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There have been some comments and questions in the RX10/etc threads about lens hoods and filters, pros and cons of using protective UV for example. Over the years I've done many tests and used hundreds of lens types, and also (probably) hundreds of filters though my best UVs have survived over 30 years. My worst UVs have lasted a day.

 

I generally don't use any lens long-term, outside the studio, without a permanently fitted filter. Today you can buy filters such as Sigma DG (which in comparison tests I've done prove to be equal best with the very top level Hoya Pro 1 Digital or best B+W MC but at much lower cost). These now have nanocrystal type lens coating which is extremely hard and can be cleaned vigorously without destroying the coating, and also rejects water. I've bought several lenses recently which should have been perfect but with their relatively soft front element glass and fragile coating have been ruined by past owners cleaning them. The filter also protects against atmospheric film deposition - this is for example when you are in a Las Vegas casino, the last bastion of heavy smoking, or shooing in Beijing smog, or at a fire. Even in your own home you'll get this (try cleaning some paintwork after it's been around ten years, especially anywhere near your kitchen). Every time you overheat some oil or burn the toast, you send particles and oils into the air, and glass loves them. As my kitchen windows tell me...

 

So, let this land on your filter and not on your lens front element.

 

There is a myth that small marks and scratches on a lens don't show in the image and do not matter. This may be true if the lens is a 50mm f/1.4 or a 300mm f/2.8, but it certainly is not the case with standard and superzooms, and retrofocus wide-angles (rangefinder wides are less affected). With a typical 20mm wide angle or the 24mm end of a zoom, the surface of the front element can be softly resolved by f/8 and may show sharp details at f/16. Of course the same applies to a filter in front of the lens. But if you get a scratch or a chip (the worst type of damage even if it's a tiny sub-mm point) on the lens it is there for good. Solutions like filling the chip with permanent marker ink might be a way to repair a valuable lens sold to you damaged for a fraction of its mint value. That was the loss the previous owner accepted by not using a filter.

 

You can do nothing about fisheyes, 14-24mm Nikkors, 12-24mm Sigmas, etc - except use them with great care and guard those vulnerable front elements. You also need to be really careful with the rear elements of RF and mirrorless wide angles. I received one with a fingerprint on it I didn't spot, ran some test shots and thought my sensor must have a fingerprint - help! No, it was the rear element, and that mark was 'projected' with surprisingly clarity.

 

UV filters are a potential danger to all your shots, mostly because so many are very poor. Hoya's output is graded; even within the Hoya brand, there are levels of planar accuracy (the more you pay, the better the filter) and the sub-brands of Marumi (moderate good) and Kenko (cheap and cheerful) also have standard and superior ranges. New Chinese filter brands using Hoya glass also vary but it's really hard to find out what's good. I've tested many filters in the way which reveals their flaws - a standard to long focal length used at a medium aperture on a distant detailed target, on a day free from haze (or an indoor substitute). The worst filters show patches of blurring, even plain protectors and UVs can reverse all the resolution benefits you've paid for in that Zeiss manual focus special lens. Polarisers are actually the worst culprits and very few have good optical properties - they also deteriorate with age.

 

Lens hoods - again I always use if possible. The modern petal lens hoods with cutaways are far more effective than old shorter 'round' ones but my favourites are full metal rectangular hoods I've found in vintage gear bins - a Konica one for 28mm, a Minolta for 35mm, clamp-on. I actually use the 35mm one on a 28mm lens without cut-off and it is 100% effective, there's no image area projected into the camera significantly outside the frame, and it is also black flock lined. Since having a filter fitted can only increase flare, no matter how well it is coated, I always use a hood when there is a filter fitted. It's also worth temporarily removing the filter, when conditions allow, for the best results - but never a good idea to do without your lens hood.

