Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-03-2019, 06:04 AM   #1
Pentaxian
swanlefitte's Avatar

Join Date: May 2015
Location: New Orleans
Photos: Gallery
Posts: 2,240
AWB, how and when the camera decides?

Been wondering about auto white balance. First when is it determined? Is it after the shot during the processing or during metering? If it's after that's all I need to know. If not is it based on my spot or matrix metering or something else if I lock focus and recompose is it locked in too? There are more questions but I suspect the camera analyses the histogram after to decide, in which case I wonder if using it will slow down the buffering in muti-shot.

04-03-2019, 06:59 AM   #2
Pentaxian
CarlJF's Avatar

Join Date: Sep 2014
Location: Quebec City
Posts: 1,074
It's applied during processing. This is why white balance can easily be corrected from the raw file after the shot. The raw file will be the same no matter which WB setting was used while shooting (outside of the metadata describing which WB was selected to be applied during processing).
04-03-2019, 07:10 AM   #3
Pentaxian
swanlefitte's Avatar

Join Date: May 2015
Location: New Orleans
Photos: Gallery
Posts: 2,240
Original Poster
Thanks.
So what determines it? I mean even if I set the white balance before I shoot it is applied after. Is it determined after or before?
04-03-2019, 07:45 AM   #4
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 3,368
I'm pretty sure AWB uses the data from the shot and that it is built into the Milbeaut processor. The processor also has to analyze the sensor data to create the review image on the back panel display and create the JPG version of the image.

It should be pretty easy to test if AWB creates a delay. Just start with a freshly formatted SD card, set the white balance to "daylight", and shoot a continuous-hi series of a stop watch. Download the data, reformat the card and repeat the shot with white balance set to AWB. You might also try the experiment using the multi-AWB setting which does an even more complex analysis of the scene.

04-03-2019, 07:49 AM   #5
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 32,897
QuoteOriginally posted by swanlefitte Quote
So what determines it?
The camera does an analysis of the capture data to generate four so-called white balance multipliers used for scaling the RGBG channels when processing the data to a viewable image. These four numbers are stored in the MakerNotes section of the EXIF for use by compatible RAW converters and are also used directly for in-camera JPEG.


Steve
04-03-2019, 08:21 AM   #6
Pentaxian
swanlefitte's Avatar

Join Date: May 2015
Location: New Orleans
Photos: Gallery
Posts: 2,240
Original Poster
Alright, it's determining after the fact and my buffer might fill a frame or 2 earlier. I won't test it because it's not worth the shutter wear.
I was hoping it was before the photo because I could manipulate it. Still will in Photoshop. Now for panorama I have to switch the setting or batch process multi shots which takes time. I hate switching settings because I am notoriously forgetting to switch them back. Would have been nice to focus on some white thing out of frame to read off of and keep that locked, especially with a manual focus lens.
04-03-2019, 08:38 AM   #7
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 3,368
QuoteOriginally posted by swanlefitte Quote
Alright, it's determining after the fact and my buffer might fill a frame or 2 earlier. I won't test it because it's not worth the shutter wear.
I was hoping it was before the photo because I could manipulate it. Still will in Photoshop. Now for panorama I have to switch the setting or batch process multi shots which takes time. I hate switching settings because I am notoriously forgetting to switch them back. Would have been nice to focus on some white thing out of frame to read off of and keep that locked, especially with a manual focus lens.
If you shoot RAW, you don't have to worry about these WB settings at all. The WB setting would only affect the thumbnail and may affect the default display of the RAW file in you software but it does nothing to the RAW data itself.

And you can "focus on some white thing out of frame to read off of and keep that locked." That's the "manual WB" setting.

