ExpoDisk

[dlscott56]

Does anyone use the ExpoDisk? I went to a photography club meeting last night and they had a pro portrait photographer there to talk about lighting. He recommended and used one to set white balance as well as setting his initial exposure. Thought I'd check here to see what you all think.

Thanks

[ziggy53]

Expodisk is a fine product, but I still use and recommend a simple Kodak 18 percent gray card, which also has a white surface on the back. That combination of white balance and middle gray for exposure is the simplest and quickest tool available, and the standard Kodak kit comes with 2 - 8" x 10" cards as well as a travel sized 4" x 5" card too. (Obviously you can also chop up one or both larger cards to any convenient size.)

http://www.amazon.com/Kodak-Gray-Card-18-R-27/dp/B00009R7B0

http://www.calumetphoto.com/item/KK9760/

http://www.bhphotovideo.com/c/product/27715-REG/Kodak_1903061_Gray_Cards.html

With an Expodisk you need one to fit your largest lens, or one for each filter size. With the Kodak gray card, it will work with any lens and any camera you have, now and ever.

[dlscott56]

Thanks Ziggy.

I'm wondering now about the 90% reflectance side of these. I understand setting my cameras white balance using the gray card. I actually have one, but what is the 90% reflectance used for?

[ziggy53]

Thanks Ziggy.

I'm wondering now about the 90% reflectance side of these. I understand setting my cameras white balance using the gray card. I actually have one, but what is the 90% reflectance used for?

White balance is set with the white side. Exposure is set with the 18 percent middle gray.

While you can use a gray card for white balance, it is not as accurate as using a white "target" because an imager is most sensitive at higher levels of illumination.

There are more accurate white targets available, but the Kodak card is still very good.

[ziggy53]

BTW, in addition to exposure and white balance, I recommend a "color balance" target. One handy target for that is your own palm. Photograph your own palm under controlled circumstances and then you know for sure that you can photograph your palm under uncertain lighting and other flesh tones in the same lighting will be easier to correct for.

Always shoot RAW for best post-processing flexibility and best results. :thumb

[dlscott56]

Thanks again Ziggy.

[rwells]

You can do a search for it. Myself, pathfinder and Icebear have commented extensively about it.

Basically: I have had excellent results using the ExpoDisk. Other methods work, but I've not seen any that are easier (under my shooting conditions).

BTW: I was shooting sports, therefore JPG and printing on-site. The WB had to be correct IN-CAMERA! No time for RAW and grey cards.


YMMV

[Freezframe]

You can do a search for it. Myself, pathfinder and Icebear have commented extensively about it.

Basically: I have had excellent results using the ExpoDisk. Other methods work, but I've not seen any that are easier (under my shooting conditions).

BTW: I was shooting sports, therefore JPG and printing on-site. The WB had to be correct IN-CAMERA! No time for RAW and grey cards.


YMMV
http://www.amplis.com/news/news.asp?id=2&yr=08&v=&pr=111008&prNum=54
I use this product with great results-
When taking pictures indoors Arenas etc ..I aim directly at light source fully zoomed for white balance as directed..Whats nice about it is that it is your lens cap ....Quick and easy !!

Brady :ivar

[Joves]

You can do a search for it. Myself, pathfinder and Icebear have commented extensively about it.

Basically: I have had excellent results using the ExpoDisk. Other methods work, but I've not seen any that are easier (under my shooting conditions).

BTW: I was shooting sports, therefore JPG and printing on-site. The WB had to be correct IN-CAMERA! No time for RAW and grey cards.


YMMV

Another user here and, love it. It is fast and easy, plus the results for me have always been good.

[dlscott56]

You can do a search for it. Myself, pathfinder and Icebear have commented extensively about it.

Basically: I have had excellent results using the ExpoDisk. Other methods work, but I've not seen any that are easier (under my shooting conditions).

BTW: I was shooting sports, therefore JPG and printing on-site. The WB had to be correct IN-CAMERA! No time for RAW and grey cards.


