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rweissman · 07-10-2016, 11:03 PM

On my two year old 645Z (has worked flawlessly until now) I appear to have lost the ability to switch to any mode other than AV or M (or X or bulb). The last time this happened, turning on auto ISO (Green button and ISO pressed together) fixed the problem. Doing this now does not fix the problem (though it does switch on Auto ISO). Every mode except X, M and Bulb shows "Aperture Priority." What am I (stupidly) doing wrong? Or is my camera's firmware somehow corrupted?

TheDocAUS · 07-10-2016, 11:05 PM

I would suggest a factory reset as a starting point. Let us know if that helps or not.

Adam · 07-10-2016, 11:24 PM

Originally posted by rweissman

On my two year old 645Z (has worked flawlessly until now) I appear to have lost the ability to switch to any mode other than AV or M (or X or bulb). The last time this happened, turning on auto ISO (Green button and ISO pressed together) fixed the problem. Doing this now does not fix the problem (though it does switch on Auto ISO). Every mode except X, M and Bulb shows "Aperture Priority." What am I (stupidly) doing wrong? Or is my camera's firmware somehow corrupted?

This could also happen due to loss of communication with the lens. Try cleaning the camera and lens mount, and trying a different lens.

rweissman · 07-10-2016, 11:37 PM

I just reset to factory defaults, but that did not solve the problem. The mode dial settings SV, TV, TAV all trigger AV. The mode does not change except for moving between AV, X, M, Bulb.

**Wild Mark** · 07-10-2016, 11:41 PM

This happened to me on my K5 - exact same issue. Never resolved it. I now use this lens in X mode for macro - grrrrr

---------- Post added 07-11-16 at 04:42 PM ----------

oh sorry, I don't get M or Av either so not exactly the same (but similar issue)

rweissman · 07-10-2016, 11:43 PM

Tried three lenses "new" 35, 55, 75; all work fine. Contacts look pristine. All lenses operate flawlessly. How do you trigger TAV? By just turning the mode dial (as I remember, as long as Auto ISO is on)? Am I forgetting to do something?

Adam · 07-10-2016, 11:50 PM

Could simply be a broken mode dial. I'm assuming your aperture rings are set to "A" (this shouldn't even matter though)?

rweissman · 07-11-2016, 12:08 AM

Adam, thanks. I had neglected to check-- the lens was set to a specific aperture. Setting to back to "A" fixed the problem. Exactly the reminder I was looking for. Much thanks! I've been a member of the forum for about 30 minutes, and, already, it has proven to be of real value. Thanks again!

automorphism · 07-11-2016, 12:46 AM

It's great to hear when a problem like this turns out to have a fix!

**Wild Mark** · 07-11-2016, 12:47 AM

What about me

Originally posted by automorphism

It's great to hear when a problem like this turns out to have a fix!

mikeSF · 07-17-2016, 02:10 PM

whew, that was close!

Kolor-Pikker · 07-18-2016, 03:12 AM

Originally posted by rweissman

Adam, thanks. I had neglected to check-- the lens was set to a specific aperture. Setting to back to "A" fixed the problem. Exactly the reminder I was looking for. Much thanks! I've been a member of the forum for about 30 minutes, and, already, it has proven to be of real value. Thanks again!

Funny, this "problem" happened to me just yesterday, I was playing around with the aperture dial for the first time since ever and noticed that TAv mode was suddenly changing shutter speed and aperture... it took me a good two minutes of finagling with the camera to realize that it was because the lens was off A.

07-10-2016, 11:03 PM	#1
rweissman New Member Join Date: Jul 2016 Posts: 4	Lost ability to use to SV, TV or TAV--mode dial only selects AV, M, X, Bulb On my two year old 645Z (has worked flawlessly until now) I appear to have lost the ability to switch to any mode other than AV or M (or X or bulb). The last time this happened, turning on auto ISO (Green button and ISO pressed together) fixed the problem. Doing this now does not fix the problem (though it does switch on Auto ISO). Every mode except X, M and Bulb shows "Aperture Priority." What am I (stupidly) doing wrong? Or is my camera's firmware somehow corrupted?

