White balance "how-to" question

[Crossfire905]

Specifically, "how to" do an accurate white balance after shooting with a camera which doesn't have a manual white balance mode...

My camera [HP PhotoSmart C618, same as a Pentax EI-200] doesn't have a manual white balance -- only Auto, Daylight, Tungsten, and Fluorescent. Usually it's right, but sometimes it isn't. However, I have an adapter which lets me use 37mm threaded filters and lenses, and I have a wide-angle lens with 49mm front threads, so I can use 49mm filters too.

I can also use 37mm and 49mm lens caps. I've seen "white balance caps" which seem to be made for use on cameras which do have user/manual modes, and while I know I wouldn't be able to use those to set my white balance in-camera [not with this camera, anyway], I'm wondering whether I could use them to get a reference point for post-processing after I unload my images.

I use Picture Window Pro for most of my work. It has a selective color/hue correction feature ["drag this color to that color"], and also has "add/remove" virtual filters for highlights, midtones, and shadows, so that's really what I'm wondering about... If I shoot a "blank white scene" through one of these caps, could I then use that as a reference to adjust my highlight/midtone color balances, maybe to get rid of unwanted casts and tints without having to guess at it?

Some experimentation would be in order, I'm sure. But would this work at all? Is it any different than, say, using white cards?

[kencaleno]

Sunrise/sunset 2400-3000 Kelvin……………………Use Auto white balance
Tungsten lighting 3200-3500 Kelvin ……………………Use tungsten/Incandescent white balance
Fluorescent lighting 4000 Kelvin …………… Use fluorescent White balance
Early morning/afternoon sun 4000 Kelvin…….Use auto white balance/ --fluorescent white balance
(Magenta filter) to counter greenish cast on skin from foliage if under trees or on really green grass
Noon sun/Sun overhead…5000-6500 Kelvin…………………….use Cloudy White balance
Flash photography in daylight 5500 Kelvin ………………………Use Flash White balance
Deep shade………………….6500 Kelvin…………………………Use cloudy/shade white balance

Regards, Ken

[Crossfire905]

Well, there's a chart I'll have to memorize, I guess...

Originally Posted by kencaleno

Noon sun/Sun overhead…5000-6500 Kelvin…………………….use Cloudy White balance
Flash photography in daylight 5500 Kelvin ………………………Use Flash White balance
Deep shade………………….6500 Kelvin…………………………Use cloudy/shade white balance

?

No such settings on this camera.

[wulf]

For post-processing, take a look at this discussion. Partway down, you'll find my recipe for picking a grey point.

If you are only interested in post-processing, because of the limitations of your camera, we can move this discussion across to the appropriate forum.

Wulf

[Crossfire905]

Originally Posted by wulf

If you are only interested in post-processing, because of the limitations of your camera, we can move this discussion across to the appropriate forum.

By all means, moderate away. I just figured white balance was a "lighting" thing.

For post-processing, take a look at this discussion. Partway down, you'll find my recipe for picking a grey point.

GIMP? I wouldn't know anything about that.

I don't think Picture Window has such tools, but I'll admit that I'm not 100% proficient in every single feature it has to offer. One thing I can do is adjust the overall balance of highlights, midtones, and/or shadows by adding or removing tints -- either automatically [highlights and shadows only; there's no "Auto" for midtones], by using the color picker, by using the filter bank [a collection of virtual filters in commonly-used values such as the 1A], or by setting some other arbitrary value. There's also the selective color correction tool -- pick a hue, drag it to another hue on a color wheel [and, optionally, change its brightness]. Sometimes "Auto" looks right, sometimes it doesn't, and sometimes I just have to guess. I haven't been in the habit of using the camera's manual balance settings very often, but I'm finding that they do sometimes make a difference.

At any rate, what I'm really wondering about is those "white-balance" lens caps. I can imagine how they work -- take a shot through one, and you get what "white" looks like under that particular lighting condition, right? If one happens to have a camera which can use that to make its own internal adjustments, that's great, but I don't. I assume that I could use such a shot as a reference point after unloading the pics -- "here's what white looked like when I took it" -- and use that for making corrections if necessary. I'm thinking, how did they do it before the digital days anyway?

They're not expensive, but should I bother with getting one [or two] when my camera doesn't have a user-defined white balance mode?

Just for the record, it's not like I have major balance problems on every single shot I get out of this camera. Here's a good SOOC example of something where I personally don't see the need for any color adjustment at all. [Daylight, no flash, auto-everything.] I'm just hoping to make corrections a bit easier and more accurate on those shots where I know the lighting is tricky, and/or where I'm really hoping for the best results I can possibly manage. [But, honestly, isn't that really every shot? ]

[LoveDSLR]

WhiBal card--check it out (at least read about how to use it to fix/set white balance in pp)

You don't have to buy one, just include a gray card in one of the photo or a separate one. Then use that photo (gray card/WhiBal) to set your WB.

One of the features in Picture Windows Pro (from what I read):
"The 7-point mode allows you to include a gray scale in your image and get extremely accurate color balance across the entire tonal range."

[wulf]

The white balance caps are for use with your camera's ability to manually create a setting for a given scene. If your camera can't do that, then caps (and cards) are pretty useless.

The only way they might help is if you take a picture with them in. If you can adjust that to show white (or 80% pure grey or whatever is on the card) you might be able to apply the same changes to the photo to also set the white balance.

BTW, the Gimp is a very powerful and free bit of image processing software. If your camera is limited, you may need a more flexible tool than Picture Window (which I've not heard of) to make up for it.

Wulf

[Crossfire905]

Originally Posted by LoveDSLR

One of the features in Picture Windows Pro (from what I read):
"The 7-point mode allows you to include a gray scale in your image and get extremely accurate color balance across the entire tonal range."

Y'know, that actually doesn't sound familiar at all, but if you got that from the web site [www.dl-c.com], it's probably something in the current version, which is not what I have. [Old computer = old OS = old version of Picture Window. v3.5.09, to be specific. To put it another way, newer versions of Picture Window require an OS which won't run on my old machine.]

Responding to Wulf:

The only way they might help is if you take a picture with them in. If you can adjust that to show white (or 80% pure grey or whatever is on the card) you might be able to apply the same changes to the photo to also set the white balance.

Yeah, that's pretty much what I was thinking -- reference points for adjusting later, if necessary. Not that I have any intention of slapping a white cap on the camera for a new reference shot every time I point the camera at a different scene... Nor do I need to -- nothing I do is so critical that it requires 100% completely accurate color, and if it were that critical, I'd probably be using a more sophisticated camera anyway.

Better color under weird light, and the best color I can manage on those shots where I really want things to look right. That's what I'm looking for. And you believe these caps could help in PP? I can get 'em on eBay for only $7.95 each [plus state sales tax, since the seller also happens to be in California], so it's hardly a major expenditure, but is it even worth that much in my case?

I've heard of the GIMP -- I just know exactly jack squat about it, that's all.

Older GIMP versions (2.0.x) could also work with older versions of Windows such as Windows 95 but they are not supported anymore.

Naturally. COULD work...?