YMMV

Thanks. I ended up trying this (http://stores.phoxlestore.com/-strse-1/Phoxle-SpectraSnap-White-Color/Detail.bok), hope it works out.

[DsrtVW]

I had looked at expo disc, but ended up with another tool Balens cap by BRNO.
I bought it for my 77mm lens and hold it over my smaller lenses. It works great.
Only problem I had was it knocked out the center dome when it was in my bag pointed down and was set down to hard. Just glue it in place because I do not use the warming lens.

[catspaw]

Happy Expo Disc (neutral) user here - just got it in 77mm and it covers the entire range of my lenses. Easy, peasy :)

[travischance]

dlscott56:

I'd be interested in seeing how the SpectraSnap works out. I too have been researching white balance filters (particularly the Expodisc & Whibal) but am on the fence (especially after seeing your post). Thanks!!!

[dlscott56]

dlscott56:

I'd be interested in seeing how the SpectraSnap works out. I too have been researching white balance filters (particularly the Expodisc & Whibal) but am on the fence (especially after seeing your post). Thanks!!!

I'll let you know how it works out. It's about half the price for the large size.

[dlscott56]

You may also be interested in this (http://digitalgrin.com/showthread.php?t=90438) thread.

[photogreen]

Happy Expo Disc (neutral) user here - just got it in 77mm and it covers the entire range of my lenses. Easy, peasy :) Same here. I like my ExpoDisc 77. i just got it a few weeks ago.
Tried it in various situations. Works pretty well.

Here is a detailed review: ExpoDisc (http://photo-tips-online.com/review/expodisc/)

http://photo-tips-online.com/review/expodisc/images/small/expodisc-full-package.jpghttp://photo-tips-online.com/review/expodisc/images/small/expodisc-bearing.jpg
http://photo-tips-online.com/review/expodisc/images/small/expodisc-sunlight-after.jpghttp://photo-tips-online.com/review/expodisc/images/small/expodisc-headlights-after.jpg

[photogreen]

Did a side-by-side comparison: ExpoDisc Portrait vs. Neutral (http://photo-tips-online.com/review/expodisc-portrait-vs-neutral/)

http://photo-tips-online.com/review/expodisc-portrait-vs-neutral/images/small/expodisc-portrait-vs-neutral-pattern.jpg

I was kind of skeptical about the Portrait version, but it adds just the amount of warmth I like :D .

[insanefred]

Nikon D700 NEF Converted with C1, energy saving florescent bulbs. (gotta get used to them, right?)

AWB no corrections
http://www.evisionphotos.com/photos/797842332_YEdRT-L.jpg

AWB, corrected using WB plucker, no other corrections
http://www.evisionphotos.com/photos/797843510_XDLXV-L.jpg

Expodisc

http://www.evisionphotos.com/photos/797844840_8yrbW-L.jpg


Honestly, I feel it is aimed at JPEG shooters, possibly land scape shooters. But otherwise, I feel it's lacking in overall performance.

[rwells]

Honestly, I feel it is aimed at JPEG shooters, possibly land scape shooters. But otherwise, I feel it's lacking in overall performance.


Not to debunk what your "feelings" are about a product, but it's been proven pretty convincingly several times, even on this board, that the ExpoDisk is VERY ACCURATE!

IMHO, of the pics you posted above, the ExpoDisk image looks the most real-to-life. YMMV

Of course WB correction is most critical to JPG images :scratch , but it also saves a lot of time in post even if your shooting RAW to not have to take the time in post to correct it.

Also, like anything else, there is a right way and a wrong way to use the ExpoDisk.

Again, you have the right to your opinion, and yours seems to vary from mine about the ExpoDisk.

[insanefred]

Not to debunk what your "feelings" are about a product, but it's been proven pretty convincingly several times, even on this board, that the ExpoDisk is VERY ACCURATE!

IMHO, of the pics you posted above, the ExpoDisk image looks the most real-to-life. YMMV

Of course WB correction is most critical to JPG images :scratch , but it also saves a lot of time in post even if your shooting RAW to not have to take the time in post to correct it.

Also, like anything else, there is a right way and a wrong way to use the ExpoDisk.

