Kenlock 80-200mm f/3.5 Auto Macro in M42

2010-03-16
Kenlock 80-200mm f/3.5 Auto Macro in M42
I got this old zoom lens knowing that it is a auto-only M42 lens. I had the previous experience in altering an auto-only diaphragm into manual diaphragm m42 lens. It is equivalent to switching to M in most of the M42 lens with A/M switch. For manual stop-down, one has to use M setting as most of the current digital bodies don't have the mechanics to depress the aperture pin for the proper stop-down.

Every lens is different and this one does not come as a surprise in terms of difficulty. I first found the aperture pin not working even upon full depress into the lens. I later found a stuck linkage between the pin the aperture diaphragm. Once I get the pin to work properly, I added a little hollow insert using a fragment of a pen refill tube to make the pin pressing on the aperture diaphragm control at all time.

Kenlock 80-200mm f/3.5 Auto Macro in M42
Kenlock 80-200mm f/3.5 Auto Macro in M42
But once I get the stop-down mechanics working with manual diaphragm opening with the aperture ring, I found another issue and it is something that I have not dealt with before. The old M42 lens leaks oil likely from the helical housing in the focus and zoom compartments.

The lens has potential and I start liking its strong build and unique character that little is known about it.

Kenlock 80-200mm f/3.5 Auto Macro in M42

It works quite well when stop downed properly. And here are some test shots done with Pentax K20D

Shot wide open in f/3.5
soft but nice bokeh

Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D
stopped down properly after fixing the aperture pin

Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D

Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D
Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D

Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D
Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D
Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D
Kenlock 80-200mm f/3.5 Auto Macro in M42 and Pentax K20D

Impressions & Notes
  • It is a bummer to be able to fix a lens with aperture issues and stop short in fixing it completely due to the oil leaking from the lens helical to aperture blades

  • The oil and wet blades don't affect the lens performance immediately as I find no issues in the test pictures but it is something to be less desirable

  • The zoom lens has internal moving part for the zooming. Upon changing from 80mm to 200mm or vice versa, the lens does't extend or retract to a different length.

  • Bokeh and sharpness are found decent. The lens perform quite evenly across the range though I prefer to shoot in 180mm instead of 200mm as I think sharpness is better in 180mm.

  • This M42 zoom can work straight in Av mode in my Pentax K20D from f/4.0 to f/11. In wide open shot in f/3.5, I usually dial in +0.3 to +0.7 Ev.

  • Contrast is sometimes low when I shoot into objects with harsh lighting. It seems lacking on coating like the SMC in Pentax. The contrast is usually a easy fix in post processing.

  • I have decided to move on and sell it for cheap to others with full disclosure on the wet blade with oil issues


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2 comments:

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Hin Man said...

Thank you Lydia.

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