 

On the RX10 (one of the cameras mentioned) the front element is very large and needs to be kept absolute pristine (the design of the lens means it can be brought slightly into focus). The lens shade is reversible, the lens allows a normal slimline filter without vignetting, and mine has a 62mm Sigma DG. The hood is taken off only for wide-angle flash shots with the built-in flash. On the RX100 I purchased the third-party filter adaptor kit with lens cap, which goes over the shutter-type cap (fragile) of the camera. Sony now has this as an official accessory, a rare example of them buying in an independent design. I can fit a filter, but for this camera I don't bother, as I always turn it off between shots and the lens is covered. I can also fit a lens hood but also don't as it defeats the pocketability.

 

The arguments against fitting a filter are not very sound because you can always remove the filter as needed. I also always use lens caps, over the filter. I don't use a filter to protect the lens the way a cap does. I do use a cap to keep the filter perfectly clean. Recently, I shot a set of pix without realising my filter had been hit by sea spray and then dried, and the electronic viewfinder was not a clear enough viewing method to alert me. The pictures were degraded, not entirely ruined, except for some in backlight which were 'delete' fodder only. The filter was easily cleaned. That would not have been the case with a lens...

 

Discuss :-)

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I too use hoods all the time, even indoors (often plenty of light sources that could flare) and they provide some protection against knocks as well. I always used to use uv filters but have got less diligent in last year or two. David makes a good case as to why I should probably  go back to the old discipline especially as my kit is getting much more use. I will have to cost it up, it will not be cheap with some currently naked fast lenses.

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Always using hoods, but can never make my mind up about the damn UV filters - so for periods they stay on, then come off, then back on again. Using Sigma DG filters which seem good enough - never seen any difference or degrading with it on.

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OK, background...
I have been a pro for 30+ years working in environments from Military aircraft, large construction projects, metal work shops and other industrial areas.

I now shoot mainly a bit of everything  :-)

 

Using 11x14, 5x4, specialist aerial kit, through Blads to 1 series canons, I never use UV filters except for aerial photography and at altitude in mountains.

I always use lens hoods, never use lens caps when working as I change lenses a lot. When not in use the lenses wear caps, live in lens bags

which I keep in a photo backpack in a spare bedroom. I have owned lenses from 14mm to 48 inches (on a F96 aerial camera.)

and I have never scratched a lens,

 

> The arguments against fitting a filter are not very sound because you can always remove the filter as needed.

I would say the opposite, you can add a filter if/when needed.

Filters I only use as needed, UV as decribed above, polorising when needed, mainly for killing reflections, very rarely I use a ND grad.

 

I agree that any scratches on lense will degrade the image, by light scatter etc.

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Mark - we never used protective filters at all on 5 x 4, panoramics, video/film, stereo (I did aerials with the huge original Nimslo-designed camera about two feet long), and I never used them on some MF gear - but I did buy a complete set when I got a brand new Hasselblad ELX with 40/80/150mm lenses in 1986, the idea of risking those was too much. But never on Fuji GX680, or on the little GS645/W etc cameras.

 

It's purely on 35mm gear - or the kind of cameras exposed to crowds, weather, desk/table/bar corners, sand... I use them routinely. Most lenses worth even trying to use now cost over £700 and many are £1000-1500 and this is not large zooms, just wide-angles and decent quality lenses.

 

The cameras most asked about are things like the NEX, Fuji X and RX models, which really are very street-friendly. The bodies are almost disposable, there's hardly anything you can't shoot now with a body costing £200 in effect. The kit lenses are not much different, £50-100. Of course 'UV' is irrelevant, the only reason I use UV filters is that they cost less than a faked-up 'digital protector' for higher quality. I have a drawer of excellent older 1A and 1B filters, mostly multicoated Minolta, which I never use now. All they do is lose you some light and force the white balance to compensate more. I might use one if I found I had a lens with a slightly blue-green balance... but that's not so likely.

 

Just this minute I've bought a 20mm Canon FD lens on eBay - been looking for three weeks, I know from trying a badly treated example that this lens is technically excellent on the full-frame A7R 36 megapixel sensor (hardly any lenses are). Vendor fitted a haze filter on purchase and it's been on the lens for about 30 years, also admits to never having cleaned the lens - hopefully that means never scratched it.

