Technical help with background in this photo?

[beckyhumphries]

Hi all

I took some photos recently when out at a local park of some blue tits. However on reviewing the pictures, in some of them (as below) I notice that I have these nasty round white circles in the background where there is a mix of dark trees with natural light. What could I have done differently to reduce the size/distraction of these in the background? If anyone could explain how they are affected/created I would much appreciate it

Thank you

Rebecca


f/5.6, 1/160sec, iso640, -0.3exposure, 600mm (35mm equivalent) - taken with a Panasonic Lumix GH2 with 100-300mm lens

[Manfred M]

This is called bokeh and is a result of how your lens handles the out of focus parts of the image. This is very much related to the lens design. When this is pleasing to the eye, it is referred to as "good bokeh" and when it is not "bad bokeh".

http://en.wikipedia.org/wiki/Bokeh

[NeiiilM]

They are not nasty at all. The other branches are distracting, I think if you have zoomed/moved in closer to your subject it would have made this better.

[Glenn NK]

Hi all

I took some photos recently when out at a local park of some blue tits. However on reviewing the pictures, in some of them (as below) I notice that I have these nasty round white circles in the background where there is a mix of dark trees with natural light. What could I have done differently to reduce the size/distraction of these in the background? If anyone could explain how they are affected/created I would much appreciate it

Thank you

Rebecca

Rebecca:

This is a common occurrence - it happens to me all the time when I don't pay attention to the background when doing flower closeup work. Leaves are very reflective, which causes blown reflections (specular highlights).

No matter how good your lens is at handling oof background (the "bokeh"), the leaves will still reflect the sun's light, and they will be distracting.

The only (easy) solution is to select a BG that is not reflective, or shoot in shadow or shade. This presents its own problems with ISO, shutter speed and aperture.

So there is no easy solution. With a small subject (a flower), I use a diffuser that blocks direct harsh sunlight from the flower and the BG). But with birds and wildlife, this obviously isn't an option.

Glenn

[Manfred M]

A lot of people will use a clear or UV filter to protect their lens element. When shooting outdoors (even in overcast conditions), I replace the clear filter with a polarizer and have one in place on every lens I happen to be shooting with that day. I picked up that trick from a local professional wildlife photographer. I do play with positioning a bit, but the technique usually lets me reduce and even eliminate the reflection off the leaves quite nicely. As you don't seem to like the bokeh, you might want to consider trying this to reduce the reflections and it should be a bit softer than what you have in your image. It's a fairly long telephoto, so you will be getting fairly shallow depth of field, even with a fairly slow lens, and will have to live with the bokeh that lens produces.

I like the lens; it's not super fast, but it has nice range. I picked one up back in the fall and used it on my video camera for wildlife shots in Africa; and yes, the polarizer was in place for those shots. I got some really nice footage of the rare (and endangered) black rhino with that lens as per the link.

http://www.youtube.com/watch?v=8g8lmSHmkx8

[William W]

. . . in some of [my pictures] (as below) I notice that I have these nasty round white circles in the background where there is a mix of dark trees with natural light. What could I have done differently to reduce the size/distraction of these in the background?

Change the Lighting on the Background (as already mentioned).

If the Background Lighting cannot be changed, then for that same shooting scenario you can to make the white circles smaller (but you choose whether such is less distracting or not) by:

Using a smaller aperture (i.e. a larger F/number).

You could also make the Shooting Distance shorter (i.e. moved in closer) and at the same time use a wider Focal Length to keep the Framing the same - this will make a minor difference to the size of the OoF Circles, compared to altering the Aperture.

The closer the background is to the Subject the MORE QUICKLY it will come into 'acceptable focus' as you stop down the lens – that is to say as you use a SMALLER APERTURE the Background will progressively come into the far range of the Depth of Field.

Quick example of an OoF Background with Specular Highlights, shot at three various F/stops and at the same Focussing Distance and at the same Shooting Distance:



WW

[jcuknz]

IMO out of focus highlights are one of the most distracting things ever. My solution is to get rid of them in editing ... this photo was full of them as I grabbed the shot before it flitted off ... I am pretty sure it flitted before the file was saved on the card.

I missed one beside its tail

[Glenn NK]

When shooting outdoors (even in overcast conditions), I replace the clear filter with a polarizer and have one in place on every lens I happen to be shooting with that day.

http://www.youtube.com/watch?v=8g8lmSHmkx8

Yes, good advice. I forgot about that trick - I use it quite often - but 90 percent of the time, I forget that the CPL is on, and don't rotate it for best effect.

It will substantially reduce reflections from non-metallic surfaces. A CPL is also very effective with calm water in a landscape if one wishes to see rocks, etc. in the foreground of the image that are below the water surface.

