To answer some , my experience regarding this lens ..|
1. FOA, I think too many of todays photographer misunderstand real world lens and optics issue. Almost no lens of consumer photographic segment can do their best at wide open, the Mir-47K not an exception, so I have to say the point #.1 is very much a misunderstanding of lens application. 20mm lens is best utilized in film ( which is what the lens designed for ) for ultra wide angle, and landscape. Having best performance in the smaller aperture is simply design goal and I think its nothing to do with its speed.
2. I have 2 Mir-47K, and both exhibit less than optimal flar control when pointing stright into light, but if one used within context. Its OK. I do not think it had anything to do witht he coating, more like the complex optical design adn that hugh front elements. Oevrall, I say this lens is average in this regard ( compared to similar priced and similar vintage lens )
3. I do not see vignetter even on my slide, so I cannot understand this observation. Admittingly if one measure with critics. The perimeter look like having roughly 1/4 to 1/2 stop less exposure in some case ( but not all ) and this stop being a problem after 4.0
4. Exactly right, not a problem though if no filter uis attached
5. One of my Mir-47 exhibit warm biased, but one exhibit neutral, so I suppose this is variation in vintage and production ( also coating difference )
6. At this price, one can hardly fault its construction. Its metal, and solid alright while not exactly tactilly great.
Extra to the above. My observation with this lens is it exhibit higher than average resolution at mid aperture, but average contrast. Its color rendering is biased mainly towards neutral most of the time. Its saturation on the green seems to be less so than the blue and red.
But overall, I rate this lens better than avergae for tis price. It certainly beat all the Zoom that cover this focal length, and the 2.5 can be used in low light situation at time of need ( in fatc my measurment is this lens is not 2.5 but faster ).