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David:

 

I agree with most of your analysis. However my overriding concern is flair and some image degradation that you will get from any filter. To me front element damage is important, but of a secondary concern.

 

Therefore I always shoot without a filter, but with a lens hood. To protect the front element when not shooting, I use screw in filters from my junk box, taped up to make them opaque so I will not inadvertently shoot through them. A lens cap is not secure enough when the lens is stored in a camera bag. I think a lens cap that pops off in the bag is where most of the front element damage can occur. More work screwing and unscrewing filters when changing lenses, but so it goes. The lens hood also provides some limited protection when shooting.

 

Filters also do not have colour consistency, and a set of good lenses do. I used filters on every shot until I went digital and noticed the degradation. With digital you do not need polarizers, split neutral density, etc as you can duplicate the effect in software. I also prefer to have some distant haze in my scenics as it gives a 3D depth clue to the image. Leonardo Da Vinci in the republication of his notebook ADVICE TO ARTISTS suggests that artists mix some blue haze in distant backgrounds to give the viewer distance clues. Removal of distant haze with a UV can work against you.

 

I inspect front elements daily. I gently clean front elements only if necessary. I have not yet had any damaged front elements. The big cleaning problem is salt deposits from ocean air.

 

I just purchased a Nikon1 AW1 waterproof ruggedized underwater camera and have been testing it in snow sleet hail freezing rain etc. I have a lens filter on order for this camera.

 

Here is an extreme example of a unfiltered shot taken with a Zeiss 28 mm prime lens on a Canon 5D11. Flair was at a minimum, shadows were not degraded. There was only one very very small light blip opposite the sun, caused by an internal lens reflection, that was easily eliminated with the clone tool. There was not the degradation, massive flair, and multiple blips that would have happened with a filter protecting the front element.

DFH6H8.jpg

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There have been some comments and questions in the RX10/etc threads about lens hoods and filters, pros and cons of using protective UV for example. Over the years I've done many tests and used hundreds of lens types, and also (probably) hundreds of filters though my best UVs have survived over 30 years. My worst UVs have lasted a day.

 

I generally don't use any lens long-term, outside the studio, without a permanently fitted filter. Today you can buy filters such as Sigma DG (which in comparison tests I've done prove to be equal best with the very top level Hoya Pro 1 Digital or best B+W MC but at much lower cost). These now have nanocrystal type lens coating which is extremely hard and can be cleaned vigorously without destroying the coating, and also rejects water. I've bought several lenses recently which should have been perfect but with their relatively soft front element glass and fragile coating have been ruined by past owners cleaning them. The filter also protects against atmospheric film deposition - this is for example when you are in a Las Vegas casino, the last bastion of heavy smoking, or shooing in Beijing smog, or at a fire. Even in your own home you'll get this (try cleaning some paintwork after it's been around ten years, especially anywhere near your kitchen). Every time you overheat some oil or burn the toast, you send particles and oils into the air, and glass loves them. As my kitchen windows tell me...

 

So, let this land on your filter and not on your lens front element.

 

There is a myth that small marks and scratches on a lens don't show in the image and do not matter. This may be true if the lens is a 50mm f/1.4 or a 300mm f/2.8, but it certainly is not the case with standard and superzooms, and retrofocus wide-angles (rangefinder wides are less affected). With a typical 20mm wide angle or the 24mm end of a zoom, the surface of the front element can be softly resolved by f/8 and may show sharp details at f/16. Of course the same applies to a filter in front of the lens. But if you get a scratch or a chip (the worst type of damage even if it's a tiny sub-mm point) on the lens it is there for good. Solutions like filling the chip with permanent marker ink might be a way to repair a valuable lens sold to you damaged for a fraction of its mint value. That was the loss the previous owner accepted by not using a filter.

 

You can do nothing about fisheyes, 14-24mm Nikkors, 12-24mm Sigmas, etc - except use them with great care and guard those vulnerable front elements. You also need to be really careful with the rear elements of RF and mirrorless wide angles. I received one with a fingerprint on it I didn't spot, ran some test shots and thought my sensor must have a fingerprint - help! No, it was the rear element, and that mark was 'projected' with surprisingly clarity.