Again, you have the right to your opinion, and yours seems to vary from mine about the ExpoDisk.

Not saying they're bad or inaccurate, just not for everyone. I will say, it DOES give consistent results, consistent = good.
I did get the 82mm for $79 new, is that a good price?

[travischance]

Not to debunk what your "feelings" are about a product, but it's been proven pretty convincingly several times, even on this board, that the ExpoDisk is VERY ACCURATE!

IMHO, of the pics you posted above, the ExpoDisk image looks the most real-to-life. YMMV

Of course WB correction is most critical to JPG images :scratch , but it also saves a lot of time in post even if your shooting RAW to not have to take the time in post to correct it.

Also, like anything else, there is a right way and a wrong way to use the ExpoDisk.

Again, you have the right to your opinion, and yours seems to vary from mine about the ExpoDisk.

Agree 100%. I use my Expodisc daily & I've been extremely happy with it thus far.....

[captain78]

I read someplace that a coffee filter will work in a pinch as an expodisk. Anybody tried comparing the two?

[NeilL]

The ExpoDisc site describes their product as measuring incident light rather than reflected light. That would be the case only if you took it to your subject and turned it on the light source. How many users do that? Most users, I suspect, use this in situations where it is not possible to do just that, eg sports, landscape, etc. In any case, I think correct WB is got from using reflected light, not incident light. Incident light for correct exposure.

So, there is something not quite straight in their description of their product, it seems to me.

Neil

[Scott_Quier]

The ExpoDisc site describes their product as measuring incident light rather than reflected light. That would be the case only if you took it to your subject and turned it on the light source. How many users do that? Most users, I suspect, use this in situations where it is not possible to do just that, eg sports, landscape, etc. In any case, I think correct WB is got from using reflected light, not incident light. Incident light for correct exposure.

So, there is something not quite straight in their description of their product, it seems to me.

Neil
Only if that reflected light is reflected from a surface of neutral color. Otherwise the color of the surface will impart a color cast on the reflected light and that will completely fool the CWB process in the camera. Try it for yourself -

Take a CWB frame with the major portion of the frame being a warm colored something. Set you CWB using that frame. Now take another shot under the same light. Your second frame will be cool - the extent to which it is cooler will be a function of how warm your CWB target is/was.
Now, reverse the process. Take a shot of a cool colored subject (where this subject fills a major portion of the frame) and use that frame to set the CWB. Now take another shot. Quite a bit warmer isn't it?

When one uses a tool such as the ExpoDisc in the manner described in their instructions, what one is really doing is getting a nice smooth frame of consistant color and exposure (from corner to corner, more or less). The color that camera sees is the "sum" of the color of the light and the color cast imparted on that light by the ExpoDisc. Since they certify that the ExpoDisc is color neutral, the color of the light received by the camera through the disk can be assumed to be the color of the light generated by the light source. The smooth consistant frame can therefore be used by the camera to set the CWB.

If the ExpoDisc were just a bit warm, the resulting CWB would cause subsequent photos to be a bit cool (and vice-versa, of course).

[pathfinder]

I read someplace that a coffee filter will work in a pinch as an expodisk. Anybody tried comparing the two?


Yes - http://www.dgrin.com/showthread.php?t=88748

The comparison is not favorable for the coffee filter. The link above lead to this thread about devices for custom white balance (http://www.dgrin.com/showthread.php?t=90438).

[Scott_Quier]

Yes - http://www.dgrin.com/showthread.php?t=88748
Actually, the only mention of a coffee filter in that entire thread had to do with either not testing on or being unwilling to use one for fear of client opinion.

But this thread (http://dgrin.com/showthread.php?t=87622) does have a discussion of ways to use the coffee filter CWB tool and some of the results.

[pathfinder]

Actually, the only mention of a coffee filter in that entire thread had to do with either not testing on or being unwilling to use one for fear of client opinion.

But this thread (http://dgrin.com/showthread.php?t=87622) does have a discussion of ways to use the coffee filter CWB tool and some of the results.

You're right Scott, about the lack of coffee filters. Comes from posting too quickly at work.

