DSLR white balance

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Jesse
Posts: 69
Joined: Sun Dec 11, 2016 6:40 pm

DSLR white balance

Post by Jesse »

Hello,

I’ve been noticing that my daylight whitebalance setting is pretty close, but not perfect. The background appears a little grey.

What is the correct way to whitebalance and meter a brightfield scene?

Should I aim to blow out the background or should I attempt to get the background perfectly white without blowing the highlights?

Thanks

JohnyM
Posts: 463
Joined: Tue Dec 24, 2013 7:02 am

Post by JohnyM »

Gray background means your WB is ok. White balance would be wrong if image was yellowish/blueish or in extreme cases color tinted.

I guess what you mean, is that in transmited brightfield photography, you would like to get nice, shiny white background?

In that case, i cant see it done without sacrificing highlights unless you shoot RAW. With RAW file, it's rather eazy to push/pull background/highlights.

If you're willing to trade resolution, stopping down the aperture increases contrast. That usually means your subject will be relatively darker against the background, making it eazier to obtain snow-white background.

What you want:
Image
What you get:
Image

hero
Posts: 72
Joined: Mon Jul 17, 2017 12:38 pm
Location: California

Post by hero »

Metering always attempts to find the exposure that would make the overall image 18% (middle) gray. Some camera metering methods are more sophisticated than others, and apply different weights to parts of the scene (e.g., center-weighted average, spot, evaulative, partial) but the target brightness is always middle gray. This is why, when metering a scene that should appear predominantly white, the selected exposure almost always underexposes; conversely, when metering a scene that should be predominantly black, the result is overexposure.

To compensate for this, you can choose to apply exposure compensation, or you can choose manual exposure. My advice, for a scene that is backlit, is to expose for the midtone part of the scene, and let the highlights go where they go. Due to the uncertainty of the dynamic range in your scene (I don't know, for example, whether your highlights are +5, +10, or +15 EV brighter than your midtones), it is not possible to set a rule for exposure based on the brightest parts of your scene. The sensible approach is to capture as much tonal range as possible in the part of the scene that contains the information you want to capture, and that is usually in the midtones.

In regard to white balance, keep in mind that the camera sensor does not change its sensitivity to different wavelengths based on a white balance setting--the sensor gain characteristics are fixed. What changes is simply a processing instruction for the resulting RAW file (if choosing to shoot RAW) or the post-processed JPEG. This is why shooting in RAW is advantageous; if the desired WB correction is severe (which can occur if wanting to adjust for strongly colored light sources in a scene), the JPEG is "cooked"--the original color data is lost, whereas the RAW file can be non-destructively adjusted after the shot is taken. When saving images in RAW format, I do not worry about WB at the time of the shot. Correct metering is far more important.

RobertOToole
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Re: DSLR white balance

Post by RobertOToole »

Jesse wrote:Hello,

I’ve been noticing that my daylight whitebalance setting is pretty close, but not perfect. The background appears a little grey.

What is the correct way to whitebalance and meter a brightfield scene?

Should I aim to blow out the background or should I attempt to get the background perfectly white without blowing the highlights?

Thanks
For best results you can easily set-up a custom profile for the camera you are using and even warm or cool in steps. The profile loads into LR or PS.

See: http://xritephoto.com/colorchecker-passport-photo

Image

Depending on your camera body model you can always underexpose to protect the highlights and brighten later, with most of the newer bodies you can underexpose and lighten in post production without any negative effect.

See: www.photonstophotos.net or

Google "ISO-Less" or "ISO-Invariant sensor" for more info.


http://www.photonstophotos.net/Charts/P ... kon%20D850

Image

RobertOToole
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Re: DSLR white balance

Post by RobertOToole »

Jesse wrote:Hello,

I’ve been noticing that my daylight whitebalance setting is pretty close, but not perfect. The background appears a little grey.

What is the correct way to whitebalance and meter a brightfield scene?

Should I aim to blow out the background or should I attempt to get the background perfectly white without blowing the highlights?

Thanks
Forgot another solution. I used to work in commercial photography and for every job, every shoot we set a custom white balance for the scene we were about to shoot.