 

UV filters are a potential danger to all your shots, mostly because so many are very poor. Hoya's output is graded; even within the Hoya brand, there are levels of planar accuracy (the more you pay, the better the filter) and the sub-brands of Marumi (moderate good) and Kenko (cheap and cheerful) also have standard and superior ranges. New Chinese filter brands using Hoya glass also vary but it's really hard to find out what's good. I've tested many filters in the way which reveals their flaws - a standard to long focal length used at a medium aperture on a distant detailed target, on a day free from haze (or an indoor substitute). The worst filters show patches of blurring, even plain protectors and UVs can reverse all the resolution benefits you've paid for in that Zeiss manual focus special lens. Polarisers are actually the worst culprits and very few have good optical properties - they also deteriorate with age.

 

Lens hoods - again I always use if possible. The modern petal lens hoods with cutaways are far more effective than old shorter 'round' ones but my favourites are full metal rectangular hoods I've found in vintage gear bins - a Konica one for 28mm, a Minolta for 35mm, clamp-on. I actually use the 35mm one on a 28mm lens without cut-off and it is 100% effective, there's no image area projected into the camera significantly outside the frame, and it is also black flock lined. Since having a filter fitted can only increase flare, no matter how well it is coated, I always use a hood when there is a filter fitted. It's also worth temporarily removing the filter, when conditions allow, for the best results - but never a good idea to do without your lens hood.

 

On the RX10 (one of the cameras mentioned) the front element is very large and needs to be kept absolute pristine (the design of the lens means it can be brought slightly into focus). The lens shade is reversible, the lens allows a normal slimline filter without vignetting, and mine has a 62mm Sigma DG. The hood is taken off only for wide-angle flash shots with the built-in flash. On the RX100 I purchased the third-party filter adaptor kit with lens cap, which goes over the shutter-type cap (fragile) of the camera. Sony now has this as an official accessory, a rare example of them buying in an independent design. I can fit a filter, but for this camera I don't bother, as I always turn it off between shots and the lens is covered. I can also fit a lens hood but also don't as it defeats the pocketability.

 

The arguments against fitting a filter are not very sound because you can always remove the filter as needed. I also always use lens caps, over the filter. I don't use a filter to protect the lens the way a cap does. I do use a cap to keep the filter perfectly clean. Recently, I shot a set of pix without realising my filter had been hit by sea spray and then dried, and the electronic viewfinder was not a clear enough viewing method to alert me. The pictures were degraded, not entirely ruined, except for some in backlight which were 'delete' fodder only. The filter was easily cleaned. That would not have been the case with a lens...

 

Discuss :-)

 

Martin +1 (more or less)

 

Since my camera workflow is probably somewhat different from David's, There are a few things I would (might) not do. Taking filters on and off while I'm shooting sounds like landscape photography; I would not be doing that out on a busy street here in NYC. The shot would be long gone. 

 

I still have a gang of filters I almost never use. They are Nikons (nice and slim) and B+W. Two great things Nikon did for owners is they kept the lens attachment the same (as best they could) and they kept as many lenses as possible fitted for 52mm filters. Bravo, Nikon. 

 

"UV filters are a potential danger to all your shots, mostly because so many are very poor." -- DavidK

 

This is basically what Jay Maisel has been saying for decades: "Why would you want to put a $10 piece of glass in front of a $300 lens?" Feel free to update the numbers. 

 

Now that I'm older and not shooting assignments, I don't take a lot of chances with my equipment or myself. Let me say (knock wood) I have never dropped or damaged a camera . . . outside of a combat zone or while covering a riot. And I never use a polarizer because I hate the depressing gray-blue they turn the sky. And, hey, we can darken the sky in PP. 

 

Tom Hogan's thoughts on hoods and filters are basically in step with David's:  http://www.bythom.com/filters.htm

Edited by Ed Rooney

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The argument that filters degrade image quality only applies if the filter is poor quality, badly coated or damaged. By the same argument, a lens with 12 groups will perform worse than one with 11 and all Planar lenses should be worse than all Tessar lenses. The filter is, after all, just another glass element. Many of the best lenses made incorporate a filter permanently (Canon and other big apo teles, mirror lenses which can't be used without a filter blank in place internally).

