Pentax Ks2 Apperture control not working

imr · 11-05-2016, 11:08 AM

Hi All,

So i have a problem with my KS2 that seems to have started when i used an old Pentax A SMC 70-200 f4 lens

Apperture control in A was not working and all photos were coming black. Setting the apperture from apperture ring and using manual mode tehy came out as expected.

After this i used my Pentax A 50 (which was previously working properly) and the same thing happened!

Putting back the kit lens it has the same problem and seems to be stuck at max apperture

Any ideas on what could have failed? Optical preview seems to work correctly and lens stops down in manual mode

AldaCZ · 11-05-2016, 11:18 AM

hmm. a Dreaded aperture block fail? if you take multiple shots in the same setting in M are the the same exposure?

and waht is the Fstop at lcd? Isn't it F- ? or is the norrmal - ie Aperture what you select via a dial?

Update: Are the contacts clean?

imr · 11-05-2016, 11:26 AM

Quick update,

I fired several shots in burst mode with the kit lens on and the problem seems to got resolved.

Contacts seem to be clean, but since the 70-200 was in a relatively bad condition it could cause that

The f-stop was at the selected apperture, it was F- only when using the A50 lens without a setting

AldaCZ · 11-05-2016, 11:30 AM

Originally posted by imr

Quick update,

I fired several shots in burst mode with the kit lens on and the problem seems to got resolved.

Contacts seem to be clean, but since the 70-200 was in a relatively bad condition it could cause that

The f-stop was at the selected apperture, it was F- only when using the A50 lens without a setting

Try to set Live view and watch the aperture in the lens if it stops to the same settings..strange, How long/shots do you have on the body?

imr · 11-05-2016, 11:39 AM

Body only has around 3000 shots.

Tried several shots both with DAL 18-50 and A 50 and it seems everything is working correctly

Could the motor have failed/begins to fail?

If i remember correctly with live view, image in screen was visible, but shots were black too

Adam · 11-05-2016, 01:01 PM

Originally posted by imr

Body only has around 3000 shots.

Tried several shots both with DAL 18-50 and A 50 and it seems everything is working correctly

Could the motor have failed/begins to fail?

If i remember correctly with live view, image in screen was visible, but shots were black too

The fact that things returned to normal after shooting a bit in burst mode is indicative of aperture block failure, but if it doesn't happen again then maybe it was something else

If your camera is still under warranty, I would send it in before the warranty ends. If it's out of warranty and the issue resurfaces, I would still contact your local repair shop as sometimes they will do the repair for free outside of warranty (though usually not).

imr · 11-06-2016, 03:43 AM - **1 Like**

The problem came back today and again it resolved after a quick burst.

Seems i have to get it serviced, luckily it is still i warranty

11-05-2016, 11:08 AM	#1
imr New Member Join Date: Sep 2016 Posts: 23	Pentax Ks2 Apperture control not working Hi All, So i have a problem with my KS2 that seems to have started when i used an old Pentax A SMC 70-200 f4 lens Apperture control in A was not working and all photos were coming black. Setting the apperture from apperture ring and using manual mode tehy came out as expected. After this i used my Pentax A 50 (which was previously working properly) and the same thing happened! Putting back the kit lens it has the same problem and seems to be stuck at max apperture Any ideas on what could have failed? Optical preview seems to work correctly and lens stops down in manual mode

11-05-2016, 01:01 PM	#6
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Originally posted by imr Body only has around 3000 shots. Tried several shots both with DAL 18-50 and A 50 and it seems everything is working correctly Could the motor have failed/begins to fail? If i remember correctly with live view, image in screen was visible, but shots were black too The fact that things returned to normal after shooting a bit in burst mode is indicative of aperture block failure, but if it doesn't happen again then maybe it was something else If your camera is still under warranty, I would send it in before the warranty ends. If it's out of warranty and the issue resurfaces, I would still contact your local repair shop as sometimes they will do the repair for free outside of warranty (though usually not). Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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11-05-2016, 11:18 AM	#2
AldaCZ Veteran Member Join Date: Nov 2013 Location: North Bohemia Photos: Gallery Posts: 1,251	hmm. a Dreaded aperture block fail? if you take multiple shots in the same setting in M are the the same exposure? and waht is the Fstop at lcd? Isn't it F- ? or is the norrmal - ie Aperture what you select via a dial? Update: Are the contacts clean?

11-05-2016, 11:26 AM	#3
imr New Member Join Date: Sep 2016 Posts: 23 Original Poster	Quick update, I fired several shots in burst mode with the kit lens on and the problem seems to got resolved. Contacts seem to be clean, but since the 70-200 was in a relatively bad condition it could cause that The f-stop was at the selected apperture, it was F- only when using the A50 lens without a setting

11-05-2016, 11:30 AM	#4
AldaCZ Veteran Member Join Date: Nov 2013 Location: North Bohemia Photos: Gallery Posts: 1,251	Originally posted by imr Quick update, I fired several shots in burst mode with the kit lens on and the problem seems to got resolved. Contacts seem to be clean, but since the 70-200 was in a relatively bad condition it could cause that The f-stop was at the selected apperture, it was F- only when using the A50 lens without a setting Try to set Live view and watch the aperture in the lens if it stops to the same settings..strange, How long/shots do you have on the body?

11-05-2016, 11:39 AM	#5
imr New Member Join Date: Sep 2016 Posts: 23 Original Poster	Body only has around 3000 shots. Tried several shots both with DAL 18-50 and A 50 and it seems everything is working correctly Could the motor have failed/begins to fail? If i remember correctly with live view, image in screen was visible, but shots were black too

11-06-2016, 03:43 AM - 1 Like	#7
imr New Member Join Date: Sep 2016 Posts: 23 Original Poster	The problem came back today and again it resolved after a quick burst. Seems i have to get it serviced, luckily it is still i warranty

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