EF 100-400mm f/4.5-5.6 USM IS L and "protective filter"

[gamitch]

I was just wondering if anyone with this lens or any other quality lens uses a

protective filter (eg: UV, Skylight). I have a Sigma UV filter (Sigma UV - Ultra

low Reflection Multi-Coating), however, I have not used it yet.

 

Will using such a filter diminish the quality of the photos?

 

Is it wise to place inferior glass in front of L glass? or is the trade off for

lens protection worth it, even if the possibility of decreased image quality arises?

[colinsouthern]

OK Here we go ...

 

General consensus is ...

 

1. Never use a cheap/bad filter, although a few will argue this

 

2. Good quality UV filters used for protection are "optically invisible", except in a small number of situation where you have extreme contrast (eg shot of the moon on a dark night, or city lights at night).

 

3. Some will say that a hood alone is good protection - but the reality is (a) on longer lenses, the hoods pop off if you drop the lens or give the end a good knock (b) shorter lenses have a hood that's more solid, but the hoods are so shallow (so as to avoid vignetting) that they do nothing to stop fingers - wet noses - sand etc. These same people seem to think (for reasons I've get to figure out) that in suggesting the use of a protective filter I'm somehow suggesting that a lens hood isn't necessary - nothing could be further from the truth - use both, but keep in mind that a hood is designed to reduce flare (which it does well), not to protect the lens.

 

4. A filter makes it much easier to clean the front of the lens - it's easy to run it under running water if you get a coating of, say, salty air.

 

5. Some like to use the argument that they don't see the logic in putting a $100 piece of glass in front of a $1000 lens - if you look at it another way, if quality is proportional to price and many of the $1000 lenses have 12 or more elements inside then the filter is probably a higher quality bit of glass that what's inside. In reality, with the exception of high-contrast scenes mentioned above, it doesn't degrade IQ an any way, shape, or form.

 

There are MANY people who have had a lens saved by using a filter. Additionally, if you check out Canons EF lens 101 they recommend using a filter for protection.

 

5. Some will assert that a lens cap offers great protection - this is true in part. They do in fact offer great protection if fitted properly - however - they tend to degrade image quality horribly if (for protective purposes) they're left fitted whilst shooting.

 

10 ... 9 ...

[ralph_jensen]

Excellent answer by Colin, one that should be archived for ready linking.

 

I would emphasize with regard to #2 that I *always* unscrew my protective filters when shooting anything that's in low light and has pinpoint light sources in the frame (e.g., the light bulbs under an old theater marquis), because those light bulbs reflect back and forth between the filter and the front element, causing at least one "ghost" per bulb.

 

Again, though, I heartily second everything Colin says.

[robin_sibson1]

What Colin said. I use a Protect filter on all my lenses (including the 100~400) pretty well all the time. I've occasionally taken test shots with and without the filter and never been able to see any difference on my own shots.

 

BUT

 

I have seen a very few published examples where curious forms of image degradation (not just straightforward loss of sharpness) were plausibly attributable to the use a filter (of what quality I do not remember) and I think the 100~400 may even have been the lens involved in one of these.

 

Conclusion: use a filter routinely, but try a shot without it if there's something bothering you.

 

Later respondents to this thread will surely express a completely contrary view, so you'll just have to make your own mind up, Greg.

[bill_morrow1]

Since we're on the subject of the 100-400 and filters...I actually

purchased a Canon polarizer. The quality is no better than any of the others, but that's not the point. Point is that...the lens cap

(Canon) will not engage the lip of the Canon polarizer on the Canon lens. Therefor, the options are while walking around, keep the lens hood on (which I do), or remove the Polarizer to replace the lens cap.

All other filters by the way, will engage the Canon cap. A call to Canon got the response..." really...I didn't know that". Anyone else

run into the same thing? It's not an ultra thin by the way, but then it's not exactly a wide angle of view. Gotten used to the anomoly,

but I'm still curious as to why.

[stillbound]

did you purchase a "slim/thin/low profile" filter? They generally have no thread or place for caps to catch into...

Good luck

JC

http://www.pbase.com/josephwcarey

[bob_osullivan]

Like Colin I find it very unusual that a quality UV filter degrades the image. I buy a good UV filter for every lens and keep them on MOST of the time. In a controlled environment, like my home studio, I can take them off. But in any unctrolled environment, or potentially hostile environment they stay on. Snow, rain, sand, salty air, drunk people and crowds all have potetial to damage your front element. Lens caps and hoods, often pop off at the wrong time.

