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12-28-2011, 09:39 PM   #1
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will a good quality ND filter retain 100% pic quality?

ok..I have a Variable Neutral Density Filter..I can see it does degrade pic quality by 1 stop..for example..the pic took with the filter at f4 is equal to the pic quality took at f2.8 without filter....that is not good...

anyway this is still expected..because I know Variable Neutral Density Filter usually degrade pic quality and since mine is not expensive..so no wonder..

now I am wondering if a good fixed ND filter can retain 100% pic quality???

12-29-2011, 12:21 AM   #2
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QuoteOriginally posted by liukaitc Quote
ok..I have a Variable Neutral Density Filter..I can see it does degrade pic quality by 1 stop..for example..the pic took with the filter at f4 is equal to the pic quality took at f2.8 without filter....that is not good...

anyway this is still expected..because I know Variable Neutral Density Filter usually degrade pic quality and since mine is not expensive..so no wonder..

now I am wondering if a good fixed ND filter can retain 100% pic quality???
Well, the purpose of the ND filter is to allow less light in and allow you to use a larger aperature for greater depth of field. Very helpful on Sunny Days or in very bright lighting. Cheap ND filters can degrade picture quality, yes. What are you expecting the ND filter to do? Maybe you're thinking a ND filter does something different than it actually does?
12-29-2011, 04:16 AM   #3
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Any filter will have an effect on image quality, the question is if it's noticeable.

Variable Neutral Density comes in many grades and they work by turning 2 polarize surfaces so it will certainly have an effect on your image quality.
12-29-2011, 04:55 AM   #4
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QuoteOriginally posted by liukaitc Quote
ok..I have a Variable Neutral Density Filter..I can see it does degrade pic quality by 1 stop..for example..the pic took with the filter at f4 is equal to the pic quality took at f2.8 without filter....that is not good...

anyway this is still expected..because I know Variable Neutral Density Filter usually degrade pic quality and since mine is not expensive..so no wonder..

now I am wondering if a good fixed ND filter can retain 100% pic quality???
no it can´t. You put extra glass (or plasic) in front of your lens, so image quality will be less. If yoy will see it, that is another story (as already mentioned above), most likely you won´t, especially when looked on screen or printed. Just don´t make the mistake of start pixel peeping, cause then nothing will be good anymore

12-29-2011, 06:55 AM   #5
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ok...so I won't notice the IQ difference with a good fixed ND filter on...
that good..this is what I want to know..
because with my cheap Variable Neutral Density Filter on, it is really noticiable in IQ drop, and that make my pic not very usable..
12-29-2011, 07:59 AM   #6
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How particular are you with these pictures? can we see them?
12-29-2011, 08:15 AM   #7
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Anything you put between the lens and the subject will affect the quality of the image no matter what. Even the quality of the air (e.g. smoke, pollution, moisture) will have an effect after some distance.

You always have to balance the results with the tradeoffs. An ND filter is typically used to take photos when your lens cannot be stopped down further (or diffraction will degrade the image quality too much) or for creative reasons such as using a wider aperture on bright conditions to maintain a shallow DOF.


Different ND filters will produce results with varying quality so chose whatever meets your needs.
12-29-2011, 08:17 AM   #8
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QuoteOriginally posted by liukaitc Quote
ok...so I won't notice the IQ difference with a good fixed ND filter on...
that good..this is what I want to know..
because with my cheap Variable Neutral Density Filter on, it is really noticiable in IQ drop, and that make my pic not very usable..
if you by a cheap ND filter, the IQ will be better that witha variable ND filter already. Somewhere on the internet there is an article why the variable aren´t that good. Just don´t remember where.
with ND filter, it is better to buy several ones with different densities instead of a variable one. even when you stack them together, the IQ should better

12-29-2011, 08:56 AM   #9
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QuoteOriginally posted by Macario Quote
Somewhere on the internet there is an article why the variable aren´t that good.
Because most of them use 2 linear polarizers to "dial-in" the amount. Linear polarizers can significantly affect the autofocus and autoexposure components of the camera. In addition, they can create color shifts and casts that further degrade the image.

Stacking multiple filters though is an invitation for flares and ghosting since there are too many additional surfaces that will reflect light. Make sure you always use a proper lens hood to minimize such effects.
12-29-2011, 10:57 AM   #10
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ok...this is the 100% crop comparsion...
I can see it is about 1 stop IQ drop..also some green color cast
just hope a good fixed density ND filter can have better result...

