Bokeh, good, bad, lens quality

[Mircula]

Hello,


I was wondering how you define the quality of the Bokeh. How does it have to be to be "good"?
And why do different lenses have different bokehs. What is the connection there?


Another question to that matter:


I shoot a bit of macro recently and it is really hard to find the right f number to get the point of interest sharp and everything else blurred. Is the doF just dependent on the distance to the object and the f number or does it depend on the lens as well. In short, do different lenses with the same distance to the object and the same f number differ in the doF?

Thank you!

Ciaociao

[jjphoto]

It's likely that your questions will be answered here;

http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN_35_Bokeh_EN/$File/CLN35_Bokeh_en.pdf

Here are a few more Bokeh related links but Google is your friend and you will probably find hundreds if you look.

http://www.bobatkins.com/photography/technical/bokeh.html
http://www.luminous-landscape.com/essays/bokeh.shtml
http://bokehtests.com/Site/About_Bokeh.html
http://www.rickdenney.com/bokeh_test.htm

Bokeh is subjective to some degree. I like smoooth Bokeh, as do most people, however harsh or funky Bokeh can really add character where there was none so can be quite a positive trait in the right circumstances.

Funky;
http://www.johnjovic.com/images/Gallery/l_281_1000.jpg

http://www.johnjovic.com/images/Gallery/l_294_1000.jpg

Smooth;
http://www.johnjovic.com/images/Gallery/l_314_1000.jpg

http://www.johnjovic.com/images/Gallery/l_306_1000.jpg

You will also find that the same lens can have different chacteristics at different focus distances and the bokeh in front of or behind the focus point can look different too.

JJ

[Mircula]

Thank you JJ. Very informative and a good source for beginners!

[Kym]

Bokeh discussed to death here: http://www.ausphotography.net.au/forum/showthread.php?t=31764

:D

[achee]

I shoot a bit of macro recently and it is really hard to find the right f number to get the point of interest sharp and everything else blurred. Is the doF just dependent on the distance to the object and the f number or does it depend on the lens as well. In short, do different lenses with the same distance to the object and the same f number differ in the doF?


I just learnt this week that the DOF is very related to the focal length. I think it is inversely proportional to the square of focal length. In any case, at longer focal lengths the DOF is much smaller, for a given aperture.

[eliemarga]

about dof: http://www.luminous-landscape.com/tutorials/dof2.shtml

Bokeh...is a very subjective matter, in some occasion what considered as bad bokeh could be beautiful in another set of photo. In macro photography it is indeed hard to get all in frame sharp from corner to corner, this is could be caused by several reason, first is your aperture is wide open, this is normal since you want lot of light enter your lens, then there's distance, which again the closer you get to the object, the dof is shallower, this is base on my experience and I could be off here :) considering my mileage isn't that great.

[Steve Axford]

I think your first question has been covered. As for the second, I almost always use f18 for macros. If the background is in focus, then it is too close. Try to get good separation between the subject and the background. If you can't do that, then either make the background a feature or try a lower fstop. The problem is that the lower the fstop, the harder it will be to get all the whole subject in focus. That's why I almost never use a low fstop.