I wouldn't say I've had bad luck with the lens, anyone who's seen my equipment knows I don't baby it, (though in the case of the 70-210mm my current version looks very nice, I've been a lot more careful with it), the biggest problem is a lot of parts are now made of unobtainum, and while the outside of the lens is very robust metal or plastic covered metal in many cases, (though there are a lot of purely plastic parts), simple vibration over time, will cause some of the interior screws to work loose and get into places where they can wreak further havoc beyond the original issue of the screw coming loose.

The information brush is especially fragile, and is easily damaged by at least two different basic failures, mostly because the first inkling that there's something wrong with the lens is the zoom ring going beyond it's limits, which mangles the brush.

Once that's happened you'll have to fabricate your own brush as no repairman I know of will do it for you, they don't have the tools and won't improvise beyond a certain point, for fear of being blamed for further problems later, and well the lens just not having that high a resale value to make it worth trying to replicate such a delicate part.

In case you're curious, part of my information comes from partially disassembling one of my lenses on my own*, part comes from the information I got through email conversation with the tech who fixed my second lens, and part from this page


by a former member of this group, unfortunately now deceased, stored in the wayback machine.

*This not to blow my own horn by the way, I got to a point where I found the mangled brush and realized that I'd get no further without jigs and tools I just didn't have and were beyond my poor skills to synthesize.  A shame really as the first lens was the best optically of the three, second being the worst, but not my much and the current one being somewhere between the other two, (ah, sample variation strikes again).

On 10/2/2018 9:00 PM, Subash Jeyan wrote:
i sure hope i have better luck with the lens than you've had. it didn't
cost much so, fingers crossed, i think it's a bargain on the whole...

On Tue, 2 Oct 2018 15:20:38 -0400
"P. J. Alling" <webstertwenty...@gmail.com> wrote:

I've owned three of them, the biggest problem is they are getting
old, first sold with the SF series bodies, (1984ish), first
"successful" Pentax auto focus system.

There are a number of points of failure that become more likely as
the lens ages.   \

The problem is that the replacement parts are all from donor lenses
which have the same wear.

Don't get me wrong I love the lens, but of the three I own, one is in
pieces for parts to repair the second which is now jammed, which I
didn't try to get repaired because I was able to buy the third, for
less than the cost of the repair and shipping.

On 10/2/2018 10:42 AM, Subash Jeyan wrote:
i've just got myself an F 70-210 f4-5.6, though it'd actually be two
weeks before i get my hands on it. the reviews of the lens on the PF
were pretty good and i was curious about the images taken with the
lens. so i went to PPG to have a look. most of the images for that
lens in PPG seems to have been taken by Ken Waller. indeed, the
first 15 images or so were his. superb stuff. recognised a few
other names from the list too.

i am glad i bought this lens though it doesn't necessary follow that
the images i make will be half as good. i was planning to take the
DA 55-300 on my trek in the himalayas next month but wondering if i
should take this lens instead (coupled with the sigma 17-50/2.8).

here is the PPG link for this lens if anyone else is interested:


America wasn't founded so that we could all be better.
America was founded so we could all be anything we damn well please.
    - P.J. O'Rourke

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