Neutral Density Filter Colour Cast

Went out today to try out my new ND filters on my K100d at my local weir.
I was using an 8, 4 and 2 stacked, white balance set to daylight, 0.5 second exposure gave me this...




Took the filters off and changed from shutter priority to Auto and got this...




Put the ND filters back on and shot in auto again...




What am I doing wrong?

Do I need to adjust the white balance to compensate for the ND filters?

I did notice that when held up in front of my eye singly there was no colour cast but when looking through all three there was.

never seen an nd filter do that... what camera?

That is dreadful, but I think we need a whole lot more information to begin to understand why.

Cheap ND filters do have a colour cast and certainly on film very long exposures will cause colour shifts. So, how was it shot, in full detail?

Looks like they have been taken through a R72 infra red filter.
John

I have seen cheap polarizers do that... especially when stacked...
possible you had a polarizer in there somewhere?

Filters are cheap ones from ebay link here
Obviously the old adage of 'buy cheap buy twice' must apply to ND filters.

Lens is a Carl Zeiss Jena Jenazoom super 28-70mm f/3.5-4.5.


Exif data from first shot.

A lot there, not sure which parts are the important ones

Camera Pentax K100D
Exposure 0.5
Aperture f/0.0
Focal Length 70 mm
Focal Length 70.0 mm
ISO Speed 200
Exposure Bias 0 EV
Flash Off, Did not fire
Orientation Horizontal (normal)
X-Resolution 72 dpi
Y-Resolution 72 dpi
Software K100D Ver 1.02
Date and Time (Modified) 2011:01:30 12:05:02
YCbCr Positioning Co-sited
Exposure Program Manual
Date and Time (Original) 2011:01:30 12:05:02
Date and Time (Digitized) 2011:01:30 12:05:02
Metering Mode Center-weighted average
Color Space sRGB
Sensing Method One-chip color area
Custom Rendered Normal
Exposure Mode Manual
White Balance Manual
Focal Length In35mm Format 105 mm
Scene Capture Type Standard
Contrast High
Saturation Normal
Sharpness Hard
Subject Distance Range Distant
Pentax Model Type 0
Preview Image Size 640x480
Preview Image Length 40864
Preview Image Start 2264
Pentax Model ID K100D
Date 2011:01:30
Time 12:05:02
Quality Best
Pentax Image Size 3008x2000
Flash Mode Off, Did not fire
Focus Mode AF-S
AFPoint Selected Fixed Center
Exposure Time 0.5
FNumber 0.0
ISO 200
Exposure Compensation 0
Metering Mode Center-weighted average
Auto Bracketing 0
White Balance Daylight
White Balance Mode User-Selected
Saturation Normal; 0
Contrast Med High; 0
Sharpness Med Hard; 0
World Time Location Hometown
Hometown City London
Destination City London
Hometown DST No
Destination DST No
DSPFirmware Version 1.02.00.06
CPUFirmware Version 1.02.00.06
Effective LV 23.5
Image Processing Unprocessed
Picture Mode Manual, Off-Auto-Aperture; 1/2 EV steps
Drive Mode Single-frame; Self-timer (2 s); Shutter Button; Single Exposure
Color Space sRGB
Preview Image Borders 26 26 0 0
Lens Type smc PENTAX-F 28-80mm F3.5-4.5 or Tokina Lens
Image Processing Count 0
Camera Temperature 18 C
AELock Off
Noise Reduction On
Flash Exposure Comp -2.0
Image Tone Bright
SRResult Not stabilized
Shake Reduction Off
SRHalf Press Time 1.07 s
SRFocal Length 70 mm
Shutter Count 4542
Black Point 0 0 0 0
White Point 13024 8192 8192 8480
Picture Mode2 Manual, Off-Auto-Aperture
Program Line Normal
EVSteps 1/2 EV steps
E- Dial In Program P Shift
Aperture Ring Use Permitted
Flash Options Normal
Metering Mode2 Center-weighted average
AFPoint Mode Fixed Center
Focus Mode2 AF-S
AFPoint Selected2 Center
ISOFloor 200
Drive Mode2 Self-timer (2 s)
Exposure Bracket Step Size 1.0
Bracket Shot Number n/a
White Balance Set Daylight
Multiple Exposure Set Off
AEExposure Time 0.5
AEAperture 0.1
AE_ ISO 200
AEXv 0
AEBXv 0
AEMin Exposure Time 1/3862
AEProgram Mode Tv
AEMax Aperture 3.4
AEMax Aperture2 3.4
AEMin Aperture 23
AEMetering Mode Center-weighted average
Auto Aperture Off
Min Aperture 22
Lens FStops 5.5
Nominal Max Aperture 4.8
Nominal Min Aperture 27
Max Aperture 4.0
Flash Status Off
Internal Flash Mode Off, Normal
External Flash Mode Off
Internal Flash Strength 0
TTL_ DA_ AUp 0
TTL_ DA_ ADown 64
TTL_ DA_ BUp 0
TTL_ DA_ BDown 64
External Flash Guide Number n/a
External Flash Exposure Comp n/a
External Flash Bounce Direct
AEMetering Segments 2.9 3.4 4.1 4.2 3.9 3.8 2.9 2.5 2.8 2.2 4.4 4.1 3.6 3.5 4.2 2.5
Flash Metering Segments 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Slave Flash Metering Segments 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
WB_ RGGBLevels Daylight 12763 8192 8192 8313
WB_ RGGBLevels Shade 15373 8192 8192 6351
WB_ RGGBLevels Cloudy 13795 8192 8192 7464
WB_ RGGBLevels Tungsten 7241 8192 8192 17294
WB_ RGGBLevels Fluorescent D 14948 8192 8192 8435
WB_ RGGBLevels Fluorescent N 12359 8192 8192 9426
WB_ RGGBLevels Fluorescent W 11004 8192 8192 11469
WB_ RGGBLevels Flash 13269 8192 8192 7808
Manufacture Date 2007:05:03
Production Code 2.2
Internal Serial Number 6593649
Power Source Body Battery
Battery States 4 0
Battery ADBody No Load 166
Battery ADBody Load 148
Battery ADGrip No Load 0
Battery ADGrip Load 0
AFPredictor -7
AFDefocus 5
AFIntegration Time 14 ms
AFPoints In Focus Center (vertical)
Compression JPEG (old-style)

check you 2 stop nd to see if it is polarized.... a cheap polarizer could easily be sold as a 2x nd....
4x possible but not likely....

I got the same set from the same seller but never had any problems. I expect a couple of deliveries tomorrow, if they come early I go out and see if I can replicate the result. Never stuck all three together so it will be interesting, Will post the result here.

An ND2 or ND4 would that gave that result would be obviously coloured. High quality filters will be absolutely neutral. It isn't a good idea to stack filters; in this case you're using three - so another three layers of glass and another six refective surface before the image even gets to the front element.

There is clearly something less than 'neutral' in the chemical composition of the glass. Bin, I think but I guess you know that

I have read of a lot of ND filters probably aside from the Lee or Hitech Ones having a cast but I've never seen anything like that!

i have cokin nd filters which if 3 are stacked it gives a magenta cast take any one away and it disappears. i bought the hi tech -just the same and their 10 stop is awful for it.

ref previous post. wasted my money on hi-tech,now saving for lee system, should have done it in the first place

damn ive bought same ones

Can anyone point us interested in these as to where we can get some good ND filters without breaking the bank? I'd greatly appreciate it!

tiffin, hoya, lee, none are actually cheap.