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04-29-2020, 05:04 PM   #1
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K-70 and pentax DA 18 - 135 mm diaphragm problem

Hello everyone!
I have a Pentax K-70 that i bought new with a Pentax DA 18 - 135 mm lens a year ago and, until yesterday, it was working fine. yesterday i bought a Pentax smc-M f2 lens, put it in the camera and take some photos, after that i put again the 18 - 135 mm lens and since that moment no matter what i try the diaphragm is only shooting at max aperture with this lens (if i manually move the bayonet open and close normaly) , so i put another lens that i have to try (Tamron 70-300 Di macro) and with this lens works fine, shoots OK in every f stop, since the tamron lens has a spring in the diaphragm and the 18-135 has no spring to close it maybe the issue has something related to the body actuator, i was closely carefully looking the diaphragm actuator in the body and comparing with photos from internet and i donīt see anything wrong.

Any suggestion would be really helpful

Thanks, Axel.

---------- Post added 04-29-20 at 05:17 PM ----------

QuoteOriginally posted by SADCritical Quote
Hello everyone!
I have a Pentax K-70 that i bought new with a Pentax DA 18 - 135 mm lens a year ago and, until yesterday, it was working fine. yesterday i bought a Pentax smc-M f2 lens, put it in the camera and take some photos, after that i put again the 18 - 135 mm lens and since that moment no matter what i try the diaphragm is only shooting at max aperture with this lens (if i manually move the bayonet open and close normaly) , so i put another lens that i have to try (Tamron 70-300 Di macro) and with this lens works fine, shoots OK in every f stop, since the tamron lens has a spring in the diaphragm and the 18-135 has no spring to close it maybe the issue has something related to the body actuator, i was closely carefully looking the diaphragm actuator in the body and comparing with photos from internet and i donīt see anything wrong.

Any suggestion would be really helpful

Thanks, Axel.
I want to add that if i shoot without any lens or if i put the clean sensor in options the actuator moves and seems OK

04-29-2020, 05:19 PM   #2
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Might seem too simple but the first thing to try is to carefully clean the contacts on both the lens and camera mount. A clean microfiber cloth works fine. Just buff them a bit. If that works, great. If not hopefully someone else can help more.
04-29-2020, 05:46 PM - 1 Like   #3
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Welcome to the Pentax Forums!

QuoteOriginally posted by SADCritical Quote
the 18-135 has no spring to close it
The Pentax-DA 18-135/3.5-5.6 does have springs to close the aperture and should be fully stopped down when not mounted to the camera the same as with your Tamron lens. If this is not true, the aperture mechanism in the lens may be defective or has been damaged.


Steve
04-29-2020, 05:50 PM   #4
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QuoteOriginally posted by SADCritical Quote
Hello everyone!
I have a Pentax K-70 that i bought new with a Pentax DA 18 - 135 mm lens a year ago and, until yesterday, it was working fine. yesterday i bought a Pentax smc-M f2 lens, put it in the camera and take some photos, after that i put again the 18 - 135 mm lens and since that moment no matter what i try the diaphragm is only shooting at max aperture with this lens (if i manually move the bayonet open and close normaly) , so i put another lens that i have to try (Tamron 70-300 Di macro) and with this lens works fine, shoots OK in every f stop, since the tamron lens has a spring in the diaphragm and the 18-135 has no spring to close it maybe the issue has something related to the body actuator, i was closely carefully looking the diaphragm actuator in the body and comparing with photos from internet and i donīt see anything wrong.

Any suggestion would be really helpful

Thanks, Axel.

---------- Post added 04-29-20 at 05:17 PM ----------



I want to add that if i shoot without any lens or if i put the clean sensor in options the actuator moves and seems OK
I have the 18-135 and the aperture is spring driven and should stop down when not installed on camera, when moving the aperture actuator there should be some "SPRING" action!

If not I would think it is either stuck or broken, possibly bent when installing it on body?

Stevebrot beat me to it!

04-29-2020, 06:01 PM   #5
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QuoteOriginally posted by SharkyCA Quote
I have the 18-135 and the aperture is spring driven and should stop down when not installed on camera, when moving the aperture actuator there should be some "SPRING" action!

If not I would think it is either stuck or broken, possibly bent when installing it on body?

Stevebrot beat me to it!
Wow, thank you so much for this i was unsure if i was normal, i am sure that the bayonet was loose from the very first day, but i was already thinking in opening the lens, and now i will have to.
thanks again i will post again if this resolves the problem.
04-29-2020, 06:14 PM   #6
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QuoteOriginally posted by SADCritical Quote
i am sure that the bayonet was loose
Whenever you buy a new lens, if upon examination you find any apparent abnormality, be sure to contact the seller regarding an exchange for another new one!
04-29-2020, 07:07 PM   #7
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QuoteOriginally posted by mikesbike Quote
Whenever you buy a new lens, if upon examination you find any apparent abnormality, be sure to contact the seller regarding an exchange for another new one!
Now i remember that it was not always loose
04-29-2020, 07:11 PM - 6 Likes   #8
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Original Poster
QuoteOriginally posted by SharkyCA Quote
I have the 18-135 and the aperture is spring driven and should stop down when not installed on camera, when moving the aperture actuator there should be some "SPRING" action!

If not I would think it is either stuck or broken, possibly bent when installing it on body?

Stevebrot beat me to it!
I already fixed, i open the lens and the spring was loose, so i just put it were belongs and close the lens, and now is fully functional again!
I use this video as tutorial (
)

Thanks everyone!!!

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