danbir1 Loc: North Potomac, MD

You are entitled to what you believe in.
As I mentioned, I have my own experience and so do you.

splatbass Loc: Honolulu

Right, understood. But the pictures posted show exactly what I saw. Taking the filter off made the difference.

Angmo

Some of my lenses were valued $2,000-$8,000. Never used a UV filter. Outdoors, anywhere. Even in muddy, dusty environments or a few weeks trekking in the Himalayas. Just another hunk of glass to get in the way.

When you buy a lens from a dealer they’ll ask “would you like fries with that?” Or rather, “would you like a filter with that?”

Xtra profit for the dealer.

danbir1 Loc: North Potomac, MD

I also understand and I don't believe for a moment that this horrible image was caused by a good quality filter, I just don't.
Oh well, put a cheapo filter or a piece of plastic in front of a lens, and yes, you can get it to look that bad...

DirtFarmer Loc: Escaped from the NYC area, back to MA

Before you ascribe a cause to an effect you have to show repeatability.

You have an effect (cruddy looking image, both in the viewfinder and in the final image).
You have an observation (the image looked much better after you removed the filter).
The observation is complicated by different exposures. (Using Auto ISO???).

You have not established a cause to that effect. If this is the first time you ever used this filter, and if the filter was the cause of the cruddy image, you would have said "What the #$*&^$*?????" and maybe tried another couple shots before throwing away the filter. If it was not the first time you used the filter, and if the filter did not produce cruddy images, you would have put it in your pile of filters and tried it again sometime later.

To establish that the filter was the cause of the cruddy images you have to perform several tests.
(1) Take more shots with the filter under different conditions. If they are all cruddy the probability is pretty good that the filter is the cause. Take it back to where you bought it and complain.
(2) If some but not all of them are cruddy, you should be able to define the conditions that lead to cruddy images. If there are very few conditions under which you don't get cruddy images, then the filter is of limited value to you. Take it back to where you bought it and complain.
(3) If only a few are cruddy, note the conditions that lead to the cruddy images and try to avoid using the filter under those conditions.

In these tests I would recommend using manual exposure so that you will be sure to compare shots with the same conditions. Also the shots should not be taken under conditions where the light was changing significantly in short periods of time (e.g. sunlight and broken cloud cover).

I should note that although I am not a proponent of leaving a filter on your lens at all times, I don't believe a good filter will significantly alter an image as long as stray light is not incident on the filter in such a way to cause flare. Even a lens hood is not always proof against stray light hitting your filter. Of course the key word is "significantly". Any change in the optical path will have some effect. Whether the effect will be observable is determined in part on how closely you look at your images.

Bipod

Consider buying a multi-coated filter...and a lens hood.

Also, you might try clicking on Search, above, and typing "UV filter" into the earch box--
these subject has been discussed at least three times in the last month.

splatbass Loc: Honolulu

I'm aware it has been discussed. That is why I posted this, because I had photographs pertaining to the argument.

splatbass Loc: Honolulu

That is exactly what I believe happened, stray light hit it in just a way to cause flare. I've been using that filter for a while, and this is the only time it has happened.

MauiMoto Loc: Hawaii

Angmo

Maybe amazon is becoming an outlet for counterfeit goods of all types.

aflundi Loc: Albuquerque, NM

Are you not telling us which B+W filter model for a reason? Without that information, it's hard to come to any useful conclusion.

Bipod

This thread was a set up. The OP deliberately omitted all the pertinent facts---filter, lens, and camera models--
even the fact that he was continuing a discussion from another thread.

Is deception OK these days? I thought that was only true in politics.

For all we know, he may have used PhotoShop to reduce the contrast of
that image. Image files prove nothing---it's just provocation.

Angmo

That’s all believable.

MauiMoto Loc: Hawaii

Last month I saw a used 70-200mm f2.8 vrii excellent condition for 500 on Amazon from a third party seller, some red flags, like to contact them directly before ordering, which I did not do. Amazon canceled the order the next day, gave no reason and the item and the seller disappeared.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

The data:

Regarding the OP's Images

The "bad" one was exposed at f/6.3 @ 1/640 sec. ISO 5600

The better image shows at f 6.3 @ 1/320 sec. ISO 4500

That's a one stop difference as per the shutter speed but the ISO is elevated in the bad image. There is still some underexposure. If the image appears as shown in the viewfinder, the introduction of flare could have accounted for the muddy image and was exacerbated by the underexposure. Perhaps that much flare could have affected the lens without the filter- sometimes moving the camera very slightly into the shade will eliminate the glare. Shooting at those high IOS settings probably ain't doing the quality any good either.

The only way to tell if the filter is at fault due to poor quality, lack of coating, or a defect of some kind is to make some tests under controlled conditions. Shoot something with back or side light and allow some light to strike the lens- with and without the filter. Make certain that your lens shade is doing its job.

Many years ago, I attended an Ansel Adams workshop. Mr. Adams was making his own lens shades- he recommended creating a very deep shade and testing it at infinity, at a landscape working distance, at your working aperture- making it deep enough where it starts to vignette the image and then cut it back. That was a long time ago, but that concept always stuck with me. In lighting conditions that may cause flare, I always use a bellows lens shade and follow that rule. I can rack it out until it shows up in the frame and then racks in back a touch. Obviously, that can not be done quickly but I will do that for architectural exteriors and landscape work.

Mr. Adams must have thought that minimizing flare was very important. Also- he did use filters when required.

I do quite a bit of aerial photography where filters are oftentimes required for haze reduction, polarization, and infrared applications. I still use some of my aerial camera filters from the 1960s and I don't have issues with flare. These are very large filters- talk about " big chunks of glass" I'll attach a shot of them- the little one in the shot is an 82mm- just to give y'all some scale. The big ones were made by Zeiss and they are uncoated. I never take off without them

Also, see a shot of my beaten up compendium lens shades.

As far as lens protection, I ain't preaching to anyone. If some folks are affluent enough to risk messing up a multi-thousand dollar lens in rough conditions - that's up to them. Some folks will handle dangerous materials without eye protection, run into a combat situation without a flak vest, and go sailing without a flotation device. Maybe it's a "Macho thing" "I don't need no damn..." whatever" are oftentimes those famous last words. Well- my gear is well insured against accidental damage but I worry that if I mess up a vital lens real bad, out on a location or while airborne, I won't be able to finish the job and deliver on time. So... that might increase my insurance premiums and put a dent in my accounts receivable.

OK- any photo retailer will tell you that add on sales really help that bottom line. So... they gotta make a living too and I don't think they are out to fool anyone. My dealer says, "hey- how about a $10,000 lighting system to go with that new camera"! It's up to me! It's up to you!