 

Before multicoating, Pentax made the Ghostless UV filter. This was double coated not SMC, but had a curved glass matched to the front element  curve of the 50mm f/1.4 Super Takumar (and also quite well matched to the 35mm f/3.5, 105mm f/2.8, 135mm f/3.5). This prevented its reflections in backlight from forming any distinct flare marks. It was in effect part of the lens. So is a flat filter.

 

If layers of glass made that much difference, Sigma's excellent design of the SD1/15 etc with an internal IR filter in front of the mirror and behind the lens would not work, nor would most digital sensors which can have between one and three glass 'filter' elements in front of the actual silicon.

Edited by David Kilpatrick
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I have UV filters on my lenses, for "safe keeping". Never an issue till a few weeks ago, when the front element of one lens took a bang. The filter broke, leaving the lens undamaged. Job done, I reckon...

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John, you were lucky. It's that simple. Here in the words of Thom Hogan is the outline of another possibility that could easily have happened: "And if you're going to bump the lens hard enough to create more than a minor scratch, you're probably hitting it hard enough to bust the filter, and glass scratches glass pretty darn well in such situations, so I don't hold much faith in the 'protection from breakage' theory."

 

Frankly I don't believe in any of these theories 100%. I believe in being normally careful and in being lucky. I'd like to have a few bucks for every anecdote I've heard about pickpockets in Rome and mugging in NYC "You should hear what happened to my cousin's friend's uncle. . . ."

Edited by Ed Rooney

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I use UV (Hoya or B+W these days) for protection on all my lenses. Personally, I don't lose any sleep over possible minor image degradation. However, one thing that I do wonder about is the importance of multi-coating. Are coated filters always better than and preferable to un-coated ones (e.g. Tiffen and even some B+W's apparently aren't coated)?

Edited by John Mitchell

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I do not use filters as a "safety" mechanism.  If I use a filter, it is for a purposeful reason - to enhance an image and give a specific effect.

 

Technology has changed...years ago, I would have said you need to have a filter to protect the lens from the elements...these days, it's not as much of a factor when you are using higher end glass that has advanced coatings and protective features.  David, I know you are referring specifically to consumer rated cameras but I have the same general feelings about this with them.  To be frank, manufacturers have a reputation to guard...part of that includes guarding against consumer sentiment.  If a consumer writes a negative review on Twitter or Facebook or Pinterest or wherever, that manufacturer is going to get a bad reputation.  It's for that reason I believe that the lens/glass/coating quality on even my newer Fuji X system cameras are ages better and more durable than the glass on my Canon FE lenses from the 80's when they were the "latest and greatest".

 

With relation to image degradation, outside in daylight, you are generally OK.  When it comes to low light, I have had issues with even the best filters with reflections occurring between the glass on the lens and the filter.  Most recently, I had this very same discussion with my father last June - he said he was having problems with his camera at night because he was getting "little orbs" on his photos.  It was dark outside at night.  I told him to take the filter off and problem resolved.  I've had this happen with B+W filters, Hoya filters, Heliopan filters, Tiffen filters, and Canon branded filters.

 

I do use a lens hood whenever I can for both image quality and lens protection.  Indoors, in low light situation, I may remove the hood at times to allow more light to reach the lens...I've had to do this in indoor sporting arenas.

 

That's my experience...and for those that think a filter will save their lens 100% of the time - they should try unscrewing a filter from a lens that has been dropped on it's edge making the circular threads a bit oblong.  It's not fun.  I also have good insurance.

Edited by Ed Endicott

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Ed, technology has changed indeed. The filters (not all of them) now have the same advanced coatings as the lenses (not all of them) but the front elements of lenses may cost $500-$5000 to replace, while the filters cost $50-$500 (and if you are buying filters costing less than $50, it's understandable why you would prefer not to use them).

