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Archive 2007 · Soft 100-400 and filter

mjmyap
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p.1 #1 · p.1 #1 · Soft 100-400 and filter

I recently bought a 100-400 as an addition to my 300/4L IS.

I was initially disappointed with the lens. In particular, results at 400mm wide open were somewhat soft, certainly a lot softer than the 300mm prime (a sharp copy) with a 1.4 teleconverter attached. I attributed this to copy variation, and to the zoom's reputation as a less-than-stellar performer at 400mm.

After a few frustrating weeks, I recently removed the Hoya coated UV filter that had been attached from Day 1 to the 100-400. The difference was remarkable. Now, the zoom at 400mm was essentially identical to the prime with a TC. That is, both were tack-sharp wide-open. I attached the problematic filter to the prime, and its IQ was immediately severely degraded. Not all filters seem to do this. I have another Hoya 'Super' UV filter which does not degrade the IQ in a perceptible way.

Here are samples at 400mm with the bad and good filter respectively.

I'm wondering if some of the soft 100-400s out there may be due to a bad filter. Certainly, I was very glad that my problem was so easily resolved, and I'm also a lot more cautious now about attaching filters to lenses. I hope this may help other users who are frustrated with their 100-400 and who may be using a bad filter.

Edited by mjmyap on Dec 18, 2007 at 11:34 PM GMT

Dec 18, 2007 at 07:55 PM

simon_says
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p.1 #2 · p.1 #2 · Soft 100-400 and filter

The 100-400L that I use is nice and sharp at the 400mm end (even with a filter attached). I suspect that a lot of people with "soft" copies can probably have things fixed by a simple calibration (or other misc. things, such as your "fix" here).

Dec 18, 2007 at 10:41 PM

mjmyap
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p.1 #3 · p.1 #3 · Soft 100-400 and filter

I agree. From what I can tell, the better filter doesn't seem to do anything to the IQ; it's the cheaper filter that really degrades the image. Interestingly, I had sent the lens to Canon for a check-up and a calibration if necessary. It's obvious now why they didn't find anything wrong with the lens.

Dec 18, 2007 at 11:36 PM

CKrueger
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p.1 #4 · p.1 #4 · Soft 100-400 and filter

Wow, that's an enormous difference! You must be ecstatic with the improvement!

I didn't notice any difference in sharpness between my bare 100-400, with my B+W MRC UV, or even my "S+W" multicoated UV filter (a generic eBay filter that performs pretty well... I use it as a sacrificial filter sometimes). I wonder what causes this softness you discovered? It would be interesting to know what the differences are between the two Hoya filters you use.

Do you see any difference in sharpness with your other lenses if you switch between this "good Hoya" and "bad Hoya"?

Dec 19, 2007 at 12:20 AM

mjmyap
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p.1 #5 · p.1 #5 · Soft 100-400 and filter

Yes, I was enormously relieved when I realized it was the filter's fault.

Your question is a good one, and I hope to follow up on it soon. I'll probably test the good vs. bad filter on a 70-200 and a 24-105 to see if the differences are less marked for these shorter focal lengths.

To be honest, the Hoya coated filter I bought must be really quite common so I'm surpised more people haven't observed this. However, if the problem only shows up at supertelephoto focal lengths, this may explain why more people haven't reported it.

Dec 19, 2007 at 12:30 AM

trenchmonkey
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p.1 #6 · p.1 #6 · Soft 100-400 and filter

I've had similar findings. Long zooms seem to be more affected by the use of any
UV filter. My 70-200 f2.8 IS did some AF hunting in less than ideal light. I took it
off, end of problem. Wouldn't think of putting one on the 100-400, the hood's all the
protection I need.

Dec 19, 2007 at 05:51 AM

Alan321
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p.1 #7 · p.1 #7 · Soft 100-400 and filter

The problem may not be a bad filter but rather that the 100-400 pre-dates the digital-friendly lens designs that minimise the effects of reflections off lens elements and filters. This is one reason why the 100-400 needs to be revamped. It's also a side benefit of buying more modern versions of lenses such as 70-200s or whatever. You often get more than just an IS.

