I think white balance is my problem, need a little help please

[Dave-M]

Hi,

I'm shooting within a light tent (80cm square) and I have a couple of 580 EXs inside the light tent, firing upwards and slightly inwards, located on either side of the subject.

The light tent is white.

The problem I have is that I can't seem to get the background to actually look white.

I can get it to a very light grey, but it's not quite there.

This pic is direct from the camera with no PP or cropping, just a resize and conversion to jpeg.

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199.jpg

I've tried all the different white balance settings and auto seems to be the most effective (although I would have thought the flash one would have been?).

I know that I can use post processing to enhance the background, but when I do that, the rest of the subject can become overly bright.

Most of my shooting is done in this light tent, or on a white background, so I really want to get this right.

Camera is a 40D and I'm using an EF-S 60mm lens along with the speedlites.

Any pointers or help will be much appreciated :)

Thanks

Dave

[Wilt]

Put the lights outside the tent

[Dave-M]

I was originally doing it like that and using 1000w halogen lights, but the heat was a bit scary.

It comes out much darker and needs more fixing in PP if I do that with the speedlites. :)

[dtrayers]

White balance won't make the BG white, it will make it neutral (no color). Gray is neutral.

The problem is with the exposure. You need to figure out how to get more light on the background without blowing out the object.

I never used a tent. Perhaps you can put a flag between the light and the object? Is the tent translucent? Can you put some light outside the tent to blow it out to white? I thought that's how it's supposed to work, and the light entering through the tent material is very soft and evenly lights the object.

Perhaps try to put the object on some kind of stand so you can light the background separately from the object?

[Wilt]

I was originally doing it like that and using 1000w halogen lights, but the heat was a bit scary.

It comes out much darker and needs more fixing in PP if I do that with the speedlites. :)


Why can't you use speedlights outside the tent?!

[Dave-M]

Thanks for the replies :)

Yes, I can put the speedlites outside the tent, but then I dont get a good light on the top of the subject, most importantly, the background is still grey!

I will leave the WB on auto and have a play around with the speedlites outside again :)

[Lowner]

Try moving your subject away from the tent surfaces (theres a shadow under it I see), then use at least one light directly onto the background - try to blow the highlight detail in the background. As already explained, it's an exposure balance issue, nothing to do with white balance at all.

[canonloader]

I'd get another speedlight.

[PacAce]

White balance won't make the BG white, it will make it neutral (no color). Gray is neutral.

The problem is with the exposure. You need to figure out how to get more light on the background without blowing out the object.

I never used a tent. Perhaps you can put a flag between the light and the object? Is the tent translucent? Can you put some light outside the tent to blow it out to white? I thought that's how it's supposed to work, and the light entering through the tent material is very soft and evenly lights the object.

Perhaps try to put the object on some kind of stand so you can light the background separately from the object?
I agree with Dave. The problem is not the white balance but the exposure. If you are using the flash in ETTL mode, bump up the FEC until you get a brighter background. If the flash is in manual mode, increase the power a little bit more.

[Dave-M]

Thanks for the replies again, all advice noted :)

Trying the speedlites outside the tent first of all. I remembered why I put them inside now and that was because of the shadows.

Again, this is straight out of the camera, resized and saved as a jpeg.

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5234.jpg

I will try elevating the subject and moving the speedlites around.

[Lowner]

Looks as though you need a bit more DoF as well.

Just an idea: Try using natural daylight as your main subject lighting and use the flashes to kill the grey background and the shadows. More "fill" than "flash" in a manner of speaking?

I'm also very curious about the subject. What is it?

[thebishopp]

Looks like some kind of heatsink. Screws into the thing that needs cooling, the copper transfers the heat to the fins where the heat is then dispersed? Computer chip cooling maybe as it's so small?

[S7000]

You need a constant light for the best effect in boxes (from what i've tried). There's a d.i.y lightbox thread in the flash section, a must read!

