Observations from a Pentax user group meeting.

ozlizard · 01-06-2012, 12:52 AM

Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135.
Also why are there two shutter sounds when using LV?

ozlizard · 01-07-2012, 06:47 PM

Anyoone know the answers to my questions?

lytrytyr · 01-07-2012, 07:36 PM

Originally posted by ozlizard

Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135.
Also why are there two shutter sounds when using LV?

I would recommend setting center point AF,
and contrast AF as the method for live view.
(See your specific camera manual for this.)

Have the camera set to AF.
Then press the LV button.
The mirror will flap up, and live view displays.
Point the center of the image where you want to focus
(preferably a large, contrasty area all at the same distance).
Half-depress the shutter button,
and wait until the white rectangle turns green.
This may take a second or two -- it's slower than phase-detect AF.
Now switch the camera to MF (so you don't lose the good focus),
compose as needed, and shoot.

The mirror will flap up and down as you shoot,
giving the two "shutter sounds" you mention.
I think this happens in order to set the exposure,
although it would be nicer
if the camera just became mirrorless in live view.

demp10 · 01-07-2012, 07:42 PM

Originally posted by ozlizard

Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135.
Also why are there two shutter sounds when using LV?

Live view will show a square that indicates where the focusing will take place. I am not sure that the type of AF (Auto, SEL or center) matters. Make sure that the subject is withing the square and press half way the shutter. When in focus the square will turn green. You can use the Info button to zoom in and see details and the cursor keys to move the square around the scene.

The two sounds you here is the mirror flipping up to get the LV and when taking a photo, returning down to take the picture as normal and then flipping up again to continue LV.

lytrytyr · 01-07-2012, 08:23 PM

Originally posted by demp10

I am not sure that the type of AF (Auto, SEL or center) matters.

Contrast-detect focusing is slow enough anyway.
I would recommend setting the center point
so you don't waste further time
by having the camera focus somewhere other
than where you want to focus.

Originally posted by demp10

The two sounds you here is the mirror flipping up to get the LV and when taking a photo, returning down to take the picture as normal and then flipping up again to continue LV.

In an SLR/DSLR, the mirror has to be up for taking the picture,
since a lowered mirror comes between the lens and the film/sensor.
As I mentioned in the earlier post,
I believe that the mirror drops down
from the raised live view position
so that the camera can set the exposure.

demp10 · 01-07-2012, 09:06 PM

Originally posted by lytrytyr

I would recommend setting the center point so you don't waste further time by having the camera focus somewhere other than where you want to focus.

I checked the manual and in LV you use Contrast AF (or face detection) on the part of the image that is outlined by the square on the screen. You can move it around with the cursor keys or you can move the camera and frame the focus point in the square.

The Auto focus points are used only by the Phase Difference system (below the mirror) in normal AF when using the viewfinder, so it does not make any difference in LV.

lytrytyr · 01-07-2012, 09:28 PM

Originally posted by demp10

I checked the manual and in LV you use Contrast AF (or face detection) on the part of the image that is outlined by the square on the screen. You can move it around with the cursor keys or you can move the camera and frame the focus point in the square.

Anyway, to save time in what is already a lengthy process,
it's better to avoid face detection or having the focus point
off-centered in the image frame when you're focusing,
instead just pointing the camera to where you want to focus.

I also use the center point for phase-detection AF with viewfinder framing,
preferring to hold the focus and recompose
rather than having the camera focus on random parts of the image.
This may be my reaction to bad experiences
with previous generations of P&S cameras.

creampuff · 01-08-2012, 01:52 AM

Originally posted by ozlizard

Anyoone know the answers to my questions?

Your answers can all found in the user manual. Take the time to read it up and try it on your own camera first. This is pretty basic stuff so please don't expect to be spoonfed.