[lester_wareham]

Yes Colin has given a good summary. I have done a lot of tests on sharpness and flare impact using a top end filter like a Hoya SHMC/Pro 1 and found any impact minimal or undetectable. Links to these tests here

 

http://www.zen20934.zen.co.uk/photography/LensTests/Filter_AF/index.htm

 

http://www.zen20934.zen.co.uk/photography/LensTests/Flare/index.htm

 

And some summary of manufacture filter performance below (the important thing is they are optical glass and have low reflectance)

 

http://www.zen20934.zen.co.uk/photography/LensTests/Flare/FilterData.htm

 

Now having said that I don't have a 100-400mm and so have not tested it. Flare performance is individual to lens but this is a lot easier to test for than any sharpness checks which is fraught with systematic errors unless you are careful, If you want to check for flare performance I suggest you follow my method in the above link.

 

The 100-400 and 400/5.6 are lenses that people complain about filters causing softness, but I have yet to see a confirmed effect in controlled conditions so most of this seems to be user error or poor test methodology. I do have a 300/f4L IS which is similar and shows no such effect.

[tapani]

Some lenses are more affected by filters than others. The only really bad case I've seen is the 70-300DO in even moderate backlighted situation. The 100-400 doesn't seem to suffer visibly from a (good) UV filter. Otherwise, Colin pretty much covered it.

[William Michael]

Why would anyone choose to spend good hard earned money and buy an L quality lens and then even consider putting a filter in front of that high quality glass?

 

Answer: I only wanted to get your attention, see above :)

 

My 2 cents compound interest:

 

1. What Colin Southern wrote: noting point 1 does NOT mean one has to buy the MOST expensive.

 

2. Add Robin`s Rule: `use a filter routinely, but try a shot without it if there's something bothering you.`

 

3. Add Lester`s sentence: `Flare performance is individual to lenses, but this is a lot easier to test for than any sharpness checks which is fraught with systematic errors unless you are careful`

 

4. Cut, Paste and Print the above on an A4 sheet, laminate and title it LENS PROTOCOL - PROTECTION FILTERS

 

Cheers

 

WW

[andy_szeto]

Maybe not on the case of 100-400 lens. But other lenses need a filter to completely seal the lens from moisture/dust, like the 17-40 f4 lens. I use B+W or Hoya Pro 1 filters on all of my lenses. I also use the hood all the time. But accident do happens (like scratching the lens surface when trying to put the lens cap on the lens with the hood still on; I had scratched a couple filters already).

[steve_dunn2]

<cite>Some like to use the argument that they don't see the logic in putting a $100 piece of glass in front of a $1000 lens - if you look at it another way, if quality is proportional to price and many of the $1000 lenses have 12 or more elements inside then the filter is probably a higher quality bit of glass that what's inside.</cite>

 

<p>You're confusing the actual value of an item with its retail price. Remember that filters are famous for being extremely high-margin items, which provide a lot of profit for the retailer. If the filter sells for $100, the retailer probably paid $25-50 for it, and it wouldn't be surprising if the actual cost of manufacturing it is something like $5-10. Sure, there's profit in the price of the 100-400, but I'll bet that the fracton of the 100-400's retail price that relates directly to materials and manufacturing costs is much, much, much higher than for the filter.</p>

 

<p>Your overall conclusion is that in most cases, a quality filter offers at least some level of protection and causes no detectable image degradation. I'll agree with that. I don't use protective filters on all of my lenses, but I do use them on some (including the 17-40 mentioned above, which is sealed everywhere but the front element and requires a filter to keep crud from getting in the front end). If you use a protective filter, take it off if you're shooting in a situation where flare is likely. Use the hood to provide some measure of physical protection as well as protection against off-axis light. And if you're putting on another filter (e.g. a polarizer), take off the protection filter; it's unnecessary (assuming the other filter is also a good quality filter), may cause vignetting (particularly on wide-angle lenses), and it's a bad idea to have two sets of parallel surfaces*.</p>

 

<p>*: Here's a direct quote from Canon regarding lens design for digital cameras:</p>

 

<blockquote><a href="http://www.canon.com/camera-museum/tech/report/200308/report.html#t9">Most super-telephoto lenses have a protective glass at the front. When this glass has a flat surface, the light that reflects off the image sensor reflects back from the protective glass, occasionally resulting in spot-shaped ghost[sic]. To eliminate this phenomenon, all of Canon's large-aperture IS super-telephoto lenses adopt a meniscus lens shaped protective glass.

<br>[...]

<br>Specifically, each lens element adopts a different design, in order to reduce the amount of repeated reflection inside the lens.</a></blockquote>

[john_donaldson1]

I thought you were asking about a dust filter. OK when you have stopped having a laugh. I felt that the constant movement of the lense body from 100 to 400mm sucks in such large quatities of air that it brought in sufficient dirt to damage my shutter. I suspect this lead to the dreaded error 99 and eventually to failure (Canon D10). I wonder if you guys have thoughts on that and is there a fix?