07-10-2016, 11:24 PM	#3
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 41,821	Originally posted by rweissman On my two year old 645Z (has worked flawlessly until now) I appear to have lost the ability to switch to any mode other than AV or M (or X or bulb). The last time this happened, turning on auto ISO (Green button and ISO pressed together) fixed the problem. Doing this now does not fix the problem (though it does switch on Auto ISO). Every mode except X, M and Bulb shows "Aperture Priority." What am I (stupidly) doing wrong? Or is my camera's firmware somehow corrupted? This could also happen due to loss of communication with the lens. Try cleaning the camera and lens mount, and trying a different lens. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

07-10-2016, 11:50 PM	#7
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 41,821	Could simply be a broken mode dial. I'm assuming your aperture rings are set to "A" (this shouldn't even matter though)? Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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07-10-2016, 11:05 PM	#2
TheDocAUS Senior Member Join Date: Feb 2014 Posts: 108	I would suggest a factory reset as a starting point. Let us know if that helps or not.

07-10-2016, 11:37 PM	#4
rweissman New Member Join Date: Jul 2016 Posts: 4 Original Poster	I just reset to factory defaults, but that did not solve the problem. The mode dial settings SV, TV, TAV all trigger AV. The mode does not change except for moving between AV, X, M, Bulb.

07-10-2016, 11:41 PM	#5
Wild Mark Site Supporter Join Date: Jun 2013 Location: Newcastle Photos: Gallery \| Albums Posts: 1,483	This happened to me on my K5 - exact same issue. Never resolved it. I now use this lens in X mode for macro - grrrrr ---------- Post added 07-11-16 at 04:42 PM ---------- oh sorry, I don't get M or Av either so not exactly the same (but similar issue)

07-10-2016, 11:43 PM	#6
rweissman New Member Join Date: Jul 2016 Posts: 4 Original Poster	Tried three lenses "new" 35, 55, 75; all work fine. Contacts look pristine. All lenses operate flawlessly. How do you trigger TAV? By just turning the mode dial (as I remember, as long as Auto ISO is on)? Am I forgetting to do something?

07-11-2016, 12:08 AM	#8
rweissman New Member Join Date: Jul 2016 Posts: 4 Original Poster	Adam, thanks. I had neglected to check-- the lens was set to a specific aperture. Setting to back to "A" fixed the problem. Exactly the reminder I was looking for. Much thanks! I've been a member of the forum for about 30 minutes, and, already, it has proven to be of real value. Thanks again!

07-11-2016, 12:46 AM	#9
automorphism Senior Member Join Date: Jun 2015 Location: Melbourne, Australia Photos: Albums Posts: 200	It's great to hear when a problem like this turns out to have a fix!

07-11-2016, 12:47 AM	#10
Wild Mark Site Supporter Join Date: Jun 2013 Location: Newcastle Photos: Gallery \| Albums Posts: 1,483	What about me Originally posted by automorphism It's great to hear when a problem like this turns out to have a fix!

07-17-2016, 02:10 PM	#11
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 5,670	whew, that was close!

07-18-2016, 03:12 AM	#12
Kolor-Pikker Veteran Member Join Date: Dec 2014 Posts: 341	Originally posted by rweissman Adam, thanks. I had neglected to check-- the lens was set to a specific aperture. Setting to back to "A" fixed the problem. Exactly the reminder I was looking for. Much thanks! I've been a member of the forum for about 30 minutes, and, already, it has proven to be of real value. Thanks again! Funny, this "problem" happened to me just yesterday, I was playing around with the aperture dial for the first time since ever and noticed that TAv mode was suddenly changing shutter speed and aperture... it took me a good two minutes of finagling with the camera to realize that it was because the lens was off A.

Lost ability to use to SV, TV or TAV--mode dial only selects AV, M, X, Bulb

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