Know the difference between the AF point settings (Auto, SEL & Center). It doesn't really matter which setting you use but you need to get the camera to focus either by means of a half press of the shutter button or pressing the AF button. The square will zoom in and focus confirmation happens when the square outline turns green. Use phase detect rather than contrast detect because it is quicker and more accurate.

lytrytyr · 01-08-2012, 11:35 AM

Originally posted by creampuff

Your answers can all found in the user manual.

My K-x manual has no answer to ozlizard's question
asking why there are "two shutter sounds when using LV."

Even now, I'm only assuming
that the reason for the mirror flipping up
is to allow the exposure to be determined,
and I would welcome confirmation
from someone who really knows what's going on.

pinholecam · 01-08-2012, 10:20 PM

Originally posted by lytrytyr

My K-x manual has no answer to ozlizard's question
asking why there are "two shutter sounds when using LV."

Even now, I'm only assuming
that the reason for the mirror flipping up
is to allow the exposure to be determined,
and I would welcome confirmation
from someone who really knows what's going on.

I guess the fastest way to find out is to personally observe the operation of the mirror/shutter by looking at the open mount when in LV and pressing the shutter.

I doubt there is anything we can do to remove this delay though ( I wish there was).

lytrytyr · 01-09-2012, 06:29 AM

Originally posted by pinholecam

I guess the fastest way to find out is to personally observe the operation of the mirror/shutter by looking at the open mount when in LV and pressing the shutter..

Well, that would confirm the mirror movement
(at some risk of letting dust get to the sensor),
but would not seem to clarify
the exact purpose of that movement.

Originally posted by pinholecam

I doubt there is anything we can do to remove this delay though ( I wish there was).

I certainly agree with that.
It would be great to have a DSLR
where you could lock the mirror up
and turn it into an EVIL mirrorless camera.

This could be a distinguishing feature for Pentax.

drougge · 01-09-2012, 08:34 AM

The mirror flops down, but only because the shutter mechanism requires it. If it was designed more with live view in mind, it wouldn't. Exposure is determined off the sensor (at least on the K-5), and the mirror flipping happens in manual mode too. I'm almost sure it's because of mechanical limitations in the shutter mechanism.

lytrytyr · 01-09-2012, 08:48 AM

Originally posted by drougge

Exposure is determined off the sensor (at least on the K-5)

That's good to know.

Classic Pentax, like the exposure reading off the silver halide sensor in the FF LX.

Originally posted by drougge

and the mirror flipping happens in manual mode too.

Yes, that really bugged me the first time I experienced it.

Originally posted by drougge

I'm almost sure it's because of mechanical limitations in the shutter mechanism.

Bizarre -- just an engineering shortcut?

creampuff · 01-09-2012, 09:00 AM

There will obviously be two distinct sounds when LV is activated because like all DSLRs, the reflex mirror directing light to the pentaprism has to be raised first. Once the mirror is raised and the mirror box is unobstructed, only then will the shutter be activated to allow light to be recorded by the sensor. This principle has been around from the time of SLR cameras. Search youtube and you'll find many videos to support this.

For example:

You Tube

You Tube

lytrytyr · 01-09-2012, 10:00 AM

Originally posted by creampuff

There will obviously be two distinct sounds when LV is activated because like all DSLRs, the reflex mirror directing light to the pentaprism has to be raised first. Once the mirror is raised and the mirror box is unobstructed, only then will the shutter be activated to allow light to be recorded by the sensor. This principle has been around from the time of SLR cameras.

No, the issue we've been discussing in this part of the thread
is that when you're in live view, and go to take a photo,
the mirror drops down first, obstructing the mirror box.

That is counter-intuitive to me,
and is the exact reverse of the old SLR principle.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax AF 1.7 TC observations	David&karen	Pentax SLR Lens Discussion	20	03-19-2013 01:35 AM
My own Photokina observations (Pentax and others)	thibs	Pentax News and Rumors	34	09-30-2010 01:11 PM
New Social Group - British Columbia User Group	bigdave69	Travel, Events, and Groups	1	09-02-2010 09:34 AM
Portraits from a Flickr group meeting	attack11	Post Your Photos!	7	06-20-2009 02:25 PM
Pentax user in London please join my new pentax DSLR London users group	m42geo	Photographic Technique	3	01-31-2009 05:32 PM

01-06-2012, 12:52 AM	#31
ozlizard Veteran Member Join Date: Jun 2009 Location: Bridgetown West Australia Photos: Gallery \| Albums Posts: 903	Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135. Also why are there two shutter sounds when using LV?