I've had the same effect on the 100-400, a 20mm and a 50mm, and so it is not just long lenses that are affected. It is not always obvious but is especially obvious when photographing city skylines at night. Sometimes it is bad no matter what you ar photographing.

I used to fit UV filters to all of my lenses and in the days of film it achieved more than just lens protection because film was sensitive to UV. These days I only use filters for specific effects (e.g. polarisers) or in bad environmental conditions where the lens needs more protection than just the rigid lens hood.

- Alan

Dec 19, 2007 at 08:14 AM

shadowoa
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p.1 #8 · p.1 #8 · Soft 100-400 and filter

I recall somebody else having this same problem with their 400mm 5.6 and UV filter about 6 months ago.

Dec 19, 2007 at 08:21 AM

ChrisGVE
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p.1 #9 · p.1 #9 · Soft 100-400 and filter

I had the same experience, I exchangeda good 70-200/2.8 lens to realize afterward that the culprit was the filter... It was a HOYA S-HMC, not supposed to be of bad quality...

Any similar experience?and should I turn to B+W or another brand rather than HOYA or is it just bad luck?

Cheers
Chris

Dec 19, 2007 at 10:28 AM

bias_hjorth
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p.1 #10 · p.1 #10 · Soft 100-400 and filter

I looks more out of focus than lack of sharpness to me

Could be due to the uv and the focus motor having a bigger task.

Dec 19, 2007 at 10:47 AM

Jammy Straub
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p.1 #11 · p.1 #11 · Soft 100-400 and filter

UV filters are evil, the only thing in photography I loathe more are those giant tupperware flash diffusers that cost ~$80. I digress.

Did you take the filter off when you sent the lens in to Canon or did you leave it on? It would just strike me as funny if you left it on and they removed the filter for testing... and then put it back on when they sent it home

Congrats on your newly acquired sharp lens!

Dec 19, 2007 at 11:43 AM

CKrueger
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p.1 #12 · p.1 #12 · Soft 100-400 and filter

Interesting that it happens with other lenses, too. Yet another thing for people to test, eh? I will say I've tested my lenses and I've never seen this behavior. I have a bunch of B+W MRC filters, a generic multicoated filter (my sacrificial lamb), a multicoated Hoya, and a couple uncoated, battle-scarred Tiffens. I guess I've been lucky.

bias_hjorth wrote:
I looks more out of focus than lack of sharpness to me

Could be due to the uv and the focus motor having a bigger task.

The UV filter won't affect AF on the 100-400... it's internal focus.

Dec 19, 2007 at 01:42 PM

Greg Feldman
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p.1 #13 · p.1 #13 · Soft 100-400 and filter

I always test new filters on whatever lens they go with, checking "with" and "without" images to be sure there is absolutely no visible (to me) degradation.

I completely understand the desire not to use UV filters, but when 90% of your photography involves canines with curious dispositions and wet snouts, there is not really much choice.

A fun little anecdote: I used to use a UV filter on a rather fancy lens, and then decided to take it off one day because, after all, who needs 'em? That very day, during a shoot in the dog park, a pup kicked up some small pebbles and one of them hit the front element of my lens. Left a mark, it did.

Good times.

Dec 19, 2007 at 01:52 PM

mjmyap
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p.1 #14 · p.1 #14 · Soft 100-400 and filter

Thanks for all the helpful replies. In response to Jammy, I took the UV filter off before sending it to Canon. The technician who was assigned the lens actually contacted me to tell me that he was puzzled because he couldn't find anything wrong with the lens' calibration

.

Anyway, I re-tested the bad filter with the 24-105, at 24mm and 105mm wide open, with and without a filter. The test is rough and the images sizes and exposures are not very well-matched but I think the trend is clear.

http://farm3.static.flickr.com/2328/2123905956_0ee35a67d8_o.jpg

At 24mm, performance with and without a filter are very similar. At 105mm, there is perceptible degradation, but nothing as extreme as 400m on the 100-400. I also tested the 105mm setting without a filter, a second Hoya filter and the bad filter.

http://farm3.static.flickr.com/2315/2123906202_d9e5d689f1_o.jpg

In this case, the second control Hoya filter doesn't seem to degrade the image as much as the bad Hoya filter.