 

I'd love to know what kind of lens hood can be removed to allow more light into the lens, as this would be a great change to the laws of physics and optics. I think that if you really observed such an effect, you were seeing flare from stadium lights veiling the image and lifting the shadows. There was a patent, can't remember who or when, for a small flashtube inside the camera which would add a fog level lifting trace exposure and double the 'filmspeed' of b/w films.

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My experience is not with filters costing less than $50 LOL...I don't think you can buy a filter costing less than $50 these days.  Have you ever seen a heliopan filter for less than $50?  If you do, PLEASE forward the link as I would like to stock up.  Yes, I understand the coatings but that doesn't take care of reflections that show up as glowing orbs in the photo.  The last time I bought a filter, I was looking for a "thin" filter for a wide angle lens.  The folks at the camera store didn't understand what I was asking....they didn't understand the concept of distortion through the glass or that it would in fact change the image.

 

When I explain to people what a lens hood does, I tell them to cup their hands around their eyes to make a tunnel to see through, or even shade their eyes with their hand - it allows them to see better in harsh (and sometimes direct) sunlight.  It's the same concept.  Would you do the same in an arena where there is indirect light with your hands?  I wouldn't....it allows more light...it allows for less contrast.  Less contrast is a good thing (at least from my workflow perspective) in these situations - the laws of physics and optics unchanged.  Try it sometime ;)

 

Ed, technology has changed indeed. The filters (not all of them) now have the same advanced coatings as the lenses (not all of them) but the front elements of lenses may cost $500-$5000 to replace, while the filters cost $50-$500 (and if you are buying filters costing less than $50, it's understandable why you would prefer not to use them).

 

I'd love to know what kind of lens hood can be removed to allow more light into the lens, as this would be a great change to the laws of physics and optics. I think that if you really observed such an effect, you were seeing flare from stadium lights veiling the image and lifting the shadows. There was a patent, can't remember who or when, for a small flashtube inside the camera which would add a fog level lifting trace exposure and double the 'filmspeed' of b/w films.

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I also once had a Pentax ghostless curved filter and it eliminated ghosts because it was part of the lens design. However the argument "so is a flat filter"(part of the lens design) does not follow.

 

Agreed that the filter is an extra glass element, but that is just the point.

 

The lens designer optimized the design of the lens without that extra glass filter element. Lenses are designed as packages with all elements tightly controlled, of different glass, of different surface profile, of specific colour, different air space between elements, chosen to do specific jobs, and to work together. That extra glass filter element from any number of manufacturers, and even if pristine and of high quality, has changed the design of the lens. With an extra filter element the lens/filter combination is a slightly different lens.

 

The lens designer has to make a lot of quality compromises to make a lens sell cheap. Therefore any filter (extra element) added to a lens that has been designed to sell cheap would probably not make much quality difference. However it would make a difference on a quality lens.

 

I used pristine B&W filters when needed with film, but they were all pre 2004. Has lens coating changed that much since I noticed the difference on digital in 2004? I once had a B&W polarizer warm up on me over time. If you are using UV filters you may want to check to be sure they do not vary individually on colour by comparing them side by side on a colour controlled lightbox.

 

A good idea is to save tests of all new lenses, and then rerun and compare if a lens has been subject to hard knocks. A lens that sustained a knock hard enough to break an attached filter should be retested. 

 

I think the tradition of a UV filter to protect the lens started when lenses were of a poorer quality so the filter effect was not noticeable, and sales people were judged on their ability to sell extra accessories such as UV filters.

 

As to a well fitting quality lens hood, always. It prevents flare and helps to keep airborne particles off the front element during shooting.

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Polarisers are actually the worst culprits and very few have good optical properties - they also deteriorate with age.

 

Now you surprised me... :huh:  Do you mean scratches, scuffs on it when using or even safe lying at home? So, what is the age of filter, are we talking about 2 years or 15 years? That's new to me...

