Topic: Adjusting infinity focus Pentax M f4 200mm

Hi

I've had this lens a while and had the bayonet professionally replaced after damage, but I've only just realised that it won't focus to infinity. The focus ring won't turn that far - its gets to the halfway point between 40 m and infinity, while you can clearly see that it's not in focus on either a Pentax MX film body or via an adapter on my NEX 6.

This lens will easily screw apart at the centre and I have read elsewhere that there should then be three screws visible to allow adjustment of the focus ring.  No such luck, there are two small circular holes diametrically opposite on the focus ring half, but no screws that I can see.

Any ideas?

Currently using Canon 5DII and NEX 6 with Olympus, Pentax, Canon and M42 converters.

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