expo disc

[mrerico]

Just wondering if I am using this right but are you supposed to shoot with the expo disc on and then review the picture and say set custom wb and then change your wb to the custom symbol?

When I take a picture using the expo disc am I supposed to shoot at something white or just whatever I am taking a picture of?


Thanks
Eric O.

[Jon]

You're supposed to point it at the primary light source for your photo (and hope that the secondary light is also about the same colour temperature).

[mrerico]

So it doesnt matter what it is just as long as its near the primary light source I am shooting in?

[Jon]

Wrong. You aim the camera at the primary light source, not something near it. Ideally, from where your subject is.

[mrerico]

So if I were in a room with wierd lighting I wouldnt aim at the white walls I would aim for the areas where the light it coming from?

[Jon]

If you're in a room with wierd lighting, IMO, is where the ExpoDisc falls doown. You're better off then placing a grey card at your subject's position and photographing that, since it'll show the effect of all the light incident on it, from whatever the source. If you use the Expodisc to photograph something other than the light source, you need to photograph a neutral grey or white target so the subject colour doesn't throw WB off. And in that case, why use the Expodisc?

[mrerico]

how about for sports? Say Ice Hockey, would I just shoot at a player under the light source and set custom wb?

[Jon]

No. You aim the camera at the light source to use an ExpoDisc. If you're shooting hockey, use the ice as a white card and set your white balance from that without using the ExpoDisc.

[mrerico]

oh ok...I got it now.

So when would be a good use for using the expodisc? From the sound of it, I think I should have bought a grey card..

[Jon]

I prefer grey cards - more versatile. An ExpoDisc will be usable only when there's uniform light sources on your subject, and you can be at, or near, the subject's position. Like maybe outside on a bright sunny day, or under uniform fluorescent lighting (which has its own problems, though).

[DeCeccoNET]

I agree, the expodisc has a purpose, but as you learn white balancing you grow out of it quickly. I was lucky to recieve one for free as part of doing a job, but as I have moved out of the kit lense range (58mm??) i cant use mine anymore, and will probably just sell it without trying to replace it.

[SkipD]

In my opinion, a neutral gray card and/or a color reference card such as this one (http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=465286&is=REG&addedTroughType=search) are FAR superior color reference tools as compared to the Expodisc.

You can use the reference cards in a couple of ways. One is to do Custom White Balance settings using a neutral reference card. Another is to shoot in RAW mode and put one or both of the cards into the scene for a test shot (using the same lighting as the rest of the series). Then you would use an "eyedropper" tool to sample a neutral portion of either card in the test shot to obtain a reference value during RAW file conversion.

[RichNY]

oh ok...I got it now.

So when would be a good use for using the expodisc? From the sound of it, I think I should have bought a grey card..

No reason that you couldn't use it for shooting hockey, just point it at the lights above the rink to take your custom white balance setting.

[JohnJ80]

but as I have moved out of the kit lense range (58mm??) i cant use mine anymore, and will probably just sell it without trying to replace it.

What does lens range have to do with it?

J.

[JohnJ80]

In my opinion, a neutral gray card and/or a color reference card such as this one (http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=465286&is=REG&addedTroughType=search) are FAR superior color reference tools as compared to the Expodisc.

You can use the reference cards in a couple of ways. One is to do Custom White Balance settings using a neutral reference card. Another is to shoot in RAW mode and put one or both of the cards into the scene for a test shot (using the same lighting as the rest of the series). Then you would use an "eyedropper" tool to sample a neutral portion of either card in the test shot to obtain a reference value during RAW file conversion.

I don't think it makes much difference as long as the device is portable (small), is truly neutral (no color tint), and you can use it quickly to set the custom white balance. Gets down to a "Tastes great- Less Filling" sort of argument.

J.

[SuzyView]

I used my Expodisc once. Then I gave up. Not worth the $95 I paid.

[mrerico]

In my opinion, a neutral gray card and/or a color reference card such as this one (http://www.bhphotovideo.com/bnh/controller/home?O=Search&A=details&Q=&sku=465286&is=REG&addedTroughType=search) are FAR superior color reference tools as compared to the Expodisc.

You can use the reference cards in a couple of ways. One is to do Custom White Balance settings using a neutral reference card. Another is to shoot in RAW mode and put one or both of the cards into the scene for a test shot (using the same lighting as the rest of the series). Then you would use an "eyedropper" tool to sample a neutral portion of either card in the test shot to obtain a reference value during RAW file conversion.


I dont think I would have time to review it on the computer though...

[mrerico]

I used my Expodisc once. Then I gave up. Not worth the $95 I paid.


Why? What are your thoughts on it?

[JohnJ80]

I dont think I would have time to review it on the computer though...

That is the big advantage to the Exposdisk. I most cases, using it and setting a custom white balance (takes <10 seconds) saves far more than that in post processing because you can essentially skip any white balance adjustment. That is why I use it and it has saved me way, way more than the cost of the thing in that alone. If I can get it more right in the camera easily, I'd happily trade that for time sitting in front of the computer any day.

J.

[SuzyView]

Why? What are your thoughts on it?

After I started shooting RAW, it just was one more step to taking pictures. I do events a lot and the lighting is awful no matter what. Trying to adjust when I haven't had time before the event to scope the lighting, it was annoying. I gave up. Now I do a little more PP, but I tweak every shot I want to print. It was easier to do the PP later.

