ExpoDisc

[-fruity-]

Cheers,

Wee, first thread! :)
Thanks for putting the board back up! I can imagine it's a lot of work and headache.

Someone in here using expodisc?
I'm shooting 80% indoors with SB28DX and rather low lights with yellow casts.
I'd need the 72mm model since i love my old Nikon 20-38.

I've used a plain white sheet of paper for white balance so far.
Expodisc: I'm excited about the easy way to meter with flash.
Is it worth the extra $$$?

If you're in Europe (Austria), do you know any local vendor?

Thanks and have a nice Xmas!

[Linda G]

Hi,

I have the expodisc, not sure yet whether it's worth it. Used it today but all my snow images look a bit on the red side.

Have a friend who uses it for wedding photography and swears by it so maybe I just need to learn how to use it.

[Bill C]

Linda - I do not have the ExpoDisc. Why/Is this better than just shooting a gray card to set custom white blance under the specific lighting condition? Also, I read that to use the ExpoDisc you are to shoot FROM the subject back to where the camera will be .. seems backwards to me..
Just came across this message thread regarding an inexpensive substitute for ExpoDisc:
http://forums.dpreview.com/forums/read.asp?forum=1020&message=6499244

Regards,
Bill

[Linda G]

The expo disc is white, balance within tolerances, and makes a white balance using the light that is going to hit the subject. Same idea when you use a white paper for white balance, it should be under the same light your subject is.

The expodisc is nice because it's small, fits in your pocket and when you use it, (my opinion) you look a little more professional than holding up a piece of paper.

I also know many people who use a gray card because of industry standards. There are many different whites. I've also talked to people who use a blue/gray card to get a nice, warm balance for skin tones. Makes it a little too yellow for me.

[rbsmithphd]

I have been making a substitute for the ExpoDisc out of readily available materials at nearly no cost, and have found that it works very well with the S2 for setting CWBs, with and without flash. Get a small (approx. 3 inch square) piece of clear or translucent plexiglass. This is generally manufactured with zero color cast. If you have a company selling plastic in your area (eg, I got mine at Tap Plastics) there is readily available a translucent (not transparent) version, so no sanding is necessary. Otherwise, sand one or both sides of the clear plastic with relatively fine (260-400 grit) sandpaper. You just want to make sure you use absolutely clear plastic with no color cast: all of Tap Plastic's basic plastics are manufactured this way.

The procedure I have settled on, with or without a flash (I have the Sunpak 383, but recently purchased the Nikon SB80DX):

1. Frame the intended picture (or general scene if a set of pictures will be taken)
2. Set exposure according to available, or expected (i.e., flash), light. It doesn't matter what mode your in (A,S,M,P)
3. Using the function dial choose set CWB, and select 1or 2
4.Depress the shutter release button 1/2 way to set autofocus
5. Before depressing the shutter release the rest of the way, raise the translucent plastic directly in front of the lens. By doing it in this way you do not need to shift the camera into manual focus mode, a distinct benefit when working in changing light.
6. While keeping the shutter button 1/2 depressed, with your left thumb rotate the exposure duration dial (if necessary) to adjust the exposure to get enough light for the CWB. This is most likely to be necessary if the camera is set in spot metering mode.
7. Depress the shutter release button to capture the CWB. It will take into account all the light available, including ambient light and any flash used. There is no practical limit to the duration of the exposure - I generally take landscapes in "manual," and have set CWBs based on exposures as long as 8-20 secs. Just continue to hold the plastic in front of the lens until the shutter closes. In response to your inquiry, put the disc in front of the lens, not the flash.
8. Reset the exposure duration to the proper setting (i.e., for when the diffusing plastic is not in front of the lens).
9. Make sure your camera is set to CWB1 or CWB2

This method is very fast and can be quickly repeated as the light changes. There's no hassle if you keep the disc or square of plastic in a pocket. Because you don't put the plastic in front of the lens until after you[ve activated auto focus, you don't have to use manual focus mode to set the CWB.

As indicated, this approach works well when the camera is point at the intended scene, but sometimes there is a minor color shift if the image uniformly, or predominantly, contains some single, bright color. In that circumstance I follow the same procedure but try to set the CWB by pointing at another aspect of the scene. One of the DP forum contributors demonstrated that when setting a CWB, the camera is using only light from the center area.

If you can't get the translucent plastic, take a piece of plastic guaranteed to have no color cast, and sand it any way you want, as long as the resulting finish is relatively uniform and causes substantial scatter of the light. The more scatter, the better. You might try sanding both sides.

Give it a try. At the most you will have spent $1.00 on plastic. I make discs about 3.5 inches across so that they will cover even my largest lenses. You can carry the plastic in your pccket, small scratches don't effect its functionality, and the methodology described above is so simple that you can reset the CWB as often as you please with almost no disruption to the pleasure of taking pictures.

