What causes this effect - IS?

whyone

whyone

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Ian
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Hi,

I have noticed this jittery pattern in the background / out of focus areas of a number of photos I have taken.



The photo was taken using my Canon 50D and EF 100 - 400 mm f/4.5 - 5.6 L IS USM lens, hand held, with the IS turned on.

Is the 'jitter' a function of the IS? Is there a way to prevent / minimise this?(other than turning the IS off!)

Many thanks in advance for your comments.

PS - the beasties are female Lesser Kudu, one of the prettiest of the African antelope in my opinion.
 
Looks odd as my 100-400 has never shown bokeh / distortion like this, with IS on or off! Could it be heat haze in the background??

Carl
 
I think it is partly down to how the lens design renders out of focus areas. It can sometimes be unpleasing to the eye. Generally, the wider the aperture you use the more out of focus the background will be and the effect you ask about should be lessened. Whether it can be completely overcome I don't know.

I have seen the effect in quite a lot of pictures, but don't recall it happening with older lenses.
There will be a technical explanation I am sure. Unfortunately it tends to detract from the whole point of rendering backgrounds out of focus, i.e. to make the main subject stand out.
 
I used to get it on my 100-400 sometimes, (depending on the light), and I've seen it on other occasions with a 100-400.
Don't know what causes it?
 
whyone said:
Hi Carl.

IS was switched on.
Click to expand...

Ian, I think that if IS was the source of the problem then everyting in the picture would be affected and not just the background.:)
 
If the image has been sharpened, can we see a un-sharpened one?
 
I would say that is air turbulence, warm air rising from the ground.

Similar thing here from a shot a few weeks back, on a cold morning the sun comes out and warms the ground, the warm air rises and you get this, I could see the image shimmering through the view finder.

176_048.jpg
 
I used to get this pattern occasionally, usually when there was lots of grass/small detail in the out of focus area.. annoying but it's not too bad really!
 
I think it's just the bokeh from that iris-shape doesn't produce particularly pleasing results...
It's for this reason that the more commonly-used portrait primes have rounded iris-blades to produce better bokeh at wide apertures...
 
I think that it might be air turbulence causing the patterns and the slight lack of sharpness. I am not sure about the lens itself, since I have never tried it (so I cant confirm its sharpness), but I think that it is air turbulence, especially in those hot areas.
 
ruvor said:
filter...
Click to expand...

Interesting suggestion - I hadnt thought of that! Can you elaborate please?

I have a Hoya UV filter on to pretect the lens from the Arican dust. Unsure which one specifically other than the fact it cost about £70.
 
certain lenses produce this nasty bokeh effect when you use filters on them, 100-400, 300 f/4 and i've heard 400 f/5.6
 
Not the filters argument again, please...? It's not the filter... get past it...
 
Arkady said:
Not the filters argument again, please...? It's not the filter... get past it...
Click to expand...

Yes it is Rob. Same as it was on the last thread you denied it on - here ;) http://www.talkphotography.co.uk/forums/showthread.php?t=205344

Sadly most of the images there are no longer hosted, but they were exactly like the OP's - and the effect disappeared when the filter was removed. There are other links in that thread with illustrations. And plenty of other recent examples posted recently on here if you search.

The problem is an imperfect filter surface magnified by a long lens. You don't see it on short focal lengths. You only get the filter-flare problem with them! :eek:

Only fit a protection filter when you absolutely need it. I would say a bit of dust is not one of those situations and a rocket blower will clean that off no problem.

Rob, you use a protection filter for good very reason, because you work in active military situations. Most folks don't, so they shouldn't. If you fit a piece of glass in front of a lens, of course it has an effect. It must do. Usually it passes unnoticed, sometimes not.

Edit: maybe not the filter per se... update on post #41.
 
I remember it well and I'm still not entirely convinced by your arguments...

