SMC Pentax-M 200mm f/4

by Johan J Ingles-Le Nobel
Last updated August 31, 2017


Like all Pentax-M series lenses, the 200mm f/4 is sharp, small and beautifully constructed.

expect to achieve 10:1 using this lens

This is a good, inexpensive telephoto prime lens that works just fine as a tube lens with an infinite objective.

SMC Pentax-M 200mm f/4

SMC Pentax-M 200mm f/4, which gives me 10:1 as a tube lens using a Nikon CFI BE 10X NA 0.25 infinite objective. A good, inexpensive telephoto prime lens that works just fine as a tube lens with an infinite objective.

200mm Magnification

Nikon, Mitutoyo and Leica Infinite objectives all achieve their rated magnification using a 200mm tube lens.

Therefore with a 10x infinite objective, expect to achieve 10:1 using this lens, which in the case of APSC means a view of 2.37 by 1.57 mm.

The filter diameter of the SMC Pentax-M 200mm f/4 is 52mm which is a little annoying as the rest of my Pentax stuff is 49mm. The lens is constructed with 6 elements in 5 groups.

SMC Pentax-M 200mm f/4 Performance

a very marked depth to shots

The colour rendering is superb, especially for blues, and the image quality is uniform across the whole APSC frame. It has a very marked depth to shots - almost a 3D type of look.

The 8 aperture blades are a nice touch, chromatic aberration is under control one stop down and at f/5.6.the SMC Pentax-M 200mm f/4 seems to have great uniformity across the frame and no feeble zoom-type centring issues.

no feeble zoom-type centring issues

The lens also seems to give better than expected results when coupled with a moderate teleconverter, for example a 1.5x. This potentially makes it usable to push a 10x up to 15:1.

Pentax-M Series Lenses

The SMC Pentax-M series of lenses were launched in the very late 1970s, a compact successor range of lenses to the first multicoated plain SMC series. This was the second series using the then revolutionary K mount. Being -M series there is no auto aperture with this lens series, which differentiates it from the successor SMC-A series of Pentax lenses. It is thought that the -M designation maybe a nod to the then Asahi factory in Mashiko. Optically they benefit from the SMC coating and perform significantly better on today's colour cameras than the earliest Pentax lenses which were designed for black and white, and can therefore show aberration with colours not being corrected for colour use.

Comments (10)

Article: Pentax-M 200mm
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Larry Eicher says...
I've read other photographers rating this lens with an 8 or 9 for CA. I read above that CA is under control with this lens. I was looking at this lens yesterday and came to think that I did not want to introduce CA with tube lens. What do you think about my reasoning?

22nd January 2019 3:19pm
Jorge Torres says...
Hi Johan, A complete newbie here. Excellent website and article! If you don't mind me asking you a few specific questions, I saw your recommendations about the Nikon 10x objective and I just ordered it. I have a canon T31 cropped sensor camera and a full frame canon 6D. Reading here and there, My understanding is that I need an adapter to connect the rear end of the nikon objective to the front end of a 200 mm prime lens (or a zoom lens) to make it work. I have a canon 70-300 zoom lens which has a 58 mm filter size, so I order Nikon CFI M25 microscope objective to M58 58mm adapter ( the questions are: Is my logic correct? Do you think this adapter will work? Is there anything else I should place in between the objective and the front of my Telephoto zoom lens to make it work?.

Another set of of questions would be regarding the SMC pentax m200 f/4
12th June 2015 3:47am
Johan says...
Should work if you have the right CFI adapter. You don't need anything between them =).
17th June 2015 9:45pm
Johan says...
Tube lenses are used with 'infinite' type microscope objectives (lenses). Have a look at =)
19th November 2013 10:50am
Mikpix says...
This is more of a question. Excuse my ignorance what is a tube lens?
19th November 2013 10:42am
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