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01-05-2012, 02:08 PM   #1
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AF not working--is it camera or lens?

I have a K100D Super with the 18-55mm kit lens. Have had it about a year; love it. All of a sudden, the auto focus isn't working. My first clue was that when I turned it on last night (having used it Tuesday afternoon with NO trouble), I got the shake-reduction screen that wants me to set the focal length--which shouldn't happen when the camera is set to AF. Up to now I've had no problems with the AF function at all. The switch IS set to AF, but the screen indicates "MF." I've checked all the settings, have reset to default settings, and have tested the shooting modes I use the most. I've even set it to Auto Pict, which I never use.

The camera has not been dropped, nor has the lens. Well, unless one of my kids dropped it and didn't tell me.... I've taken the lens off and put it back on, thinking that maybe a contact was loose or it wasn't seated right, or something. No luck.

So I'm using manual focus right now, but my old eyes are not the the best. Even though I've gotten some pretty sharp pictures today , it took me awhile, as I generally use AF.

Coincidentally, I've been looking for another lens, so I'm "hoping" this problem might be the lens. LOL. But I have no idea. Also, I have another problem with the camera body, which is that the playback function doesn't work (at least not through the arrow button; I can access the pics through the menu, but with a lot of futzing around). I can live with that, though, as I've set my instant review to 3 seconds so I can look closely at each shot as I go. But this leads me to wonder, is it the camera that's going bad and not the lens? I wonder if both the focus and playback switches themselves are bad? Or, is the camera falling apart? In the case of the AF, maybe the camera isn't "reading" the lens?

This is my first dslr, and I'm sure it won't be my last (I'd love an upgraded Pentax, but was planning on just settling for a new lens for right now). Any help anyone can give is greatly appreciated! TIA!

01-05-2012, 02:33 PM   #2
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Sounds like a lens problem- if the camera is asking for the focal length, then it isn't able to read info about the lens via the lens contacts.

If you want a new lens, you have two choices: to supplement your kit lens, or replace it.
If you want to supplement it, the 55-300mm is a nice tele lens:
Pentax-DA 55-300mm Review - Introduction - PentaxForums.com

If you want to replace it with something better, then Tamron 17-50mm F2.8 is fast and sharp
DA* 16-50mm vs. Sigma and Tamron 17-50mm F2.8 Comparison - Introduction - PentaxForums.com

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01-05-2012, 02:43 PM   #3
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Cleaning the electrical contacts of the lens and the camera would be worth a try: these not making proper contact would explain why the camera figures it is an old manual focus lens. (I'd put some drops of rubbing alcohol (or Eclipse) on a micrfiber cloth, rub with that and then follow up with a dry spot of the cloth.)
01-05-2012, 02:44 PM   #4
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Thanks, Adam! I was thinking about replacing it with something with a bit wider range, so I'd have a good, everyday lens, instead of replacing it with a similar range or with an additional one. I understand that the Tamron lenses are nice. I was thinking maybe something like the Pentax FA series in the 28-70mm or 28-105mm. I haven't bought lenses for a camera in decades (not just years!) and have forgotten most of what I knew (which wasn't a lot to begin with). Most of my shooting is indoors, under decent fluorescent lighting (5500k overhead and side lights), but not exactly "bright light" or daylight conditions.... But I do like to take it out once in awhile and do some things "just for fun" with it....

Any suggestions are most appreciated!

01-05-2012, 02:45 PM   #5
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jolepp, I thought about cleaning the contacts, but wasn't sure if plain old alcohol would be OK. I will try that--thank you!
01-05-2012, 03:04 PM   #6
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I'd stick with a clean, dry, lint free cloth myself - no alcohol or other liquids. Polishing the contacts often helps with this kind of thing.

