Expodisc and Studio Light ?

I have been considering the purchase of a white balance tool... namely the Expodisc, but I have questions. My questions are in regards to how to use it in a studio and how often?

I've read that you can either:

1. Install Expodisc on said lens and shoot into (towards) your shooting position.

or

2. Install Expodisc on said lens and shoot into your light.

Which option is better? Which light do you shoot into if 2. is the best way? Also, If I buy the Expodisc for my 17-40 and 70-200 (same size) but plan on using my 85... do I have to buy one specifically for the 85 or can I use the data from one of the other two lenses and simply swap to the 85?

Thanks,
Robert

You attach the ExpoDisc to your lens, stand at subject position and point the lens at the main source of illumination at the correct exposure. You use it in the same way you would use an incident light meter. You definitely do not stand at camera position and point at the subject.

Once the data is recorded with say... my 70-200 2.8 can I then do a simple lens swap to my 85 1.8 or does the data not apply?

I cant afford two Expodisc's and need to decide which I would use more.

Thanks for the help.

Rob~

duckiller01 wrote in post #9487520
Once the data is recorded with say... my 70-200 2.8 can I then do a simple lens swap to my 85 1.8 or does the data not apply?

I cant afford two Expodisc's and need to decide which I would use more.

Thanks for the help.

Rob~

Why would you need two ExpoDisc's? The disc isn't lens specific. Using the ExpoDisc is like using another other tool for setting custom white balance. You only need to set a new custom white balance if the lighting or modifiers change. In other words, anything that would affect white balance is reason to establish a new custom white balance.

If you know that switching from one lens to another affects color then you should set a new white balance but that's as simple as putting the disc in front of the new lens, standing at subject position and shooting the reference image.

Most excellent!

I know lenses are different but was not sure if it would warrant the purchase a specific unit for the smaller lens diameter or if the data needed to be recorded through the lens (to be used) to be accurate. You make a great point... place the 77mm filter in front of the 58mm 85 1.8 or 100 macro.

Thanks again!

duckiller01 wrote in post #9487603
Most excellent!

I know lenses are different but was not sure if it would warrant the purchase a specific unit for the smaller lens diameter or if the data needed to be recorded through the lens (to be used) to be accurate. You make a great point... place the 77mm filter in front of the 58mm 85 1.8 or 100 macro.

Thanks again!

What most people are doing is to buy the ExposDisc for the lens with the largest filter size you have. You can then use that disc for any other lens you own. It doesn't have to clip on to the lens. Just hold it in front. So, for instance, you buy the 77mm disc for your 70-200 and then it's good for any other lens that has that filter size or smaller.

With an ExpoDisc, you always want to measure with it from the subject's position back toward your light source.

I have an ExpoDisc, but I never use it. I find a WhiBal card to be much more useful. I have two WhiBals, a small one (credit-card size) and a larger one. I use them to take a test shot for reference whenever I find myself in an unusual lighting condition.

If I'm in some variation of daylight though, I'll just use AWB. And if I'm indoors with incandescent bulbs, I'll just use the standard Tungsten setting.

I shoot in raw format, so I always process white balance after the fact. I don't usually try to set a custom white balance in the camera in the field. If you want to set a custom in-camera white balance, the ExpoDisk is probably better than a grey card, but if you're just trying to get a reading of neutral grey to use in post processing, a WhiBal card (or equivalent) is probably easier to use.

Even with a "correct" grey reading (or an AWB or Tungsten setting) I'll usually tweak it a bit in post to whatever values look best. Ultimately, there's really no such thing as a true "correct" white point. It really comes down to what looks best for the scene, IMO.

Just buy the Douglas gray card, which is useful for exposure determination and for White Balance...far less expensive than the Expodisc! I have one and can recommend it.