[Dave-M]

Looks as though you need a bit more DoF as well.

Just an idea: Try using natural daylight as your main subject lighting and use the flashes to kill the grey background and the shadows. More "fill" than "flash" in a manner of speaking?

I'm also very curious about the subject. What is it?

Yes, I agree about the DoF, I can fix that later, that was my previous quest for knowledge :lol:

Daylight is very good, but it doesn't quite give me the look I'm after, and also, with the winter on the way, I will be limited to the time I have to get the shots done :)

Its interesting what you say about using the flash to kill the grey, I'm not having much luck at achieving that at the moment.

The subject is a chipset heatsink and I think that the fact it's aluminium isn't helping the grey thing (at least that's how it seems :))

Looks like some kind of heatsink. Screws into the thing that needs cooling, the copper transfers the heat to the fins where the heat is then dispersed? Computer chip cooling maybe as it's so small?

Yes :)

You need a constant light for the best effect in boxes (from what i've tried). There's a d.i.y lightbox thread in the flash section, a must read!

I was using a pair of 1000w halogen lamps, but the heat was immense and quite scary, so I asked in another thread on here and was recommended a second speedlite, which is excellent so far, but it's just that background that's the problem.

Thing is, I'm not limited to the light tent, but I would like to keep the white background. I have one of those giant reflectors and an umbrella stand for the flash that I can use, but I haven't tried them yet :)

[Mark1]

You dont need a ton of light to do still life in a tent!!!!!! You just need to know how to expose for the light you are useing. I have made some great shots with 3 100 watt compact florescents. Sure it was a 1.5 second exposure but since the subject didnt move it did not matter. Moveing the lights out side of the box will also help get rid of the shadows, making the PP a lot easier. It looks a bit like you are following the meter to make the exposures then trying to correct for a meter that is off. You should be overexposing (according to the meter) by 1.5-2 stops. This will help blow out the background.

I think yo are also post - ing the exposure wrong as well. By the way you were explaining it, you are useing the exposure slider to correst the image. That is not what you want to do . Open Levels and pull down the white point and then adjust the mis point. This will blow out the whites but leave the reat of the image alone.

[PacAce]

Its interesting what you say about using the flash to kill the grey, I'm not having much luck at achieving that at the moment.


If you need more light out of the flash, just increase its power output. If you are shooting with the flash in manual mode, move the slider closer to the 1/1 setting. If you are using the flash in ETTL mode, increase the FEC to +2 or more, if necessary.

[dtrayers]

Yes, I agree about the DoF, I can fix that later, that was my previous quest for knowledge :lol:


Could you explain what you mean by fixing it later? You can't add DOF in post processing.

And if you mean that you'll just stop down the lens, then you need to dial up the power on the strobes.

Your example was at f/4. I'd bet you'll need at least f/11 more (or would the correct term be less? :confused: ) to get the DOF you want, and at that aperture you might not be able to get the power from speedlights you need to blow out the BG. Going from f/4 to f/11 is eight times the power on the strobes.

I think you're back to using hot lights and a long shutter speed if you want any appreciable DOF, or go rent some monobloc strobes.

[Lowner]

"The subject is a chipset heatsink and I think that the fact it's aluminium isn't helping the grey thing (at least that's how it seems )"

To solve that you need to keep the subject lighting seperate from the background. Treat it as two entirely seperate challenges. This may well mean that you need at least a third flash, although I'm not a studio expert. What would be useful is a diagram showing set-ups others use to achieve similar shots. There used to be a series of articles on the Manfrotto site. It pushed their tripods and heads but if you ingnored that, one of the articles featured a model car, how it was lit, the changes made to achieve the best result etc. Could be useful to glance at it? It did not use a tent however, so might not give you all the answers.

