Mirror cycling on optical preview, stopped-down movie recording

bwDraco · 11-26-2010, 10:57 PM

This may be a silly question, but why does the mirror go up and down on exiting optical preview?

I've also noticed this behavior when using an aperture other than the maximum when in movie mode. Specifically, the mirror cycles when recording starts and when recording ends, except when shooting wide open. Does stopping down require cycling the mirror?

--DragonLord

Last edited by bwDraco; 05-15-2012 at 11:38 AM.

Adam · 11-27-2010, 12:07 AM

Isn't it so that you can look through the VF and preview your image?

bwDraco · 11-27-2010, 08:58 AM

When the Green Button is assigned to Optical Preview, pressing and holding it will cause the lens to stop down to the set aperture, darkening the viewfinder and displaying the depth of field for the set aperture. However, upon releasing the button, the mirror will cycle. Why can't the camera simply reset the aperture without cycling the mirror?

--DragonLord

jolepp · 11-27-2010, 09:12 AM

This is similar to the mirror up/down quirk on green button metering with an M-lens (k-x). No apparent need for that either. Maybe the firmware routine is shared with exposure?

bwDraco · 11-27-2010, 09:18 AM

Originally posted by jolepp

This is similar to the mirror up/down quirk on green button metering with an M-lens (k-x). No apparent need for that either. Maybe the firmware routine is shared with exposure?

I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary?

--DragonLord

jolepp · 11-27-2010, 09:54 AM

Originally posted by DragonLord

I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary?

--DragonLord

I have wondered about that myself :-) Just speculation about firmware above: the idea is that they might already have had subroutine(s) used for exposure that could be conveniently used for green button metering and optical preview that also happened to raise the mirror.

Oog · 09-11-2011, 10:57 PM

Originally posted by DragonLord

I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary?

--DragonLord

Have no idea, but maybe the whole shutter mechanism is designed differently enough from film cameras that the shutter/mirror mechanics need to be reset after doing this? And for some reason, it's not required if the aperture is set wide open? Does this happen on all Pentax digital SLRs?

You may be right.

falconeye · 09-12-2011, 04:13 AM

Originally posted by DragonLord

This may be a silly question, but why does the mirror go up and down on exiting optical preview?

The K-5 doesn't behave as you describe.
It won't touch the mirror in all operations you describe.

Of course, if you have electronic preview (rather than the default optical one), the mirror must move to unblock the sensor. This is pretty clear though and I guess isn't what you meant.

What you hear is the shutter and the shutter must move because otherwise, the sensor won't receive light

After an exposure, the shutter must close and then, both curtains must rewind and then, the shutter must open again. That's almost as loud as the K-5's silent mirror.

Lesser bodies (K-r etc.) have a traditional mirror-box where shutter-rewind and mirror-down are mechanically linked. So, what you describe may apply to the K-r and if it so, it is indeed a hardware limitation the K-5 wouldn't have.

bwDraco · 09-12-2011, 06:14 AM

Originally posted by falconeye

The K-5 doesn't behave as you describe.
It won't touch the mirror in all operations you describe.

Does this mean that if you pull the optical preview lever on the K-5, the mirror will not cycle on releasing the lever?

On my K-r, the mirror actually cycles with the viewfinder blacking out momentarily when I let go of the Green button for optical preview.

If possible, can someone post a YouTube video comparing the K-5 or K-7 and the K-r or K-x in optical preview?

--DragonLord

falconeye · 09-12-2011, 06:43 AM

Originally posted by DragonLord

Does this mean that if you pull the optical preview lever on the K-5, the mirror will not cycle on releasing the lever?

I said so and say it again: yes.

Optical preview (which is a third stop in the ON-OFF lever) activates the aperture motor to engage and release the aperture. The aperture motor is rather silent (much more than a mirror) but it isn't unaudible. There is no black out of course.

On a K-5, the green button can't be configured to optical preview which has it has its own lever.

Originally posted by DragonLord

On my K-r, the mirror actually cycles with the viewfinder blacking out momentarily when I let go of the Green button for optical preview.

The K-r has no aperture motor (the little bump in the K-5 body on the right side (left if you look onto the lens) of the mirror box.

Therefore, it needs a second source to pull the aperture spring back. It is all part of a single mechanics which rewinds the shutter curtains, rewinds the mirror and pushes the mount's aperture lever. The K-7/5 needed to get an entirely new mirror box (new dampened mirror, new shutter, new aperture motor) to separate functions.

Originally posted by DragonLord

If possible, can someone post a YouTube video comparing the K-5 or K-7 and the K-r or K-x in optical preview?

Or you simply believe me ...

bwDraco · 09-12-2011, 06:50 AM

Sorry, Falk. I understand. That also explains the extra bump at 10 o'clock around the lens mount. Thanks.

--DragonLord

11-26-2010, 10:57 PM	#1
bwDraco Veteran Member Join Date: Jul 2010 Location: New York Photos: Albums Posts: 1,071	Mirror cycling on optical preview, stopped-down movie recording This may be a silly question, but why does the mirror go up and down on exiting optical preview? I've also noticed this behavior when using an aperture other than the maximum when in movie mode. Specifically, the mirror cycles when recording starts and when recording ends, except when shooting wide open. Does stopping down require cycling the mirror? --DragonLord Last edited by bwDraco; 05-15-2012 at 11:38 AM.