As you know this topic has been discussed over and over here on dgrin and across the web as well. Googling will find many many articles about custom white balance, some of real value, and some of very limited value.

I do know that neither you, nor I, nor Randy use coffee filters for white balance. I suspect we all know why we don't too!! None of us are unwilling to use cheaper tools if they work as well as good tools, but we are not willing to give up on quality just to save a buck and end up with inferior work.

[insanefred]

FWIW, I watched the videos on how to use the expodisc that came with it.
I tried to use it, while it give me pleasing results half the time. I felt that it just was not worth it. I got a new gray card for 7.59, at works even better.
As for incident light meter, I don't need one.

82mm Expodisc = $84.99, bigger heavier, works only when you have access to your subject and lighting.

3 swatch gray card = $7.59, easy to carry, more accurate, cheap, reliable.
Best of all, I won't feel bad if I lose it.

*gets ready to take cover...

[NeilL]

Only if that reflected light is reflected from a surface of neutral color. Otherwise the color of the surface will impart a color cast on the reflected light and that will completely fool the CWB process in the camera. Try it for yourself -
Take a CWB frame with the major portion of the frame being a warm colored something. Set you CWB using that frame. Now take another shot under the same light. Your second frame will be cool - the extent to which it is cooler will be a function of how warm your CWB target is/was.
Now, reverse the process. Take a shot of a cool colored subject (where this subject fills a major portion of the frame) and use that frame to set the CWB. Now take another shot. Quite a bit warmer isn't it?When one uses a tool such as the ExpoDisc in the manner described in their instructions, what one is really doing is getting a nice smooth frame of consistant color and exposure (from corner to corner, more or less). The color that camera sees is the "sum" of the color of the light and the color cast imparted on that light by the ExpoDisc. Since they certify that the ExpoDisc is color neutral, the color of the light received by the camera through the disk can be assumed to be the color of the light generated by the light source. The smooth consistant frame can therefore be used by the camera to set the CWB.

If the ExpoDisc were just a bit warm, the resulting CWB would cause subsequent photos to be a bit cool (and vice-versa, of course).

Thanks Scott for the fine information.

I present this for your consideration:

"• flat spectral response – the filter should pass all visible wavelengths of light uniformly"

This is from the Spectrasnap site. That product and the ExpoDisc are functionally equivalent.

The above quote seems to be saying that no matter what colours are reaching the filter, the filter will only pass light as neutral in that particular situation.

The implication as I see it is that the filter makes no distinction between light from a light source and light reflected from an object illuminated by that light source, both of which are likely to be non-neutral. The filter is showing the camera what neutral light looks like in that particular lighting situation. Isn't this actually the exact same as what filling the camera field of view with a neutral grey card does, which is a reflected light measurement? In effect, the filter is doing to light the exact same as what a neutral grey card does - the information it gives is in effect reflected light information, not incident.

That's why I said above that correct WB is got from reflected light information, light reflected from a neutral (I omitted that critical word, you are right) material (*in effect* the same information the filter gives), and exposure from a lightmeter reading of incident light.

Neil

[NeilL]

FWIW, I watched the videos on how to use the expodisc that came with it.
I tried to use it, while it give me pleasing results half the time. I felt that it just was not worth it. I got a new gray card for 7.59, at works even better.
As for incident light meter, I don't need one.

82mm Expodisc = $84.99, bigger heavier, works only when you have access to your subject and lighting.

3 swatch gray card = $7.59, easy to carry, more accurate, cheap, reliable.
Best of all, I won't feel bad if I lose it.

*gets ready to take cover...

Both have their special uses, eg you can't always put a card on your subject, and you can't always measure incident light on your subject.

Neil

[Scott_Quier]

Thanks Scott for the fine information.

I present this for your consideration:

" flat spectral response – the filter should pass all visible wavelengths of light uniformly"

This is from the Spectrasnap site. That product and the ExpoDisc are functionally equivalent.

The above quote seems to be saying that no matter what colours are reaching the filter, the filter will only pass light as neutral in that particular situation.

