White balance

What is the forums opinion on white balance lens caps. To me they seem to be an easy way to get the correct setting but on the other hand they may just be a waste of money. Can some of the experts advise me please.
Glenafton

I've never used one. Had to read up on them.

It says "Simply flip your camera into custom White Balance mode, snap a photo with your White Balance Lens Cap on, and your camera creates a perfect profile of the actual lighting in front of you."

I wonder why the camera's built-in sensor/algorithms does not produce as good or even better reading than this? What makes this partial light through the bubble sensor in the cap thing work better? No idea.

I'd have to see it in action before I trusted it to be better. Maybe at a photo convention or something.

G

I have one, it's great for when you need/want the perfect WB on the spot. They can also be used for exposure metering too. I don't use it that often since I do most of my WB tweaking in Lightroom. However, getting it right on the spot eliminates this extra work in PP, so there's that trade off.

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Originally Posted by GB1

I've never used one. Had to read up on them.
...
I wonder why the camera's built-in sensor/algorithms does not produce as good or even better reading than this? What makes this partial light through the bubble sensor in the cap thing work better? No idea.
...

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I've never used one either. I correct in NX2 when necessary (rare).

The lens cap thing still uses the camera's sensor/algorithms, but it presents a subject which is white lit by ambient light, so the camera can get it just right (a sheet of white paper would do just the same).

When the camera is reading a normal scene the scene content is full of colours and the camera might possibly base its measure on something that is not white and get the colour balance wrong.

I use a sheet of white paper too (or the back of a business card, or anything else that is of a genuinely white shade. I think those white balance discs are very unnecessary.

I use my white lens cleaning cloth, or a white shirt, white lines on roads.
I prefer to use what is on hand and convenient at the time.

Try that technique using the cap from a can of Pringles, or some similar piece of neutral translucent plastic. :)

Bigger deal if you shoot jpeg than if raw - with raw I shoot a camera that rarely needs adjustment; with jpeg I shoot a compact that's pretty good too. I just adjust in post production and always stay in auto WB.

White Balance Caps are another quick and dirty tool, but one that doesn't always work! If the camera is one that uses a spot mode of custom white balancing (like most Canon DSLR's by default) the cap better provide even illumination over the area of the sensor that takes the measurement or it will not work properly.

For cameras like that or if the quality of 'the white' is suspect the more expensive option of the filter type (like an ExpoDisc) WB tool may be an option. Any thing white can work well as long as you remember what it was and it can be duplicated later.

These caps or filters, even the beloved Pringles can lid, do have an advantage over a white reflective surface when there is a predominant color influencing the light. If you are shooting near water, under or along side a bank of trees, in a room with a solid colored wall, even a ceiling that is a different than neutral color it can reflect from the white surface and tinge/tint/alter the Custom WB reading. Then this way of setting white balance can work much more effectively than a card.

Custom white balance measurement is important with mixed light. Then custom white balance is important to review images without concern even if correcting from RAW files later. Examples are flash and tungsten or fluorescent and daylight such as by a window or under a skylight in candid or at an event. A combination of open shade and daylight can be especially tricky and a custom WB may prevent strange tints and unwanted coloration like extra green.

Custom white balance only works well if you remember that light changes (time of day, shadows and or clouds, reflections, etc.) and if you use the same white reference throughout a shoot under the changing light conditions. Using different references for Custom WB at different time during a day can lead to a visible difference or at least additional post process work.

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Originally Posted by drg

A combination of open shade and daylight can be especially tricky

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I forgot about this - try shooting outside on a partly cloudy day and you'll really be interested in RAW workflow... Shoot the custom white balance and 30 seconds later it's really far off. Shoot it again and the same thing happens. Our eyes can get used to seeing the light level change, but learning to see the color temperature change is a whole different thing.

Jpeg with custom white balance to me would only be useful with a high volume of shots (more than you'd want to deal with in RAW) under controlled lighting. I can't think of many applications; even something like a wedding reception would have different lighting effects as you walk around the room.

Personally, Id sooner use the camera settings and correct in RAW development.

Dave

Sounds rather fun, but a white sheet of paper really will do just fine and has for over a century.