Pentax 50mm lens fix

I acquired an SMCA 50mm f1.7 from eBay. Well, what do you expect.. The aperture ring was would only turn between f1.7 and f11. Meaning no A position action for my DS. So I did a bit of reading round the net and found that this seems to be a problem peculiar to this one specific Pentax lens. I need very little encouragement to take things to bits, so I went for it, and here are my observations.

First, unscrew the five screws securing the bayonet mount.

Take it off, and it looks like this

The aperture lever cam just lifts off, like this.

Next, the tricky bit. You have to take the aperture ring off, VERY CAREFULLY. It is worth doing this in a box or perhaps a plastic bag, because there are a couple of tiny bits that could fly off and get lost. If you happen to have one of those handy magnetised parts trays (available from all good automotive tool supply shops), so much the better. Once the ring is eased off, and all the bits are accounted for, relax. But not totally. You may have one or more minute ball bearings rolling around. They are teeny tiny. Keep good track of them and BEWARE, they are soo small that if you brush against one accidentally, you can pick one up on your skin without realising it - until it is too late and you've lost it. Best advice - pick them up with a bit of Sellotape until you are ready to put it all back together. The A position button will probably fall out of the aperture ring, but it's large by comparison and hard to lose.

Now it looks like this. Note that little silver bullet-on-a-spring thingy. That's the 'A' connector, as it were, that tells the camera when the lens is in A mode. Most likely it fell off when the aperture ring came off. The bullet thingy sits on a metal tab in that grove. The bullet thing disassembles into three bits; the bullet, the spring and the carrier. If yours drops off and falls to bits, just press the bullet bit back into the carrier and shove the spring back up its arse and, come reassembly time, put the metal tab back in the grove and sit the bullet thingy assembly back on it.

Now to the main event. There are two metal tangs controlling the A position clickstop. These are held in place with plastic welds. These welds are a bit fragile and commonly fail. It seems that Pentax only used this fixing on this one specific lens, but I haven't looked inside any others to check. Yet. So there's the problem - the weld has failed on one tang and it has become detached, jamming the ring.

Solution: I have read that some people have drilled tiny holes and reaffixed the tangs with tiny screws. Far too much effort for me. I just used a blob of Araldite adhesive, which seems to have done the job perfectly. Perhaps you could lash it down with duct tape. There there, all better. Original plastic weld on the right, Araldite blob on the left.

Now to stick it all back together. Remember the detent - here's the spring, pulled a bit out of its hole so you can see it.

And there you have it. It's not brain surgery, just a bit fiddly. I do hope you didn't lose any of those ball bearings now...

Canon A430 fix

The Canon A430 is a nifty and inexpensive little P&S. We got it as an upgrade for my old Canon A60 as a family snaps camera. The red colour matches my wife's car. Anyhoo.. only six months old, the lens jams half in and half out. The camera is unusable. It beeps and says "lens error" then turns itself off. Fair enough, so send it away to the authorised Canon service centre. But oh no, they send back a fuzzy 6x4 picture showing what they say is sand in the lens mechanism. They say this invalidates the warranty and would I care to pay £99.83 for them to fix it? Seeing as a new one now costs rather less than that, I decline. I then have to fork out another £8.50 for them to post it back to me. I am not a happy punter. But with nothing to lose I decide to try and fix it myself. It turns out to be a doddle. I see no reason why this same approach will not work with any other Canon models with stuck lenses caused by grit in the mechanism. (If the mechanism itself is irreparably damaged, say after dropping the camera, you're out of luck.)

First, remove the three screws on the base (note how the serial number has rubbed off. This seems to be a modern design feature - the self-erasing serial number. I've seen it on a number of very recent consumer products)

Then remove the screw on the AV in/out connection side. Then on the opposite side, remove the screw hidden under the rubber flap

covering the USB connector.

Five screws, that's all there are.

Now gently pry open along the seam and ease off the front half of the casing.

Now you can begin to see where we're going. Just above that 6105, underneath that orange ribbon connector, is where the problem lies.

But we need more access. So remove the rear casing. As with the front casing, it just eases gently off. However, the orange ribbon cable

will remain connected between the camera and the LCD.

Now we can get at the problem. Half hidden by the strip of orange ribbon cable, by the ball of my thumb, is a worm (spiral) gear that engages with a cog. Some grains of sand or grit have got in and jammed between the gear and cog teeth. All that is required is to take a paintbrush and blower, or whatever you have to hand, and dust out the grit. At the top of the worm gear are some small turning vanes that are useful because you can use them to turn the worm gear whilst dusting.

If your eyes are sharp you may be able to make out the axe-head shape of one of the vanes in the shot below. (Travel north from 6105 and it's underneath the small stub of ribbon connector.)

After blowing and dusting and turning the screw, it is time for a test; so put the batteries back in.

Push the power button and see what happens. With luck, and perhaps a bit of a residual grinding sound, the lens mechanism will operate as designed.

I got lucky. I just slid the casings back on - remembering to locate the rubber cover grommets for the USB and AV connectors as I did so - and replaced the five screws. Now all is well. So Canon can stuff their "invalid warranty" and kiss what goodwill I had towards them goodbye. On the other hand; they do make a camera that is remarkably easy to take apart. But next time I'll be buying one of those Pentax or Olympus waterproof numbers..