expo disk, etc.

I have seen ads for the Expo disk for white balancing. I was at a
show in NY and saw a competing product that supposedly does the same
thing for a little less $. Does anyone have an opinion on these
products? And does anyone know who makes that competing product. I
have lost their literature. TIA

I have the expo disc and like it a lot. I bought the largest size so I could
use it with any lens. I also use it with my video camera. They aren't cheap,
but well made and work well. If you can find something cheaper and as
durable I would say go for it. I don't recommend cards because they get
dirty and can get bent and wrinkled which makes the mess effective.

The Spider

"gp photo" <gpayerle@adelphia.net> wrote in message
news:cb578d39-5370-40fc-a05f-c6d4ae96140d@l1g2000hsa.googlegroups.com...
>I have seen ads for the Expo disk for white balancing. I was at a
> show in NY and saw a competing product that supposedly does the same
> thing for a little less $. Does anyone have an opinion on these
> products? And does anyone know who makes that competing product. I
> have lost their literature. TIA
>
The concept of these discs is to allow you to obtain an average white
balance by blurring everything and just allowing the light to be the
influence. There are cheap (as in $5) versions on eBay from Hong Kong. They
work well enough too.

The thing you need to understand about white balance is how inaccurate it
can be and still "look" right! You could for example use the bottom of a
frosted plastic bottle. If it were 50 Kelvins out, it wouldn't matter all
that much unless you measured the colour of the bottle and that would be a
wasted exercise anyway.

Douglas

On Mon, 19 Nov 2007 20:27:44 +1000, "Douglas" <just@the.group> wrote:

>
>"gp photo" <gpayerle@adelphia.net> wrote in message
>news:cb578d39-5370-40fc-a05f-c6d4ae96140d@l1g2000hsa.googlegroups.com...
>>I have seen ads for the Expo disk for white balancing. I was at a
>> show in NY and saw a competing product that supposedly does the same
>> thing for a little less $. Does anyone have an opinion on these
>> products? And does anyone know who makes that competing product. I
>> have lost their literature. TIA
>>
>The concept of these discs is to allow you to obtain an average white
>balance by blurring everything and just allowing the light to be the
>influence. There are cheap (as in $5) versions on eBay from Hong Kong. They
>work well enough too.
>
>The thing you need to understand about white balance is how inaccurate it
>can be and still "look" right! You could for example use the bottom of a
>frosted plastic bottle. If it were 50 Kelvins out, it wouldn't matter all
>that much unless you measured the colour of the bottle and that would be a
>wasted exercise anyway.
>
>Douglas
>

You have to be careful if using translucent white plastics for these purposes.
When I was designing a compact (and somewhat innovative) flash-diffuser for my
P&S cameras for macro photography I came to find out that some of these plastics
may look pure white from the reflected light but they absorb a large portion of
the blue spectrum of transmitted light. In my case I had to compensate for it by
using some mild violet & blue filtration (red absorption) to bring things back
into balance. Rather than find a different plastic source, my design worked so
well it was easier to just use some simple filtering on it instead. (Aside: A
neat little gadget that just clips on any camera's pop-up flash, acting as a
light-pipe, the flash output reflects internally in its shape and dumps it out
in front of any large lens. Very little light loss and perfectly even diffusion
allowing for macro shots as close as 1-2 cm from the front lens element. Cost to
make, $1.50. I used it for an extensive entomology study in one region, many of
the "rarest of the rare" insect images now being used for science publications.)

If you are lucky enough to have one of the P&S cameras that run CHDK you can
make use of its various Y&RGB histogram displays to check the absorption
spectrum of different plastics, if planning to test and use some translucent
plastics for these purposes.

While the "Expo Disk" is an interesting idea, harkening back to the use of
incident light-meters from long ago, I tried doing the same thing using simple
home-made designs (as you suggest). Mainly because I couldn't see spending that
much money for something that looked to be nothing more than a cheap novelty
item, yet I still wanted to see how useful incident light-metering would be
after I went digital. I finally found a simple translucent plastic cap that fit
my filters perfectly. Its transmitted spectrum pretty even. It works just as
well as the Expo-Disk idea. I have it in my camera bag. Guess how often I use
it? Never. It's been in the bottom of my camera bag all this time, I really
should take that out of there to make room for something I would actually use.

It's fun for the gadgeteer but impedes any real photography effort.

This is not unlike those that feel the need to still carry an 18% gray-card. The
only reason 18% gray was ever used in the past was to adjust for proper exposure
when taking a photograph with hand-held light meters (now done with internal
exposure metering and live histograms) and when its image is included in one
frame on a roll of film, used as a color balance check during print making.
That's what auto white-balance and manual-balance off of a white piece of paper
are for today. All the past necessities for an 18% gray card are already built
into your digital camera today. Anyone who still keeps one of those in a digital
camera bag is spending more effort trying to impress others into making them
think the owner of it knows something about photography, rather than impressing
anyone with their actual photography. When I am traveling around and run into
others who have an 18% gray-card dangling from their digital-camera gear I
silently chuckle to myself. While wishing I was wearing one of those T-shirts
with an arrow pointing to the side, beneath the phrase "I'm with stupid".

MacRonson wrote:


> You have to be careful if using translucent white plastics for these purposes.


Just for what it's worth... The white semi-clear drink lids from Burger King
fast food outlets make great 'expo disk' diffusers. I tried one just on a
lark once and the results were so good, that I now make it a point to carry
a couple in my camera bag

In article
<cb578d39-5370-40fc-a05f-c6d4ae96140d@l1g2000hsa.googlegroups.com>, gp
photo <gpayerle@adelphia.net> wrote:

> I have seen ads for the Expo disk for white balancing. I was at a
> show in NY and saw a competing product that supposedly does the same
> thing for a little less $. Does anyone have an opinion on these
> products? And does anyone know who makes that competing product. I
> have lost their literature. TIA

It's a little bit different, but I've gotten nice results with WhiBal
(a plastic light gray card). It only took a couple of experiments to
open my eyes to the difference it makes and ease of making a
known-neutral spot really neutral in Photoshop.

