To Multi-coat or NOT?

Is there an advantage to using a multi-coated ND filter vs. NOT?...and if so is there a significant difference in image quality that justifies shelling out more for them. There's so many opinions on brands, etc.....anyone have any recomendations for my three lenses, 1.) EF 70-200 IS 2.8L, 2.) EF 17-55 2.8L , 3.) EF 85 1.8

I currently have UVs on the first two, but they are not real quality glass filters. Without wading thru thousands of posts, does anyone have any suggestions. I'd like to purchase within the next two weeks before our Rehoboth vacation.

DD974 wrote in post #10646003
Is there an advantage to using a multi-coated ND filter vs. NOT?...and if so is there a significant difference in image quality that justifies shelling out more for them. There's so many opinions on brands, etc.....anyone have any recomendations for my three lenses, 1.) EF 70-200 IS 2.8L, 2.) EF 17-55 2.8L , 3.) EF 85 1.8

I currently have UVs on the first two, but they are not real quality glass filters. Without wading thru thousands of posts, does anyone have any suggestions. I'd like to purchase within the next two weeks before our Rehoboth vacation.

Multicoating of filters cuts down on the unwanted reflections on both of the filter's surfaces. This, in turn, helps to reduce the flare and other image degradation caused by cheap filters.

I'm curious as to your reason for wanting neutral density filters for all your lenses in the first place. They certainly are NOT what most folks would think of for "protection".

You would be far better off investing in proper lens hoods for each lens if "protection" is your only goal. Lens hoods can actually improve image quality and they provide physical protection that no filter can. If you intend to shoot in a sandstorm or driving rain, a high quality clear filter can give you a measure of protection of your lenses. Otherwise, I would never suggest using a filter for "protection" but only for creative purposes.

SkipD wrote in post #10646025
I'm curious as to your reason for wanting neutral density filters for all your lenses in the first place. They certainly are NOT what most folks would think of for "protection".

I guess I should have been more specific...I'm not wanting NDs for protection...I'd just get UVs for that, my purpose for wanting NDs is for lowering ISOs on bright days and slower SS around waterfalls, etc.

SkipD wrote in post #10646025
You would be far better off investing in proper lens hoods for each lens if "protection" is your only goal.

I have hoods for two of the three lenses...looking to get one for the 85mm.

DD974 wrote in post #10646054
I guess I should have been more specific...I'm not wanting NDs for protection...I'd just get UVs for that, my purpose for wanting NDs is for lowering ISOs on bright days and slower SS around waterfalls, etc.

I don't quite understand the "lowering ISOs" part, as a ND filter certainly cannot do that. In fact, if you wanted to keep the same shutter speed and aperture, using a ND filter would require you to increase the ISO setting value.

A ND filter is often used to allow slower shutter speeds for the classic blurred moving water images.

The bottom line - any and all filters you choose to use should be the absolute highest quality multicoated filters that are available to avoid problems with your image quality.

I highly suggest forgetting any UV filters at all and instead invest in AND USING good quality rigid lens hoods - the ones suggested by the lens manufacturer for each individual lens.

SkipD wrote in post #10646072
I don't quite understand the "lowering ISOs" part, as a ND filter certainly cannot do that. In fact, if you wanted to keep the same shutter speed and aperture, using a ND filter would require you to increase the ISO setting value.

I see your point....and I know the NDs reduce the amount of light hitting the sensor but but I've always heard that nuetral density filters decrease the effective ISO (above ISO 400), and allow it to be used outdoors in brighter situations.

DD974 wrote in post #10646095
I see your point....and I know the NDs reduce the amount of light hitting the sensor but but I've always heard that nuetral density filters decrease the effective ISO (above ISO 400), and allow it to be used outdoors in brighter situations.

I think you've either been confused by what you've read or you may have been reading something that's been incorrect.

Let's assume that you have a "two-stop" neutral density filter and the lighting for a scene allows the settings of ISO 100, f/8, and 1/250 shutter speed. If you put the ND filter on your lens, and want to keep the f/8 and 1/250 shutter speed, you would have to bump the ISO value to 400 to keep the exposure the same.

Typical uses of a neutral density filter are:

• to allow slower shutter speeds because you cannot lower the ISO setting any further than you have it and you want to use the same aperture you now are using
  
• to allow you to use a wider aperture (for shallower depth of field) because you are already at minimum ISO setting and slowest practical shutter speed

DD974 wrote in post #10646003
Is there an advantage to using a multi-coated ND filter vs. NOT?...and if so is there a significant difference in image quality that justifies shelling out more for them. There's so many opinions on brands, etc.....anyone have any recomendations for my three lenses, 1.) EF 70-200 IS 2.8L, 2.) EF 17-55 2.8L , 3.) EF 85 1.8

I currently have UVs on the first two, but they are not real quality glass filters. Without wading thru thousands of posts, does anyone have any suggestions. I'd like to purchase within the next two weeks before our Rehoboth vacation.

Personally, I think too much is often made of the absolute need for multicoating. I have many filters that aren't multicoated, including B+W ND filters (B+W polarizer is MRC, however), Singh-Ray polarizers/variable ND filters, and others from Lee. I have never seen any image degradation whatsoever when using these filters. The folks at Singh-Ray feel that any benefit that may be derived from multicoating their filters will be outweighed by other negative issues. I don't look at the lack of multicoating as a complete negative, as long as the filter is high-quality from a reputable manufacturer.

