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View Full Version : Highlight Clipping only when autofocusing??


Talkingdrum
30th April 2017, 05:59 PM
Ok another question (forgive me, I haven't had the camera long).
I'm using the EVF in style 2 in manual setting. I have it showing me the histogram and clipped areas in orange. When I am in manual focus everything seems fine but if I have it in C-AF, when I half depress the shutter suddenly the histogram spikes and all the bright areas are now showing clipped on the screen. I notice it does the same with S-AF but only for the brief fraction of a second when the camera is focusing. What is going on here?
Having done a little experimenting it would appear that he accurate histogram is the one when the camera is in autofocus and is only available to me when I depress the shutter halfway. Why is manual focus mode giving me an inaccurate histogram readout?
Also in the menu item "EVF Adjust", when I enter that there are 2 sub menus "EVF Auto Luminance" which I can enter and either set it to "On" or "Off". Underneath that however is a sub menu "EVF Adjust" with icons I assume represent Temperature and Brightness with a little arrow to the right but I cannot get into this menu. When I use the right arrow pad the screen just goes blank???

Edit: Ok, done a little more experimenting and it seems to occur in the monitor as well. The overall brightness doesn't change but all the pixels towards the top end of the histogram clip in the monitor and the EVF when the shutter is pressed halfway in C-AF.

pdk42
30th April 2017, 06:57 PM
I've noticed the same thing too. Odd. I'd call it a bug.

Talkingdrum
30th April 2017, 07:17 PM
I've noticed the same thing too. Odd. I'd call it a bug.

I'd call it more than "a bug". It means the live histogram is worthless. For me I shoot in manual and rely totally on the live histogram to give me an accurate picture of the the scene. If what you say is correct, that this is a "bug" I'm beginning to think I've just bought into a really expensive worthless piece of junk.
What sort of "professional" tool is this?

DerekW
30th April 2017, 07:32 PM
Phone the Olympus help line and explain your problem, it is probably a candidate for a firmware fix.

Talkingdrum
30th April 2017, 07:56 PM
Phone the Olympus help line and explain your problem, it is probably a candidate for a firmware fix.

Going to do that first thing after the weekend.

drmarkf
30th April 2017, 10:52 PM
Yes, I'm getting this too. I'd been concentrating on learning and trying other things, but today I was playing around to see if this was something to do with focus point number or size or position and weighting of exposure, but didn't reach a conclusion.
So far I think Paul's suggestion of a bug is most likely.

Gwyver
1st May 2017, 06:16 AM
Have you set 'Live View Boost' to OFF (Menu D4)? The default setting in Manual Mode = On1.

Note also the LV Boost is also an option lower down this menu tab - as a sub-setting of the 'Settings' item.

There have been other discussions on this forum concerning how the Live View boost modifies the histogram.

drmarkf
1st May 2017, 07:28 AM
Have you set 'Live View Boost' to OFF (Menu D4)? The default setting in Manual Mode = On1.

Note also the LV Boost is also an option lower down this menu tab - as a sub-setting of the 'Settings' item.

There have been other discussions on this forum concerning how the Live View boost modifies the histogram.

It's D2, and mine's 'off'

Talkingdrum
1st May 2017, 07:41 AM
Have you set 'Live View Boost' to OFF (Menu D4)? The default setting in Manual Mode = On1.

Note also the LV Boost is also an option lower down this menu tab - as a sub-setting of the 'Settings' item.

There have been other discussions on this forum concerning how the Live View boost modifies the histogram.

Live boost is off in both cases.

I've done some more experimenting this morning and my conclusion is that the histogram is accurate BEFORE the camera goes into auto focus and not after. This in fact causes me little concern. I panicked because initially I thought it was the other way round. I shoot in manual with manual focus most of the time but I will go to C-AF on moving targets. I envisaged having to come out of MF to C-AF and half pressing the shutter so I could set the exposure and then going back to MF to take the shot - every time! This way if the histogram spikes when auto focus is engaged it can just be ignored as exposure has already been set.

drmarkf
1st May 2017, 07:48 AM
Live boost is off in both cases.

I've done some more experimenting this morning and my conclusion is that the histogram is accurate BEFORE the camera goes into auto focus and not after. This in fact causes me little concern. I panicked because initially I thought it was the other way round. I shoot in manual with manual focus most of the time but I will go to C-AF on moving targets. I envisaged having to come out of MF to C-AF and half pressing the shutter so I could set the exposure and then going back to MF to take the shot - every time! This way if the histogram spikes when auto focus is engaged it can just be ignored as exposure has already been set.

Yes, that's the way mine is behaving.
For most of my usage this isn't an issue for me, either. For example, for street shooting I'm using BBF and aperture priority, and will set an exposure compensation if needed before starting to focus and shoot: once I'm shooting there's enough to do keeping the subject framed to worry much about further exposure adjustments.
It's a bit more of an issue for, say, birds in flight if I'm using aperture priority, when I do regularly give the exposure compensation a tweak while not losing focus lock on the bird. I am doing more manual exposure setting now for this, though.
I still think it should be reported.