On the whole, I found this experience educational. Clearly, there is an interaction between filters and lenses. That is, filters have a deleterious impact on your images, but the effects are far more pronounced at longer focal lengths. I might not have noticed the impact of the bad filter on the 24-105, but its effects were very clear at 400mm.

The question of course is whether this is due to the intrinsic characteristics of my filter, or whether this is just copy variation and I happened to have gotten a bad copy.

Dec 19, 2007 at 06:30 PM

danmitchell
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p.1 #15 · p.1 #15 · Soft 100-400 and filter

In your "A filter and bad filter" examples, both filtered images seem to have less contrast and definition than the filterless image.

It seems to me that if you pay a lot for an excellent lens it doesn't generally make much sense to add an extra piece of glass on the front.

And if you buy an inexpensive lens it sure as heck doesn't make sense to spend a lot of money for a good filter than won't degrade its image quality to protect the front element. Well maybe if you are _sure_ you will slam the front element in to something it might make some sense, but odds are you won't. Putting a filter on sub $100 lens seems nuts on either of two counts - putting a cheap filter on a optically good cheap lens turns it into a cheap and optically poor lens; or putting an expensive filter on a cheap lens might double the cost of the lens.

YMMV.

Dec 19, 2007 at 09:49 PM

Venus
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p.1 #16 · p.1 #16 · Soft 100-400 and filter

A reminder - it's vital to have specially designed filters for telephoto lenses. Good filters aren't cheap then again you don't wanna put a $5 filter on a 1K (or more) lens.Quality filters (all fully multi-coated) for long lenses are specially designed to ensure the best image quality. Better still if they are provided by the manufacturers such as the 500mm F4 L lenses.

Dec 20, 2007 at 12:37 AM

jkurkjia
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p.1 #17 · p.1 #17 · Soft 100-400 and filter

Venus wrote:
A reminder - it's vital to have specially designed filters for telephoto lenses. Good filters aren't cheap then again you don't wanna put a $5 filter on a 1K (or more) lens.Quality filters (all fully multi-coated) for long lenses are specially designed to ensure the best image quality. Better still if they are provided by the manufacturers such as the 500mm F4 L lenses.

I can't help but add another reminder. If you must use filters (e.g. I live in a "blowing sand" environment and must use filters) a high quality multi-coated filter is important for ALL lenses in the bag. Yes, filters can be expensive but guess what, that is the cost of doing business if you want high quality images.

Regards,

Joe Kurkjian

Dec 20, 2007 at 12:49 AM

aero145
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p.1 #18 · p.1 #18 · Soft 100-400 and filter

I have a 100-400, with a B+W MRC, and I haven't been really happy with the quality, from since I got the lens. I'm planning to stop using filters, just have them in the bag in case, and see if I spot a difference.

Ciao,
Aero

Dec 20, 2007 at 06:18 AM

Jman13
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p.1 #19 · p.1 #19 · Soft 100-400 and filter

jkurkjia wrote:
I can't help but add another reminder. If you must use filters (e.g. I live in a "blowing sand" environment and must use filters) a high quality multi-coated filter is important for ALL lenses in the bag. Yes, filters can be expensive but guess what, that is the cost of doing business if you want high quality images.

Well, you don't need them for every lens...you need them for every filter size.

Dec 20, 2007 at 08:36 AM

Greg Feldman
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p.1 #20 · p.1 #20 · Soft 100-400 and filter

Venus wrote:
A reminder - it's vital to have specially designed filters for telephoto lenses. Good filters aren't cheap then again you don't wanna put a $5 filter on a 1K (or more) lens.Quality filters (all fully multi-coated) for long lenses are specially designed to ensure the best image quality. Better still if they are provided by the manufacturers such as the 500mm F4 L lenses.

This makes sense in terms of superteles with their own drop-in filters, but are you suggesting that there are UV and polarizing filters "specially designed for telephoto lenses?" Or did you just mean "really good" when you said "specially designed?"

Dec 20, 2007 at 10:24 AM


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