[Dave-M]

You dont need a ton of light to do still life in a tent!!!!!! You just need to know how to expose for the light you are useing. I have made some great shots with 3 100 watt compact florescents. Sure it was a 1.5 second exposure but since the subject didnt move it did not matter. Moveing the lights out side of the box will also help get rid of the shadows, making the PP a lot easier. It looks a bit like you are following the meter to make the exposures then trying to correct for a meter that is off. You should be overexposing (according to the meter) by 1.5-2 stops. This will help blow out the background.

Thanks, I'll investigate that tonight :)

I think yo are also post - ing the exposure wrong as well. By the way you were explaining it, you are useing the exposure slider to correst the image. That is not what you want to do . Open Levels and pull down the white point and then adjust the mis point. This will blow out the whites but leave the reat of the image alone.

Those images haven't had any PP done at all, just a resize and conversion to jpeg. To make the backgrounds lighter, yes, I have been using the brightness slider mainly.

Thanks, I'll check out your suggestion later too :)

If you need more light out of the flash, just increase its power output. If you are shooting with the flash in manual mode, move the slider closer to the 1/1 setting. If you are using the flash in ETTL mode, increase the FEC to +2 or more, if necessary.

I've got the hang of that bit, but my problem is that if the flash is any brighter, the subject is then over exposed :)

Could you explain what you mean by fixing it later? You can't add DOF in post processing.

And if you mean that you'll just stop down the lens, then you need to dial up the power on the strobes.

Your example was at f/4. I'd bet you'll need at least f/11 more (or would the correct term be less? :confused: ) to get the DOF you want, and at that aperture you might not be able to get the power from speedlights you need to blow out the BG. Going from f/4 to f/11 is eight times the power on the strobes.

I think you're back to using hot lights and a long shutter speed if you want any appreciable DOF, or go rent some monobloc strobes.

Because of the kind of photography I want to do, I've done a lot of asking questions about DoF because on slightly larger items, I'm getting blurred edges even at higher stops (f11), so I have been playing with a program called helicon focus which I've found to be perfect for what I want to achieve - I take a series of photos of the subject with, say the front of it in focus, then several shots of the middle and then the rear, then dump the raw files into the program and it processes them and gives you a fully focussed image.

I'm not sure how weird these images would look with other subjects, but for this kind of stuff, it's a godsend for me :)

"The subject is a chipset heatsink and I think that the fact it's aluminium isn't helping the grey thing (at least that's how it seems )"

To solve that you need to keep the subject lighting seperate from the background. Treat it as two entirely seperate challenges. This may well mean that you need at least a third flash, although I'm not a studio expert. What would be useful is a diagram showing set-ups others use to achieve similar shots. There used to be a series of articles on the Manfrotto site. It pushed their tripods and heads but if you ingnored that, one of the articles featured a model car, how it was lit, the changes made to achieve the best result etc. Could be useful to glance at it? It did not use a tent however, so might not give you all the answers.

I will take a photo of the setup when I get back later, it's pretty basic - light tent on top of an old chest of drawers, couple of speedlites on stands outside the tent at the moment.

One interesting thing that people have mentioned is that shadows should be less with the speedlites outside the tent? Its quite the opposite for me at the moment (see above pics) - maybe I'm too close to the tent with the speedlites, or not close enough? :lol:

Thanks for all the help, much appreciated :)

[dtrayers]

...I have been playing with a program called helicon focus which I've found to be perfect for what I want to achieve - I take a series of photos of the subject with, say the front of it in focus, then several shots of the middle and then the rear, then dump the raw files into the program and it processes them and gives you a fully focussed image.

Huh, shows what I know. I've never heard of this program... I'm going to check it out. Thanks!

[Bobster]

you're nearly a whole stop under exposed..

[Dave-M]

Huh, shows what I know. I've never heard of this program... I'm going to check it out. Thanks!

http://www.heliconsoft.com/heliconfocus.html

I'm liking it so far, great for macro too.

you're nearly a whole stop under exposed..

How can you tell this, is it just by looking?

