Expodisc/cap.......

[Furgus]

I have been toying around the idea of picking one of these up. It seems like half the forums I have read love them or hate them, and I just wanted to know if anyone here uses one. I have noticed a lot of my images from my D50when shooting in low light with my Tamron 28-75 f/2.8 indoors without flash are very warm when my WB is set to Auto. I heard about a little trick to use my white sock to set the WB, and WOW what a difference that made. I am very capable of fixing WB issues in PS, and I only shoot in RAW. This disc/cap will just take out a step, ok maybe half a step in my workflow. I am currently selling my 18-55 kit lens, so I should have a most of the disc paid for, but I still wanted to know what some of you think of these. BTW the Caps are much cheaper, but my local camera stores are limited on the sizes. I will need at least a 77mm so I can sue it on all of my lenses.

Thanks
Casey

 

[Gdad]

I have been considering one also- curious to see the feedback.

 

[KrazyPete]

I've been considering it as well. Wolf Camera here has the caps on clearance. I've put together some DIY methods of doing the same thing and gotten pretty good results. I made a disk out of translucent milk carton plastic and another out of the plastic lens from a office flourescent light fixture.

The milk carton plastic gave a white balance setting that was a lot better than the camera's AUTO setting. It wasn't as good as pre setting the WB in camera off a gray card though. The piece of plastic from the light fixture was arguably as good setting the WB off the gray card.

No matter what I do in camera I'm always tweaking the color some in post. I don't know if an ExpoDisk is good enough to eliminate that step for me. If it's just matter of getting it a tiny bit better in camera then I don't know if it's worth it to me.

 

[SharonLowe]

I have an expodisc and use it mostly for night photography although it is very helpful in other situations too. Since I believe you get the best results if you set your white balance in camera rather than in post processing, it is a very valuable and easy to use tool. I've not use the expocap and am not sure why it would be a better alternative than the expodisc. I guess it is cheaper, which is why it might appeal to some.

 

[MarkBarbieri]

I've got one and don't find it all that useful for photography. It's OK, but I can think of other things I'd spend the $100 on.

The first problem is that it is designed to be pointed at the light source, not your subject. So in other words, to use it properly, you must walk over to your subject area and shoot back at the light. If you just pop it on your lens and shoot your subject with it, you'll risk getting a color cast from your subject.

The second problem is that I find that accurate white balance isn't all that it's cracked up to be. I typically like to have my light include some or all of the color cast of the original light. The classic example is a sunset...if you white balance, you'll lose the warmth.

For most situtations, a grey card or a bit of white clothing is just about as easy to use and much cheaper.

If I wanted spot on white balancing, I'd be happier with it. With a desire for "good enough" and "I like it better this way" white balancing, I don't find it that helpful.

I actually use mine more for dust checking than white balancing. I take a high aperture shot with it on and then zoom in on my LCD and look for dust spots. If they are bad, I clean them. If they aren't too bad, I at least have a map of where they are when I want to clean up shots later.

Where I have found the expodisc to be very, very useful is with video. There is no RAW with video, so if you don't get the white balance right at the start, you pay a much bigger price later.

So in summary, it works as claimed. It's somewhat useful. Because it needs to be pointed at the light source and not your sujbect, it's not as easy as popping it on, taking a test shot, and then taking your real shot. I suspect that a homemade version would do good enough for much less money.

 

[Furgus]

The first problem is that it is designed to be pointed at the light source, not your subject. So in other words, to use it properly, you must walk over to your subject area and shoot back at the light. If you just pop it on your lens and shoot your subject with it, you'll risk getting a color cast from your subject.

I read that also. I think the Cap can be pointed at the subject......need to do some more research.....

 

[MarkBarbieri]

I read that also. I think the Cap can be pointed at the subject......need to do some more research.....

It's not a problem with the product so much as it is an inherent limitation to the whole approach. It is sort of like the problem with reflective light meters being fooled by black or white subjects and over or underexposing them.

As an example, let's say that you are taking a picture in a room. Behind you is the sole light source - a reddish/orange tungsten bulb. In front of you is your subject wearing a blue dress, with blue hair, in front of a blue wall, blue floor, and blue ceiling. The expodisc acts as a diffuser mixing up all of the light hitting it. The light is originally reddish/orange, and that's what you really want to correct for "accurate" white balance. However, the blue light reflected from everything in the room creates a rather cool bluish cast to the light coming through the expodisc. As a consequence, your white balance is off. You can fix the problem by zooming in on the light itself and letting the expodisc see only that. If you had a grey card lit primarily by direct light from the bulb, this wouldn't be as much of an issue.

I don't see how any form of on-the-lens diffuser will work any differently in this situation. At it's best, it can neutrally diffuse the light hitting it. At it's worst, it can introduce it's own color cast. The expodisc is a very effective diffuser (better at it than a typical translucent piece of plastic) and is neutrally balanced (or warmly balanced if you by the warming one). Aside from that, I can't think of anything short of magic that it really can do.

To accurately white balance a photo, you need to know the color of the light source for the picture and compensate for that. With an on-the-lens diffuser, the only accurate way to do that is to capture the light directly from the light source and not reflected from an object.

All of this also assumes that you have a single light source. In the real world, you might be blending white direct sunlight with blue skylight with green light reflected from grass. In that case, there is virtually no way to totally eliminate color casts. Even in the example above, if you compensate for the color of the light source, you will then be left with extra blue from the light reflected by the floor and ceiling. White balance in all but the most controlled circumstances is a compromise. The expodisc makes it relatively easy to get a reasonable and consistent compromise. So does a grey card, a white sock, etc. For me, for photography, the expodisc doesn't add enough value to justify the cost. For video, it's a better value. Reasonable people have come to very different conclusions.