Depending on the body you shoot something neutral a grey card or white card (or blue card to warm the image or green card for uni-wb) and go into the menu and select 'custom white balance' and choose the white card image. Then you set the white balance setting to custom, the pictagram sometimes resembles a flower.

This works great but can be slow the first few times you use it.

Hope that helps.

Robert

Jesse
Posts: 69
Joined: Sun Dec 11, 2016 6:40 pm

Re: DSLR white balance

Post by Jesse »

RobertOToole wrote:
Jesse wrote:Hello,

I’ve been noticing that my daylight whitebalance setting is pretty close, but not perfect. The background appears a little grey.

What is the correct way to whitebalance and meter a brightfield scene?

Should I aim to blow out the background or should I attempt to get the background perfectly white without blowing the highlights?

Thanks
Forgot another solution. I used to work in commercial photography and for every job, every shoot we set a custom white balance for the scene we were about to shoot.

Depending on the body you shoot something neutral a grey card or white card (or blue card to warm the image or green card for uni-wb) and go into the menu and select 'custom white balance' and choose the white card image. Then you set the white balance setting to custom, the pictagram sometimes resembles a flower.

This works great but can be slow the first few times you use it.

Hope that helps.

Robert
I have a grey card, but I'm not sure how you'd use one under a microscope.

anoldsole
Posts: 24
Joined: Tue Feb 27, 2018 5:49 pm

DIY color check micro

Post by anoldsole »

Has anybody tried cutting up a color check card into smaller bits and making a tiny version? There are small ones for sale but they are quite pricey. I've got a spare lying around, before I destroy it is there an obvious reason it wouldn't work?

RobertOToole
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Re: DSLR white balance

Post by RobertOToole »

Jesse wrote:
RobertOToole wrote:
Jesse wrote:Hello,

I’ve been noticing that my daylight whitebalance setting is pretty close, but not perfect. The background appears a little grey.

What is the correct way to whitebalance and meter a brightfield scene?

Should I aim to blow out the background or should I attempt to get the background perfectly white without blowing the highlights?

Thanks
Forgot another solution. I used to work in commercial photography and for every job, every shoot we set a custom white balance for the scene we were about to shoot.

Depending on the body you shoot something neutral a grey card or white card (or blue card to warm the image or green card for uni-wb) and go into the menu and select 'custom white balance' and choose the white card image. Then you set the white balance setting to custom, the pictagram sometimes resembles a flower.

This works great but can be slow the first few times you use it.

Hope that helps.

Robert
I have a grey card, but I'm not sure how you'd use one under a microscope.
Would help if you mentioned that it was a microscope from the start, maybe in the subject line?

:roll:

Next time list the equipment you are asking about and you will get a more useful response and you wont waste people's time that are trying to help.

BTW, the Passport card is used to set a profile for a specific camera body color response profile. You would know that if you followed the link. It has nothing to do with the lens or objective attached but it would be ideal to calibrate it with a lens.

FYI, I un-followed this thread (so I won't see any more posts here).

Beatsy
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Location: Malvern, UK

Re: DIY color check micro

Post by Beatsy »

anoldsole wrote:Has anybody tried cutting up a color check card into smaller bits and making a tiny version? There are small ones for sale but they are quite pricey. I've got a spare lying around, before I destroy it is there an obvious reason it wouldn't work?
I use colour correction a lot (X-Rite ColourChecker Passport and LumaRiver s/w to create ICC profiles for Capture One - to use with Sony cameras). It's mostly for product photography, but often for all my other photography too. It's amazing how certain colours can completely disappear under certain lighting conditions when not properly profiled and corrected (purples going blue-ish or too dark, and that kind of thing).

For macro, I took separate shots of each square of the Passport and composited them into an image of the whole colour checker (just pasting colours over their relevant squares using Affinity Photo). That composited image with "as shot" colours added, then went through the usual workflow to create a profile. No need to chop up the colour checker.

I did separate profiles for each of my main macro-lighting arrangements with a 5x Mitty, MP-E 65mm and Minolta 5400. The profiles for each lens were *extremely* similar under each light setup though - so I didn't bother doing any other lenses (yet).

