Tuesday, July 05, 2011

Ephotozine DA70 and FA31 Lens Reviews

http://www.ephotozine.com/article/smc-pentax-da-70mm-f-2-4-limited-lens-review-16835

http://www.ephotozine.com/article/smc-pentax-fa-31mm-f-1-8-al-limited-lens-review-16866

Nice reviews. They are still confused with the actual meaning of the MTF, though. I recommend do read the MTF50 charts only as at MTF of only 20%, everything is almost meaningless. How could one distinguish between the white and the dark colours if there exists only a marginal difference of 20% - i.e., the contrast will be very low as a result.

So, when you read, do bear in mind that the MTF20 is NOT about the "resolution of coarse details" nor the "overall contrast of a lens", the resolution is measured as per the resolution unit in lw/ph (line-widths per picture height) as shown in the Imatest results and there is nothing to do with the MTF set threshold figure after all. And, as I've mentioned above, the contrast is really very low at a MTF of 20% anyway.


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