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Thread: exposure problems

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kasenyee

Posts: 126
Location: Toronto, Canada
Registered: 22 Jun 2012
exposure problems
Posted: 25 Feb 2013 at 0:46 GMT
Hey all

I've recently started a large pano tour (for myself) and I find that sometimes exposure of a wall or floor, changes in brightness from point A to point B of my rotation. I'd share some of the images but have no clue how to.

This was especially clear to me inside a hallway, with lots of light coming from both ends. All shots were on Manual Exposure Aperture, Shutter, ISO, everything.
Shooting on a D600 with 16mm Fish at f/8 with a NN5, set to rotate 6-8 times (I know 8 isn't necessary but I'm experimenting with different stuff).

Am I missing something crucial or just blind to some

thanks!
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Four80sparky

Posts: 12
Location:
Registered: 25 Dec 2012
Re: exposure problems
Posted: 25 Feb 2013 at 1:27 GMT
What is the issue? If you're shooting in manual, then all the exposures should be the same, which is what is desirable. It's normal for the camera's meter the change while you rotate the camera.... that's why you shoot in manual: to keep the camera from adjusting the exposure.
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kasenyee

Posts: 126
Location: Toronto, Canada
Registered: 22 Jun 2012
Re: exposure problems
Posted: 25 Feb 2013 at 1:31 GMT
the problem is that they're not the same. the exposure of the wall changes when i rotate the camera. I look at the overlap and the wall will be darker in shot A but then in Shot B (exact same part of a wall) it gets much much brighter, and then it dosn't create a smooth transition when stitching
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Smooth

Posts: 4310
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
Re: exposure problems
Posted: 25 Feb 2013 at 4:50 GMT
updated: 25 Feb 2013 at 4:51 GMT
Are you sure that the ISO and White Balance are locked?
Check the EXIF Data of the shot images.

Without actually seeing them (the images) it's all just a guess with suggestions.

Regards, Smooth cool
www.omnipix.com.au
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: exposure problems
Posted: 25 Feb 2013 at 8:10 GMT

kasenyee said:

I'd share some of the images but have no clue how to.

You can upload jpeg copies of images to www.ge.tt (up to 250MB without creating an account). Then post a link to the images here.

John
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Nick Fan
[NodalNinja]

Posts: 770
Location: Hong Kong
Registered: 26 May 2006
Re: exposure problems
Posted: 25 Feb 2013 at 14:18 GMT
not sure if the Active D-lighting has any effect in manual mode. but you can try to turn it off.
Note that the exposure variation can simply be vignetting of your lens.

Nick
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kasenyee

Posts: 126
Location: Toronto, Canada
Registered: 22 Jun 2012
Re: exposure problems
Posted: 25 Feb 2013 at 23:03 GMT
double checked, every was set to manual.
I was shooting in raw, would D-light affect it in any way?
finally managed to upload them, here's the link.
the problem comes in images 5/6/7/ and 14/15/16. that area seems to change in exposure. I see it even more when i do a stitch - using PTGui

ge.tt/5tkJvRZ/v/0?c
ge.tt/5tkJvRZ/v/0
not sure which one is the acrtual link so i'm tryign both

thanks for all your help guys
much appreciated!
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No One

Posts: 541
Location: Sri Lanka
Registered: 14 May 2004
Re: exposure problems
Posted: 26 Feb 2013 at 0:01 GMT
If you are not shooting in RAW format you should be. If you are, what are you using to convert the Raw images to your workflow? Understand, Adobe's RAW converter will adjust each image based on the image, so two manual exposures may get very different conversions with the "same" settings.

You may want to try Photo Ninja Raw converter, it has a Absolute mode which will do much more consistent results from RAW files vs PS ACR. It also will produce dramatically better base images from Auto convert.

www.picturecode.com/index.php

Robert
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kasenyee

Posts: 126
Location: Toronto, Canada
Registered: 22 Jun 2012
Re: exposure problems
Posted: 26 Feb 2013 at 3:25 GMT
I'm using LR4 and apply the edits to all the images so they're identical, then export them as tiffs/jpg
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Smooth

Posts: 4310
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
Re: exposure problems
Posted: 26 Feb 2013 at 8:24 GMT
I'm not seeing any major issue with this image set as far as blending is concerned?

Here is the Panorama Editor preview where no blending has taken place.



Here it is after allowing PTGui to blend.


Are you getting different results?

Regards, Smooth cool
www.omnipix.com.au
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: exposure problems
Posted: 26 Feb 2013 at 9:01 GMT
Smooth, If you reverse the order of the images, the Panorama Editor windows looks like this:

This is unblended and without correction for vignetting/exposure. The auto correction feature isn't able to correct this very effectively. It may be that the vignetting is asymetrical or maybe the exterior light was changing as clouds floated past. But, as you say, PTGui's blending is able to hide these differences.

John
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OrmarT

Posts: 111
Location: Tallinn, Estonia
Registered: 11 Mar 2006
Re: exposure problems
Posted: 26 Feb 2013 at 9:27 GMT
I have a feeling, there is some amount of "auto" correction built into ACR/LR converter. Often I get nadir image darker from those. Using some other converter, problem doesn't exist. Sure, ACR give a lot more details from lights.
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hindenhaag

Posts: 901
Location: Netherlands
Registered: 7 Mar 2010
Re: exposure problems
Posted: 26 Feb 2013 at 9:33 GMT
updated: 26 Feb 2013 at 9:36 GMT
Kasenyee,

I feel like this would be a place to shoot HDRI. You can try to get the info right by underexpose the info from the windows but over expose the light by the floor for example. You could vary from +2EV, 0 EV, -2EV for example. Then make one shot out of the three and stitch.

Is this what you mean?

Heinz
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Smooth

Posts: 4310
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
Re: exposure problems
Posted: 26 Feb 2013 at 11:08 GMT

John Houghton said:

Smooth, If you reverse the order of the images, the Panorama Editor windows looks like this:

This is unblended and without correction for vignetting/exposure. The auto correction feature isn't able to correct this very effectively. It may be that the vignetting is asymetrical or maybe the exterior light was changing as clouds floated past. But, as you say, PTGui's blending is able to hide these differences.

John
I didn't see any need to reverse the image order as they were shot in the correct rotation.

Anyway the upshot is, the images are fine (as far as blending is concerned). So we wait to find out what the result complaint is or differences are...

Regards, Smooth cool
www.omnipix.com.au
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John Houghton

Posts: 3934
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
Re: exposure problems
Posted: 26 Feb 2013 at 13:15 GMT

Smooth said:

I didn't see any need to reverse the image order as they were shot in the correct rotation.

There was no need to reverse the images, but doing so reveals a difference in tone between neighbouring images, which is what's troubling Kasenyee. PTGui doesn't mind which way the camera is turned.

John
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