Hi all,
Read thru the links posted by the friendly members here. Forgive my ignorance. I still ask the same question.
Shooting birds on flight or stationery with a len 100-400 4.5-6 aperture. Should not be having a good bokeh base on my understanding below.
1. Len aperture not wide enough ( good bokeh should have a wide aperture)
2. Shooting distance is too far to create a bokeh effect considering a focal length of 400mm and a shooting distance of 30-40 metres.
3. Read the provided link, focal length do contribute to having a nice bokeh without using a wide aperture but the subject should be near the len.
I sincerely apologise if my above questions are stupid but if the len 100-400 is having a aperture at 2.8, i should not be asking this question. Please help to explain in layman term. Thank you all.
P.s: can't find the picture which show birds and bird in flight having a nice bokeh with a 100-400mm 4.5-6 aperture
The best way to learn is to go out and take some photographs on your own. Use the longest focal length you have and shoot at the widest aperture, then stop down (increase the f-number) and shoot again. You will find out how far the background / foreground needs to be away from your subject for it to be enough out of focus.
Another way is to look at others photographs, flickr has a good repository and many provide the exif data (what the camera settings the photograph was shot at) as well. This is a group with photographs taken with the older Canon 100-400mm f4.5-5.6 lens:
https://www.flickr.com/groups/81265875@N00/pool/
For example in this randomly selected photograph:
https://www.flickr.com/photos/100473799@N05/32189266711/in/pool-81265875@N00/
It was shot on the Canon 600D, which has the same APS-C sensor size as your 400D, shot at 400mm, at aperture of f6.3. What do you think of the background?
Do note some photographs do not have exif data, and the members may have posted photographs not taken with the Canon 100-400mm lens in that group.
However it is good to note that at the usual distances the 100-400mm lens is used at, the depth of field is relatively shallow and background/foreground is generally quite blur. Experienced photographers will take note of the background when taking the shot, so as to move and select a more favourable background so their subject will stand out as far as possible.
And note that the original meaning of bokeh is the quality of blur, which is subjective and depends on the lens (or rather it's construction), rather than 'how blur the background is'. So a photograph taken with the Canon 100-400mm f4.5-5.6L IS will have a different bokeh compared to a photograph taken with the Canon 100-400mm f4.5-5.6L IS II lens, even with the same camera, at the same subject distance, aperture and focal length. Whether it's good or not is subjective and depends if you like it's rendering quality more or not