Here's an image taken at about 20 secs based on a CWB done just before hand. http://www.pbase.com/image/22605631/original

Randall

[HulaMike]

very good Randall. I'll try it!

[Wichita Wayne]

My ExpoDisk works great pointed at either the subject or back at the light sourse. The only problem with it is the auto WB in the S2. It works great with a lot less fuss, and with auto WB you don't have to remember to redo the WB when you change environments. I will use it in churches with strange lighting but I have not found it to be too helpful so far. In the future I may change my mind and I ewill let you know if I do.

[Linda G]

I, too, have found the auto white balance very good in the S2. Not so with my old Canon, that's when I aquired the expo disc.

I will say, when photographers use different backlighting in studios (red, ect) auto white balance gives an awful result!

[-fruity-]

thanks for the replies...

I've now tried the selfmade "expodiscs".

Pringles: EU-version of the transparent cover produces very blue-ish results. Esp. that pimple in the middle seems to confuse.
I dont'k know about US packaging.
Anyway, i had a couple of beers to get that chemical taste out of my mouth. :guzzle: sort of happy end.

Plexiglass: Same here. Blue casts but much more accurate.
I'll try to test other products. Maybe it's product related.

Anyone knows the exact area in which the custom WB meters?
Esp. when using flash I've troubles metering the graycard or white sheet.
I'm mostly using wideangles, so i've to get close to the card which makes it hard to keep exposure constant (flash).

[rbsmithphd]

Fruitty: I can't speak about plexiglass in Europe, but the product I get here (near San Francisco, from Tap Plastics) has no cast whatsoever, even in 3/16" thickness. When the CWB is set as I described above, and a picture is then taken of a grey card, the readings from the card are nearly perfectly neutral. Ask a plastics provider about color cast, and use new plastic (as there may be some acquired cast with age).

[rbsmithphd]

Fruity: Sorry I spelled your handle wrong on the previous post.

With regard to the area used for CWB: one of the frequent contributors to the DP Review Fuji DSLR Forum did an experiment in his studio using a grey card in the center and colored cards on the periphery around it - there was no separation between the cards. It turns out that the S2 uses only the area in and around the central focusing area for setting the CWB. In other words, you do not have to fill the whole visual field to get a correct CWB. If my memory serves me correctly, simply filling the central 1/3 of the vewfinder with grey/white/Expodisc/or substitute should suffice. Do an experiment yourself if you are not confident.

Regards, Randall

[Sleeping Bear]

Just now finding this thread thanks to a link from Bill. I've used the expodisc in low light situations with great results. The auto WB on the S2 just does not get the low light colors, but the expodisc does. Still wouldn't trade my S2 for any other camera. Well, maybe the S3.:)

[dhphy]

I have been following this thread for a while and would like to find an easier and more acurate method of white balancing.

I don't know how the fuji white balances in auto mode.
I know how to set the various settings but I don't know how the camera actually works it out.
In custom WB it is easy to see how the camera would probably work. You tell the camera that it is looking at a white card or a grey card and then you present the camera with a "dose" of light reflected from that card. The camera then stores the information and applies a "correction" in colour balance to each subsequent image.

For example, lets say that we are photographing under tungsten light. Our white card is exposed under this light. the camera sees that there is too much red and reduces that amount from each subsequent image.

Ok, but how does it mange to do this in auto, whithout a reference from a white object to start with?

It must have some pretty sophisticated software.

Now, this expodisc I can see working if pointing back to where the picture will be taken from. IE taking a reading of the light that would be falling ON the subject. But I find it hard to imagine how the custom balance could work correctly if pointed AT the subject.
Maybe it would work OK for "average" scenes, but what about those scenes, for example an object/person up against a yellow or blue wall. Surely the camera will interpret the overal blue or yellow data as a colour tint from the lighting source and modify the colour of the image incorrectly.

And I would assume that whatever system is brought into play with the auto white balance is switched off in custom otherwise there would be no point in having it.
So in custom WB you are telling the camera that it is looking at a pure white scene, and therefore asking it to eliminate any colour that is predominant.

I could only see this disc being used on the camera pointing at the subject being effective for a scene that did not have a predominant colour in it.
Certainly it is a lot easier single handed to point the camera from the subject position than it is to white balance the grey card (although not that much).

However I would be interested in seeing a few before and after shots of this disc pointing at the subject, if any one has some.

Also does anyone know what colour temperature is for the daylight setting on the camera. I'm just wondering if it is the same as most flash guns, which is I think about 6000K.
Dave

[Mike Roe]

I've been using a video camera lens cap from a svhs camera. This cap is white plastic, the same color as the dome on a meter. I figured if I can set the white balance on a video camera with it why not the s2. I point it at my light source to set it and I think it works great. I keep it attached to the camera strap for ez access.