11-27-2010, 12:07 AM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Isn't it so that you can look through the VF and preview your image? 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:

09-12-2011, 06:14 AM	#9
bwDraco Veteran Member Join Date: Jul 2010 Location: New York Photos: Albums Posts: 1,071 Original Poster	Originally posted by falconeye The K-5 doesn't behave as you describe. It won't touch the mirror in all operations you describe. Does this mean that if you pull the optical preview lever on the K-5, the mirror will not cycle on releasing the lever? On my K-r, the mirror actually cycles with the viewfinder blacking out momentarily when I let go of the Green button for optical preview. If possible, can someone post a YouTube video comparing the K-5 or K-7 and the K-r or K-x in optical preview? --DragonLord Last edited by bwDraco; 09-12-2011 at 06:28 AM.

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11-27-2010, 08:58 AM	#3
bwDraco Veteran Member Join Date: Jul 2010 Location: New York Photos: Albums Posts: 1,071 Original Poster	When the Green Button is assigned to Optical Preview, pressing and holding it will cause the lens to stop down to the set aperture, darkening the viewfinder and displaying the depth of field for the set aperture. However, upon releasing the button, the mirror will cycle. Why can't the camera simply reset the aperture without cycling the mirror? --DragonLord

11-27-2010, 09:12 AM	#4
jolepp Veteran Member Join Date: Oct 2010 Location: Finland Photos: Albums Posts: 3,196	This is similar to the mirror up/down quirk on green button metering with an M-lens (k-x). No apparent need for that either. Maybe the firmware routine is shared with exposure?

11-27-2010, 09:18 AM	#5
bwDraco Veteran Member Join Date: Jul 2010 Location: New York Photos: Albums Posts: 1,071 Original Poster	Originally posted by jolepp This is similar to the mirror up/down quirk on green button metering with an M-lens (k-x). No apparent need for that either. Maybe the firmware routine is shared with exposure? I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary? --DragonLord

11-27-2010, 09:54 AM	#6
jolepp Veteran Member Join Date: Oct 2010 Location: Finland Photos: Albums Posts: 3,196	Originally posted by DragonLord I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary? --DragonLord I have wondered about that myself :-) Just speculation about firmware above: the idea is that they might already have had subroutine(s) used for exposure that could be conveniently used for green button metering and optical preview that also happened to raise the mirror.

09-11-2011, 10:57 PM	#7
Oog Forum Member Join Date: Sep 2011 Posts: 85	Originally posted by DragonLord I feel that this is a hardware limitation, but correct me if I'm wrong. Why is this necessary? --DragonLord Have no idea, but maybe the whole shutter mechanism is designed differently enough from film cameras that the shutter/mirror mechanics need to be reset after doing this? And for some reason, it's not required if the aperture is set wide open? Does this happen on all Pentax digital SLRs? You may be right.

09-12-2011, 04:13 AM	#8
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by DragonLord This may be a silly question, but why does the mirror go up and down on exiting optical preview? The K-5 doesn't behave as you describe. It won't touch the mirror in all operations you describe. Of course, if you have electronic preview (rather than the default optical one), the mirror must move to unblock the sensor. This is pretty clear though and I guess isn't what you meant. What you hear is the shutter and the shutter must move because otherwise, the sensor won't receive light After an exposure, the shutter must close and then, both curtains must rewind and then, the shutter must open again. That's almost as loud as the K-5's silent mirror. Lesser bodies (K-r etc.) have a traditional mirror-box where shutter-rewind and mirror-down are mechanically linked. So, what you describe may apply to the K-r and if it so, it is indeed a hardware limitation the K-5 wouldn't have.

09-12-2011, 06:43 AM	#10
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by DragonLord Does this mean that if you pull the optical preview lever on the K-5, the mirror will not cycle on releasing the lever? I said so and say it again: yes. Optical preview (which is a third stop in the ON-OFF lever) activates the aperture motor to engage and release the aperture. The aperture motor is rather silent (much more than a mirror) but it isn't unaudible. There is no black out of course. On a K-5, the green button can't be configured to optical preview which has it has its own lever. Originally posted by DragonLord On my K-r, the mirror actually cycles with the viewfinder blacking out momentarily when I let go of the Green button for optical preview. The K-r has no aperture motor (the little bump in the K-5 body on the right side (left if you look onto the lens) of the mirror box. Therefore, it needs a second source to pull the aperture spring back. It is all part of a single mechanics which rewinds the shutter curtains, rewinds the mirror and pushes the mount's aperture lever. The K-7/5 needed to get an entirely new mirror box (new dampened mirror, new shutter, new aperture motor) to separate functions. Originally posted by DragonLord If possible, can someone post a YouTube video comparing the K-5 or K-7 and the K-r or K-x in optical preview? Or you simply believe me ...

09-12-2011, 06:50 AM	#11
bwDraco Veteran Member Join Date: Jul 2010 Location: New York Photos: Albums Posts: 1,071 Original Poster	Sorry, Falk. I understand. That also explains the extra bump at 10 o'clock around the lens mount. Thanks. --DragonLord