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12-11-2010, 11:58 PM   #1
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DA 40 Diaphragm Blade Problem? (Update) :(

While I was testing my new lenses (shooting focus and sharpness charts) I noticed something with my DA 40 Limited.

While looking at the lens off the camera, I noticed that the diaphragm, while fully closed, didn't make a circle. One of the blades is not fully closing, so instead of a complete circle, there is a circle with a point at one end.

I didn't think this was right, so I manually opened the diaphragm while looking at the lens and the diaphragm blades open somewhat erratically, not in a smooth motion like I'd expect.

The aperture doesn't stay in the center of the lens while opening the diaphragm, it moves around when opening and closing the blades.

Is this normal, or do I have a defective unit?

It seems like they should all open and close at once so that the aperture would remain in the center of the lens.

I checked all my other lenses and none seem to have this problem.

Do any of you guys/gals have a DA 40 that does the same thing?


Last edited by Colorado CJ; 12-24-2010 at 11:41 AM.
12-12-2010, 10:31 AM   #2
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Just checked mine and I don't seem to have the same problem.
12-12-2010, 10:37 AM   #3
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Mine has no such problem.
12-12-2010, 10:38 AM   #4
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QuoteOriginally posted by Colorado CJ Quote
Is this normal, or do I have a defective unit?
Sounds defective.

12-12-2010, 12:12 PM   #5
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can you make a picture of it?

thanks
12-12-2010, 01:18 PM   #6
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Here is a couple of pictures. I also noticed that the aperture doesn't start opening until the lever is moved over 1/8", they just "wiggle" around a little.

Not to mention the 10 or so pieces of dust/particles on the inside elements. Looks like I'll have to send this one back




12-12-2010, 01:26 PM   #7
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and this is a brand new limited lens ?

well...
12-12-2010, 01:29 PM   #8
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Yes, brand new. Just received it 8 days ago.

12-12-2010, 01:32 PM   #9
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this fact kinda scares me, cause i've just bought a 40mm and the person is receiving it in us is coming home (to Europe) for Christmas...

i just hope mine doesn't have this defect... it would be a pain the ... to have it shipped back to us...
12-12-2010, 01:33 PM   #10
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QuoteOriginally posted by Colorado CJ Quote
Yes, brand new. Just received it 8 days ago.
time to return it IMO!
This doesn't look OK, I've seen irregular apertures which didn't make full circle but kind of oval instead, but this definitely doesn't look OK

my 2p
12-12-2010, 01:36 PM   #11
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it would be nice if someone else, having a 40mm, would post a picture showing it's blade on same aperture.
12-12-2010, 03:14 PM   #12
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My DFA100 sort of has an irregular aperture when I manually actuate the lever, mostly at 1-2 stops down from wide open but not so different from this lens when all the way down... Doesn't seem to make for weird bokeh or metering issues so I'm not too concerned. Mostly I shoot wide open or stopped down to f8 or f11. I bought it used for a great price so I'm okay with it not being perfect, don't have the original receipt so I can't even consider warranty. Might take it apart and see what the deal is if it ever bothers me.
12-12-2010, 03:51 PM   #13
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QuoteOriginally posted by greymda Quote
this fact kinda scares me, cause i've just bought a 40mm and the person is receiving it in us is coming home (to Europe) for Christmas...

i just hope mine doesn't have this defect... it would be a pain the ... to have it shipped back to us...
I wouldn't be too worried. This is probably an isolated incident.
12-13-2010, 06:08 AM   #14
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QuoteOriginally posted by PrimeObjectif Quote
I wouldn't be too worried. This is probably an isolated incident.
i really hope so. thanks.
12-13-2010, 06:20 AM   #15
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I see many many times diaphrams that do not retain the symmetrical shape at minimum aperture

Although I have not catalogued my 30+ lenses, I know at least 3 do not have all the blades close down perfectly, including an SMC 50F1.4 and a couple of rikenons. None have ever failed because of it. I have also seen evidence of the same in posts by others where they have imperfect Bokeh, around bright lights and flare.

You may wish to contact pentax and ask if this is something to worry about, and make sure you have both the origonal contact, and their response in writing, just in case something does develop later, you have a record of the first complaint, which will set the time the issue was noticed to within the warranty.
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