Dear Pentaxian, newbies need help on lenses..

[Dormant]

Currently using 18-55mm AL II, d blur background is not blur enough although alr adjust it to the maximum 55mm f5.6. Does it mean i have to buy a new lens with higher mm? To create d blur background i need larger aperture (f2.8)?

 

[night86mare]

Currently using 18-55mm AL II, d blur background is not blur enough although alr adjust it to the maximum 55mm f5.6. Does it mean i have to buy a new lens with higher mm? To create d blur background i need larger aperture (f2.8)?

dormant,

you *can* get shallow dof out of 18-55. the trouble is that it won't be as easy to do it as compared to say, using a 50mm f/1.4.

just a quick recap on what you need to do to minimise dof:

1) longer focal length = shallow dof
2) larger aperture (or smaller f-stop) = shallow dof
3) greater background-camera distance compared to subject-camera distance = shallow dof

if you are using 55mm f/5.6 then what you can work on is 3, 1 and 2 have already been maximized.

if you are shooting with the subject right next to the wall, then obviously it doesn't matter what lens you use.

 

[pinholecam]

Try focusing nearer.
Up to the minimum focus distance of the lens.

If that still fails, you might want a faster lens or longer lens.
What are you thaking btw? That would help in the lens suggestions.
Budget as well.

 

[rocaway]

Example: Taking a subject with a wall behind it. The wall will not be very blur because it is still considered close to the camera

Now, try taking a subject with the sky/faraway buildings behind. Confirm more out-of-focus background than previously.

 

[darrrrrrrrrr]

I read something about how a longer focal length gives the illusion of shallower DOF even if it's the same DOF as the a narrower area of a background is more magnified thus making it appear more out of focus. (http://www.film-and-video.com/dofmyth.htm)

That's why I recommended getting a longer lens, which doesn't have to cost big money, until you go into the f/2.8 territory. If you wanna stick with the kit lens for now, try to get as close to the subject as the lens will allow you to, and keep the background uncluttered and far away, which means your flower should not be framed against a nearby bush.

 

[Dormant]

i get what u mean now...thx!