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05-09-2019, 08:44 AM   #1
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DA 300 mm with screw drive AF, Camera doesn`t detect focus length

Hi,
I got a DA 300 mm f4 which has been changed to screw drive AF. The Cameras (KP, K01) don`t detect the right focus length. The KP detects 42 mm, the K01 27 mm. KP overexposes around 2 stops, the K01 underexposes around 1 stop. It reads the aperture with 1 stop to wide open.. Does anyone have an idea about what can be done about this ?


Last edited by SME; 05-09-2019 at 10:44 AM.
05-09-2019, 09:01 AM   #2
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Have you tried to clean the contacts?
05-09-2019, 09:06 AM   #3
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is this a new problem or has this lens always had this issue?
05-09-2019, 09:11 AM   #4
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well, I just bought it. It was used on a KP without any issues (as has been told), and the seller confirms that the contact worked well on his camera. The price was heavily reduced due to the change in AF mode. The optics itself appear flawless.

05-09-2019, 11:32 AM   #5
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It should not overexpose by 2 stops, even if the FL is being misinterpreted as 42mm. In an AE mode, it would set a lower shutter speed, but also an appropriate aperture to match for the lighting at hand.

What other lenses do you have, and do they function normally?
05-09-2019, 11:56 AM   #6
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Yes, the other lenses function normal. I just found out, that the underexposure on the K01 is not consistent, sometimes it exposes correctly, but it never reads the 300mm and ir reads aperture down til 2,8, though it`s a 4,0 lens.. My KP is with my girl friend at the moment, so I cant doublecheck right now..

Last edited by SME; 05-09-2019 at 12:09 PM.
05-09-2019, 12:16 PM   #7
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Sounds like either a problem with the lens contacts. It could be a problem with the internal electronics also. Double check that the contacts are clean.
05-09-2019, 12:20 PM   #8
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QuoteOriginally posted by UncleVanya Quote
Sounds like either a problem with the lens contacts. It could be a problem with the internal electronics also. Double check that the contacts are clean.
yes, they are clean, and all other lenses connect fine

05-09-2019, 12:22 PM   #9
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QuoteOriginally posted by SME Quote
yes, they are clean, and all other lenses connect fine
Then I'd guess the lens internal electronics are damaged.
05-09-2019, 12:36 PM   #10
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QuoteOriginally posted by manishved Quote
Have you tried to clean the contacts?
yes, they seem fine

---------- Post added 05-09-19 at 09:42 PM ----------

QuoteOriginally posted by UncleVanya Quote
Then I'd guess the lens internal electronics are damaged.
Do you have any advice who can check this ?
05-09-2019, 12:49 PM   #11
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If I were you I would return the lens.
05-09-2019, 12:51 PM   #12
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QuoteOriginally posted by pschlute Quote
If I were you I would return the lens.
got it for 250 EUR; would you still return it ?

Last edited by SME; 05-09-2019 at 12:57 PM.
05-09-2019, 01:01 PM   #13
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QuoteOriginally posted by SME Quote
got it for 250 EUR; would you still return it ?
I would without hesitation pay 250 EUR/280 USD for that lens as you've described it. However, if the seller did not describe this condition accurately then I would seek some sort of compensation.
05-09-2019, 01:04 PM   #14
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QuoteOriginally posted by SME Quote
got it for 250 EUR; would you still return it ?
It has been converted to screwdrive by someone who I do not know; it does not report correct focal length; it does not expose correctly; and it reports incorrect aperture.....yes I would return it.
05-09-2019, 01:38 PM - 1 Like   #15
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Since the lens doesn't have an aperture ring, problems with exposure will probably cause you a lot of headaches later down the road. Despite the low price, I would either seek compensation or return it. One option would be to get it repaired. Even then you'd be getting a great deal!

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