01-07-2012, 06:47 PM	#32
ozlizard Veteran Member Join Date: Jun 2009 Location: Bridgetown West Australia Photos: Gallery \| Albums Posts: 903	Anyoone know the answers to my questions?

01-07-2012, 07:36 PM	#33
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by ozlizard Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135. Also why are there two shutter sounds when using LV? I would recommend setting center point AF, and contrast AF as the method for live view. (See your specific camera manual for this.) Have the camera set to AF. Then press the LV button. The mirror will flap up, and live view displays. Point the center of the image where you want to focus (preferably a large, contrasty area all at the same distance). Half-depress the shutter button, and wait until the white rectangle turns green. This may take a second or two -- it's slower than phase-detect AF. Now switch the camera to MF (so you don't lose the good focus), compose as needed, and shoot. The mirror will flap up and down as you shoot, giving the two "shutter sounds" you mention. I think this happens in order to set the exposure, although it would be nicer if the camera just became mirrorless in live view.

01-07-2012, 07:42 PM	#34
demp10 Veteran Member Join Date: Jun 2011 Location: Atlanta Photos: Albums Posts: 602	Originally posted by ozlizard Couple of questions about AF and LV. How do you AF with LV? I just tried some test shots but found it really difficult to focus on anything eg trying to focus on a flower and pick it out from the background. I have AF set to auto and was using a DA 50-135. Also why are there two shutter sounds when using LV? Live view will show a square that indicates where the focusing will take place. I am not sure that the type of AF (Auto, SEL or center) matters. Make sure that the subject is withing the square and press half way the shutter. When in focus the square will turn green. You can use the Info button to zoom in and see details and the cursor keys to move the square around the scene. The two sounds you here is the mirror flipping up to get the LV and when taking a photo, returning down to take the picture as normal and then flipping up again to continue LV.

01-07-2012, 08:23 PM	#35
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by demp10 I am not sure that the type of AF (Auto, SEL or center) matters. Contrast-detect focusing is slow enough anyway. I would recommend setting the center point so you don't waste further time by having the camera focus somewhere other than where you want to focus. Originally posted by demp10 The two sounds you here is the mirror flipping up to get the LV and when taking a photo, returning down to take the picture as normal and then flipping up again to continue LV. In an SLR/DSLR, the mirror has to be up for taking the picture, since a lowered mirror comes between the lens and the film/sensor. As I mentioned in the earlier post, I believe that the mirror drops down from the raised live view position so that the camera can set the exposure.

01-07-2012, 09:06 PM	#36
demp10 Veteran Member Join Date: Jun 2011 Location: Atlanta Photos: Albums Posts: 602	Originally posted by lytrytyr I would recommend setting the center point so you don't waste further time by having the camera focus somewhere other than where you want to focus. I checked the manual and in LV you use Contrast AF (or face detection) on the part of the image that is outlined by the square on the screen. You can move it around with the cursor keys or you can move the camera and frame the focus point in the square. The Auto focus points are used only by the Phase Difference system (below the mirror) in normal AF when using the viewfinder, so it does not make any difference in LV.

01-07-2012, 09:28 PM	#37
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by demp10 I checked the manual and in LV you use Contrast AF (or face detection) on the part of the image that is outlined by the square on the screen. You can move it around with the cursor keys or you can move the camera and frame the focus point in the square. Anyway, to save time in what is already a lengthy process, it's better to avoid face detection or having the focus point off-centered in the image frame when you're focusing, instead just pointing the camera to where you want to focus. I also use the center point for phase-detection AF with viewfinder framing, preferring to hold the focus and recompose rather than having the camera focus on random parts of the image. This may be my reaction to bad experiences with previous generations of P&S cameras.

