[OM] 200mm f4 broken at small apertures?

[Simon Worby]

I've just had some photos back taken with my new-old 200mm f4 Zuiko. I have two 
shots of the same thing, one fast speed, low DoF (probably f4), and one low 
speed, high DoF (probably f22). The latter is blurred -- like camera shake, but 
I know for sure I took it on a tripod with cable release. IIRC speed was around 
1/4 second. All the small aperture shots taken with this camera/lens 
combination (OM-1N & 200 f4) are blurred; all were taken using cable release 
and tripod. Small aperture shots taken with my 35-105 lens seem fine (same 
camera).

Is it possible to have a lens that is "broken" at small apertures? Would the 
sympoms be consistent with mine? Is there any further way of telling / 
conclusive tests I can run?

Thanks in advance...

Simon Worby
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