Last year I got Lee and Heliopan and it's not cheap... I care about it more that my eyes ;) Now you say it may have self destruction :P

  :)

 

Btw. Do you have any idea how to transport big filters? I have my little backpack for lenses and body and filters are in big case/ pouch (each separately) which is quite pliable. Bag on one arm is not good option for long walks and at the same time I'm affraid of wearing huge backpack ;)

Edited by Arletta

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Hi David

 

The argument that filters degrade image quality only applies if the filter is poor quality, badly coated or damaged. By the same argument, a lens with 12 groups will perform worse than one with 11

 

I think that the difference is that a lens designer uses the elements to work with each other, I would assume that would also be the case for

incorporated filters.

 

As you say good quality filters are very expensive and I do not feel the need to spend large amounts of money fitting all my lenses with filters.

Especially as my experience shows no need, your experience may vary.

In fact it would probably cost the same as one replacement lens should I finally scratch one.... inevitable as I keep saying that I have never

scratched a lens :-)

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A single thin, optically plane filter should have no effect on lens performance up to an angle of coverage of 85°. Beyond 85°, the thickness of the filter has a significant effect, which is why Käsemann sandwich polarisers (with three layers) are not a good idea for wide angles. Actually modern lenses have considerably leeway in the positioning of elements, and despite all the computer design involved the best quality lenses involve individual measurement of glass batch qualities and fitting or removing of shims accordingly, or matching to an adjusted barrel part. Some also may involve custom modification of the radius of elements, and in the case of Zeiss, keeping aside a small number of spare matched front component lenses (guess which elements are usually damaged) serial numbered to repair specific batches. When those spares are gone, lenses from that batch can no longer be repaired.

 

Ref the coatings, there really is a huge difference. Fortunately my older Minolta filters were AC - Achromatic Coating - which was an early multicoating and also have glass roughly half the thickness of standard Hoya, and rims which are thinner too. From around 1970 Minolta, Olympus and Nikon all made thin-glass, thin-rim precision filters with multicoating. Canon didn't for some reason and continued with rather clunky filters. Hoya caught up after about a quarter of a century. Mostly, they needed the thicker glass because achieving deep homogenous colour was a very expensive process and in the 1970s filters for b/w mattered - 8X red, 4X orange, 2X yellow etc. The cheapest way to get the right density (and higher densities) was to change the glass thickness, so most popular market filters had 'approximate' glass colour modified by altering the thickness. Some were very thick! Minolta, Olympus and Nikon all made their own glass batches and as scientific instrument makers with strong interests in colour science they produced coloured glass of an entirely superior quality - the density was achieved in the glass, without changing thickness. Despite the price superiority of Schott/Zeiss (B+W, Heliopan. Zeiss for Hasselblad, Rodenstock, Schneider etc) they were not actually very much better, often worse.

 

Here's a modern comparison of coating efficiency:

 

original.jpg

 

Left - circa 1995-2000 - Rodenstock standard UV filter. This is a single coated filter of claimed high quality. In five identical filters purchased I found one with local planar distortion of the glass; never worth keeping for any use. I now have a simple technique for holding any filter up to a light about a foot from my eye, and moving it round; it's easy to see surface flatness errors this way.

Top - B+W Slimline MC UV, circa 2004. Intended for wide angle lenses, this design is actually no slimmer than a standard Minolta rim of 30 years earlier (and on). It uses a thin glass, but has a peculiarly thick retaining ring, which removes the front thread making it impossible to fit a lens cap... the multicoating is moderately effective. I keep this for bad weather now.

Right - current Sigma DG. All are 62mm. Though the rim looks and feels chunky it's actually slim enough, and the retaining ring is a flat type, leaving sufficient thread to fit a cap. The new multicoating (Carl Zeiss equipment installed by Sigma c. 2010) is ridiculously effective as you can see compared to the Rodenstock single coated. Under most conditions, the Sigma DG filter will never produce reflections even for night photography.

 

As for polarisers, they vary greatly and they are not solid glass, always a crystalline or film layer sandwiched into glass, or just a plastic version. I don't have a colour meter any more but I tested many back in the day, and very few have neutral colour transmission, even fewer stay neutral as the polarising effect becomes visible (so they have a relative colour shift in polarised areas). They can delaminate, distort optically, cloud, fade or change colour. Only answer - buy top quality, keep carefully, don't expose to heat or extreme cold or leave out in the light, check and replace if needed every ten years or so. I must revisit this whole thing in Cameracraft and do some measurements.