You take a photo that includes the card in the same light as your
subject. Instructions on the WhiBal site.

The little one is enough. Nice holiday gift.

-=- Rick

--
Richard Karash <Richard@Karash.com>
Richard "at" Karash "dot" com

"MacRonson" <mronson@hotmail.com> wrote in message
news:7tp2k35du03923u476oaiuk6fe4hqiedc9@4ax.com...
> On Mon, 19 Nov 2007 20:27:44 +1000, "Douglas" <just@the.group> wrote:
>
>>
>>"gp photo" <gpayerle@adelphia.net> wrote in message
>>news:cb578d39-5370-40fc-a05f-c6d4ae96140d@l1g2000hsa.googlegroups.com...
>>>I have seen ads for the Expo disk for white balancing. I was at a
>>> show in NY and saw a competing product that supposedly does the same
>>> thing for a little less $. Does anyone have an opinion on these
>>> products? And does anyone know who makes that competing product. I
>>> have lost their literature. TIA
>>>
>>The concept of these discs is to allow you to obtain an average white
>>balance by blurring everything and just allowing the light to be the
>>influence. There are cheap (as in $5) versions on eBay from Hong Kong.
>>They
>>work well enough too.
>>
>>The thing you need to understand about white balance is how inaccurate it
>>can be and still "look" right! You could for example use the bottom of a
>>frosted plastic bottle. If it were 50 Kelvins out, it wouldn't matter all
>>that much unless you measured the colour of the bottle and that would be a
>>wasted exercise anyway.
>>
>>Douglas
>>
>
> You have to be careful if using translucent white plastics for these
> purposes.
> When I was designing a compact (and somewhat innovative) flash-diffuser
> for my
> P&S cameras for macro photography I came to find out that some of these
> plastics
> may look pure white from the reflected light but they absorb a large
> portion of
> the blue spectrum of transmitted light. In my case I had to compensate for
> it by
> using some mild violet & blue filtration (red absorption) to bring things
> back
> into balance. Rather than find a different plastic source, my design
> worked so
> well it was easier to just use some simple filtering on it instead.
> (Aside: A
> neat little gadget that just clips on any camera's pop-up flash, acting as
> a
> light-pipe, the flash output reflects internally in its shape and dumps it
> out
> in front of any large lens. Very little light loss and perfectly even
> diffusion
> allowing for macro shots as close as 1-2 cm from the front lens element.
> Cost to
> make, $1.50. I used it for an extensive entomology study in one region,
> many of
> the "rarest of the rare" insect images now being used for science
> publications.)
>
> If you are lucky enough to have one of the P&S cameras that run CHDK you
> can
> make use of its various Y&RGB histogram displays to check the absorption
> spectrum of different plastics, if planning to test and use some
> translucent
> plastics for these purposes.
>
> While the "Expo Disk" is an interesting idea, harkening back to the use of
> incident light-meters from long ago, I tried doing the same thing using
> simple
> home-made designs (as you suggest). Mainly because I couldn't see spending
> that
> much money for something that looked to be nothing more than a cheap
> novelty
> item, yet I still wanted to see how useful incident light-metering would
> be
> after I went digital. I finally found a simple translucent plastic cap
> that fit
> my filters perfectly. Its transmitted spectrum pretty even. It works just
> as
> well as the Expo-Disk idea. I have it in my camera bag. Guess how often I
> use
> it? Never. It's been in the bottom of my camera bag all this time, I
> really
> should take that out of there to make room for something I would actually
> use.
>
> It's fun for the gadgeteer but impedes any real photography effort.
>
> This is not unlike those that feel the need to still carry an 18%
> gray-card. The
> only reason 18% gray was ever used in the past was to adjust for proper
> exposure
> when taking a photograph with hand-held light meters (now done with
> internal
> exposure metering and live histograms) and when its image is included in
> one
> frame on a roll of film, used as a color balance check during print
> making.
> That's what auto white-balance and manual-balance off of a white piece of
> paper
> are for today. All the past necessities for an 18% gray card are already
> built
> into your digital camera today. Anyone who still keeps one of those in a
> digital
> camera bag is spending more effort trying to impress others into making
> them
> think the owner of it knows something about photography, rather than
> impressing
> anyone with their actual photography. When I am traveling around and run
> into
> others who have an 18% gray-card dangling from their digital-camera gear I
> silently chuckle to myself. While wishing I was wearing one of those
> T-shirts
> with an arrow pointing to the side, beneath the phrase "I'm with stupid".
>


That is true white isn't always white. The human eye is easy to fool.
However, even if it is slightly off white it should still give you much
better white balance than no calibration at all. It is also interesting to
point out that tints of certain colors can be used to give your white
balanced calibrated images a warm or cool tone. ExpoDisc makes a warming
disc that warms up your images.

Personally, If I could find a small set of plastic tiles in varying but
similar shades of white to play with I think it would be a lot of fun to
play with.

The Spider

--
Ignorance really is bliss, just look how happy President Bush is.

The Spider Formally Seated Next To Little Miss Muffet wrote:

> Personally, If I could find a small set of plastic tiles in varying
> but similar shades of white to play with I think it would be a lot of
> fun to play with.

Here's a very simple homemade Expo Disk that is easy to make.

<http://www.geocities.com/ritaberk2007/expod.htm>





Rita