I have always used UV or skylight filters to protect the lens (not that I have ever needed one for that purpose as all my filters are in perfect nick) but something a poster said on another thread made me wonder if I should use them. Is there any benefits or will they just reduce the quality or sharpness. BTW I use top end hoya filters mainly.
Edited by Scott Sewell on May 21, 2006 at 10:16 AM GMT (Reason: Moved; not a Canon-mount topic.)
Some people think they all have negative effects. I think if you're using top-quality filters (multicoated B+W, or Heliopan), that there is no degradation.
there are many that argue filters degrade quality, and I have to say that is partially true. I used to have a cheap UV filter on my 70-300 IS and was never really happy with the pics - they always seemed a little "smeared". I figured it was technique, but even at 1/4000 shutter speed I had bad results. Just before sending it back, I compared shots with and without the filter - an viola! The filter was causing the smear and not my technique!
Now, that was a cheapie "noname" filter (may it rest in peace), but I no longer put a filter on the 70-300IS. I do have a filter on my 28-75, though, it is a good coated hoya.
I’ve seen a lot of claims that filters degrade the picture quality. I’ve yet to see any test pics with top MRC filter (Hoya or B+W) confirming the claim.
I look at it this way... if you can't tell there's a difference in image quality anyways, better to have one on than to risk a scratch on the front element of a good lens. I use multicoated B+W and Hoya, and can't tell the difference between them, except that the B+W feels a bit heftier and better-built.
Also, it's common sense to match the quality of the filter to the lens. Why put a B+W filter on a kit lens that costs less than the filter? And why put a cheapo filter on a $2k L lens? Just my 2 bits.
Filters are an extra medium thru which light must pass before hitting your film/sensor. Light passing from air to glass to air to glass, will change the speed of the light, which introduces refraction. Whether or not the net result is acceptable is up to you to decide. Personally, I feel that with high quality filters, the net impact to my final image is insignificant. But the laws of physics do dictate that changes to the light do occur.
I have a filter on all of my lenses, but I just recently did a test with and without the filter, and I did notice a difference in IQ. It is definitely noticeable that a lens is sharper without the filter (I use Hoya S-HMC filters). So I guess it really depends. Do you need that extra IQ, or do you want the extra protection? I shoot a lot of kids in a nursery setting and they grab at almost anything, so I usually keep mine on. But I think I'll have to make a mental note to remove it when I'm in a calmer environment.
I've tested a variety and it really does depend. Out of three Tiffen UVs I tested (I had extras) one really did wreck the image quality, the other two had no material effect. I've never noticed any effect on image quality from B+W MRCs. I think you are taking pot luck with cheap filters, but the high quality (expensive) ones shouldn't hurt.
A filter will make a lens more prone to flare, but I use my lenses at the beach a lot so the sand protection is much more significant.
Standard non Multicoated = large loss of contrast, slight sharpness loss, ghosting, flare boosts.
Multicoated - lesser but still contrast loss, no effect on sharpness seen, ghosting and flare increased but less then non MC.
Basically it's glass. We knew that. If filters had no effect canon would build one into the filter thread and sell 149$ "Front element" protectors instead of putting raw front elements on them.
The Hoya Super HMC (or Pro1) are pretty damn good for the money. I've got a Pro1 72mm that I use on my Tamron 24-135 and my Magic Drainpipe and the shots don't seem to be less sharp with the filter. B&W and Heliopan have an excellent rep, but I've never used them.
I have best quality Hoya Pro 1 DG UVs on all my lenes now, and have always made it a practice to mount UV/Skylight(with film) filters during the many years I've been serious about photograpy. All I can recommend is cleanliness and sticking to one type(UV)/brand of high quality filter all lenses so that color cast will be maintained across all lenses/focal lengths employed
I shoot a lot of indoor sports using 'L' glass, and I've found that UV filters can affect the focussing speed/lock in low light conditions. And I don't use cheap filters (mainly B/W). Can't say I've noticed picture quality differences though.
I used high quality multicoated UV filters all the time when shooting film. Working with digital files at 100% in Photoshop, I have noticed a degradation in IQ with filters on, so I've stopped using them. I still keep one or two in my bag, in case I have to shoot in blowing sand, but have not yet had the opportunity to use them (the front elements are quite resilient, and I think people worry too much!).
In 20+ years of shooting, I have only marked ONE filter (and that was very slight, and MY fault). I figure I'd rather pay for the one repair in the next 20 years, and enjoy the superior image quality from my L lenses every day! Life is too short to worry...
Edited by rudiphoto on Jun 11, 2006 at 11:04 AM GMT
Any physicist will tell you if you put something, however high quality in the light path of a lens it will refract, to some small extent. It simply has to. Add to that tolerances, dust particles and other minute debris and also that autofocus has to focus through it and you will get *some* degredation of the image. It might be considered imperceptable but it will be there.
Seems odd to me that 'folk' will measurebate thier highly expensive lenses and them put glass in its light path.
I only use filters in environments where there is potential for damage, otherwise I jut use the biggest lens hood I can
If filters had no effect canon would build one into the filter thread and sell 149$ "Front element" protectors instead of putting raw front elements on them.
Actually many of the Canon's great white telephotos have a build-in plain glass protective filter. Even my humble EF 300 4L USM sports one. Some of that exotic glass is really soft...
Gochugogi wrote:
Actually many of the Canon's great white telephotos have a build-in plain glass protective filter. Even my humble EF 300 4L USM sports one. Some of that exotic glass is really soft...
Putting it there as part of the design process, and adding it afterwards are two different things.
I did my own tests, and sharpness, colour and contrast all suffered with the (high quality) filter ON, specially without the hood. In the tests I did, using a hood made more difference than anything, and a hood wil 'generally' protect the front elecment too.
Do this..... add 10 filters (or add as many as you have) to the front of your lens and see if it degrades. If you see any degradation then you are getting that same degradation (divided by as many filters as you used) with just one. If you see NO degradation then you are clearly good to go with just one..... Don't take my word for it, do you own tests.
So, I USE a filter in harsh conditions (driving rain, sand etc), but DON'T use one most of the time.
HOWEVER, at the end of the day, does it really matter? As long as you are happy with the prints or screen shots that you get, choose which ever method you want, i.e. with/without, and be happy. Don't take every one else's word for things, do your own tests, that way you know what the results really were.
The problem with filters isn't just refraction (which impacts pure sharpness), but reflection too (which effects ghosting, flare, contrast). Plain glass reflects something like 4% of incident light, multi-coated reflects under 1% (I was a physicist in another life: all this from memory - so might not be exactly right). Add another glass layer and you will increase the amount of internally reflected light, and potentially flare – the question is whether it’s noticeable or not. A single cheap filter probably has more light reflected off it than all the multi-coated elements in a lens so it will almost certainly effect contrast and flare, multicoated filters should have a much less pronounced effect.
The canon super-teles don’t have a flat piece of glass in front of them; it’s a multi-coated meniscus lens that was designed in.
Canon should make their front elements easily-removable and have them available to buy off-the-shelf as replacement parts for around the same cost as a good filter.
