Neutral Density Filters

[Daniel Browning]

At 10 stops you start to get issues from infrared, so you might consider a hot mirror to reflect the IR. They are more very expensive, but it will save you from increased fringing, flare, and inaccurate color due to infrared. (Normal ND filters only block regular light, not IR, so a 10-stop ND increases the I.R. by one thousand times.)

[M_Six]

I've been doing this lately. You can get some very cool images. I stacked a 3-stop ND, a 6-stop ND, and a 2-stop CPL for a total of 11 stops. It turns a 1/60 shot into a 30 second shot. ISO 100, f22, 30 secs

[Busted Knuckles]

I am on the quest for ND and was thinking about this very item.

At 10 stops you start to get issues from infrared, so you might consider a hot mirror to reflect the IR. They are more very expensive, but it will save you from increased fringing, flare, and inaccurate color due to infrared. (Normal ND filters only block regular light, not IR, so a 10-stop ND increases the I.R. by one thousand times.)

I found an industrial optics company that appeared to do the very high end filters, etc though the pricing actually seemed pretty reasonable. They had two types of ND, absorption vs. reflecting. I was going to give them a call and discuss if the reflecting would be Visible and near infra red to address this very issue. Then I got to wondering - why aren't any of the of the NDs in the photo world mirrored - they all appear to be absorption i.e. non mirror/reflecting

Any of the high science guys have thoughts on this? I "demo'd" an inexpensive variable and found even at its least setting to reduce sharpness and warm color cast - sent it back. I am thinking a 3 or 4 stop and then a 10 stop set should do the trick. Many comments that a 1 or 2 stop is largely a waste of glass.

Also any comments on brand? other than you get what you pay for.