10 stop filter

Search pro photoshop or item 250830955303 on ebay. These do have a colour cast but it isn't much and can be fixed.
There are some youtube videos of it being used by a mad French man to remove people from scenes

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here is the link to his videos
 
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While a neutral colour is obviously nice to have, it actually doesn't matter much and even the best and most expensive extreme ND filters like B+W and Lee Big Stopper have a noticeable cast. They all do. I've tested about ten different types and they all have a cast of some sort, even if it's slight. But the important thing is colour accuracy after the image has been neutralised in post-processing and the likes of B+W and Lee would say you actually get more accurate colours throughout the spectrum this way, rather than compromising the final output by going for a filter than merely looks more neutral to start with.

If you want neutral colour SOOC, then do a custom white balance. That can be a bit of a faff on the day, so do some tests at different Kelvin values and note the setting that looks best under typical lighting conditions, then just use that when needed.
 
HoppyUK said:
While a neutral colour is obviously nice to have, it actually doesn't matter much
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This is true up to a point. If the colour cast is really bad (I'm thinking welding glass here) then the image is virtually monochromatic and certain colours are lost forever.
 
hollis_f said:
This is true up to a point. If the colour cast is really bad (I'm thinking welding glass here) then the image is virtually monochromatic and certain colours are lost forever.
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True in practise too. Even with welding glass, and that's bottle-green, it's amazing how other colours come through. The net effect there is that greens/grass are rendered lighter in tone, but even the least neutral of the filters generally sold for this purpose are nowhere near that bad.

The other thing about that rather poor review in Amateur Photographer mag is it implies the vignetting effect is down to the filter. It's not, it's down to the lens and unavoidable with wide-angles.
 
HoppyUK said:
But the important thing is colour accuracy after the image has been neutralised in post-processing and the likes of B+W and Lee would say you actually get more accurate colours throughout the spectrum this way, rather than compromising the final output by going for a filter than merely looks more neutral to start with.

If you want neutral colour SOOC, then do a custom white balance. That can be a bit of a faff on the day, so do some tests at different Kelvin values and note the setting that looks best under typical lighting conditions, then just use that when needed.
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But the underling problem with these high density ND filters like the Big Stopper is that as the exposure increases only the visible spectrum is filtered. The invisible like UV and more importantly for digital sensors the infra red are not touched. A simple white balance just does't work any longer for colours like green that are very absorbent of IR light. These can take on all manner of strange colour effects and even the time of day can effect the outcome. Grey stuff like rocks or blue like water and sky are not effected the same so a simple 'global' balance just doesn't work.

If you like the surreal effects of some of these filters than that's ok but for a faithful rendition you need to be a little more picky.
 
gazwas said:
But the underling problem with these high density ND filters like the Big Stopper is that as the exposure increases only the visible spectrum is filtered. The invisible like UV and more importantly for digital sensors the infra red are not touched. A simple white balance just does't work any longer for colours like green that are very absorbent of IR light. These can take on all manner of strange colour effects and even the time of day can effect the outcome. Grey stuff like rocks or blue like water and sky are not effected the same so a simple 'global' balance just doesn't work.

If you like the surreal effects of some of these filters than that's ok but for a faithful rendition you need to be a little more picky.
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Take your point, but who says they only work on the visible spectrum? If they didn't also supress IR, they'd be pretty useless in normal daylight that is rich in IR. All the extreme NDs I've tested, I've checked for IR contamination in different conditions and all but one passed with more than acceptable results for good pictorial photography. As you say, it is greens that are most susceptible, and dark blacks turn a give-away shade of chocolate brown when IR gets through. For the record, the best filter for this, and also for every other aspect of performance, is the B+W 3.0 MRC. Lee Big Stopper is good on IR too.

The best extreme ND filters are all glass, and multicoated, it can't be done so well with dyed resin (Lee have tried hard, and opted to import their glass Big Stopper). The only poor one I've tried was the resin Hitech ProStop, though I've not tried the new IRND version.
 
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double post
 
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All the high-density filters I've tried have had problems caused by them letting IR through. But those problems haven't been with colour problems. Two of the worst were the Heliopan 10-stopper and the Hi-Tech 10-stopper. The Heliopan gave quite a warm colour cast, while the HiTech was distinctly cool.

But both let through a lot of IR. The giveaway was the way that the exposure meter gave readings that were grossly wrong. Auto Exposure (Av mode) with the Heliopan wanted a shutter speed of 1/4s, whereas a correct exposure required 1.5s - a difference of almost three stops. The HiTech wanted 1/20s according to the metering yet 2 seconds gave a correct exposure. That's about 5 stops difference. See this thread for the images and more details.

The reason for the difference between what the AE says is the correct exposure and what is the real correct exposure is that the AE sensor is sensitive to IR and the imaging sensor isn't.
 
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