:)

[Bobster]

How can you tell this, is it just by looking?
by looking at the image in Photoshop yes...
looking at the histogram i can see that the image is lacking contrast and is under exposed...
http://www.rjwhetton.co.uk/touchup/Exposure.jpg

corrected
http://www.rjwhetton.co.uk/touchup/Corrected.jpg

[Lowner]

Thats a bit over the top! I prefer the original. Or maybe halfway between the two?

[Bobster]

how can a correct exposure be over the top?

[Mark1]

Looks a bit much to me as well. It's a bit too contrasty in the dark lowlights. I do think you have the exposure corrected. Just pulled up the black point a bit to far.

[Dave-M]

Thanks Bobster,

I'm not sure if its my screen, but I'm seeing some weird reds and blue/greens in the background of the corrected one and some horizontal stripes as if a brush has been used?

I see what you are getting at anyway :)

Regarding the histogram, what should it look like? I must admit, I don't really know much about those.

I've had a play in Adobe RAW with the original and came up with this.

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199-edited.jpg

original, no PP.

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199.jpg

[René Damkot]

how can a correct exposure be over the top?
Exposure is good, contrast too high ;)

IMO a levels adjustment of something like 0 ; 1.35; 201 is al that's needed...
Almost a stop too dark sounds about right ;)

Regarding the histogram, what should it look like? I must admit, I don't really know much about those.
understanding histograms (http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml)

I've had a play in Adobe RAW with the original and came up with this.
Better for the most part. A bit too much though. And the copper looks way over the top.

Also, if you are okay with people editing your images, please go to user CP > Edit profile and set "Image edit and repost permission" to "yes".

Also: The image you posted is AdobeRGB, which will look off in a non color managed browser, and certainly isn't needed for an image like this (well inside sRGB gamut)

[Dave-M]

Thanks René :)

The histogram article makes perfect sense, I've bookmarked it for a thorough read later :D

I have set the image editing thing to yes - i didn't realise that was for that.

About the AdobeRGB, I didn't purposely set that, so I'll check it now. Meanwhile, this one is probably adobeRGB too :lol:

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199edited2-1.jpg

[Bobster]

I'm not sure if its my screen, but I'm seeing some weird reds and blue/greens in the background of the corrected one and some horizontal stripes as if a brush has been used?
JPG compression ;)
Exposure is good, contrast too high ;)
personal tastes ;)

[Bobster]

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199edited2-1.jpg
a touch over exposed, you can't see the detail on the top of the block anymore..

[PacAce]

JPG compression ;)

personal tastes ;)
Not necessarily. When processing an image, why would you move the leftmost part of the histogram to the extreme left (black point) when there is no black in the scene? Doing so makes the image look too contrasty.

[Dave-M]

a touch over exposed, you can't see the detail on the top of the block anymore..

This is where we come back to the reason I started the thread - If I get what looks like a reasonable set of realistic colours in the subject, I end up with a more grey background. :)

http://i451.photobucket.com/albums/qq233/dave-mm/IMG_5199edited3.jpg

I'll try some more!

[Mark1]

I think you need to change your shooting set up. There is not enough difference between the subjecte color and the background. Get a piece of glass or plexi to seperate the subject from the background. By about a foot. Point your mega-lights at the background with the edge of the light barely includeing the sink. This way you can more easily controol the light difference between the subject and the background. by changeing the angle of the lights. If the background is white you only need about 1.5-2 stops of extra light on the background. If you go to far the light will start to wrap arround the sink and make it glow. If you do not want the reflections the glass will provide they can be edited out rather easily.

[René Damkot]

Good point.
Another option would be to use a translucent "floor" (plexiglass) and light that from below (subtle!)

Q&D way to do it in PS: Use an additional levels or curves adjustment to get the background to clip to white, and use a mask.
(not color managed screenshot, so might look a bit off)
http://img.skitch.com/20080917-gf4d8qrap7s2ajb7u82w2rmgbu.jpg