Inaccurate Aperture Markings on Meike 28/2.8

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Schleiermacher Senior Member • Posts: 2,370
Inaccurate Aperture Markings on Meike 28/2.8
1

Having read a few comments online that the aperture markings on the Meike 28/2.8 are inacurrate, I got curious and did some comparison testing today. Indeed, they are off, I believe.

I metered the exact same scene without variation in illumination with my adapted Pentax M28/3.5 and the Meike 28/2.8. Here’s what I found:

The shutter speed assigned for F/22 on the Meike is actually the shutter speed for F/16 on the Pentax. It would seem that F/16 is really the smallest aperture on the Meike.

Actual F/11 on the Meike occurs when the aperture dial is set halfway between "22" and "16" on the dial.

Actual F/8 on the Meike occurs when the aperture dial is set to about 1/16" past where the missing "11" should be.

Actual F5.6 on the Meike occurs when the aperture dial is set to "8".

Actual F4 on the Meike occurs when the aperture dial is set to halfway between "4" and "5.6"

Oddly I don’t see much meaningful change in shutter speeds when the Meike aperture is set at "2.8" on the dial and when it is set to "4". The actual widest aperture of this lens seems to be F/3.5 or thereabouts.

Of course it is possible that my Pentax M28/3.5 isn’t an accurate reference lens, but I believe it is. Each click between full aperture settings yields a doubling of shutterspeed as it should. In other words a click is a true stop on the Pentax.

Now, I’m not an optical expert and don’t understand much about lens design, but in my crude test, it appears that the Meike markings are quite inaccurate.

I’m willing to be schooled and corrected by those of you who know more than me. If I’m wrong, please help me make sense of it.

Thanks,

Matt

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Schleiermacher
www.mmathews.zenfolio.com
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'At our best and most fortunate we make pictures because of what stands in front of the camera, to honor what is greater and more interesting than we are. We never accomplish this perfectly, though in return we are given something perfect -- a sense of inclusion. Our subject thus redefines us, and is part of the biography by which we want to be known.' --Robert Adams, Why People Photograph

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