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Old Apr 20, 2007, 10:18 PM   #1
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I finally got around to updating the firmware in my K100d as I bought a 4 gig SD card. Immediately after this I found that my F 50mm f1.7 lens is badly overexposing shots. The first time it happened I wrote it off to odd conditions. But I was taking pics yesterday and found that the problem went away as soon as I switched to the kit lens and came back with the F 50mm. This is not acceptable to me, that is probably my favorite lens. My suspicion is that the firmware is responsible but I can't find anyone else posting about a similar problem online.

Anyhow, here are some examples. I was in Av mode, set to f 6.3 and the camera chose 1/200.
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Old Apr 20, 2007, 10:19 PM   #2
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Same conditions only this time I was at f8.0.

The lens seemed to meter fine indoors at f 1.7 but outdoors it was awful. Any thoughts on what could be causing this?
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Old Apr 20, 2007, 10:25 PM   #3
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Ugh, well after typing out the symptoms a possible cause occurred to me. After examining the lens off of the body I find that the aperture blades are sticking. This really sucks, I got the lens second hand in a pawn shop but it was brand new. Has anyone ever sent a lens to Pentax for repair, do you know if they are reasonable?

Tim
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Old Apr 21, 2007, 1:03 AM   #4
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I was going to suggest oil on the aperture blades, but you beat me to it. I have a Kiron lens that's like that, I can only use it reliably wide open.

I talked to my local camera shop that has a repair department (though I think they contract the work out to someone else) about repairing it. It would cost somewhere around $75.00, all labor and that's not worth it (the going rate for the 80-200 is less than that on ebay, when they turn up). So I have a nice paperweight at the moment.

Good luck with your situation.
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Old Apr 21, 2007, 3:28 AM   #5
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Yeah out of warranty... you are talking a good chunk of its worth... maybe even as much if as you say gotten used.

Did you check it out well when you first got it? (and buy from someone with at least minimaly return policy if not cheap)... unfortunate but true, maybe the seller saw that situation coming on, and dumped it before blatantly obvious.




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Old Apr 21, 2007, 3:46 AM   #6
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NonEntity1 wrote:
Quote:
Ugh, well after typing out the symptoms a possible cause occurred to me.* After examining the lens off of the body I find that the aperture blades are sticking.* This really sucks, I got the lens second hand in a pawn shop but it was brand new.* Has anyone ever sent a lens to Pentax for repair, do you know if they are reasonable?

Tim
Tim,

Gee what a pity. The lens has been discontinued for maybe 10 yrs at least if not 15. It was the stock lens for SF1 film camera first came out in 89.
You meant it looked brand new?

Daniel, Toronto
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Old Apr 21, 2007, 7:16 AM   #7
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I bought this lens at a local pawnshop. It was still in the box with the manual, warranty cards etc and looked brand new to me. This was back in September and I have used the lens regularly since then, it is ALWAYS in my bag. So whatever is the cause of the aperture blades not working has only happened very recently.

I also have some Kiron lenses withoily aperture blades. I had never heard of the problem with Pentax lenses or AF lenses before. The lever feels diferent than the oily lenses, though, and I wonder if a spring inside might have broken.

In any case, I appreciate the sympathy. Keh's online quote to fix it is $134. Pentax has "most F series lenses" on the list of equipment they no longer service. I have an inquiry submitted to another company, we will have to see.It is a good thingI still have the A 50mm f 1.7, because I am leaving this morning for St Augustine and was really counting on that lens for the interior shots.

Tim
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Old Apr 21, 2007, 7:44 AM   #8
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Sorry to hear about your loss... Hope you find someone who can fix it cheap enough to keep it.

OT: Love the strobes in the front of the 'Stang. In SCI think there is a limit on the number of strobes in/on an officer's personal car, so you don't see much like that around here.
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Old Apr 21, 2007, 8:28 AM   #9
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It is actually a patrol vehicle, it is just so blown out you can't see the paint scheme, roof lights,or emblems on the door. Actually in FL there is no authorization to put emergency equipment on a personal vehicle for law enforcement. Volunteer fireman can have red lights and siren. I can't imagine even wanting that stuff on my own vehicle, though it would be unique to seemy Oldsmobile mini-van running code 3 :-).

Tim
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Old Apr 22, 2007, 6:47 PM   #10
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It is always hard to lose a favorite lens, but if not unique there are plenty of others out there to replace it. Lubricantscan deteriorate with age, but if this happened suddently after working well for any length of time, I can't help but wonder if you didn't leave your bag in the sun or in a hot car - I grew up in Florida and know how hot a car can get. It doesn't take long to liquify grease at high temperatures, which could then bleed out from the bearings at the base of the blades and slow their operation.
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