Talkingdrum
1st May 2017, 08:07 AM
Yes, that's the way mine is behaving.
For most of my usage this isn't an issue for me, either. For example, for street shooting I'm using BBF and aperture priority, and will set an exposure compensation if needed before starting to focus and shoot: once I'm shooting there's enough to do keeping the subject framed to worry much about further exposure adjustments.
It's a bit more of an issue for, say, birds in flight if I'm using aperture priority, when I do regularly give the exposure compensation a tweak while not losing focus lock on the bird. I am doing more manual exposure setting now for this, though.
I still think it should be reported.

Yes definitely. I will still call them tomorrow morning and point it out.

Gwyver
2nd May 2017, 06:12 AM
...
I've done some more experimenting this morning and my conclusion is that the histogram is accurate BEFORE the camera goes into auto focus and not after. ...

Perhaps what your are experiencing is inevitable - but most noticeable when using C-AF because whenever acquiring AF the lens aperture is wide open & and only closes to your selected f-stop when the shutter activates.

Growltiger
2nd May 2017, 07:52 AM
Perhaps what your are experiencing is inevitable - but most noticeable when using C-AF because whenever acquiring AF the lens aperture is wide open & and only closes to your selected f-stop when the shutter activates.

I think that is probably the explanation. In which case it can't be corrected, but what they could do is remove the histogram display whenever it is incorrect. This could be suggested to them.

drmarkf
2nd May 2017, 08:22 AM
Perhaps what your are experiencing is inevitable - but most noticeable when using C-AF because whenever acquiring AF the lens aperture is wide open & and only closes to your selected f-stop when the shutter activates.

Ah, yes, that could well be it. I don't recall it happening with my E-M1, but I don't have it with me to check and I don't use CAF anywhere near as much with it.

Talkingdrum
2nd May 2017, 08:26 AM
I think that is probably the explanation. In which case it can't be corrected, but what they could do is remove the histogram display whenever it is incorrect. This could be suggested to them.

I'm not sure it is an aperture issue as it happens to the same degree whether the lens is stopped down or not. You're suggestion of removing the histogram made me think about what happens on other cameras. I've used so many in my life and never come across this before so I checked my little Fuji X100T and that's exactly what it does; when autofocus is engaged the histogram disappears. There must be something in the process of auto focusing (I think it's something to do with contrast which is why you get the spike at the top) that the camera is using that means you can no longer get an accurate histogram reading. Removing it is exactly what they should do. If Fuji can do it on a X100T Olympus should do it on this.
It may seem a minor point to some but if nothing else it gave me one sleepless night thinking I had just bought an expensive camera with an unreliable histogram. It's not difficult to imagine a scenario also when perhaps somebody is tracking a subject, suddenly notices the histogram and dials in an incorrect exposure and loses a shot. It should definitely disappear when giving incorrect information.

kbouk
2nd May 2017, 02:23 PM
It's more complicate because especially when you focus with CAF and L mode (10fps mechanical up to 18fps electronic) as you half press the exposure is continuous changing according to the light surround the moving target, so you have to watch and trust the EVF or the LCD that is the right exposure, not something else and of course we are not talking here about spot metering which has another menu option to follow the focus point ...

Gwyver
6th May 2017, 12:10 PM
Perhaps what your are experiencing is inevitable - but most noticeable when using C-AF because whenever acquiring AF the lens aperture is wide open & and only closes to your selected f-stop when the shutter activates.

Ah, yes, that could well be it. I don't recall it happening with my E-M1, but I don't have it with me to check and I don't use CAF anywhere near as much with it.

Because this thread increased my awareness of this issue, the effect seemed more noticeable whilst using the camera recently - especially that of the highlight indicators lighting up briefly.

On reflection, I think this also happened on my EM5 & EM1 - but was less apparent. I suspect it is more obvious with the EM1M2 because of the faster EVF frame refresh and the multiple processor cores. With one core the control would be either updating the EVF or controlling AF acquisition & aperture. With multiple cores both these activities will occur in parallel and the EVF will be more likely to show the histogram/blinkies whilst the aperture is temporarily fully opened for focussing.

pdk42
10th May 2017, 03:27 PM
I've noticed the same thing too. Odd. I'd call it a bug.

And it seems that it's fixed in firmware 1.2!

drmarkf
10th May 2017, 03:39 PM
So what happens? Does it give a proper reading, or stop showing the histogram?

Talkingdrum
10th May 2017, 09:25 PM
So what happens? Does it give a proper reading, or stop showing the histogram?

When the camera is in autofocus the histogram remains on the screen but is unaffected. *chr

pdk42
10th May 2017, 09:36 PM
Yep - a great result. Doing what it should do!

drmarkf
11th May 2017, 08:38 PM
Interesting - presumably that means it can't have been due to the aperture diaphragm closing.