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Do filters make flare resistance irrelevant?


piblondin

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Quick question: With regard to flare, specifically, should getting a more flare resistant lens matter if I'm just going to cover it with a UV or UV/IR filter? In other words, will a filter cause flaring on its own?

Yes a filter can cause some flare but it does not make flare resistance of lenses irrelevant at all. A flare free lens will keep most of its qualities fortunately. It's just that the filter may introduce ghost images in low light and some expected (on inexpected) light reflections from time to time.

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Not forgetting the quality of the filter itself and its coatings, the front surface is not necessarily the only contributor. Important too that its properties can be greatly affected simply by not being clean.

A hood is a very good idea in every case. No lens is completely immune though in extreme conditions (sun directly in frame shining right on front element for example).

 

I would add that (veiling glare) can come from reflections within the lens elements and the lens body itself.

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Geoff's point is important. Oh, and adding a coated filter won't help an uncoated lens.

 

See any flare here? http://www.l-camera-forum.com/leica-forum/members/23965-albums4157-picture6609.jpg

 

The flare about the figures is light bouncing back from the pressure plate or film. Halation.

.

Sometimes it works.

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Resistance to flare, in all its forms, and of internal reflections, is one of the most important properties of a lens. Not least with a RF camera, where we can't see it in the finder, and take appropriate measures.

 

Flare or stray light occurs mostly for two reasons: Strong sideways light on the first lens surface, like sunlight on a dirty car windshield (use a hood, keep the lens clean, and watch the light), and light reflected off internal element surfaces and parts of the mounting, and then careening around inside the lens and the camera. Internal reflections are extreme manifestations of this problem.

 

Clearly, a filter does only (and at most) remove some unwanted wavelengths of light. A UVa filter does not do even that, it removes UV light that cannot pass through a modern Leica lens. It does however add two extra glass-air surfaces for light to bounce off. So even a first class multi-coated filter cannot combat flare behind it. It can on the other hand add problems. A UV-IR filter e.g. can give rise to multiple green reflections from a strong point light source. See picture, taken with a M8 with UV-IR filter – in the lower part of the picture you can see (most clearly on the coat-tails of the left terracotta warrior) diagonal rows of green reflections of the two rows of lights in the ceiling.

 

Consequently, I use UV filters for mechanichal protection only on lenses whose front elements are exposed because of collapsible or very shallow hoods. The new wide angle lenses with the screw-in hoods (my examples are 35mm Summilux ASPH and 21mm Super-Elmar) have no filters and are protected by the hoods and their slip-on front caps.

 

The old man from the Age of the Yellow Filter

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I find this topic interesting as I´ve always used filters (B+W) on all my lenses. And that´s mainly because I´m neurotic about dirt and scratches on the lens surface. Even wiping the lens surface itself is something I cannot do for fear of wiping some coating along with it! :eek:

Is this fear ungrounded and should I get rid of my filters, provided the hood is there for protection?

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alw this is one of those perennial subjects where you will read strong opinions in opposite directions.

 

As a practical matter I doubt that you could demonstrate any quality difference in shots with and without your high quality filters fitted and mechanical protection of the front surface is a perfectly valid reason to keep using your filters if you prefer.

 

I think that lens hoods are always a very good idea both for their intended purpose and that mechanical protection too.

Personally I can say that hoods and filters have saved my lenses from impact damage on a couple of occasions. I have never scratched a lens nor filter in thirty odd years so far.

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I agree with Geoff (Hoppyman). Personal preference and strongly polarises opinion (pardon the pun).

 

Personally I always use hoods and high quality filters (Leica or B+W), although I may rarely take a filter off at night with potentially more difficult lighting (although I don't know whether it really made any difference.

 

They are primarily there for protection and have saved my lenses over the years from damage, both scratching and a few times with my old AI-S Nikon lenses used without hoods the filter rim took the impact that would have damages the lens or filter mounting thread.

 

Filters are cheap, lenses are not.

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In case one needs to use a liquid solvent for cleaning lenses/filters, what is recommended, alcohol?

 

I use ROR, bought a bottle about 15 years ago and it's still nearly full. Details here...

 

Screen Cleaner | Lens Cleaner | LCD Screen Cleaner

 

Remember to always spray any cleaner on a cloth before cleaning, never directly onto the lens.

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