GX7 AF behaviour: no big deal but weird

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

Have to agreed that it is weird. Luckily it is not only rare but during last 4 years no similar problem has ever occured to me (underexposure vs AF ability).

What is the lens you are using? What was the targeted object (no, low or high contrast condition) that GX7 had problem to lock focus?

Panasonic 45-150/4-5.6. Wooden floor, lowish contrast. Next time I have a problem getting focus I can try turning up EC so in a way it's more a solution than a problem, just funny.

rurikw wrote:

Panasonic 45-150/4-5.6. Wooden floor, lowish contrast. Next time I have a problem getting focus I can try turning up EC so in a way it's more a solution than a problem, just funny.

45~150 is one of the 2 pany lenses I need to use with extra caution. The other is 12~32 in poor lighting condition.

It is also about in dark environment. I first found the problem on GX85 shooting a Lantern Carnival in evening in a park. Although AF confirmed (fast as normal), some results were OOF. Might be of the high ISO I used, and might be the slow shutter speed for the 150 end. But a few OOF shots were within usual 1/60" that normally I should have sharp images from it.

So, I usually shall half hit shutter for multiple times to lock focus repeatedly and the result is perfectly fine. It is mainly used on GX7. Having said that, not find underexposed will affect AF speed.

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

alcelc wrote:

rurikw wrote:

Panasonic 45-150/4-5.6. Wooden floor, lowish contrast. Next time I have a problem getting focus I can try turning up EC so in a way it's more a solution than a problem, just funny.

45~150 is one of the 2 pany lenses I need to use with extra caution. The other is 12~32 in poor lighting condition.

Interesting tip. Hope wife hasn't had too much problems with the 12-32. Hasn't said anything and what I've seen looks ok though she shoots a lot in low light. I mostly use 20/1.7 and 45/1.8 in those situations which is why I've only lately noticed anything strange

It is also about in dark environment. I first found the problem on GX85 shooting a Lantern Carnival in evening in a park. Although AF confirmed (fast as normal), some results were OOF.

I recall having similar experience with fireworks. Chalked it up to inexperience at the time.

Might be of the high ISO I used, and might be the slow shutter speed for the 150 end. But a few OOF shots were within usual 1/60" that normally I should have sharp images from it.

So, I usually shall half hit shutter for multiple times to lock focus repeatedly and the result is perfectly fine. It is mainly used on GX7.

Good tip. Shall try if happens.

Having said that, not find underexposed will affect AF speed.

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Albert

Paulmorgan wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

Is all this with the one lens, seen similar from sticky aperture blades.

I'm not sure. I think I first encountered it when shooting nightscape with the 45-150. Last time I tried (successfully) to replicate it I also used that one. I tried to check the blades by looking into the lens while focussing and pressing shutter. Seemed to close down and open up normally. Could it be a firm/software thing?

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

Is all this with the one lens, seen similar from sticky aperture blades.

I'm not sure. I think I first encountered it when shooting nightscape with the 45-150. Last time I tried (successfully) to replicate it I also used that one. I tried to check the blades by looking into the lens while focussing and pressing shutter. Seemed to close down and open up normally. Could it be a firm/software thing?

What is your lens firmware?

alcelc wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

Is all this with the one lens, seen similar from sticky aperture blades.

I'm not sure. I think I first encountered it when shooting nightscape with the 45-150. Last time I tried (successfully) to replicate it I also used that one. I tried to check the blades by looking into the lens while focussing and pressing shutter. Seemed to close down and open up normally. Could it be a firm/software thing?

What is your lens firmware?

No idea. Never bothered with it. Must try to find out.

rurikw wrote:

alcelc wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

Is all this with the one lens, seen similar from sticky aperture blades.

I'm not sure. I think I first encountered it when shooting nightscape with the 45-150. Last time I tried (successfully) to replicate it I also used that one. I tried to check the blades by looking into the lens while focussing and pressing shutter. Seemed to close down and open up normally. Could it be a firm/software thing?

What is your lens firmware?

No idea. Never bothered with it. Must try to find out.

Go to the Setup Menu and look for the latest on pany fw page.

alcelc wrote:

rurikw wrote:

alcelc wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

Paulmorgan wrote:

rurikw wrote:

My GX7 is rather good at focussing in low light, at least leagues better than my former camera. But sometimes it can't lock. I recently ran into such a situation. Then I noticed I had EC on -1 or something which would result in underexposure. When I corrected that it also could focus. Of course it could have been that I'd moved the camera ever so slightly but I got curious and started experimenting with EC values in low light situations and there was indeed a consistent pattern: lower exposure and focus hunts, raise exposure and focus locks. Now I can't imagine any reason why these things should be connected. AF always works with aperture fully open so no way the intended exposure could influence its behaviour? Besides I was in A priority mode. Changing the (intended) aperture had no such effect on AF.

For focusing the aperture blades are always fully open, irrespective of selected aperture, unless its an old vintage lens with no communication.

Exactly. That's why thus phenomenon feels so weird.

Is all this with the one lens, seen similar from sticky aperture blades.

I'm not sure. I think I first encountered it when shooting nightscape with the 45-150. Last time I tried (successfully) to replicate it I also used that one. I tried to check the blades by looking into the lens while focussing and pressing shutter. Seemed to close down and open up normally. Could it be a firm/software thing?

What is your lens firmware?

No idea. Never bothered with it. Must try to find out.

Go to the Setup Menu and look for the latest on pany fw page.

Thanks. Shall do.