What causes this? UPDATED FINDINGS!

squizza

squizza

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I've noticed it on many photographs. The bokeh is diagonal lines rather than being smooth.

For info purposes:

Canon 50D
1.4x converter (L)
300mm f4 IS USM L
Hoya pro filter

All help greatly appreciated.

4343799442_47340aa0d1.jpg
 
I've heard of DO (diffractive optics) lenses giving unusual ridged effects in out-of-focus highlights, but not seen this before.. and you're using a L, which doesn't use DO tech anyway.. :thinking:
 
Have you got a 100% crop too?

Is it like that when you zoom in on the camera display?
 
Usual question - does it happen with different lenses/filters?

Try taking the teleconverter out, not using a filter.. change one thing at a time and see if it makes a difference.

A.
 
See anorakus' answer. I'd be willing to bet it's either the filter or the teleconverter. Place bets.
 
looks like a fingerprint
 
Anorakus said:
Usual question - does it happen with different lenses/filters?

Try taking the teleconverter out, not using a filter.. change one thing at a time and see if it makes a difference.

A.
Click to expand...

This is using 300mm +1.4x - shows no problems

3922734825_b4a0d06044.jpg


3922677287_7858e5ec42.jpg
 
It's the filter...the 300/4 is prone to getting the bokeh destroyed like this. There was a post a few months back by Philthejugler showing exactly the same pattern.

Bob
 
Canon Bob said:
It's the filter...the 300/4 is prone to getting the bokeh destroyed like this. There was a post a few months back by Philthejugler showing exactly the same pattern.

Bob
Click to expand...

Weird.. is this a problem with the 300mm and Hoya filter combo?

I always use Hoya UV filters on my L's (although I only have a 70-200 at the high end) and I've never seen this.

A.
 
Anorakus said:
Weird.. is this a problem with the 300mm and Hoya filter combo?

I always use Hoya UV filters on my L's (although I only have a 70-200 at the high end) and I've never seen this.

A.
Click to expand...

I just looked for Phil's post....wrong forum :$...but here's the quote anyway (I'm sure he won't mind)
"I remember seeing similar results with a 300 F4 I had before - a cheap UV definately seems to give poor bokeh (odd diagonal lines) to these longer lenses"

Bob
 
Canon Bob said:
I just looked for Phil's post....wrong forum :$...but here's the quote anyway (I'm sure he won't mind)
"I remember seeing similar results with a 300 F4 I had before - a cheap UV definately seems to give poor bokeh (odd diagonal lines) to these longer lenses"

Bob
Click to expand...

That filter on my 300mm cost me a fortune! :eek:
 
I'll try the lens tomorrow without the filter and also without the t/c.:bang:

The thought of no filter = no protection scares me. Even though my lenses are very well cared for. Still scares me!
 
Anorakus said:
I wonder if a plain glass filter would do the same thing?
Click to expand...
It probably would....even more without the coating.

Increased the background isolation by either greater horizontal separation or wider aperture should eliminate the lines.

Bob
 
I've already suggested the following to Sarah directly:

I would do some tests with/without the TC and filter. Try the TC on another lens and see if it happens. I take it the owl shots are earlier than the dunnock?

It would have to be a big fingerprint (on the rear element rather than the front) to cause such a weird bokeh effect.

Dropping the lens or TC may have misaligned an element, or the moving elements in the IS mechanism may be stuck too. Whichever way, it's definitely there and worth a trip to the lens fixers.

I would recommend these guys: www.ehffs.co.uk/Contact.htm - they are not too expensive and should be able to help.

Another thing I have seen is the bokeh fringing is much more noticeable in the dunnock shot vs the owl shot - so I suspect something has gone out of alignment between the shots being taken.

Andy
 
AndyElliott said:
I've already suggested the following to Sarah directly:

I would do some tests with/without the TC and filter. Try the TC on another lens and see if it happens. I take it the owl shots are earlier than the dunnock?

It would have to be a big fingerprint (on the rear element rather than the front) to cause such a weird bokeh effect.

Dropping the lens or TC may have misaligned an element, or the moving elements in the IS mechanism may be stuck too. Whichever way, it's definitely there and worth a trip to the lens fixers.

I would recommend these guys: www.ehffs.co.uk/Contact.htm - they are not too expensive and should be able to help.

Another thing I have seen is the bokeh fringing is much more noticeable in the dunnock shot vs the owl shot - so I suspect something has gone out of alignment between the shots being taken.

Andy
Click to expand...

What would cause the change of alignment? I'm so careful with my stuff :(
 
squizza said:
What would cause the change of alignment? I'm so careful with my stuff :(
Click to expand...

An accidental knock - plus, the IS system may be suspected as there are optical elements that move. It could also be that there has been something loose since manufacture - I have read reviews of the 300/4 that mention 'bad' and 'good' copies - potentially the lens or the TC has slipped through the QC net and has been susceptible to a minor knock. I would have agreed with the posts regarding the filter, except I expect the owl shots were with the same filter, and filters don't really go 'bad'!

Anybody who is long-sighted (like me!) can tilt their glasses whilst looking at the writing on the monitor and see how 'fringing' appears - there is red-green fringing on the dunnock shot.

Andy
 
Why have you got a filter on there? It already has a protection filter!

All Canon super-teles have a thin meniscus glass on the front for protection, which is slightly curved to prevent reflections you get off the sensor (though this effect looks different). From EF Lens Work III, lens construction is quote: "15 elements in 11 groups (protective glass included)".

