I bought an used Kenko MC Soft 85mm F2.5 and enjoy it mainly for flower
photography. First, let's see the key specifications.
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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. |
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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!
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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 |
F2.5
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0
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0
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0
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F4
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0
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F5.6
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F8
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Measured aperture value |
F2.5
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F2.8
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F3.2
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F3.5
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F4.1
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F4.5
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F5.6
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F9.5
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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.
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F2.5
You can get maximum soft effect at this aperture. Very smooth background.
Sometimes this soft effect would be excessive. |
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F2.8
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. |
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F3.2
Softness is reduced from F2.8 in the background. But still good,
I think. |
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F3.5
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. |
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F4
Very small soft effect even on the film. |
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F4.5
Almost no soft effect on the film. I don't like this background
quality. |
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F5.6
It looks like a photo taken with very low quality lens. |
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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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