P.S. I seriously doubt AWB delays anything. The processor has to analyze the image anyway before it can make the JPG (or the thumbnail). That analysis is almost certainly computed as the data arrives from the sensor so that it is completed merely an instant after the processor gets the last pixel from the sensor.
04-03-2019, 08:44 AM   #8
Pentaxian
CarlJF's Avatar

Join Date: Sep 2014
Location: Quebec City
Posts: 1,074
QuoteOriginally posted by swanlefitte Quote
Would have been nice to focus on some white thing out of frame to read off of and keep that locked, especially with a manual focus lens.
Well, by definition the WB can't be "locked" and auto at the same time, like any other settings. The easisest way to lock the WB is to switch the one of the preset. The daylight preset will work fine most of the time and will give you the exact same WB on all shots.

If you want to use a white card, choose custom WB on the camera and select the white card as the target to use for WB and use this for the following shots. It's really not difficult to do... I've done it many times in unusual lighting situation. This also can be done after the shooting either by software (any decent one will allow to do this) or using in camera processing. This last option will take only a few seconds to generate jpgs SOOC balanced with the custom WB from the selected target...

04-03-2019, 08:45 AM - 1 Like   #9
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 32,897
QuoteOriginally posted by photoptimist Quote
And you can "focus on some white thing out of frame to read off of and keep that locked." That's the "manual WB" setting.
That is why many pros include a frame with a Macbeth color checker before the start of an outdoor session. That frame may be used to apply white balance in PP and/or to create a custom import profile for Lightroom and ACR.


Steve
04-03-2019, 08:54 AM   #10
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 32,897
QuoteOriginally posted by CarlJF Quote
If you want to use a white card, choose custom WB on the camera and select the white card as the target to use for WB and use this for the following shots. It's really not difficult to do... I've done it many times in unusual lighting situation.
Yep!

The important thing to remember, however, is that even a white or gray card sampling is limited to the light striking that surface and will never generate more than the four multipliers used for biasing the color balance.


Steve
04-03-2019, 09:13 AM   #11
Pentaxian
swanlefitte's Avatar

Join Date: May 2015
Location: New Orleans
Photos: Gallery
Posts: 2,240
Original Poster
I can lock autofocus so why not think autocolor could too. I know I can set my own wb but that takes time in menus. Most of the time I don't want true color but for a fast panorama it sucks changing everything. I changed my wb and then an opportunity arose and I had the wrong settings. That means even more time. Now I am sure when I am done i will forget to change back meaning even more time in post redoing things. A quick aim holding a button down to lock the readings like half shutter press for autofocus or green button for auto metering would be nice.
....still waiting on my panorama to merge this whole time writing but then it took more minutes loading the batch to apply settings.
04-03-2019, 09:28 AM   #12
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 3,368
QuoteOriginally posted by swanlefitte Quote
I can lock autofocus so why not think autocolor could too. I know I can set my own wb but that takes time in menus. Most of the time I don't want true color but for a fast panorama it sucks changing everything. I changed my wb and then an opportunity arose and I had the wrong settings. That means even more time. Now I am sure when I am done i will forget to change back meaning even more time in post redoing things. A quick aim holding a button down to lock the readings like half shutter press for autofocus or green button for auto metering would be nice.
....still waiting on my panorama to merge this whole time writing but then it took more minutes loading the batch to apply settings.
If you shoot RAW or RAW+, you don't need worry about WB at all. It's only if you want decent SOOC JPGs that WB is an issue.

The key challenge with WB is that it is NOT about the colors in the scene, it's about the color of the light illuminating the scene. That's why AWB is more complicated than AF and the camera has to carefully analyze the actual sensor data and guesstimate the color of the light source based on the non-whiteness of the whitest objects in the scene. But if you know the light source for a panorama -- e.g., sunlight -- then pick "Daylight WB" as shoot away. Note that even for sunrise and sunset panoramas, Daylight WB does a nice job because retains the warmth of the light rather than make the scene look like it was shot midday.
04-03-2019, 09:38 AM   #13
Pentaxian
CarlJF's Avatar

