If you do not notice the images being better, keep the filter on the lens.

I have a number of Leica, B&W, Schneider, and Nikon multicoated filters. They are all high quality. The only time to remove them would be shooting bright lights at night, due to possible relfections.

I don't use any filters for anything.

B&W are excellent filters. The multi coated ones are as good as any others. I stopped putting a UV filter on my lenses because I got flare a couple of times and ruined what would have been excellent shots. Just go w/ a hood now. If I need more contrast, or need to darken the sky a little, I'll put a yellow or orange filter on, along w/ a good hood of course. Any time you put a filter on a lens you're adding another piece of glass and an airspace, so it could possibly add some flare. Some lenses are more prone to this than others.

You used them on the M8, and the M9 has the filter over the sensor. Otherwise the world would look like this:

Given the wrong lighting conditions, any filter will negatively impact image quality. I'm not risking it. A hood will protect the front element, plus modern coatings stand up to proper cleaning methods well.
BTW, Brian, what did you want to prove with that woods scene with motion-blurred leaves? I see no IR-Effect there.

I think you could spend a lifetime trying to find the 'wrong lighting conditions' that would outwit a B&W MRC filter.

A filter can be more than a filter, mine are lens caps, leaving the black caps at home. Speed changing lenses is increased, as is cleaning because a filter can be wiped with the corner of a shirt, or rubbed with a glove. And they are especially good at keeping rain off the front element, something that usually drives non-filter users indoors for protection.

So if a good quality filter has an effect on image quality the fact I haven't spotted what this effect is in thirty years is a reasonable risk. Certainly more photographs would have been compromised or lost by checking and re-checking the front element, and endless careful cleaning, rather than just getting on with the job before the light changes or people move. I'm not an obsessive lens cleaner anyway, dust having little or no effect, but a filter even encourages me to give it a wipe, so I'm sold.

Steve

Huh? This is a typical IR shot. Maybe with some UV mixed in. Did you use a 708 filter, Brian?

I see now that we're in the post-M8 era, that tired old UV vs no-UV argument has crawled back out from under it's rock.

I don't know which of my older lenses Leica still has front elements for, and which ones are "unrepairable", but in any case given what Leica's lens prices are nowadays, I'll take whatever theoretical trade-off there is to using a modern multi-coated filter. But I have nothing but respect for whoever refuses to use them...just as long as it isn't my lens they're using

old lenses like the collapsible summicron had soft coatings and glass that did not stand up to cleanings, leave a filter on.
Modern leica glass has hard coatings, so unless you take sandpaper to it it should be ok.

I leave a Band W or leica filter on everything, because ive noticed that lenses that had a filter on from the 195o's were pristine, and lenses that didnt have scratches.

do whatever you feel most comfortable with,
Nik

...or, rather than sandpaper, a single grain of sand adhering to the glass perhaps by static, that in your hurry or perhaps dim light you don't notice, and that your blower/brush happens to miss, and it gets picked up on your microfiber cloth and dragged all over the surface. Ask me how I know

Saver sex, allways!!!!!

I usually mount filters onto my lenses, but my 35 Summicron doesn't have a threaded barrel (I think it's version 2 or 3). It's a bother sure, and I haven't found any A42 filters but I can deal with it. It's a lens from the 60s with no scratches on the glass, so I look after it well considering how time has treated it

If I want to protect my lens, I'll use a hood or a lens cap.

Like Leica says in their manuals "better to have a clean lens then to have to keep cleaning it"

I always use a high quality UV lens (B+W or hoya), 50 years from now the front element will look like it came out of the Leica factory yesterday.

I'm not sure what your images demonstrate? I'm sure none of my Leica lenses are as marginal in their performance that just adding a filter makes so much difference. It doesn't seem like a test that results in a new rule of photography to me.

Steve

Quite right, Steve. This test does not tell me to avoid a filter, it tells me to avoid that lens. Even the unfiltered shot shows an amazing amount of flare...

The next time I'm shooting a highly multi-element, wide angle zoom that has a known propensity to flare directly into an extremely bright spotlight, I'll remove the filter.

Looking at just the spotlight itself it appears the filter also increased overall brightness about 1.5 stops

I prefer to filter ... if only for the purpose of lens glass protection. That's just my comfort zone.

After making a 2,000-mile trip recently by air I took my M3 out of its bag to find this:

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After removing the filter, it looked like this:

[IMG][/IMG]

IMHO, always protect your precious lens with a filter.

Well, good example.

Even though I didn't take a picture of it, a filter did save a Nikkor lens of mine once. Somebody opened a door and BAM, right in the glass. Yes, I did have a hood, but it was a small door handle and went in anyways (that was very unlucky, I admit). Filter was shattered, lens was perfectly fine.

I believe that, as long as you use good quality filters, you won't notice any problem or additional flare in 99% of situations. I've used Nikon, B+W and Zeiss filters with no problem for years.

Wind, salt, dust, sand, all this can damage your lens's coating. And, as posted before, you want to clean the lens when a small grains of sand is here... you could be in a very bad situation.

If only for the peace of mind, please, put a filter, just find a good one.

I see absolutely no reason not to use a good filter on an expensive lens. For protection I always use B+W MRC Clear filters only taking them off when using another filter or shooting at night around bright lights. There are many circumstances where a hood won't do anything to protect a front element.

Everyone of my lenses are insured, but that doesn't mean I want to go through the hassle of squeezing the money out of my insurance company, then getting back on an eight month waiting list for a Leica lens.

In 25+ years of photography, I've had two lens front elements saved by a UV filter that took the force of a blow. They were wearing lens hoods and lens caps too at the time. Now every single lens that I own has a filter of some kind.

If you have small children, you will soon find out that they love to poke at the shiny glass with their fingers. Or, they spit/sneeze when you're about to take their picture. They will find your lens element, lens hood or not.

Finally, I find that the color rendition of certain films such as Fuji FP-100C is too blue/green without a compensating Tiffen 812 filter to correct the color rendition.

I wonder how a B&W or Heliopan filter's would fare with this test,
that what I use on my lenses.

Range