The filter needs at least the quality of the coating of the lens.
Since it introduces two more reflective surfaces plus an unknown distance towards the lens and therefore unknown behaviour in relation to the outer most coating of the lens it should probably be better.
My last experiments were some twenty years, so given the recent improvement in lenses my guess is that filters have improved, too.
But in those 20 years I have not lost a single front element to destruction¹ – knock on wood – so my current strategy still works out fine.
Also I am well aware of highly destructive environments and use some filter on those occasions.
¹) I handle my glass with utmost respect but not with care.
The thickness of the front element is really quite variable. Sometimes very thin towards the center. Particularly on wide angle lenses.
Regardless it’s scratches that would be my main concern not actual cracking of the front element. I don’t use filters for damage protection anyway. Not paying significant cash for coatings and finely tuned lenses designed to minimise ghosting, flare and chromatic aberrations only to add random glass surfaces in the optical path.
I see your point, but like almost everything in photography, this is a trade-off.
It is best to experiment with actual lenses and filters. FWIW, my experience is that recent, high-quality UV filters (K+F, Hoya) result in very little (if any) IQ degradation for my longer focal length lenses, but for wide angle it is noticeable on test shots.
(Perhaps because the ratio of filter to lens glass is higher, and light comes in at an angle for a large part of the field, but I never pursued the theory on this).
I’ve had some nasty flares manifest when shooting a backlight scene with a filter on. Not to say the filter was the best / most expensive one but definitely some harsher lighting can expose the weaknesses. I’ve ditched any filters after noticing this.
Anyway, I’ll second the recommendation about Zeiss lens cleaning wipes. I bought the Zeiss lens cleaning kit as well, which contains those wipes, a pump, brush, cloth and cleaning liquid. The pump and brush are essential before cleaning with wipes. I haven’t had much success with the cloth and liquid, but the wipes have given me the best results ever.
I use a glimmer glass on my X100V for just the right amount of degradation I was quite surprised how even with all the added diffusion it still manages to maintain a good base sharpness. The protection + weather sealing it provides (X100V requires a filter to comply with the ‘weather resistant’ description) is just an added bonus.
You’ve all got me thinking that I should take some test shots with/without clear filters!
At present I have one on my 70-200, which is my main motorsport lens, and gets covered in dust regularly, so I will keep that there at least for events, but I don’t have one on my (new to me) 24-70 mm - because I forgot to buy one - so I might do a comparison with that when I get a chance.
I have used IPA (isopropyl alcohol) for cleaning, in combination with a microfibre cloth, which seems to work well.
I do also have a LensPen, which is great for a final polish, but you do need to make sure there’s not much of anything gritty on the lens or it looks like it might get stuck in the cleaning… pad?.. for want of a better word.
I realized that I got sidetracked by the UV filter question and did not share my lens cleaning routine. So here it goes:
get dust off with a blower or a soft brush (Lenspen!)
remove minor smudges with Lenspen rubber part, when I am sure I am not grinding in dirt
if the above are not enough or applicable, microfiber cloth + distilled water. Both are cheap, widely available when I travel, and surprisingly effective. I rarely get smudges that require a solvent. I try to dab the affected part repeatedly first, instead of moving the cloth around.
if all else fails, lens cleaning solution (no particular preference) with microfiber cloth.
1–2 are part of my field cleaning routine (I mostly get dust and fingerprints, and it only needs a Lenspen), 3 I do when I am at home, but I have done it while travelling, 4 I have only done at home.
And here is a comparison without an with an UV filter (everything else the same, only lens correction applied, sigmoid with a contrast of 3.0 to bring out details):
This is a hand-drawn b/w chart (using a felt-tip pen) that I use for calibrating my lenses (for correcting with diffuse and sharpen). I don’t really see any difference, so I am deliberately not going to say which has the filter so that everyone can guess.
I don’t think filters will have any negative effect in ideal circumstances. You’ll see the issues when triggered by more difficult shooting circumstances.
Thing is that generally speaking what you pay for in camera equipment is performance across circumstances. Sharpness across apertures, weather sealing, low light, shallow and deep DOF, AF that handles most situations, flare resistance etc. If shooting static subjects, stopped down near standard focal lengths, with diffused light behind the camera you should be satisified with very cheap gear.
I understand the theory, but I would be interested concrete examples. All the images I found online suggest that the issue is generally negligible or even undetectable with modern filters.
(I will of course conduct my own experiments too when I get to it.)
Don’t worry; you’re not the only one. I have filters attatched to most of my lenses, and they’re cheap-as-chips ones. If there is any loss of quality (probably), neither I nor anyone else has really noticed.
Having said this, though, you have to keep in mind that I shoot street and documentary photography; as such, unless the degredation was outragiously horrendous, it won’t cause much of an issue. Plus, I mainly shoot with older vintage lenses.
Very true. A little tip: get one of those little brushes that often come free with a gent’s beard trimmer or electric shaver, then use it to brush the lens-pen pad before using it on the lens — I use this method all the time when carring out repairs and refurbs. I always give the glass itself a few alternate light brushes and blows with a very soft make-up brush and a good dust blower beforehand, also.
You can also get a soft synthetic painter’s brush from hardware store or paint shop. They do not shed and most good brands have graduated softness (choose the softest) and are not supposed to accumulate static electricity (check before using it on lenses).
Don’t get the “natural hair” ones, they are more expensive and can shed bristles, anyhow they are becoming rare these days.
My kit is modest compared to many. My most expensive lens is a Tamron 70-180/2.8.
After owning it just a few weeks I found a 1/4-inch scratch on the front element. It is close to the side, and I doubt that it will ever affect the image. Maybe with no lens cap and an astronomically rare shaft of sunlight.
I’m equally sure that it will do a lot of harm to it’s resale value! Not that I expect to ever sell it, but still.
How did it happen? I have no clue. the lens is mostly used indoors and has never had a big bump.
I had stopped bothering with filters. I started again quickly.
I was taking photos in a zoo, and figured that I could stick the lens through the wire mesh (observe its shadow on the bird). The bird endured this patiently for a while, and then struck with pinpoint precision, shattering my UV filter. The lens survived intact.
I was looking though the viewfinder, so it was somewhat scary, but it happened really fast and by the time I understood what happened it was over
In any case, the lens is OK and that’s what matters. I understand that some photographers prefer lenses without UV filters, but I have come to the conclusion that for me they are worth it, even if there is a minor degradation in IQ in some situations.
I was quite surprised how even with all the added diffusion it still manages to maintain a good base sharpness. The protection + weather sealing it provides (X100V requires a filter to comply with the ‘weather resistant’ description) is just an added bonus.
That’s really good…