3-stop ND filter reduces saturation

[sfogel2]

I just bought a 3-stop ND filter for my Canon 5D Mark IV to use with a few lenses. Tried it in the studio with a strobe yesterday and noticed a distinct desaturation of the photo compared to using high-speed sync without ND.

Is reduced saturation expected with 3-stop ND filters? This is a high-quality ($160) filter from B+W. Thanks.

 

[Strodav]

I just bought a 3-stop ND filter for my Canon 5D Mark IV to use with a few lenses. Tried it in the studio with a strobe yesterday and noticed a distinct desaturation of the photo compared to using high-speed sync without ND.

Is reduced saturation expected with 3-stop ND filters? This is a high-quality ($160) filter from B+W. Thanks.

Did you increase the ISO for the shot with the ND filter?

 

[sfogel2]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

 

[Scott Whaley]

I have a 9 stop ND filter. Best to use a tripod and lower the shutter speed. Also, you may want to cover the viewfinder with something to keep light from getting into the lens.

 

[photoflyer]

That does not surprise me but can you bring it back in post?

I figure that there is always a trade off. Any additional glass in front or behind the lens, no matter how good, will have the intended benefit at some cost elsewhere.

 

[smoke665]

Assuming you compensate for exposure the color saturation on a shot with an ND filter should be no different than one without. I have a wide range of filters that I've used frequently and never notice any difference.

There will be significant differences between a shot taken with an ND filter and one taken with HSS. An ND will darken the image equally across the frame while HSS provides light in the shadow areas to lower the DR across the frame.

 

[480sparky]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

NDs aren't selective. They reduce light in the entire scene, not just the background.

Their only effect they can have on the background is a result of opening the aperture and throwing it further out-of-focus.

 

[smoke665]

Actually there's another effect, depending on shutter speed, how stable the camera is and wind, you can get motion blur.

Just to be sure you don't have a UV Haze filter on also?

 

[Space Face]

I have a number of ND filters, grads etc and can't say I've noticed this issue. Interesting reading the replies tho.

 

[petrochemist]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

NDs aren't selective. They reduce light in the entire scene, not just the background.

Their only effect they can have on the background is a result of opening the aperture and throwing it further out-of-focus.

I've found many 'neutral density' filters that are far from neutral, so are selective to an extent. However these simply introduce a overall tint. If the image is being desaturated that sounds like an exposure issue or perhaps severe flare (similar to what I've seen using 90 year old uncoated lenses).

 

[480sparky]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

NDs aren't selective. They reduce light in the entire scene, not just the background.

Their only effect they can have on the background is a result of opening the aperture and throwing it further out-of-focus.

I've found many 'neutral density' filters that are far from neutral, so are selective to an extent. However these simply introduce a overall tint. If the image is being desaturated that sounds like an exposure issue or perhaps severe flare (similar to what I've seen using 90 year old uncoated lenses).

I'm referring to exposure...... not color rendition.

 

[Strodav]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

That was the point of the question, you don’t want to increase ISO as it reduces DR and increases noise. I use Lee 100mm filters, mostly soft gradient, but have used their 10 stop “big stopper” and haven’t seen any desaturation or color casts.

 

[petrochemist]

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

NDs aren't selective. They reduce light in the entire scene, not just the background.

Their only effect they can have on the background is a result of opening the aperture and throwing it further out-of-focus.

I've found many 'neutral density' filters that are far from neutral, so are selective to an extent. However these simply introduce a overall tint. If the image is being desaturated that sounds like an exposure issue or perhaps severe flare (similar to what I've seen using 90 year old uncoated lenses).

I'm referring to exposure...... not color rendition.

I see, my mistake.
However shutter speed is often used with strobes to control background luminance & ND filters will allow that, in just the same way as aperture. Adjusting the power of the strobe might be an easier method if it's within the range the strobe can handle.

 

[480sparky]

Here's what my (apparently confusing) post was referencing:

I didn’t increase the ISO, no. Wouldn’t that defeat the purpose of using the ND filter to reduce the luminance of the background? Thanks.

I don't know of any ND filter that is capable of selecting the background and acting on it alone.

 

[smoke665]

However shutter speed is often used with strobes to control background luminance & ND filters will allow that, in just the same way as aperture. A

The ND Filter reduces the ambient light "equally" across the frame. When you add a strobe you're changing the EV on selective portions of the frame. I use an ND outside to lower the overal EV of the scene so that I can balance aperture and shutter for the intended shot. Using an ND with strobe is somewhat counterproductive, because switching to HSS negates the need for an ND.