Lense Confusion

Hi
I've just purchased a Pentax FA 80-320 Lense from a guy on E-Bay Who reasured me that it was O.K. But i am a bit confused as i understood that this type of lense was Auto Focus but it does'nt. It seems to have the AF coupler on it but i can only use it in manual. I'm using it on a Pentax MZ6

The SMC Pentax-FA 80-320mm is indeed an AF lens. It sounds to me like its faulty.

Do you have other AF lenses that do work OK on your MZ6?

Have you tried the lens on another body?

I don't know this particular lens, but on some FA zooms you push the focus ring forward or back to switch between AF and MF. I thought my first FA zoom was faulty, too, until I discovered this.

G

Have the same lens with MZ6 - should be fully AF.

Mike

Yes, I have this lens too and it's fully AF.
Check that you have the camera's AF/MF switch in the AF position! If it was already in the AF position, switch it to MF and check that you can manually focus.

The autofocus mechanism in Pentax cameras is a mechanical linkage between the body and the lens - there's what looks like a little "screwdriver" slotted coupling. The body has a slotted pin that is withdrawn when you switch the body to MF mode.
Occassionally this pin doesn't engage first time when you mount the lens, but a slight movement on the focus ring of the lens usually clicks it in.

When in AF mode, the focus ring of the lens should be very difficult to turn - because you're trying to move the motor in the body through a series of gears. In MF mode, the linkage decouples and the focus ring is easy to move.

Hope that helps!
Matt

Both of my other lenses work fine and i havent another body to try it on. I've also noticed that i don't get an F stop reading in the view finder even when set to manual. The focusing part does lock up when fitted to the camera and lense set to A.

I've seen similar symptoms in a lens yhat had a slightly warped lensmount, causing the af coupling to bind and seize. trying to use that lens may result in the af motor in your camera body to burn out.

Have you tried cleaning the electrical contacts? My preferred method is with a soft cloth with about one drop of WD40. Don't overdo the cleaning or touch the rear lens with the cloth and leave it for a while before refitting it to the camera.

Finally, try turning the AF coupling of the lens with a suitably sized flatblade screwdriver. It should not need much effort at all to turn it. If it doesn't turn, its faulty.

Don't risk damaging your camera with it either.

Failing all that, send it back for a refund and look for another sample. The lens is excellent and you will not be disappointed when you find a good one.

I've given the contacts a clean with a soft cloth (not sure about WD40). The AF coupler turns ok when lense is dismantled and i turn the focusig ring. I just don't understand why there is no F stop reading in the view finder when set in any mode. I must say though that when i did give the contacts a clean it did try and auto focus and i did get a glimps of a F stop reading but that was when i played around with the A setting trying to wriggle the lense. Since then nothing. i Can't even change apature setting manually when moving selector switch.

You haven't said what your other lenses are but if they are Pentax AF lenses and they work in all respects on your camera, I think it reasonable to assume that the 80-320mm is faulty in more ways than one. You will only really know by trying another sample or trying the lens you have on another Pentax body.

WD40 in very small amounts will do no harm in my opinion. It eventually dries out completely anyway but you will be assured of as perfect electrical contact between lens and body as is possible . . . assuming there is no misalignment issue.

Of course, if you do intend to send it back, it might be wiser not to use WD40 but Isopropyl Alcohol (IPA) instead. This will clean any grease and soluble contaminants from the contacts, but leave no trace after a few seconds of evaporation.

I wouldn't leave it too long before asking for a refund. To be fair to the seller, at least tell them that the lens is not working for you and you'd like some more time to investigate its failure.

Another option is to send it to Pentax in Langley for a free estimate for its repair. It'll cost you postage but that's all. If they find its faulty, they'll tell you how much it'll cost to repair it, then make your decision.

That at least will qualify whether or not there is a problem with the lens rather than your camera.

I don't think I can advise you further on this. When you take a lens/camera combination out to use it, you need to have confidence in its reliability. I don't think you will have that confidence with this lens.

Good luck.

My other lenses are Pentax 28-90 & 100-300 they both work O.K with no problems at all. I got the 80-320 to replace the 100-300. Thanks for your help looks like i've got a duff one. One problem with purchase the seller took the lense off e-bay for be to have it at an off auction buy it now price. I have contacted him but no reply yet.

If he/she is a reputable ebay seller and you offer to pay the relist fees, there shouldn't be a problem. You'll be out of pocket a little, but a lot less than keeping a lens you can't use. These normally sell for about £60 - £90 because they are known to be very good lenses (normally). My son, lucky devil, bought a near perfect example with only a very slight 'ding' in the filter ring which does not affect filter attachment for only £40. I must have been asleep that day, else I would have had it myself.

Just don't be put off by this experience, look for another, you'll not be disappointed when a good one turns up.

Cheers.

The guy has finally contacted me and things look promising in getting money back. Now i'm going to have to start looking for another one.

I would like to thank all of you who replied to me with your help and advice.

Richard

Richard,

I sent you a private message.

Regards,