[RichNY]

An advantage to setting a custom white balance (with Expodisc or a card) is that the camera's histograms will be accurate. If your white balance is off then your histograms will be off. If you use the histogram to evaluate exposure and clipping then having the correct white balance in-camera has its advantage to correcting it in post even with a reference card in the image.

[Jon]

What does lens range have to do with it?

J.A 58 mm ExpoDisc doesn't fit very well on a 77 mm filter diameter lens.

[JohnJ80]

A 58 mm ExpoDisc doesn't fit very well on a 77 mm filter diameter lens.

Doesn't really matter. You just need to cover the center 10-15% of the lens to establish the white balance. If you hold the ED encircled by your index finger and thumb, you can do that with the rest of your hand covering the rest of the lens. I never clip the ED to my lens but use only this method.

J.

[jrsforums]

That is the big advantage to the Exposdisk...because you can essentially skip any white balance adjustment...
J.

With all respect....I disagree....

Perfect WB does not mean the shot will have the look you want. I often find "perfect" WB to be too "cold", particularly of people and "golden time" images.

Having a custom WB gives a good starting point. Actually, having a custom WB and a grey card image in the scene, which you can refer back to, is best.

At, the minimum, having the grey card image allows me to set the WB in ACR, adjust for the "look" I want, and then copy those settings to all the other, similar images. Doing it this way is actually not much more time than it takes to do the in-camera settings to create a CWB.

[jrsforums]

Doesn't really matter. You just need to cover the center 10-15% of the lens to establish the white balance. If you hold the ED encircled by your index finger and thumb, you can do that with the rest of your hand covering the rest of the lens. I never clip the ED to my lens but use only this method.

J.

It is not clear to me that you are using the ED as it was intended for WB.

First, I believe it is designed to be used with incident, not reflctive light.

Second, holding it up in front of the lens means that you are imaging more of the reflective surface of the ED (like a grey card), rather than the light which is coming throught the translucent ED. the reflective surface light will have only conincidental relationship to the lighting of the scene.

[JohnJ80]

It is not clear to me that you are using the ED as it was intended for WB.

First, I believe it is designed to be used with incident, not reflctive light.

Second, holding it up in front of the lens means that you are imaging more of the reflective surface of the ED (like a grey card), rather than the light which is coming throught the translucent ED. the reflective surface light will have only conincidental relationship to the lighting of the scene.

how do you use it if you don't hold it in front of the lens? I use it just as the tutorial on the ED website shows. Whether incident or reflected depends on where you point the lens.

Per your other post - it means I get an accurate white balance of what I shot. True, that may not be what I want (presuming I want to play with it) but I still don't have to deal with color casts that I surely didn't want BEFORE I have to PP. 99% of the time it is what i want - I'm not often into adding color casts to my images that weren't there in the first place.

J.

[jrsforums]

how do you use it if you don't hold it in front of the lens? I use it just as the tutorial on the ED website shows. .

Holding a larger expodisc over a smaller lens will block out most of the ambient light and have all/most of the light come through the translucent portion. I was under the impression that you were using a smaller ED. This would allow light to reflect off the ED, throwing of the intended reading of the ED. 58mm vs 77mm (if that is correct) allows a *lot* of light to get by and reflect.

Whether incident or reflected depends on where you point the lens[

I believe Expodisc specifically recommends incident light only for accurate WB. Reflective light can be used for exposure metering. AT least that was what they once stated....maybe physics has changed so they could change their recommendation.

Frankly, if you are using the ED to set WB with reflective light, you might as well just use AWB (except you need to understand Canon's slight "flackiness" in the tungsten region). Plus the AWB will ensure a reading in the area that the lens "sees" not a wider range that the ED may include.
Per your other post - it means I get an accurate white balance of what I shot. True, that may not be what I want (presuming I want to play with it) but I still don't have to deal with color casts that I surely didn't want BEFORE I have to PP. 99% of the time it is what i want - I'm not often into adding color casts to my images that weren't there in the first place.

Sorry, I was just responding to what you stated, "...you can essentially skip any white balance adjustment..." BTW....using reflective light with the ED *will* be prone to color casts, if they are a part of the reflected light....one of the primary reasons for the incident light recommendation.

[JohnJ80]

Holding a larger expodisc over a smaller lens will block out most of the ambient light and have all/most of the light come through the translucent portion. I was under the impression that you were using a smaller ED. This would allow light to reflect off the ED, throwing of the intended reading of the ED. 58mm vs 77mm (if that is correct) allows a *lot* of light to get by and reflect.

My point here was to encircle the ED with your hand using the index finger and thumb to hold it. This should pretty much make sure that the only light that comes in is through the ED because the rest is blocked by hand and fingers. You only need the center portion of the VF to establish WB.


I believe Expodisc specifically recommends incident light only for accurate WB. Reflective light can be used for exposure metering. AT least that was what they once stated....maybe physics has changed so they could change their recommendation.

Correct. You should use incident light - aim the ED at the source of light.



Frankly, if you are using the ED to set WB with reflective light, you might as well just use AWB (except you need to understand Canon's slight "flackiness" in the tungsten region). Plus the AWB will ensure a reading in the area that the lens "sees" not a wider range that the ED may include.

of course.


Sorry, I was just responding to what you stated, "...you can essentially skip any white balance adjustment..." BTW....using reflective light with the ED *will* be prone to color casts, if they are a part of the reflected light....one of the primary reasons for the incident light recommendation.

Correct. reflected light will have a color cast depending on what was reflected.

J.