A CPL has its downside too - with birds etc. one can lose critical f/stop, and rotating a CPL while trying to capture a "flitty" bird only adds to the difficulties one encounters with a difficult subject.

Glenn

[beckyhumphries]

Great thank you all for you help.

Sounds like a polarizer would be a good investment; I just have a UV filter on at the moment.

I thought it was 'bokeh' but a quick google search with my incorrect spelling got me off track I do normally like the bokeh from this camera, its just this setup where the white circles are almost as large as the bird that put me off a bit.

Also thanks Bill for the aperture demonstration, that helped me understand a lot.

[William W]

Sounds like a polarizer would be a good investment;

Ensure: 'Circular' Polarizing Filter. Filter code: CPL
will be a more flexible and useful filter overall.

WW

[jcuknz]

Ensure: 'Circular' Polarizing Filter. Filter code: CPL
will be a more flexible and useful filter overall.

WW

bearing in mind that circular describes the construction of the filter not its physical shape. There are also linear types which apparently interfere with auto focusing ... may be more expensive but not better

[drjuice]

Hi all

... I have these nasty round white circles in the background where there is a mix of dark trees with natural light....

Hi, Rebecca - For starters, when I'm in this situation, I invariably use a polarizing filter and twist the filter to fit whatever direction I need to get rid of the bokeh (the white dots). Fortunately, when I'm shooting something like a bird, if it stays on the same twig or branch, the same angle of the filter generally works. If it moves, I nearly always need to change the angle that the filter cleans up the bokeh.

HTH.

v

[Glenn NK]

A CPL doesn't get rid of the bokeh - it eliminates the specular highlights which many lenses can't render into a pleasant bokeh (I suspect that very few lenses can handle this difficult situation).

Bokeh isn't the white circles, bokeh is the quality of the background blur - it's somewhat subjective, but we can tell the difference between pleasing bokeh and non-pleasing bokeh.

http://www.rickdenney.com/bokeh_test.htm

Test Scenario 1 in this article has specular highlights in the BG (reflections off the wine glass). On Test Scenario 2, the specular highlights near the right edge of the image are quite bad in some cases (images 2, 3, and 8).

It seems that the specular highlights were the most difficult part of the BG to render into pleasing bokeh, so the use of a CPL would be of great benefit (thanks to Manfred, post #5).

My last two paragraphs (post #4) were wrong - the CPL is the best bet.

Glenn

[jcuknz]

If you enjoy working with your editing programme then there is another solution ... that is to organise a new background for your bird. I am pretty sure the blurr on the neck feathers comes from the very fine mesh of the cage through which I was pointing the camera at our local aviary...Camera Nikon5700 bridge camera so lens quite small but not small enough to quite see through the one inch diagonal mesh.
I am glad to see the universal use of a CPL is questioned becuase I cannot see how it would help but obviously some people believe it does. Remember that you need to rotate the filter in setting up and view the different effect you get.

Interesting EXIF infor on this shot taken quite a time ago, May 2003, 280mm AoV shutter 1/17 handheld of course. I know I would have let the camera focus, the lens moves back and forwards doing this, and then placed lens barrel against cage mesh after AF did its job.

[jcuknz]

Rebecca ... Just belately noticed that yiou are using a GH2. I have a G3 which is somewhat similar. I notice that the bird is not sharp but the twig which appeared to be a wee bit closer is.
My suggestion if your camera has the feature of adjustable target area for AF as mine does is to use a small area for focus, I use the smallest possible.
It seems to me that you could have been using a larger target area and AF thought you wanted the branch sharp and not the bird.

The only time this practice has let me down was when trying to photograph a Mustang plane flying past I doubt if I ever got the plane within the target area and only by pure luck did I get some of the frames sharp. I was shooting in burst mode. Using the 14-140 lens at full zoom.

At a casual scan of the answers I don't think people have answered your question as to why it happens only how to avoid it

This diagram explains how we have depth of field. The circle much bigger than in real life isthe 'circle of confusion' one gets when the lens is not precisely focused on the light source. You will see from the red and green lines that they focus off the sensor and as they travel to and away from the sensor they get larger .... that is what is happening in your photo ... the out of focus areas of brightness as getting larger and larger the further away from the point iof focus, the branch.
In practice the CoC could be 1/1000 inch diameter or smaller if the image is to be enlarged considerably.
Bill showed you it happening when you close the aperture down ... the angle of the entry rays gets smaller and they stay withing the given CoC longer giving greaster depth of field and less magnification of spot of light etc.

[beckyhumphries]

Thanks Jcuknz, I do tend to flick between a small focus area (for birds like these) and a large focus area when I am (badly!) trying to get birds in flight or a moving subject. It is possible I had it on a larger focus area for this picture, or I missed the best focus point by accident. Thanks for the diagrams as well, sometimes a picture speaks a thousand words and they have helped me understand a lot more.