KEN's Report vol.1
Kenko MC85 (MC Soft 85mm F2.5)
I bought an used Kenko MC Soft 85mm F2.5 and enjoy it mainly for flower photography.  First, let's see the key specifications.
Kenko MC Soft 85mm F2.5
(Kenko MC85 in USA)

Lens : 3 groups 3 elements, Multi-coated
Closest Focus Distance : 0.8m
Weight : 315g
Dimensions : 66mm in diameter x 76mm
Filter Size : 52mm
F Stop : F2.5 - F8
Number of Diaphragm Blades : 13
Mount : Detachable, P mount (42mm, Pitch 1.0mm)
New Price in Japan : 29,800 yen (incl. mount and case)

As you can see in the photo, F stops are not at even intervals.

The lens has 13 diaphragm blades, and keep fine circle shape till the smallest aperture.

Focus ring has very good feeling for manual focus operation.

Mount System

I bought the lens with Olympus OM mount, though I don't have any OM but Canon EOS SLR system.  It is not well known that Kenko's soft lens series (MC Soft 45mm F2.8, etc.) have detachable mount system maybe because Kenko sold the lenses together with mount.    I have a Kenko camera mount for Canon AF for Kenko Pin-hole Lens, and I applied the mount to MC85 and fitted it to my EOS.  This mount is screw-in type and called "P mount" in Japan, and major dimension is
  Diameter : 42.0mm
  Pitch of screw : 1.0mm
  Flange back distance : 55.0mm
This is identical in terms of diameter and pitch with M42 universal screw mount (Pentax screw mount or Practica screw mount), therefore, if you have any of M42 camera mount adapter you can fit Kenko lens to your camera.  However, flange back distance of M42 is merely 45.46mm while Kenko lens is designed for 55.0mm, so the lens does not focus very close.  Another disadvantage of M42 adapter is that the adapter does not have rotational adjustment. When you fit a screw-in type lens to your camera, sometimes top of the lens would be off from top of the camera.  If you have Kenko genuine mount you can adjust rotational direction of the lens by loosening 3 screws on peripheral side of the mount.
The genuine mount seems to be called as "T-adapter" in USA, which is sold for the camera mount of "Kenko Spotting Scope Camera Adapter".  Based on the Kenko's Japanese Catalogue, camera mount adapter for spotting scope is identical with that for soft lenses.  So you will be get the mount from Kenko. 
I think the naming of "T-adapter" is very confusing, because, as someone aware, T-mount is very popular in astronomical scope, but T-mount has different dimensions from Kenko's mount.  T-mount is 42mm in diameter and pitch is 0.75mm (P mount is 1.0mm).  You can't apply T-mount for astronomical scope to Kenko lens. Be careful!

Camera Mount Adapters Applicable to MC85
Left one is Kenko genuine "P mount" or called "T-adapter".  Yellow arrow indicates one of the three screws.  You can adjust rotational direction of the lens by loosening these screws.
Right one is M42 - Canon FD mount adopter.  It's very thin because M42 flange back distance is merely 45.46mm, while P mount has 55.0mm. 

Aperture Value Test

I've found a curious thing while I checked the lens with EOS-1N.  When I change aperture value from F5.6 to F8, shutter speed varied from 1/60 sec. to 1/20 sec.  Theoretically, it should be 1/60 sec. to 1/30 sec.  So I've conducted an extensive test with Sekonic Exposure Meter and a light box as stable light source.  The results was :

Aperture value on the lens
Measured aperture value

As in the table, real aperture value at F8 is F9.5, 0.5EV slower than lens indicates.  You'd better be careful if you use it with external exposure meter.

Soft Focus Effect Test

Kenko's catalogue says that the soft focus effect varies by aperture value, the faster the bigger, and no soft focus effect at F8.  Namely you can use the lens as normal lens at F8.  To confirm this, I've taken photos at all the aperture value on the lens and checked soft focus effect.


You can get maximum soft effect at this aperture. Very smooth background.  Sometimes this soft effect would be excessive.


There seems no difference from F2.5 at a glance, but when look closely at the photo, background is somewhat more clear, less soft.  I think this soft effect would be good for various subjects.


Softness is reduced from F2.8 in the background.  But still good, I think.


You may feel little soft effect on the sample photo, but still it's apparently a soft focus photo on the film. It's the slowest aperture value to get good soft focus, I think.


Very small soft effect even on the film.


Almost no soft effect on the film.  I don't like this background quality.


It looks like a photo taken with very low quality lens.

F8 (Actually F9.5)

Low quality photo!  Not sharp enough, not smooth in the background / parts of out-of-focus.
I do not recommend to use F4 or slower aperture with this lens.

As you can see in the samples, it's a fun lens as far as you use it between F2.5 and F3.5.  If you are an US resident, you can get it from Yahoo Kenko Mall only for $56. Sold out!

(March 4, 2002)

Sample Photos  (added on July 5, 2003)

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