Neil, I fear you have mis-intrepreted the quote.

Flat spectral response means/implies that it adds nothing to nor takes anything away from the signal received. So, in the case if light, if the light recieved is a bit cool, the light passed will be a bit cool. It is this cooler light that is used by the camera to generate the CWB.

Consider the alternative ... the ExpoDisc (or any other tool) receives light with a cool cast, "normalizes" it and passes this result to the camera. Where does the camera receive any benefit?

One can, in fact, test this. Set your camera to any WB setting other AWB. Mount the ExpoDisc on the lens and take a shot of incandescent light source. Now, without making any changes to the WB setting, take your camera outside and take a shot of the light from a clear blue sky. Final step, examine these two shots side by side on your computer (the nice thing here is that you don't even need a calibrated monitor for this step) and compare the colors of the two frames. You will note that the frame from the incandescent source is quite a bit warmer than that of the clear blue sky source.

The implication as I see it is that the filter makes no distinction between light from a light source and light reflected from an object illuminated by that light source, both of which are likely to be non-neutral. The filter is showing the camera what neutral light looks like in that particular lighting situation. Isn't this actually the exact same as what filling the camera field of view with a neutral grey card does, which is a reflected light measurement? In effect, the filter is doing to light the exact same as what a neutral grey card does - the information it gives is in effect reflected light information, not incident.
I agree, the filter can make no distinction between light from any given source - there's no brains in the tool.

To get any idea of the "true" color of the light incident on the subject, you need to sample the light that is incident on the subject.

Light reflected by the subject will be altered by the fact that nothing (except a true neutral) will reflect light without altering it's color - that's how we see the color of an object. Without additional information, sampling the light reflected from a subject tells you nothing about the light source. That's how a gray card works (either in setting the camera CWB or in post) - you know this subject is neutral and can use other tools (the camera or the appropriate picker in, for example, ACR) to determine in what ways the incident light varies from "normal" light and, thus, make appropriate adjustments to the color cast in the photo.

That's why I said above that correct WB is got from reflected light information, light reflected from a neutral (I omitted that critical word, you are right) material (*in effect* the same information the filter gives), and exposure from a lightmeter reading of incident light.

Neil

This last part I completely agree with, assuming the surface reflecting the light is, indeed, neutral.

[NeilL]

Neil, I fear you have mis-intrepreted the quote.

Flat spectral response means/implies that it adds nothing to nor takes anything away from the signal received. So, in the case if light, if the light recieved is a bit cool, the light passed will be a bit cool. It is this cooler light that is used by the camera to generate the CWB.

Consider the alternative ... the ExpoDisc (or any other tool) receives light with a cool cast, "normalizes" it and passes this result to the camera. Where does the camera receive any benefit?

One can, in fact, test this. Set your camera to any WB setting other AWB. Mount the ExpoDisc on the lens and take a shot of incandescent light source. Now, without making any changes to the WB setting, take your camera outside and take a shot of the light from a clear blue sky. Final step, examine these two shots side by side on your computer (the nice thing here is that you don't even need a calibrated monitor for this step) and compare the colors of the two frames. You will note that the frame from the incandescent source is quite a bit warmer than that of the clear blue sky source.

I agree, the filter can make no distinction between light from any given source - there's no brains in the tool.

To get any idea of the "true" color of the light incident on the subject, you need to sample the light that is incident on the subject.

Light reflected by the subject will be altered by the fact that nothing (except a true neutral) will reflect light without altering it's color - that's how we see the color of an object. Without additional information, sampling the light reflected from a subject tells you nothing about the light source. That's how a gray card works (either in setting the camera CWB or in post) - you know this subject is neutral and can use other tools (the camera or the appropriate picker in, for example, ACR) to determine in what ways the incident light varies from "normal" light and, thus, make appropriate adjustments to the color cast in the photo.

This last part I completely agree with, assuming the surface reflecting the light is, indeed, neutral.

Thanks, Scott.

You know you are preaching to the converted!:D Just that in my last post words sometimes got in the way.

