Hi guys,

With lens design getting forever more complicated and manufactures using state of the art glass hybrids, it always gives me great pleasure when I pull out my Pentax SMC M50 F4 Macro, like the name, it is compact, measuring 64 mm in diameter and retracted 54mm in depth, 85mm extended, weight 166 gms. 49mm filter size.

Construction is "only" four elements in three groups ( all in the round), both front and rear elements elements being approx. 14mm in diameter, the front being recessed and well protected some 30mm behind the front filter ring. I'm no optician but from what I have gleaned from reading, it is a Tessar design from way back, symmetrical ( hence the front and rear 14mm elements) but with the benefit of Pentax's SMC coatings.

How does it perform? Surprisingly, very well indeed! It must be said that it only has a macro ratio of 1:2 so it's a little limited in it's close focusing distance, 0.234mts/ 0.77 ft. but if you can live with that and the fact that it's a manual lens there's really nothing at all to criticize.

First off resolution; well it's very good from F4 sharp to the corners ( it's a FF lens sweet spotting on APSc), F5.6 and onwards the lens is tack sharp up to F11 across the frame, F16 is still very sharp and for macro will be often used.

CAs are non existent, there's nothing, really looking around leaves on the trees, no fringing.

Distortion; as far as I can see there isn't any, I guess were in the 0.1-2 %.

Flare seems at least very well controlled.

Sharpness certainly holds up well at infinity as well as in macro.

So where's the downside? no AF, macro 1:2 and only F4, but really who uses macro at larger apertures than F4? I have noticed (only) with extension tubes a purple reflection stain can appear, a sign of non-digitised coatings.

Upside; light and compact (shirt pocket job), really top quality all metal build, mine is an old copy with a deformed and re-straightened filter ring but the focusing is silky smooth while the aperture clicks are as good as new. Jpg users will love it, no CAs or distortion to correct, images are great straight OOC. Mounted on my K01 ( the brick) using the green button and focus peaking I can nail the focus 95% of the time. However, the real upside is the price, I paid £60 from the bon coin in France.

In short this simple little lens is a gem! [ATTACHMENT NOT FOUND]