I've recently noticed that when stacking ND filters on the Canon XL1s with Manual lens, there is a distinct color shift to the brown. For example, lush green leaves appear yellowish brown and sickly.

I've done some tests, and here's what I've found:

1) Happens when stacking any combination of .3, .6, and .9 one the Canon 14x lens on the Xl1s AND the XL1. (Tiffen Filters).

2) Does not happen on the 16X lens with the built in ND -- but begins to show up once you add additional ND's to the front of the lens.

3) Happens when using the ND .9 ONLY on the manual lens. Happens less severely with the .3 and the .6.

4) Happens -- but is FAR less noticeable when using the ND .8 that Canon includes with the 14X lens. (Incidentally, the Canon ND appears slightly greener in tint than the Tiffe ND's).

So.....any idea what's up. It's clearly a color shift problem with the Xl1, but I'm dumbfounded as to why. Manually white balancing through the ND's can compensate somewhat, but if you use the daylight setting, it looks awful.

I've talked to a few other XL1 users, and they think I'm crazy -- but none of them stack ND's, relying instead on the Canon ND and the iris for bright situations. I found one other person who stacks ND's -- and he reported the same issue.

I guess I have 2 questions:

1) Has anyone ever heard / seen this?? If so, any idea why it is happening?

2) Does anyone know if Canon is aware of the issue ?? If so, what is their stance ??

I have a sneaking suspicion that Canon knows about the issue, and "corrects" the ND they ship with the Manual Lens as well as the one built into the standard 16X (which I've noticed tends to shift colors toward the green a bit.) But then again, I may just be paranoid.

Anyway.........any insight would be welcome.

thanks,
mike

Filters can and do cause color shifts. I stack ND filters occasionally and I don't have this problem. I have an XL1 and XL1s. I'm doing 2 things different from you. I manually WB a lot. I don't rely on AWB too often. I use square polymer filters, Cokin, Singh-Ray, Schneider and others. I think they take a little more care with their filters than Tiffen. Tiffen does have some very inovative filters. Their Promist filters get very good press. But overall I think their filters are just average. So, I think the combination of the 2 variables are resulting in your color shift.

Jeff

If stacking filters causes the color balanced to go funky, probably can blame the filters, not the camcorder. The fact that few people do it should be an indicator. CCD's can 'see' light outside of the nominally visible spectrum, and the ND filters you have may be effecting the overall color balance in this area. That may account for some of the color shifts with high filtration.

Try different brands and see whether or not you get different results.

Using the fixed "daylight" color balance setting presumes that the daylight is the same as the standard setting (5600 K), likely to be the case for only a couple hours a day at best and then only with the proper weather conditions. Thus this setting can be expected to frequently yield 'off' results. There is no good substitute for a frequent manual color balance.

Thanks for the feedback guys.....

Don -- what is a "square polymer" filter, and why/how is it better/different than the Tiffen glass filters ???

Just curious....

mike

Cokin http://www.cokin.fr/ Singh-Ray http://www.singh-ray.com/ and Schneider http://www.centuryoptics.com/products/filters/index.htm make filters that are square (3x3, 4x4 etc.) I use square filters that fit my matte box. The filters are made of optical glass or polymer (plastic). The mfgs. pay particular attention to the materials and coatings to insure that color and contrast are not affected. As you have found out not all mfgs. pay as much attention to the fine details. The above filters are more costly but if reasonably cared for can last a life time. Buying your filters twice is not very cost effective.

Jeff