Let me try again. WB is commonly described as making the camera read a neutral target with a colour cast as neutral. So, if the grey card is reflecting coloured light, say blue, the camera makes that blue cast neutral target its neutral. Everything in its field will be shifted away from blue.

I was a bit more successful with:

"The filter is showing the camera what neutral light looks like in that particular lighting situation."

As before, and as we already agree, it doesn't matter that the filter is getting incident blue light or blue light reflected from a neutral target.

So, you can see we are in total agreement that the light reflecting off a grey target, or passing through the filter, must be interpreted by the camera as being neutral, that is, the camera normalises it.

However, I have one concern, and that is unless you are in a studio with exactly only one light source, in which case the reading of that incident light is the reading of colour cast, unless that, then you are in a situation of having light from multiple sources, and multiple reflections, each probably with its own colour contribution to the scene. Considering that the filter stuck on the end of a lens is going to be pretty directional in sampling the light, just as the lens itself is, which direction, which incident light source, which reflected light, are you going to turn your filter to? On the other hand, a neutral grey target is reflecting the total incident light, from all sources, it is gathering light from all sources to feed into your directional lens cum filter, and this more comprehensive reflected light, it seems to me, is going to give a more accurate measure of the color shift affecting the subject of the photograph.

Neil

[Scott_Quier]

Thanks, Scott.

You know you are preaching to the converted!:D Just that in my last post words sometimes got in the way.

Let me try again. WB is commonly described as making the camera read a neutral target with a colour cast as neutral. So, if the grey card is reflecting coloured light, say blue, the camera makes that blue cast neutral target its neutral. Everything in its field will be shifted away from blue.

I was a bit more successful with:

"The filter is showing the camera what neutral light looks like in that particular lighting situation."

As before, and as we already agree, it doesn't matter that the filter is getting incident blue light or blue light reflected from a neutral target.

So, you can see we are in total agreement that the light reflecting off a grey target, or passing through the filter, must be interpreted by the camera as being neutral, that is, the camera normalises it.
Yup - it's now clear we are on the same page.

However, I have one concern, and that is unless you are in a studio with exactly only one light source, in which case the reading of that incident light is the reading of colour cast, unless that, then you are in a situation of having light from multiple sources, and multiple reflections, each probably with its own colour contribution to the scene. Considering that the filter stuck on the end of a lens is going to be pretty directional in sampling the light, just as the lens itself is, which direction, which incident light source, which reflected light, are you going to turn your filter to? On the other hand, a neutral grey target is reflecting the total incident light, from all sources, it is gathering light from all sources to feed into your directional lens cum filter, and this more comprehensive reflected light, it seems to me, is going to give a more accurate measure of the color shift affecting the subject of the photograph.

Neil
Studio setting .... one would hope (at least I would insist) that the strobes are all pretty much the same temperature and that any reflected light is either being reflected from neutral colored surfaces and/or the reflected light is of a strength insignificant enough that it doesn't contribute in any meaningful way to the exposure.

And, yes, there's going to be slight variations in the color of the light delivered by multiple strobes - based on duration of the pulse of light each strobe delivers, the amount of power of each strobe, and a whole host of other factors. But, for the most part, "matched" studio strobes are going to be pretty much the same color. Even "unmatched" strobes are going to be close enough in color (or they should be) that the differences are going to be a non-issue ... remember, photography (as an artform) is is not rocket science where we have to get the data precise to five decimal places.

But, in more random situations, one very well could have light from multiple sources .... none of which are controlled by the photographer. In this case, as in most cases, one does the best they can -- you point your lens at the strongest light source (as perceived from the point of view of the subject) as it is probably going to contribute most strongly to any color issues.

And, I agree - in a situation with multiple light sources, a good and known neutral target will do you better as the light reflected from it will be a functional average of the light incident upon that target .... which is why I have two gray targets in my kit (in case I loose one) and I don't even really know where I would find my ExpoDisc.

[NeilL]

.... which is why I have two gray targets in my kit (in case I loose one) and I don't even really know where I would find my ExpoDisc.

I think it's this touching, personal confession which really clinches the argument!!:D:rofl:clap

Neil