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10-16-2009, 04:17 PM   #1
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My FA-50mm f/1.4 just fell apart in my hands

I'm planning to take some informal pictures of a friend's dance performance Sat night. In sorting out which lenses to take with my K10D, the FA 35 f/2 and FA 50 f/1.4 come to mind due to the low light scenario.

I've never done any theater or concert shooting, so I put the FA 35 on the K10D to test autofocus in low light. Everything works just fine.

I do the same with the FA 50 and notice it's not autofocusing to infinity. Not even close. So I switch to manual focus, turn the focus ring a bit, and hear a very slight, light scraping sound. Concerned, I remove the K10D from my eye, tilt the camera a bit so I have a better view of the lens and listen of the sound as I very slowly and gently rotate the focus ring, and...the bulk of the lens falls off into my hand. The mount and outer shell remain attached to the K10D, but the rest of the lens is now resting comfortably in my hand.

Never whacked, smacked, or dropped it since I got it 19 months ago. Never even used manual focus before. I've used it strictly with AF and cared for it very well.

WTF! Of course, it's out of warranty (by about 7 mos). And, wouldn't you know, the price has more than doubled since I bought mine new. Hmph!

I've attached a few pictures (sorry for the poor lighting / shallow DOF). The last picture shows four pairs of needle-y thingies, the top and bottom of which are bent to hell and seem like the culprit of the scraping sound I heard. Looks to me like these needles line up with the screw drive, so perhaps the screw drive mangled them. (How, I haven't the foggiest idea.) I'm having difficult visualizing how the gear in the shell (not pictured), driven by the body screwdrive, interfaces with this section of the lens. (Of course, I'm only assuming these components interface, from a rough look at how things line up if I visualize putting it back together.)

And I still can't tell, just from looking at it, how it plum fall apart. Don't see any missing screws, on first look.

I figure I'll contact Pentax USA to find out how much a repair will cost. Based on a quick search here on PF, I may contact Eric Hendrickson, too, and/or one of the other repair shops in the External Links area to see if he/they are willing to work on it.

So, the inevitable questions:
  • Anyone ever experience something like this with an FA 50 f/1.4 before? (I found one thread where someone had a similar experience with DA 40.)
  • Any recommendations how, or with whom, to proceed for repair?
  • Anyone have a line on a new or excellent condition FA 50 f/1.4 for <= $200?
  • Anyone have an FA 50 f/1.4 I may borrow in the Chicago area?


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10-18-2009, 09:47 AM   #2
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Pic #3...at 12 o'clock...is that notch supposed to be there?

Pic #5...those "needles" are there to provide an electrical connection. My Adaptall mounts with the A option also have some of these to provide aperture info to the lens.

As for why it fell apart...not sure :/ Depends if that notch in pic 3 is supposed to be there or not. Initially, it seems that the front part of the lens may have had excess pressure on it that possibly caused the helicoid to skip a thread...and from there...was able to unscrew itself.

Or something like that.

Were there any rattles inside? Did anything fall to the floor? Anything that looks out-of-round or bent?
10-18-2009, 04:09 PM   #3
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Wow...I don't think that notch in the 3rd picture at 12 o'clock belongs there...looks like the plastic ring cracked and I'm sure Pentax would probably claim you dropped it :-P
Send it in and see if they can fix it...
10-18-2009, 04:14 PM   #4
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Crimey, mate--that bites!

10-18-2009, 04:22 PM   #5
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Never seen or heard anything like that.
Nothing happened for it to have fallen apart like that? Very strange.
That chip referred to before does look suspicious.
No other loose connections anywhere?
Hope it works out for you.
10-18-2009, 08:00 PM   #6
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Thanks for the comments, everyone. A few responses and a couple extra pics, for reference...

QuoteOriginally posted by ryan s Quote
Pic #3...at 12 o'clock...is that notch supposed to be there?
Looks like it's supposed to be there to me. Based on the comments, and my review of the previously posted pictures, I think original picture #3 is perhaps a bit misleading. It perhaps looks as though the notch is in the plastic ring around the rear lens element. It is not. The notch is part of the metal helicoid. Upon close inspection, it's very smooth & flat, no marks of any kind, no debris, no wear, no broken / leftover bits to be found anywhere (and if the notch did break off, that's a big honkin' chunk of metal to have floating around inside the lens...I surely would've heard it, felt it, and seen it when the lens fell apart). I've attached a couple close-ups of the notch for reference.

QuoteOriginally posted by ryan s Quote
Pic #5...those "needles" are there to provide an electrical connection. My Adaptall mounts with the A option also have some of these to provide aperture info to the lens.
Thanks for the clarification...I was wondering about those needles. This is really the only damage I see to the lens, and the needles / contacts look easily replaced -- just a couple screws to drop in the new plate + needles. I'm tempted to put it back together myself, but I'm at a loss for how the lens as a whole holds together once the shell and core are slotted back together.

QuoteOriginally posted by ryan s Quote
Were there any rattles inside? Did anything fall to the floor? Anything that looks out-of-round or bent?
That's what's so mystifying to me. No rattles, no loose bits or debris, nothing fell onto the floor or into my hand, no loose or missing screws, no interior signs of stress or wear (aside from the bent needles/contacts). I have zero technical knowledge of lens design and manufacture, so maybe one or more of these signs exist and I'm not seeing it. But I've looked it over quite carefully and don't see anything unusual.

QuoteOriginally posted by ryan s Quote
As for why it fell apart...not sure :/ Depends if that notch in pic 3 is supposed to be there or not. Initially, it seems that the front part of the lens may have had excess pressure on it that possibly caused the helicoid to skip a thread...and from there...was able to unscrew itself.