Join Date: Sep 2014
Location: Quebec City
Posts: 1,074
QuoteOriginally posted by swanlefitte Quote
I can lock autofocus so why not think autocolor could too. I know I can set my own wb but that takes time in menus. Most of the time I don't want true color but for a fast panorama it sucks changing everything. I changed my wb and then an opportunity arose and I had the wrong settings. That means even more time. Now I am sure when I am done i will forget to change back meaning even more time in post redoing things. A quick aim holding a button down to lock the readings like half shutter press for autofocus or green button for auto metering would be nice.
....still waiting on my panorama to merge this whole time writing but then it took more minutes loading the batch to apply settings.
If you only need constant WB, the easiest is to use one of the presets. For landscape panomarama, the daylight setting should do just fine most of the time. Yes, you have to go through the menu but it's only a matter of seconds... Most camera bodies even have a WB button which makes this operation a quick and easy operation. The WB button is no more difficult to press than the green button... Just press the WB button, select the daylight preset, press OK. It's not like it's a complex or time consuming operation.

It's even possible to make it quicker by recording all the settings in one of the user mode on the dial. Just turn the dial to the user mode when making panorama and turn it back to whatever it was before when finished... Could not be much simpler or faster than that.

As for forgetting to going back to AWB, it's not different than any other settings. Do you forget to turn back on AF ? Or forget to get out of M mode ? In fact, it's even more minor than mos other settings since it can be corrected afterward with any adverse effect on the picture.

---------- Post added 04-03-19 at 12:51 PM ----------

QuoteOriginally posted by photoptimist Quote
But if you know the light source for a panorama -- e.g., sunlight -- then pick "Daylight WB" as shoot away. Note that even for sunrise and sunset panoramas, Daylight WB does a nice job because retains the warmth of the light rather than make the scene look like it was shot midday.
In fact, for this reason, many people even prefer to stick to "Daylight" WB instead of AWB for anything but artificial lighting. Some photography teachers even recommend this to their students.

Last edited by CarlJF; 04-03-2019 at 10:25 AM.
04-03-2019, 10:00 AM - 1 Like   #14
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 12,890
QuoteOriginally posted by swanlefitte Quote
I can lock autofocus so why not think autocolor could too.
You can absolutely set a manual white balance exactly the way you do manual focus and manual exposure.

You can even set it to the same degrees Kelvin. You'll get consistency right across your panorama.



04-03-2019, 10:32 AM   #15
Pentaxian
swanlefitte's Avatar

Join Date: May 2015
Location: New Orleans
Photos: Gallery
Posts: 2,240
Original Poster
I am going to reset my settings now. I forgot. I forget iOS settings I forget to switch back to manual and I forget to drop 2 second delay all the time.
When I wait 10 minutes for a butterfly to land and miss my 1 shot it's not fun.
Any change is a major chance I miss a shot so I am against doing it.
I shoot raw and color balance in post . I have grey cards and color checkers I rarely use. Awb gets me close so I use it.
Follow a monarch around in shade then with a blue wall etc. No time to menu dive and set wb. Hardly time to frame and focus. I was hoping for something faster, that's all. I compose and reframe more often than changing my focus point because it's faster than the controller esp when my controller is toggled to wb.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
button, camera, daylight, light, mode, operation, panorama, photography, press, settings, technique, time, wb
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
People Ebony decides to wear some glitter clackers Post Your Photos! 4 11-17-2017 10:41 PM
AF: Which Decides.. Camera or Lens? delboy65 Pentax SLR Lens Discussion 8 05-24-2016 10:44 AM
K-x AWB better than K-5 AWB WerTicus Pentax DSLR Discussion 14 12-20-2010 02:31 PM
So my 2 Part Question - Is there absolute truth and who decides. joodiespost General Talk 61 10-15-2010 03:28 AM
idle curiosity: who decides prime focal lengths? WMBP Pentax SLR Lens Discussion 11 06-04-2009 08:29 PM



All times are GMT -7. The time now is 04:53 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top