I'll keep saying it as well - it doesn't happen on any of the lenses I've ever used, from 17mm to 1200mm...
Unless it's only applicable to Canon lenses, in which case they're crap and you should swap to Nikon optics immediately.
I still think it's an iris-problem making unpleasant bokeh effects...

If you choose to think otherwise you are entirely welcome to do so - I think we'll have to agree to disagree on this one, however; I've said my piece.
 
Arkady said:
I remember it well and I'm still not entirely convinced by your arguments...

I'll keep saying it as well - it doesn't happen on any of the lenses I've ever used, from 17mm to 1200mm...
Unless it's only applicable to Canon lenses, in which case they're crap and you should swap to Nikon optics immediately.
I still think it's an iris-problem making unpleasant bokeh effects...

If you choose to think otherwise you are entirely welcome to do so - I think we'll have to agree to disagree on this one, however; I've said my piece.
Click to expand...

It doesn't happen on any of my lenses either, but then I don't have any poor quality filters. Or rather, I don't have any faulty filters - the effect is so marked in certain situations, and so obvious when you remove the filter, that I can't think that all filters behave like this.

Basically, it only seems to show itself in back-lit situations with bright out-of-focus highlights and long lenses. That's not an unusual situation in itself at all, so if it was just a general filter problem I think there would have been a bit more of a fuss. I've seen exactly the same thing with a 70-300 IS, 300L 4 and 100-400L posted quite recently and they are all quite different designs so I don't think it can be that.

It's the filter for sure, but I'm now thinking it is a faulty filter with an unlucky flaw just in the wrong place, rather than filters in general or even cheap filters necessarily.

So maybe don't throw them away ;) but be aware of potential problems. And they all produce flare and ghosting in extreme situations, eg bright lights at night - even the very best. I've posted examples of that often enough, as here http://www.talkphotography.co.uk/forums/showthread.php?t=212297 I think you've seen that link before Rob ;) :D

Edit: update on the filter theory on post #41.
 
I think even I grudgingly accepted that it was a cheap filter in that instance *grumble-grumble*
 
I had the same thing with my 100-400. Remove the filter, it will go away. I don't use filters on any of my lenses now.
 
Well, that seems to have precipitated a bit of healthy debate! :lol:

Many thanks for taking the time to post.

I will certainly experiment with removing the filter, though taking lenses deep into the African bush for 8 days at a time without filters does worry me.
 
OK...having thought about this quite a lot...does this only happen with Canon telephotos, or has anyone with a Nikon lens experienced this? If they have can they post up some examples, please?

These lenses come with a front filter-thread - I for one would be mightily p'd off if I couldn't use a UV filter with such an expensive lens...
I know I may be in a minority of users, but c'mon - motorsports, wildlife etc. all environments where crap flies around unexpectedly...
Gravel on a woodland rally-stage? That's a lens-killer if I ever saw such a thing...
 
I only had a cheapish filter on mine. I would imagine a high quality filter would not have the same effect. I agrre in sandy situations etc a filter is a must.
 
purpleclouds said:
I used to get this pattern occasionally, usually when there was lots of grass/small detail in the out of focus area.. annoying but it's not too bad really!
Click to expand...

This is what my first thought was. I've got a similar thing going on with some photos I took yesterday with my 70-300 IS. I wasn't using a filter, so it certainly wasn't that.

There was lots of detail in the BG, grass and twigs, and allsorts. Whereas I've managed super-sharp photos with similar settings and focal length when the BG was uncluttered.

I should add; the beasties above look a little soft, as well as the BG being a bit funny. Maybe viewed at 100% would confirm that? T'was much the same with my photos from yesterday.

But I'm a noob, so perhaps that's all just rubbish.
 
The Canon 100-400 can produce unpleasing bokeh now and again and even sometimes produce donut oof highlights resembling the mirror lens effect. It seems to depend on how far the oof background is from the main subject and the nature of the background itself coupled with the aperture used.

I'm not sure any that is relevant to this particular shot though - given that the shots were taken in Africa (I'd guess) then I think Martyn may be right and it's just a heat haze effect?
 