[jknights]

I have a friend in Chicago and he swears by his ExpoDisc.

I havent tried it but I have been recommended hat the following is a good substitute.
reverse side of high quality inkjet paper, e.g. Xerox gloss works well.

If you meter off this and then close downby 3 stops you should be OK.
I usually believe what my matrix metered S2 says except in sunsets, etc.

If it is really difficult. I have found over the years that if you take a reading off the palm of your hand (any skin type) then this is the right exposure (+/- one stop). Grubby hands, need washing !!

[easternherp]

I have never done a CWB as I always shoot everything in RAW and then adjust the colours later in EX Converter or PS CS. This saves worrying about changing the colour setting when the colour of the scene changes.

[AzRich]

the point of the expo disc is that you won't have to adjust color later.

Anyone interested in a 58mm expodisc? I just replaced it with a 77mm, and I don't have any more 58mm lenses.

[easternherp]

I have just updated the Ex RAW converter and it seems to be underexposing all my shots by at least 1 stop. In PS CS it doesn't but the images are softer. As I have to do some correction I use the RAW and adjust colour afterwards. Surely you wouldn't do a CWB for every shot at a wedding say as the clouds come in and out?

[MikePL]

I think that the expodisc is exaggerated. It does just what a white piece of paper does, nothing more. Once I have set up my camera to the light of my strobes, I keep shooting with that setting, even outdoors. I just like to have the feel of a daylight-balanced film and swear by it. The factory setting for daylight is a bit too cold and desaturated. I have a beige background and in auto WB or daylight it is just too cold. So CUS1 is set permanently as my basic shooting mode, and CUS2 is just for some extreme settings. Some time ago I was making a folder with pictures of a factory and they used there sodium lighting (I guess that's the name), and autoWB got crazy and the pictures were monochromatic. A guy standing in a red uniform againgst a white wall and a blue machine was represented by the camera as an orange guy with a dark orange uniform against a light orange wall and a dark orange or grey machine. The problem was that while setting the custom WB, the camera informed me that the value is out of range. I got scared, but fortunately the once the camera gets an out of range input, it sets as close to it as possible instead of completely refusing to work. So finally I did my job.

The picture below shows the differences. The left side is AWB and the reight side is custom (although the camera informed about out of range settings, the picture looks OK straight from the camera).

[Linda G]

I have found over the years that if you take a reading off the palm of your hand (any skin type) then this is the right exposure (+/- one stop). Grubby hands, need washing !!


This is how I learned metering! can't tell you how many slides I have of my hand. <g> My favorite is of a cornrow and a fuzzy palm reaching toward the camera. Kind of erie! But it was a rare day it didn't give me a beginning of a correct exposure reading back in the full manual days!

I have carried my expo disc with me the last three places I've gone to try it and always forget, caught up in the moment of photography. Il'l keep trying, honest!

At the Will Crockett seminar, it was mentioned-and discarded by him-but I found his logic flawed because he was using it incorrectly, not aiming it at the subject but at the light source so I wish he would revisit it and give us an idea of why it will or won't work then.

He's a believer in light meters and i have no problem with them, but the seminar was set up for studio photographers only. I'd like to see someone try all the methods of photography. (can you imagine a studio photographer using their hand to meter?!?)

[HulaMike]

(At the Will Crockett seminar, it was mentioned-and discarded by him-but I found his logic flawed because he was using it incorrectly, not aiming it at the subject but at the light source so I wish he would revisit it and give us an idea of why it will or won't work then.

He's a believer in light meters and i have no problem with them, but the seminar was set up for studio photographers only. I'd like to see someone try all the methods of photography. (can you imagine a studio photographer using their hand to meter?!?)

You're both right Linda. In the field most would want to use Expodisc or a grey card addressing the subject, and you can use Expodisc this way. However, it will ONLY give you a correct white balance aiming at the subject. But if you have the luxury of time, as in a studio; Expodisc recommends aiming it at the light source as this will not only give you a correct WB but the correct exposure as well.

[Linda G]

Thanks for the explanation, Mike. Makes better sense, now.

[dennisj]

I've had an expodisc for some time now, and think it works quite well.I purchased a 55mm and have since used step down rings as opposed to buying another for different lens. When using it outdoors I find that pointing at the sun or brightest part of the sky sets a nice overall CWB, regardless of subject position. Works well in studio too.

Dennis

[AzRich]

I've got a 58mm expo disc that is extra, I replaced it with a 77mm that I just hold over smaller lenses.

Hmm.... that step down idea was probably cheaper than my idea, huh!

Anyway, The 58mm is extra, if you're interested let me know. I still think they should have an eBay store and sell them there. If no one here is interested in it, that's where I'll sell it.