Pentax 24-70 lens problem with extreme clipping to the right

k2parn · 08-10-2019, 08:07 PM

The last few weeks my Pentax 24-70 clips extremely to the right with any setting higher than 5.6 aperture even at exposure compensation at -5, and ISO 100. I have a k1, and other Pentax lenses that I have tried on the K1 with no problems so I've narrowed it down to the 24-70.

stevebrot · 08-10-2019, 08:27 PM

Originally posted by k2parn

Pentax 24-70 lens problem with extreme clipping to the right

Lenses don't clip, though they might have a lazy or sticky aperture mechanism. With the lens off the camera, examine the aperture opening while operating the aperture actuator lever by hand, first by flicking from its smallest opening and then by releasing from its wide open position. In both cases the action should be snappy without hesitation.

Question: What exposure mode is this happening in and what meter configuration (matrix, center-weighted, or spot) are you using?

Steve

Sandy Hancock · 08-10-2019, 10:31 PM

Please post some sample images with EXIF details included.

**Rondec** · 08-11-2019, 02:32 AM

As Steve says, lenses don't clip. They can have sticky aperture blades or be decentered, but post some images that show the problem.

k2parn · 08-11-2019, 03:35 AM

Originally posted by k2parn

The last few weeks my Pentax 24-70 clips extremely to the right with any setting higher than 5.6 aperture even at exposure compensation at -5, and ISO 100. I have a k1, and other Pentax lenses that I have tried on the K1 with no problems so I've narrowed it down to the 24-70.

The first image settings were ISO 140, F/8, 1/180 at 24mm
The second image settings were ISO 200, F/16, 1/160 at 70mm
They were taken in aperture priority, and matrix metering,
I'm planning to check for sticky aperture blades later today, and I appreciate the help.

Sandy Hancock · 08-11-2019, 04:35 AM

It's interesting that the EXIF for the second image, which is of course dramatically overexposed, does not include anything about exposure bias, while the first one does (-0.5EV).

I tend to use centre weighted metering, and expose for the brighter parts of the image. I'd much rather push shadows than pull highlights. These are rather extreme though, so I'd be interested to learn of your results checking the aperture.

**Rondec** · 08-11-2019, 05:49 AM

The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience).

StephenHampshire · 08-11-2019, 05:59 AM

Originally posted by Rondec

The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience).

Sticky apertures do not stop down enough and therefore overexpose - so this could well be the problem, as others have said

RonHendriks1966 · 08-11-2019, 06:06 AM

Clean the contact on the lens mount.

k2parn · 08-11-2019, 06:57 AM

Well, I think I have discovered the issue because when I checked the aperture blades with the lens off, the aperture blades do not close automatically any more except manually so my 3 year old lens needs repair it looks like. Thank you for helping find the culprit!

stevebrot · 08-11-2019, 01:49 PM

Originally posted by Rondec

The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience).

The EXIF indicates a reasonable metered EV. I suspect a problem with the lens aperture mechanism or the camera is failing to stop down the lens for the exposure.

Steve

stevebrot · 08-11-2019, 01:51 PM

Originally posted by k2parn

Well, I think I have discovered the issue because when I checked the aperture blades with the lens off, the aperture blades do not close automatically any more except manually so my 3 year old lens needs repair it looks like. Thank you for helping find the culprit!

Are you saying that it does not stop down when the lens is attached to the camera?

Steve

k2parn · 08-13-2019, 02:04 PM

Yes, the aperture blades do not open or close manually, and I can only get images at 5.6 or larger without being totally blown out, so I shipped it off for repair yesterday.

08-10-2019, 08:07 PM	#1
k2parn Junior Member Join Date: Aug 2016 Location: Concord, New Hampshire Photos: Gallery Posts: 46	Pentax 24-70 lens problem with extreme clipping to the right The last few weeks my Pentax 24-70 clips extremely to the right with any setting higher than 5.6 aperture even at exposure compensation at -5, and ISO 100. I have a k1, and other Pentax lenses that I have tried on the K1 with no problems so I've narrowed it down to the 24-70.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Undies,Histograms,Reds,and Clipping.	GUB	Photographic Technique	26	05-23-2019 02:30 AM
Help! Clipping in bright lighting conditions	Pheo	Pentax K-30 & K-50	2	12-29-2012 11:16 PM
about Pentax KX highlight clipping	RayJayR	Pentax DSLR Discussion	2	12-31-2010 01:33 PM
Pentax K-x single channel clipping	gaeriel	Pentax DSLR Discussion	8	09-20-2010 02:27 AM
Clipping on CS3	netuser	Digital Processing, Software, and Printing	4	12-23-2009 08:24 AM

08-10-2019, 08:27 PM	#2
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by k2parn Pentax 24-70 lens problem with extreme clipping to the right Lenses don't clip, though they might have a lazy or sticky aperture mechanism. With the lens off the camera, examine the aperture opening while operating the aperture actuator lever by hand, first by flicking from its smallest opening and then by releasing from its wide open position. In both cases the action should be snappy without hesitation. Question: What exposure mode is this happening in and what meter configuration (matrix, center-weighted, or spot) are you using? Steve

08-10-2019, 10:31 PM	#3
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,275	Please post some sample images with EXIF details included.

08-11-2019, 02:32 AM	#4
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,662	As Steve says, lenses don't clip. They can have sticky aperture blades or be decentered, but post some images that show the problem.

08-11-2019, 04:35 AM	#6
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,275	It's interesting that the EXIF for the second image, which is of course dramatically overexposed, does not include anything about exposure bias, while the first one does (-0.5EV). I tend to use centre weighted metering, and expose for the brighter parts of the image. I'd much rather push shadows than pull highlights. These are rather extreme though, so I'd be interested to learn of your results checking the aperture.

08-11-2019, 05:49 AM	#7
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,662	The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience).

08-11-2019, 05:59 AM	#8
StephenHampshire Veteran Member Join Date: Oct 2009 Location: Winchester Photos: Gallery \| Albums Posts: 2,523	Originally posted by Rondec The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience). Sticky apertures do not stop down enough and therefore overexpose - so this could well be the problem, as others have said

08-11-2019, 06:06 AM	#9
RonHendriks1966 Banned Join Date: Jan 2009 Photos: Gallery Posts: 9,675	Clean the contact on the lens mount.

08-11-2019, 06:57 AM	#10
k2parn Junior Member Join Date: Aug 2016 Location: Concord, New Hampshire Photos: Gallery Posts: 46 Original Poster	Well, I think I have discovered the issue because when I checked the aperture blades with the lens off, the aperture blades do not close automatically any more except manually so my 3 year old lens needs repair it looks like. Thank you for helping find the culprit!

08-11-2019, 01:49 PM	#11
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Rondec The camera is way over exposing for the situation. Not sure why that is, but maybe some problem with the aperture mechanism (although that typically gives darker images in my experience). The EXIF indicates a reasonable metered EV. I suspect a problem with the lens aperture mechanism or the camera is failing to stop down the lens for the exposure. Steve

08-11-2019, 01:51 PM	#12
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by k2parn Well, I think I have discovered the issue because when I checked the aperture blades with the lens off, the aperture blades do not close automatically any more except manually so my 3 year old lens needs repair it looks like. Thank you for helping find the culprit! Are you saying that it does not stop down when the lens is attached to the camera? Steve

08-13-2019, 02:04 PM	#13
k2parn Junior Member Join Date: Aug 2016 Location: Concord, New Hampshire Photos: Gallery Posts: 46 Original Poster	Yes, the aperture blades do not open or close manually, and I can only get images at 5.6 or larger without being totally blown out, so I shipped it off for repair yesterday.