GrittyShaker said:
I should add; the beasties above look a little soft, as well as the BG being a bit funny. .
Click to expand...

You are quite correct - it is not the sharpest 'photo in the world, I simply selected it on the basis that it was a good example of the 'jittery background' effect I wanted to understand better.
:)
 
Looks like a fairly classic "100-400 doesn't like its filter" to me

Bob
 
Arkady said:
OK...having thought about this quite a lot...does this only happen with Canon telephotos, or has anyone with a Nikon lens experienced this? If they have can they post up some examples, please?
Click to expand...

I don't get the effect shown here, rather a diagonal pattern when using a cheap filter on my Sigma 150-500mm. You can see this effect on the foreground pebbles in this shot
 
I've had similar shooting birds with my 100-400 and also with the 500 4.5. In my case it was the BG being too close to the subject and harsh lighting too. What f No. were you using?
 
Arkady said:
OK...having thought about this quite a lot...does this only happen with Canon telephotos, or has anyone with a Nikon lens experienced this? If they have can they post up some examples, please?

These lenses come with a front filter-thread - I for one would be mightily p'd off if I couldn't use a UV filter with such an expensive lens...I know I may be in a minority of users, but c'mon - motorsports, wildlife etc. all environments where crap flies around unexpectedly...
Gravel on a woodland rally-stage? That's a lens-killer if I ever saw such a thing...
Click to expand...

I don't think there's any problem with all filters here Rob, just either low grade or perhaps faulty filters. Possibly bootleg copies and the like. I think you use Hoya Pro-1 don't you? Sorry if I've got that wrong but I have a Pro-1 UV and can't replicate the effect on my longest lens - 70-200 x1.4. It's sharp as you like, smooth bokeh, identical with and without the filter.

If I was working in the same conditions that you have described from time to time, or those you've mentioned above, I would use a protection filter too. Of course. In fact, that's why I've got one even though I've never used it so far - it's salt sea spray I'm wary of, horrible stuff.

PS Now I think about it, I've got a cheap n nasty old polariser that I know has sharpness issues - might do some with and without comparisons tomorrow if the sun shines. But I know before I start that it will be rubbish ;)

Edit: update in post #41
 
RJL2005 said:
I've had similar shooting birds with my 100-400 and also with the 500 4.5. In my case it was the BG being too close to the subject and harsh lighting too. What f No. were you using?
Click to expand...

That shot was F/8.0 at 500mm. I seem to get the diagonal effect at the upper end of the zoom range rather than in harsh light.
 
Arkady said:
I think it's just the bokeh from that iris-shape doesn't produce particularly pleasing results...
It's for this reason that the more commonly-used portrait primes have rounded iris-blades to produce better bokeh at wide apertures...
Click to expand...

Pretty sure you have hit the nail on the head, Rob.
I am sure I read a technical explanation along those lines somewhere.
 
mac2474 said:
I don't get the effect shown here, rather a diagonal pattern when using a cheap filter on my Sigma 150-500mm. You can see this effect on the foreground pebbles in this shot
Click to expand...

I think that's exactly what we're seeing in the OP...just in a different area - it's almost like a CA effect but without the colour-fringing associated with that type of distortion...
The 'lines' as you call them look to me to be duplicates of the hard highlights along the edges of the pebbles... If that's the case then I could accept that it's the fault of a cheap filter.

One thing I've always said is there's no point in not protecting a plus-£1k lens with something, but equally, there's no point putting a £10 filter on a plus-£1k lens either.
You have to factor the cost of that £80 filter into your buying decision if you use lenses like this outdoors in blowy conditions...

I just got round to doing a clean on all my kit the other day after two studio shoots and found what appeared to be dried baby-oil on one of the lenses... you never can tell where crap will come from... It took ages to get the stuff off and I'm so-oooo glad it was a filter I was scrubbing away at and not the front element of the lens... in the end it had to go under the tap with some washing-up liquid to get it off... try doing that with a 70-200...lol
 
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