I recently managed to (almost) match the physical colour checker with it's own on-screen photograph. Pretty amazing considering one is reflected light and the other is emitted (and both shot with a different camera to the one used to take the on-screen picture)....
Image

Deanimator
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Joined: Tue Oct 23, 2012 7:01 pm
Location: North Olmsted, Ohio, U.S.A.

Re: DSLR white balance

Post by Deanimator »

RobertOToole wrote:Forgot another solution. I used to work in commercial photography and for every job, every shoot we set a custom white balance for the scene we were about to shoot.
I literally HAVE to do that with Jansjos, or I get a blue cast to my images.

At least in a Canon EOS, it's easy to do.

Chris S.
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Location: Ohio, USA

Post by Chris S. »

With the caveat that I'm not very experienced in using traditional microscopes, here's a thought: Buy a roll of inexpensive PTFE plumbers' tape. Affix a piece of this tape a microscope slide. White balance on this in brightfield, then switch to your subject slide and make your images.

This thought is based on an article current at Petapixel.com: Plumber’s Tape is a Cheap Way to White Balance Photos. The article cites information indicating that when used with reflected light, such tape is a nicely neutral material for white balancing. They also say that it is translucent, requiring four wraps to be fully reflective. Not measured in the article, but by reasonable extension, such tape might be just as neutral for transmitted light. Worth a try, anyway.

I've used this sort of tape plenty of times in macro photography, but always for shimming lenses to hold them in slightly-oversized adapters--never for white balance. (I've also used it for plumbing jobs around the house, unsurprisingly.) It's quite cheap and available in any hardware store.

For macro work, my preference in white balancing is very basic: Shoot a white card under the same lighting I'll use for the actual shot, exposing to produce a peak a stop or two from the right side of the histogram. Then adjust the color temperature setting of the camera until the red, green, and blue peaks have coincident apices. I imagine that this--changing the relative amplification of the color channels--is all that automatic color balance is doing.

--Chris S.

Pau
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Post by Pau »

I just take a WB with no slide or with a blank part of the slide, or -more often- I shot raw an just use the eyedropper in a blank or neutral zone during conversion.
Be aware that changing the halogen lamp intensity it changes colour temperature
Pau

Jesse
Posts: 69
Joined: Sun Dec 11, 2016 6:40 pm

Re: DSLR white balance

Post by Jesse »

RobertOToole wrote:
Jesse wrote:
RobertOToole wrote:
Jesse wrote: What is the correct way to whitebalance and meter a brightfield scene?
Depending on the body you shoot something neutral a grey card or white card
I have a grey card, but I'm not sure how you'd use one under a microscope.
Would help if you mentioned that it was a microscope from the start, maybe in the subject line?

:roll:

Next time list the equipment you are asking about and you will get a more useful response and you wont waste people's time that are trying
Sorry, Robert. I forgot that not everyone is using a microscope here. I did say brightfield, but you’re right, I should have been more explicit.

Jesse
Posts: 69
Joined: Sun Dec 11, 2016 6:40 pm

Post by Jesse »

Pau wrote:I just take a WB with no slide or with a blank part of the slide, or -more often- I shot raw an just use the eyedropper in a blank or neutral zone during conversion.
Be aware that changing the halogen lamp intensity it changes colour temperature
I shoot raw for stills, but I don’t have quite as much flexibility when shooting video. I use the Nikon flat profile for video and unfortunately I have a tendency to not edit it much in post. That’s a bad habit and I should break it.

Normally I shoot stills in manual mode, but I may start using an auto metering mode for video as the brightness changes a bit when switching objectives. I still need to keep an eye on the ISO though, and I know I have a bit of flexibility with my brightness using filters on this scope (Nikon E600).

It sounds like fully blowing the background (similar to high key lighting) is a bad plan for brightfield as it loses detail? I guess some shade of grey is ideal? Should I aim to get as close to blowing the background as possible and back off just a tad? Or is there an ideal background brightness for contrast?

Sorry, I’m still trying to figure out my process with this new tool.

Pau
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Post by Pau »

For video my first method will work wel for WBl.
For microscope BF you need to apply the adequate exposure compensation, if most of the frame is empty about +2EV...you'll need to perform your own tests.
Pau

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