If that doesn't help, visit a local camera shop and try out a couple lenses. Most I've been to are happy to let you try them out in store. That should narrow the issue down to lens or body.
01-05-2012, 03:05 PM   #7
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QuoteOriginally posted by amc654 Quote
jolepp, I thought about cleaning the contacts, but wasn't sure if plain old alcohol would be OK. I will try that--thank you!
Sure . The important thing IMO is use the alcohol sparingly as in a slightly moist, not soaked spot a a cloth. That way no significant amount can't seep in or maybe splatter to a glass surface (to dry off leaving a smudge behind). A small amount should help to bring any grease and other crud into solution and ultimately off the contact surfaces.
01-05-2012, 03:53 PM   #8
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Well, I succeeded in cleaning the contacts and the ring without messing anything up, and, yes, they were dirty. But.... now that they are clean and dry, the AF is still not working....

It was worth a try, though; thanks!

01-05-2012, 05:28 PM   #9
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QuoteQuote:
If that doesn't help, visit a local camera shop and try out a couple lenses. Most I've been to are happy to let you try them out in store. That should narrow the issue down to lens or body.
Excellent idea! Alas, our last local camera shop (Ritz) went out of business, but I wonder if Best Buy or one of the other big box stores will let you try lenses out? Worth a try....
01-05-2012, 06:18 PM   #10
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Odd thought but it has worked for others - have you tried taking the battery out and restarting from scratch? Also, does the battery have a good charge?
01-05-2012, 06:53 PM   #11
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QuoteOriginally posted by amc654 Quote
I wonder if Best Buy or one of the other big box stores will let you try lenses out? Worth a try....
Only for Nikon and Canon, most likely, unless you are in New York City :-(

Frankly, I would look for a K-x. K-r or similar used body in the Marketplace and bail from the K100DS. Lots of people are upgrading (like they do for every model) so decent bodies turn up from time to time.

Ditto for used a Tamron 28-75 lens, though I prefer the 17-70 range for a casual single-lens, i.e., "walk-around" option.
01-05-2012, 08:48 PM   #12
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QuoteQuote:
have you tried taking the battery out and restarting from scratch? Also, does the battery have a good charge?
Hmmm... now, that's a thought. I've not put fresh batteries in since this problem started. The batteries are maybe 2/3 depleted, but generally the only issue I have when battery power gets low is that the camera slows down and gets very obstinate in low lighting. But, I have a set of batteries charging now and will put them in tomorrow and see what happens. Thanks for the tip!

QuoteQuote:
I would look for a K-x. K-r or similar used body in the Marketplace and bail from the K100DS.
Well, I've been thinking about that--not because I don't like my K100DS, but because I DO like it so much! And after having it almost a year, I'm just now really starting to work up to potential (mine and the camera's....). I've recently gotten compliments from some colleagues on my "new & improved" photography. Not that it was terrible before, but here it's really starting to get better and something gives out. Murphy's law. I've been checking out the classifieds here for a k-x, but I really don't have the extra $$ at the moment. I saw a used K20D at a good price, but I don't think I'm "advanced" enough to use it! Eventually I'll move up a step. Which is, in a way, why I'd like to keep the K100DS going for a bit longer, then step up next time, instead of buying another "entry-level" unit, then upgrading again later. If I can determine that it's the lens and not the camera, I'll get a decent lens I can use on the next body. If, OTH, it's the camera, I'm not going to spend the $$ to get it fixed--not likely to be worth it. Then I'll have to see what I can find at a reasonable price.
01-17-2012, 06:37 AM   #13
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Did changing the batteries solve the problem?
01-17-2012, 07:56 AM   #14
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I find it very strange it says mf, you sure the camera is set to af?
01-17-2012, 08:05 AM   #15
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Thanks for following up, joebob and Anvh! The problem was the lens--the camera was indeed set to AF, changing the batteries didn't help, nor did cleaning the contacts or resetting the camera to default settings. So, I ordered a brand new DA II lens for it, and everything is working perfectly.

The old lens works beautifully as a manual-focus one; got some great shots out of it. But clearly there is something "broken" with its AF....
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