01-08-2012, 01:52 AM	#38
creampuff Veteran Member Join Date: May 2007 Location: Singapore Photos: Gallery Posts: 3,953 Original Poster	Originally posted by ozlizard Anyoone know the answers to my questions? Your answers can all found in the user manual. Take the time to read it up and try it on your own camera first. This is pretty basic stuff so please don't expect to be spoonfed. Know the difference between the AF point settings (Auto, SEL & Center). It doesn't really matter which setting you use but you need to get the camera to focus either by means of a half press of the shutter button or pressing the AF button. The square will zoom in and focus confirmation happens when the square outline turns green. Use phase detect rather than contrast detect because it is quicker and more accurate.

01-08-2012, 11:35 AM	#39
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by creampuff Your answers can all found in the user manual. My K-x manual has no answer to ozlizard's question asking why there are "two shutter sounds when using LV." Even now, I'm only assuming that the reason for the mirror flipping up is to allow the exposure to be determined, and I would welcome confirmation from someone who really knows what's going on.

01-08-2012, 10:20 PM	#40
pinholecam Pentaxian Join Date: Oct 2009 Location: North Photos: Gallery Posts: 4,709	Originally posted by lytrytyr My K-x manual has no answer to ozlizard's question asking why there are "two shutter sounds when using LV." Even now, I'm only assuming that the reason for the mirror flipping up is to allow the exposure to be determined, and I would welcome confirmation from someone who really knows what's going on. I guess the fastest way to find out is to personally observe the operation of the mirror/shutter by looking at the open mount when in LV and pressing the shutter. I doubt there is anything we can do to remove this delay though ( I wish there was).

01-09-2012, 06:29 AM	#41
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by pinholecam I guess the fastest way to find out is to personally observe the operation of the mirror/shutter by looking at the open mount when in LV and pressing the shutter.. Well, that would confirm the mirror movement (at some risk of letting dust get to the sensor), but would not seem to clarify the exact purpose of that movement. Originally posted by pinholecam I doubt there is anything we can do to remove this delay though ( I wish there was). I certainly agree with that. It would be great to have a DSLR where you could lock the mirror up and turn it into an EVIL mirrorless camera. This could be a distinguishing feature for Pentax.

01-09-2012, 08:34 AM	#42
drougge Veteran Member Join Date: Jan 2010 Location: Malmö Photos: Gallery Posts: 787	The mirror flops down, but only because the shutter mechanism requires it. If it was designed more with live view in mind, it wouldn't. Exposure is determined off the sensor (at least on the K-5), and the mirror flipping happens in manual mode too. I'm almost sure it's because of mechanical limitations in the shutter mechanism.

01-09-2012, 08:48 AM	#43
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by drougge Exposure is determined off the sensor (at least on the K-5) That's good to know. Classic Pentax, like the exposure reading off the silver halide sensor in the FF LX. Originally posted by drougge and the mirror flipping happens in manual mode too. Yes, that really bugged me the first time I experienced it. Originally posted by drougge I'm almost sure it's because of mechanical limitations in the shutter mechanism. Bizarre -- just an engineering shortcut?

01-09-2012, 10:00 AM	#45
lytrytyr Pentaxian Join Date: Nov 2011 Photos: Gallery \| Albums Posts: 4,310	Originally posted by creampuff There will obviously be two distinct sounds when LV is activated because like all DSLRs, the reflex mirror directing light to the pentaprism has to be raised first. Once the mirror is raised and the mirror box is unobstructed, only then will the shutter be activated to allow light to be recorded by the sensor. This principle has been around from the time of SLR cameras. No, the issue we've been discussing in this part of the thread is that when you're in live view, and go to take a photo, the mirror drops down first, obstructing the mirror box. That is counter-intuitive to me, and is the exact reverse of the old SLR principle.