Sorta OT: Auto White Balance on the FX1

riredale wrote on 5/22/2006, 8:32 PM
This is probably a really dumb question, but here goes:

My FX1 HDV camera has a couple of White Balance modes. You can manually balance it by pointing at a white object and hitting the button, or you can put it in "Auto White Balance." Near as I can tell, however, there is no "Auto" about it--the camera just defaults to outdoor or indoor color temperature, as set in a menu item.

I had always thought that a camcorder would actually look at the overall scene and make a best guess as to what to make white. At least that's how my little Sony TRV8 miniDV camera did it. But it appears that the FX1 just sets the color to outdoor (or indoor) and that's that.

The reason for my question is that I used AWB in a shot yesterday that stretched over a couple of hours. It was an indoor performance with lots of indirect lighting, and by the end of the shot everything was turning bluer as the sun got lower on the horizon. If "Auto" doesn't really mean that the FX1 will gradually change as the lighting changes, then I will have to manually do a white balance every now and then.

Am I missing something?

Comments

Spot|DSE wrote on 5/22/2006, 9:17 PM
Nope...you've got the gist of it. If the light is changing, you'll need to white balance reasonably regularly anyway. Or, turn the cam off/on, and let it see light. If I recall, that resets it's view. I might be incorrect, I don't use the auto anyway.
Serena wrote on 5/22/2006, 9:47 PM
Just did a check to make sure about it. When you switch the FX on it does a surprisingly good job of getting white balance (in auto). You wouldn't want a camera to continuously adjust white balance on the scene (think what would happen as you panned across green gardens to red roofed cottages. Maybe your other camera had a separate sensor checking ambient light falling on the camera (like a colour temp meter), but I'll be surprised. With the camera in manual it will adjust WB when you press the WB button. This is a good thing to get very familiar with.
Exercise: in manual mode turn on the camera under daylight and allow self set WB. Trundle (camera on) into a room lit by globes and you'll have a very orange image. Press WB and the colours will adjust. Obviously you should do this on a white card, but having tried it on an ordinary room I'm surprised how well it does.
You should set WB at the start and adjust whenever the light is changing; really it's much better not to rely on the auto function but it's workable. You can preset two conditions in addition to the default daylight and incandescent (extra settings A & B), which might be useful sometimes. I didn't try that exercise in fully auto.
johnmeyer wrote on 5/22/2006, 10:26 PM
I just checked page 27 of the manual (helps to have a PDF version of the manual). For automatic white balance, you simply have to have the AUTO LOCK switch set to AUTO. Once you are on manual, the WB must be set manually, along with the other functions.

Auto white balance does have its place, such as when you follow the bride and groom from indoors to outdoors. Too darn many things to fiddle with to deal with WB at that point. However, it can definitely cause problems. The panning example given earlier in fact DOES cause the WB to change on one of my cameras, although you have to stay focused on the new lighting for many seconds before things change.
Serena wrote on 5/22/2006, 11:48 PM
John, in manual mode pressing WB toggles between auto and manual (as on the other buttons). That's why I got the camera out -- to make sure what it actually did.
MH_Stevens wrote on 5/23/2006, 9:12 AM
Serena:

As iredale suspects the FX1 does not have an "auto" WB in manual mode. What is referred to as Auto is just two standard presets, one for in and one for out.

For true AWB the camera must be in full auto mode with auto lock on. As you say, the AWB does a good job. I've always thought what a pity it is one can't use it to set the camera WB and then turn on manual for exposure. - Maybe it does this? I'll do some tests today.

Michael
riredale wrote on 5/23/2006, 10:08 AM
Well, color me mistaken.

After reading the replies (thanks to all), I took my FX1 and turned it on in an incancescent room. Yup, it balanced out to white "AUTO"matically, just like it said it would. Then I turned it off, and took it to an outdoor window. After turning it on, it balanced to outdoor light automatically also. So the default choice in the menu of outdoor or indoor I guess is just a suggested starting point for the balance circuits in the camera.

Then I took the outdoor-balanced camera, and moved to the incandescent room. As expected, everything looked yellow in the viewfinder. I set the camera down and came back 5 minutes later. It had rebalanced to the incandescent light, just as my old TRV8 had done! So it does try to seek an overall white in the scene, only with a time frame of perhaps 5 minutes. So AUTO means automatic. I guess the blue scene in the recording of a few days ago happened because the lighting changed too quickly for the auto circuit to keep up. Clouds in the sky can do that, I guess.

I don't know how I could have done this "white balance" manually during the performance, since there would be an obvious glitch at the time of balancing. At least with the auto method, I can go back in post and keyframe the color balance corrections--assuming that it's not too far out of whack.
Serena wrote on 5/23/2006, 8:37 PM
Michael,

Funny thing that -- manual is the default operating mode as far as I'm concerned, which why I got the camera out before answering the query. In fact, if we're falling back on the instructions, on page 27 of the users manual after discussing setting of WB we read: "To restore automatic white balance press WB or set switch to AUTO LOCK." Similarly IRIS (p 28). GAIN (p29). SHUTTER SPEED (p30). You must set HOLD if you don't want to be caught by that.

Serena
JohnnyRoy wrote on 5/24/2006, 6:57 AM
> As iredale suspects the FX1 does not have an "auto" WB in manual mode. What is referred to as Auto is just two standard presets, one for in and one for out. For true AWB the camera must be in full auto mode with auto lock on.

Sorry but Serena is correct. Everything that is available when the camera is in Auto Lock mode is also available in Auto/Manual mode (middle position). That’s what the 4 buttons (Iris, Gain, Shutter Speed, & Wht Bal) are for next to that switch. They turn each individual feature from auto to manual.

Auto Lock is a quick way to place them all in auto mode together, while the AUTO/MAN setting allows for individual toggle from auto to manual. So you still get AWB when the camera is in Auto/Man mode with the WHT BAL button deselected.

> So the default choice in the menu of outdoor or indoor I guess is just a suggested starting point for the balance circuits in the camera.

No, the default choice of indoor/outdoor is only use in manual mode. It has nothing to do with auto mode. In manual you have three settings: Default, A & B where default will be either indoor or outdoor depending on how you set this up in the menu, and A & B will be whatever you manually white balanced them to last. Auto mode bypasses all this and just automatically white balances based on what the camera sees.

~jr
MH_Stevens wrote on 5/24/2006, 9:04 AM
Good Morning All:

I have been out early with the FX1 and Serena and Johnny were right.

To confirm I will note here what I found from experiment that I believe clarifies a somewhat unclear manual:-
Firstly, if A or B, or one of the two presets is NOT showing on the data screen then the camera IS in AWB.
Secondly, you CAN switch back and forth from AWB to A/B in either Auto or Manual mode. Only "AutoLock" mode is AWB only.

BUT I noted the histogram was squashed when I moved to AWB. In my first test with A/B WB I had a histogram from 3 to 254 (while the Waveform showed 4% to 100%) but when I switched to AWB the histogram shrunk to 18 to 251 (Waveform from 8% to 96%.) I also noted a CHANGE IN EXPOSURE evidenced by a change in the Zebras, even thought when I went from Auto to Manual I set the manual exposure to the same settings as Auto used. Switching from AWB to A/B in Auto mode may NOT be a good idea.

Thanks all for getting me to look into this.

Michael
johnmeyer wrote on 5/24/2006, 6:21 PM
Very useful testing. Thank you!