Or something like that.
I've been wracking my brain trying to determine if I could've stressed it in any way...and coming up completely blank. Perhaps I stressed it and simply didn't realize it. I'm pretty careful with my gear, though. At any rate, I'm going to ring Pentax customer service and a repair shop or two this week and see if any of them are willing to take a look at it.

Thanks for the comments, everyone.
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10-18-2009, 10:53 PM   #7
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So back to square one...
No evidence of it fraying at the seams or being loose prior to falling apart?
Very odd.
10-19-2009, 03:34 AM   #8
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When I look through the images, I would guess, that simply the stop screw, which normally prevents you from turning the helicoid until the counterpart falls off, has been missing. May be, it was never screwed into place. After assembly the lens would probably perform correctly in AF mode, until one day, you involuntarily and unknowingly turned the helicoid manually (simply placing it in a photo bag and wiggling it a bit, could do that). That would then explain, why then recently the AF would not focus on infinity. When you then tried to focus manually, you srewed the front part out of the helicoid. Looks to me like a production fault - but that would be near impossible to prove.
On the other hand, it looks like an easy repair.
Ben

10-19-2009, 04:30 AM   #9
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Someone on a Chinese Photography forum had exactly the same experience:


My God!, My FA50/1.4 Broke to Two Parts


On the third page someone (who is a very capable lens/camera repair guy, for a hobby) fixed the lens, seems not so easy though. I think the lens needs some professional service.

Good luck.
10-19-2009, 04:31 AM   #10
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Someone on a Chinese Photography forum had exactly the same experience:


My God!, My FA50/1.4 Broke to Two Parts


On the third page someone (who is a very capable lens/camera repair guy, for hobby) fixed the lens, seems not so easy. I think the lens needs some professional service.

Good luck.
10-19-2009, 06:41 AM   #11
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QuoteOriginally posted by Ben_Edict Quote
I would guess, that simply the stop screw, which normally prevents you from turning the helicoid until the counterpart falls off, has been missing.
Please forgive my ignorance, Ben. I know you're guessing and working with limited information and limited images. When you say "top screw", I'm having difficulty visualizing where, exactly, this screw might (should?) reside. Could you please provide some guidance on where this "top screw" might be positioned?

QuoteOriginally posted by frank Quote
On the third page someone (who is a very capable lens/camera repair guy, for hobby) fixed the lens, seems not so easy. I think the lens needs some professional service.
Hmmmm...interesting! Thanks for the link, Frank. I don't really harbor any confidence in fixing it myself. Definitely pursuing professional service, if only for peace of mind and proper calibration (assuming it's fixable).
10-19-2009, 08:00 AM   #12
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QuoteOriginally posted by thirdofthree Quote
Please forgive my ignorance, Ben. I know you're guessing and working with limited information and limited images. When you say "top screw", I'm having difficulty visualizing where, exactly, this screw might (should?) reside. Could you please provide some guidance on where this "top screw" might be positioned?.
I never disassembled an AF lens, only manual lenses, so I only have a vague idea. There needs to be some kind of stop to prevent the helicoid to come apart, as it is an opend ended thread. This could be a simple screw or a more elaborated arrester. In manual focus lenses sometimes the screws under the rubber on the focusing rinf serve the purpose.

Ben
10-20-2009, 09:44 AM   #13
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From the thread Frank linked to:



My guess is that little guy went missing...
10-20-2009, 11:27 AM   #14
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QuoteOriginally posted by ryan s Quote
From the thread Frank linked to:

http://www7.xitek.com/forum/200901/456/45633/45633_1231256186.jpg
(IMG tags removed since target site prevents hotlinking)

My guess is that little guy went missing...
Nope, all three of these screws are in place. It's tough to tell from the pictures, but there are three main outer shells surrounding the helicoid / glass (sorry, I don't know the proper terminology; see attached). From outer (top) to inner (bottom): the mount / aperture / focus distance "window" shell (the one that fell off in my case), the focus ring shell, and the front lens element shell. The screw you note (circled, of which there are three) secures the innermost, front lens element shell to the helicoid / glass.

For reference (see attached), the helicoid / glass is secured in the focus ring shell by two components: the focus ring shell itself has an interior metal ring (arrow), and two arrestors are attached to the helicoid with two screws each (ellipses).

I think the outer shell is also secured by the arrestors ellipsed in the attachment. There are two slots in the outer shell (see attached, rectangles) into which the top end of the arrestors fit. But I can't figure out how they're secured, once slotted. I'd have to disassemble the outer shell to find out, and I'd rather put it in the hands of a pro.

Speaking of pros, and on a positive note: Eric indicates he's seen this problem before and he's willing to take a look at it. One potential issue: he hasn't sourced the brushes (what I called needles/contacts) in a while, so isn't positive of their availbility. Fingers crossed!
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10-20-2009, 02:21 PM   #15
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The 2 "arrestors"(helicoid guide plates) were put in placed from the rear w/o the lens mount. That means to assemble it probably, the arrestors, the mount & the aperture ring should be removed and then put back again with specific steps. The cause I could see, is probably those 2 arrestors were not pushed outward when tightened, or not tightened enough, that leaves a big enough gap for them to escape the rail. Being unable to focus at infintiy was the 1st sign of problem as the front group was slowly unscrewing itself. If you tried to diy, the only concern is that the very fragile contact brush (detects the distance) might be damaged already, but the Pentax parts department should have plenty to supply.
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