: 5 blades
Focussing: Manual
Minimum Focus: 25cm
Maximum Magnification: 0.12x
Filter Size: 49mm
Weight: 150g
Length: 29.5mm
Production: 1977 until 1984
Serial Number: 6847539

More information on Pentax

Samples:





More pictures will be added in the future...

Sources:
Wikipedia - Pentax
Pentax Forums

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