Skip, I think you're confusing him even more than he was to begin with.

OP - yes, an ND filter will give you the effect of shooting at a lower ISO setting without a filter.

And no, I don't consider multicoating as important on ND filters (especially 3 stop or more) as it is on regular filters. Here's why - Lens flare and reflection is a problem because the light is reflected off the internal surfaces of the lens or filter. If you have an uncoated UV filter, something around 5-8% of the light entering the filter will be internally reflected and contributes to flare, loss of contrast, and ghosting. Multicoating reduces this to as little as 0.5% on the best filters. Now if you have a 3 stop, uncoated, ND filter, only about 1/8 of the incoming light is passed through (and the internal reflection from the back of the filter is reduced accordingly). And most of the damage from flare is due to multiple internal reflections within a lens element or filter, but with 3 stop ND, every internal reflection is going to be weakened by that same 3 stops of attenuation.

As for getting multiple NDs, both your 17-55 and 70-200 take the same filter size; unless you plan on shooting both with ND filters at the same time, I wouldn't bother getting separate filters for each. Since the 85 takes a 58 mm, I'd get a separate one for it, just to avoid the hassles of a 58-77 mm step-up ring hanging off the front of it. I do have multiple 77 mm polarizers for my 24-70, 70-200 and 100-400 because I don't want to have to change filters when I change lenses and with multiple bodies I usually want a polarizer for each lens in use, so I don't have to change filters every time I change the lens in use. But I only have one set of ND grads for the whole lot.

Jon wrote in post #10646223
Skip, I think you're confusing him even more than he was to begin with.

I wasn't confused to begin with...unless what's posted here on B&Hs site on the Features tab for the ND filter is completely wrong. See under "four main uses", bullet #1 & #3...........let me know if this is incorrect.

DD974 wrote in post #10646557
I wasn't confused to begin with...unless what's posted here on B&Hs site on the Features tab for the ND filter is completely wrong. See under "four main uses", bullet #1 & #3...........let me know if this is incorrect.

Bullet #3 says: To decrease the effective ISO of high-speed film (above ISO 400), and allow it to be used outdoors in bright situations, and that would be a very correct statement.

Note that the complete statement refers to high-speed film. With film, one could not dial in different ISO values. Thus, if the photographer needed to have a "slower film" for a shot or two in bright lighting he/she may have to use a neutral density filter to accomplish the task. That is why the "above ISO 400" part is in the statement.

With digital cameras, one would merely dial down the ISO setting in the camera for most similar tasks.

I had mentioned that ND filters are often used to allow use of a slower shutter speed to blur flowing water. This is, in effect, lowering the "effective ISO" setting relative to the dialed-in value (or the ISO speed of the film in the camera).

I think what threw me was the partial quote of the bullet item that you gave in post #6 which to me seemed out of context a bit.

SkipD wrote in post #10646782
Bullet #3 says: To decrease the effective ISO of high-speed film (above ISO 400), and allow it to be used outdoors in bright situations, and that would be a very correct statement.

Note that the complete statement refers to high-speed film. With film, one could not dial in different ISO values. Thus, if the photographer needed to have a "slower film" for a shot or two in bright lighting he/she may have to use a neutral density filter to accomplish the task. That is why the "above ISO 400" part is in the statement.

With digital cameras, one would merely dial down the ISO setting in the camera for most similar tasks.

I had mentioned that ND filters are often used to allow use of a slower shutter speed to blur flowing water. This is, in effect, lowering the "effective ISO" setting relative to the dialed-in value (or the ISO speed of the film in the camera).

I think what threw me was the partial quote of the bullet item that you gave in post #6 which to me seemed out of context a bit.

ahhh...understood Sir....Thanks for the insight!

SkipD wrote in post #10646782
I had mentioned that ND filters are often used to allow use of a slower shutter speed to blur flowing water. This is, in effect, lowering the "effective ISO" setting relative to the dialed-in value (or the ISO speed of the film in the camera).

Skip,, I kind of know what you mean here but it's a tad confusing for any new chum to photography..

The ISO will remain the same irrespective of a ND filter used or not.. Sensor sensitivity (ISO) will not change when a ND filter is used, just as sensor sensitivity won't change when aperture or shutterspeed is changed.. Sensor sensitivity is solely a property of the sensor not the optics..

A more accurate property would be a change in aperture without depth of field being effected..

yogestee wrote in post #10646879
Skip,, I kind of know what you mean here but it's a tad confusing for any new chum to photography...

I agree that the subject can be quite confusing if the newbie does not understand the very basics of the three primary elements of exposure control (ISO, aperture, and shutter speed) and how they interact normally.

Adding a fourth element such as a filter that cuts out light or even things like flash fill would not be the easiest things to fully comprehend without the background in the basics.

If I can find spare time, I may work on writing an article for the beginning photographer on the subject of how various filters work for the beginning photographer and assuming a minimal background in the basics of exposure control.

The harm of NOT multicoating, demonstrated vs. multicoating.

I'm not sure I am in agreement. As the link above shows, in low light the affect of multicoating vs. not is quite apparent. ND simply turns brighter light into 'low light' entering the optics, and it is the rear surface of the filter which causes the reflections visible in Ken & Christine's comparison.