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Interestingly while this discussion has been taking place I have damaged a Canon EF50mm f1.4 and I suspect the filter was a contributing factor. It was on a camera on a tripod that gently fell over on to a carpeted floor (from less than 3ft extension). It fell on to the cap/filter, cracked it and now will not focus (rattles ominously); without the filter it would have fallen on the external barrel rather than the moving focusing cell possibly without serious damage. But then again who can tell...

 

I guess I will have to send it off for inspection or do I just buy a good second-hand one (or manage without)?

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If it fell with enough impact to crack the filter, it probably would not have survived without it. The lenshood and cap assembly saved my 8-16mm Sigma last year - I now have a spare cap and good, inseparable, and a new one without a dent... but the lens is perfect. Plastic bayonet lens hoods are the best protection. I've had a lens skid away across the floor a couple of times and be unscathed, apart from the hood taking the hit and springing off. Metal screw-in lens hoods - probably make any potential damage worse!

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Unfortunately it did not have a hood on, I had been trying various things in the studio and had taken it off :( I agree it would probably have survived with the hood on (unless it was reversed, which is why I had slipped it off). Only other time I have damaged a lens so it needed a repair (have had a few dinged filter rings) was an EF24-105, again with the hood reversed, I dropped it as I got it out of my bag and it fell 18inches on to a terrazzo floor, fell flat on the cap and popped the front element out.

 

Obviously I should learn and leave hoods on the right way out! (I will need a bigger bag tho')

Edited by Martin P Wilson

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"Plastic bayonet lens hoods are the best protection." -- David K

 

That would be my policy. Although exactly how any event will play out is impossible to know. 

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I reverse my lens hoods in my bag so my lenses take up less space. Unless I am going through airport security where an inspector may try to pick up the lens by the hood only.

 

I had a very high quality very expensive 82mm polarizer delaminate and warm up after about 10 years of very hard use. The filter had scratches on the surface and nicks on the mount. It had some cross threading. I was satisfied with 10 years use, and ready to replace it at my expense. However out of scientific curiosity only, I showed it to the Canadian distributor. They went ballistic with apologies. You would think I had found a mouse in my soup at an expensive restaurant. They gave me a brand new replacement free, without my asking!! Wow

 

I transported all my circular filters by screwing same size filters together and using a product called a stack-cap to close off both ends of the filter stack.

 

I transported gels in a notebook made up of pages with individual glassine pockets to hold the gels in order. I did a some available light industrial work at one time. A colour meter with gels was the only way to get acceptable skin tones under mixed factory lighting.

 

Cokin P filters were simply a pain in the butt due to their size, and therefore mostly for beside the car type shooting.

 

All of this filter stuff, and my colour meter, are back in the days of film.

 

Digital is so easy.

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I used to use Tiffen filters at one time. They were much touted in U.S. and Canadian photo mags and apparently won awards (in the motion picture industry, I believe). Then I read somewhere that because of the unusual manufacturing process (?) used by Tiffen, their filters cannot be coated (or don't need to be). Does anyone know if this is true? I replaced most of my Tiffens after I heard this, even though I didn't have any issues with them. However, I still have a 15-year-old Tiffen polarizing filter that I use now and then. It still seems OK to me, even if it isn't coated. I haven't noticed any deterioration either, but then I haven't really looked at it very closely.

Edited by John Mitchell

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Thanks to David for the suggestion of removing my Hoya UV Pro1 filters occasionally, I had not considered this for table top stuff when the camera is on a tripod in a safe environment, and for suggesting the cheaper Sigma filters.

I did try a cut price set of Tiffen filters once but was so annoyed with their performance or lack of that I threw them away.

I may be wrong but I seem to remember that some lenses need a filter to be completely weather sealed. If this is the case then they are designed with filter use intended.

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