20D White Balance Question - DPChallenge Forums

Canon EF-S 18-55mm f/3.5-5.6

04/10/2006 10:11:46 AM · #1

I was out yesterday photographing my daughter and her friends in mid-afternoon (about 4:30-5:00). I had my 20D on daylight, because there wasn't a cloud in the sky - very clear.

When I got inside to check out the damage - I noticed each photograph WB was off - it was at daylight K value but the color cast was quite blue. ( I had a polarizer on the lens)

Letting Bridge auto the WB on the photos I worked on produced a more accurate setting (I like that Bridge!)

This is not a unique problem I have, I seem to have issues with WB ALL THE TIME! I have some indoor horse arena that is lit with halogen / sodiums / HID that I can't get right of a yellow / green color cast for the life of me.

Can anyone list or point me towards a list of color temps for different lighting sources and time of day? Sometimes I just can't get the grey card into play.

How about playing with the custom color casts in the 20d - find it useful - in different lighting?

Thanks,

Rick

bluenova

Canon EOS-350D Rebel XT

04/10/2006 10:28:45 AM · #2

I think the problem is that the 'daylight' setting or any of those settings are a fixed K number, where as in reality the colour temp could be anything in a range of numbers, never a fixed number. I always use either auto or custom, depending on how the camera handles the light on auto.

jent

Canon EOS-90D

Canon EF-S 18-135mm f/3.5-5.6 IS USM

04/10/2006 10:53:33 AM · #3

If you shoot in RAW white balance will not be an issue since you can change that later just as you would on the camera. If you find WB is cripling your photography you may think of start shooting in RAW, because IMO this is one of the best benifits of RAW.

With that aside offten what I do to get that perfect white balance is take the camera and make it as out of focus as possible. Then use this image as my neutral gray for custom white balance. I find this to be a pretty effective means. Maybe not as good as a card, but close enough for me. Some fine WB adjustments can be made to jpg's later in post processing.

Canon RF 24-70mm f/2.8 L IS

04/10/2006 10:56:49 AM · #4

Originally posted by bluenova:

I think the problem is that the 'daylight' setting or any of those settings are a fixed K number, where as in reality the colour temp could be anything in a range of numbers, never a fixed number.

I totally agree - and I'd like to get some values that I can use for various TOD and under wierd light bulbs. My camera has a flourensent setting - but that is no good for sodium lighting.

I don't think that shooting with auto as a rule will fit my needs as the auto was what I used in the arena lighting and I now have a yellow-green cast I can't get rid of.

I'd love to shoot totally custom WB , but sometimes it isn't prudent to set up a grey card or white card before the 'shoot'. E.g. the arena shots - I had no opportunity to send a rider out there with a grey card - the only time the arena was open to riders was during competition.

-Rick

kirbic

Canon EOS R5

04/10/2006 11:02:47 AM · #5

I'm going to hazard a guess that the outdoor pics were taken in "open shade." If so, it's normal for them to have a color cast. Often you'll see a blue or green cast; the blue comes from the sky, which scatters blue better than red, and so is a cooler light source than sunlight, and a green cast can come from due to light reflected off vegetation. The BEST way of nailing WB is to set a custom WB off of a card.
Halogen lightinng in indoor venues is particularly problematic. Thele lamps don't emit a continuous spectrum at all, but a series of "emission lines" that are a function of the gas in the lamp. One type of lamp is bad enough, but venues often mix lamp types to improve visual color rendition, which is poor with halogen lighting. That results in a completely unpredictable lighting situation that actually varies from place to place. Ugh. There's really no way to compensate for this, other than to use auto WB to get in the ballpark, then tweak in post.

Message edited by author 2006-04-10 11:03:27.

Canon RF 24-70mm f/2.8 L IS

04/10/2006 11:29:49 AM · #6

Originally posted by jent:

I do shoot RAW, I always have. The outdoor scenes were easy to adjust. The indoor scenes were more problematic - and reading Kirbic's post he has a point about the arena not using one type of light.

The outdoor shots had a blue case because I shot Daylight (5500?) with a Circular Polarizer on the lens. That surely will give a blue cast. Taking the temp down a couple hundred on the K and adding 13 units to the magenta side brought it out perfectly. I don't mind that. It's the unknown settings (HID, Sodiums, etc) that isn't a setting on the camera, that I'd like to get on paper to give me a starting point.

Originally posted by kirbic:

Halogen lightinng in indoor venues is particularly problematic. Thele lamps don't emit a continuous spectrum at all, but a series of "emission lines" that are a function of the gas in the lamp. One type of lamp is bad enough, but venues often mix lamp types to improve visual color rendition, which is poor with halogen lighting. That results in a completely unpredictable lighting situation that actually varies from place to place. Ugh. There's really no way to compensate for this, other than to use auto WB to get in the ballpark, then tweak in post.

With a single halogen / sodium type will a grey card for a custom WB work? How about with multiple but different types?

-Rick

kirbic

Canon EOS R5

04/10/2006 11:45:55 AM · #7

A gray card should give results about as good as can be obtained when one type of lamp is used. When multiple types are used, the predominant emission lines will change based on position on the floor, and this situation is really problematic. The only thing you really can do, short of balancing for a particular area, is to use auto WB and manually correct later; every shot could be different :-P

Prof_Fate

04/10/2006 12:49:31 PM · #8

Google is a cool tool....you should try it some time!

//www.sizes.com/units/color_temperature.htm

to save you the click...but this is not as nicely formatted..

Source Color temperature in kelvin
Skylight (blue sky) 12,000 - 20,000
Average summer shade 8000
Light summer shade 7100
Typical summer light (sun + sky) 6500
Daylight fluorescent (caution!) 6300
Xenon short-arc 6400
Overcast sky 6000
Clear mercury lamp 5900
Sunlight (noon, summer, mid-latitudes) 5400
Design white fluorescent 5200
Special fluorescents used for color evaluation 5000
Daylight photoflood 4800 - 5000
Sunlight (early morning and late afternoon) 4300
Brite White Deluxe Mercury lamp 4000
Sunlight (1 hour after dawn) 3500
Cool white fluorescent (caution!) 3400
Photoflood 3400
Professional tungsten photographic lights 3200
100-watt tungsten halogen 3000
Deluxe Warm White fluorescent 2950
100-watt incandescent 2870
40-watt incandescent 2500
High-pressure sodium light 2100
Sunlight (sunrise or sunset) 2000
Candle flame 1850 - 1900
Match flame 1700

04/10/2006 02:18:11 PM · #9

Originally posted by Prof_Fate:

Google is a cool tool....you should try it some time!

Be it far from me to force you to participate in a 'forum' thanks anyway for the list.

-Rick

colema19