Strongly suspect the filter. Filters are never good news for image quality, and long lenses are particularly prone. I really don't know why people fit them, except in extreme situations obviously. I have one that fits most of my lenses but I've never actually used it. Bought it off a nice guy not a million miles from this thread - I don't think he used it either ;)

You can see what the filter is doing in the dunnock and deer shots because of the bright bokeh behind. A finger print wouldn't do that, it would cause a bit of blurring and flare but waaay out of focus. Isn't the rear element well recessed on that lens and hard to touch accidentally?

You've got a deep built-in lens hood with that lens. That should be all the protection you need. I don't suppose the front protection glass is cheap to replace, but don't be afraid to give it a proper clean when you have to.
 
Was the IS on or off in these pics? The IS can give odd effects like this in the bokeh if it has to be very active while taking a shot

Ed
 
HoppyUK said:
Filters are never good news for image quality, and long lenses are particularly prone. I really don't know why people fit them, except in extreme situations obviously.
Click to expand...

Come on now - in 99% of situations a good filter will make no noticable difference to your images - unless you create your images under lab conditions and enlarge the resulting images to the size of a house...

This is a clear example of the other 1%... a possible conflict between a screw-on filter and the existing (but oft-forgotten) built-in filter that some 'long' Canons have fitted...

I know my circumstances are more extreme than most, but I've gone through nearly all of the filters bought by the kind folk here and am on the last two as we speak.
I trashed the last pair on a job a fortnight ago when I plunged into a drainage ditch on a night patrol - fell right on top of the cameras, both of which were propelled lens-first into the mud by my full body-weight...both lens hoods also died to save the lenses - the location tabs snapped clean off and both hoods ended up halfway up the lens barrels...

I could have kept using those filters, though - and actually did for another two days before I got back... you can't tell from the images:
http://www.flickr.com/photos/arkady001/sets/72157623239553979/

Filters are a 'Good Thing'...
 
I don't buy the filter thing as the issue - given the problem seems to have recently appeared since the filter had been on the lens. FWIW, I have a contax P-filter on by ZD 300/2.8 without issue issue to the IQ (that's a whopping 112mm filter), and various protector filters on other lenses. The lenses are weather sealed and I do use them in the rain. It is useful to be able to clean the front without risk of scratching them. I do use Hoya filters, but I prefer the B&W and Marumi ones (very good quality without the high price) - the hoya ones seem to be more of a pain to clean if you get a greasy finger smudge on them.

Anyway, an academic discussion - lets see what Sarah found after her tests...

Andy
 
Maybe worth reading through this thread Sarah...with suitable images for comparison http://www.talkphotography.co.uk/forums/showthread.php?t=89349

I don't want to dismiss Andy's theories but the thing you're seeing is not uncommon. It is usually seen with the 300/4 IS, the 100-400 IS and the 400/5.6...the last option not having IS but the lined bokeh comes up pretty much the same.

Bob
 
I used to get it with a 100-400mm occasionally, I even posted about it as well, here

edit: Bob beat me :)
 
The examples in the 100-400 bokeh thread just look like bad bokeh - rather than the weird (unrelated to the pattern behind the main subject) diagonal pattern of Sarah's.

I could imagine if the built-in lens protector (which I would assume is flat) being near to a reflective filter that you could get some sort of repeating pattern (a bit like in a lift with two opposing mirrors) effect.

What also troubled me was the fringing on the bokeh just behind the focus point (you can see it better on the full size pic on the flickr page) - that looked like an alignment sort of issue. Whether this is normal for this lens (I would hope not for premium Canon glass), I don't know. I have never seen this on my Oly glass... Anyway, hopefully it will all be revealed when Sarah has completed her tests...

Andy
 
AndyElliott said:
The examples in the 100-400 bokeh thread just look like bad bokeh - rather than the weird (unrelated to the pattern behind the main subject) diagonal pattern of Sarah's.

I could imagine if the built-in lens protector (which I would assume is flat) being near to a reflective filter that you could get some sort of repeating pattern (a bit like in a lift with two opposing mirrors) effect.

What also troubled me was the fringing on the bokeh just behind the focus point (you can see it better on the full size pic on the flickr page) - that looked like an alignment sort of issue. Whether this is normal for this lens (I would hope not for premium Canon glass), I don't know. I have never seen this on my Oly glass... Anyway, hopefully it will all be revealed when Sarah has completed her tests...

Andy
Click to expand...

Integral protection glass is curved meniscus, for the reason you describe.
 
Thanks for clarifying that...
 
You need to do one with and one without of the same subject using the same settings please...
otherwise there could have been other factors involved...
 
I knew that... :$

Okay, both examples taken with the same settings - literally less than a minute between them.

With the filter

4372990356_72a0bda999.jpg


Without the filter

4372242493_1265a5b0a4.jpg


And to think that bloomin filter cost me an arm and a leg.
 
I feel somewhat vindicated in having never spent more than £12 for a UV/skylight filter now.
I just never saw how a £50 filter could be better than a cheap one, and I've done quite a bit of pixel peeping.
 
That seems to have nailed the bokeh issue - it obviously wasn't visible with the earlier shots of the owl etc.

Does this affect the bokeh fringing or the front-focussing? Is this just because of this filter or do all filters do it? Either way, I'd send the filter back for a refund.

Here's what I mean by the bokeh fringing:

4372302675_db70f983d4.jpg


larger version: http://farm3.static.flickr.com/2706/4372302675_1e411359ff_o.jpg

Given the front-focus on this shot, you can see the purple and green fringes.

Andy
 
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