Last edited by liukaitc; 06-02-2013 at 12:04 PM.
12-29-2011, 12:35 PM   #11
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Liukaitc, I am not clear what you mean by “1 stop IQ drop”. Image quality is not measured in stops. Actually there is no real measure of “Image Quality”; it is a subjective construct. You can measure resolution, contrast, color rendition, distortion, aberrations, etc., and you can create a composite “measure” of image quality. A good lens will produce high quality images that have high resolution, high contrast, accurate colors, low distortion and low aberrations.



Not knowing the other variables in your images, specifically camera, lens, focal length, shutter speed, ISO, value of ND filter and if SR was used, it is difficult to analyze them and make comparisons.
  • From what I see, the one with the filter has a color cast implying that the filter is not “Neutral” enough.
  • All three seem to have different exposures (look at the density of the tree).
  • The one at f2.8 is clearly overexposed compared to the others.
  • The lens at f2.8 seems softer than at f4, which is very normal for most lenses. If f2.8 is the fastest f-stop of your lens, then it is expected the IQ to increase as you stop down the lens until diffraction kicks in at around f11 and higher.
  • The image with the ND filter was shot at a much slower speed than the one at f4; all things being equal it was done as many stops slower as the value of the ND filter. That may have been too slow and the image could have suffered from motion blur. Again without knowing the EXIF data it is difficult to draw conclusions.
As I mentioned on an earlier post, the purpose of using an ND filter is to take a picture that otherwise is not possible as in the case of a very bright day or when you want shallow DOF (small f-number) and slow speed (to show motion). An ND filter does not “enhance” an image, it just make it possible to capture it under adverse conditions, so it should be used as a last resort.
12-29-2011, 02:09 PM   #12
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I mainly means the sharpness or resolution drop by 1 stop with the filter on..
can see it from the comparsion..this is pretty noticiable difference of resolution drop with filter and without filter..

again I assume this is the consequence of my cheap variable ND filter..

actually my question is pretty simple..maybe because my poor english make people hard to get it..

I have a cheap variable ND filter..and the resolution or sharpness of the pic has dropped with the filter compare to without the filter..
and it is pretty noticeable difference..
and I wonder if a good non-variable ND filter can retain better resolution of the lens and possiable the difference can not be noticeable?
if the answer is yes..then I will throw away my variable ND filter and buy a good non-variable ND filter.
if a non-variable ND filter would not do any better than my current one..then I have no need to buy it..
This is what I want to know..

Last edited by liukaitc; 12-29-2011 at 02:18 PM.
12-29-2011, 02:59 PM   #13
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Can you share with us the focal length and shutter speeds you used for the 3 photos? That will help determine how much degradation was due to motion blur. I assume that you used the same ISO.
12-29-2011, 03:07 PM   #14
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The answer is yes, a non-variable and good ND filter will be better than a crappy variable ND filter in terms of image quality transmission. Whether or not you will notice the IQ drop from a good filter is hard to say - pixel peeing you may notice it a little less resolution, but I doubt it would be like what you are seeing with your current filter.
12-29-2011, 04:45 PM   #15
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QuoteOriginally posted by liukaitc Quote
I mainly means the sharpness or resolution drop by 1 stop with the filter on..
can see it from the comparsion..this is pretty noticiable difference of resolution drop with filter and without filter..

again I assume this is the consequence of my cheap variable ND filter..
I see sharpness or contrast loss but it may not be 100% due to the cheap variable nd. Such contrast loss can also be caused by indirect light striking the filter & causing uniform flare. I recommend that you try the test again with a hood on the lens.

QuoteQuote:
I have a cheap variable ND filter..and the resolution or sharpness of the pic has dropped with the filter compare to without the filter..
and it is pretty noticeable difference..
and I wonder if a good non-variable ND filter can retain better resolution of the lens and possiable the difference can not be noticeable?
if the answer is yes..then I will throw away my variable ND filter and buy a good non-variable ND filter.
if a non-variable ND filter would not do any better than my current one..then I have no need to buy it..
This is what I want to know..
Yes most probably a multicoated nd filter will provide less degradation than a variable nd filter. This is because the variable nd filter has many layers in its construction so the total probability of a defect is greater.

Another factor to remember is that filters affect IQ for long focal length lenses more than for short focal length lenses.
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