How to blur the background

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danny842003

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IMG_0398 by danny842003, on Flickr

So I went out last weekend having read plenty of things online about how to blur backgrounds when taking photos.
Clear looking at the above photo of Horatio im being a total newbie and missing something very key as i could not achieve it.
Its taken me so long that I have forgotten what input I had made to the camera to take the photo i did. It was taken using a 550D with a efs 18-55mm lens. To take the same photo but with a blurred background how would you go about doing it?
Many thanks for any help in advance.
 
It would be best if you used the longer end of your lens @ 55mm, wide open e.g f3.5 while standing further back, this decreases depth of field (DOF) giving you the desired effect, for a subject this size a 70-200 f2.8 would be perfect.
 
Graham00 said:
It would be best if you used the longer end of your lens @ 55mm, wide open e.g f3.5 while standing further back, this decreases depth of field (DOF) giving you the desired effect, for a subject this size a 70-200 f2.8 would be perfect.
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Nupe. Standing closer to the subject will throw the background more out of focus, but as you'd want to use the longer end of the lens it's got to be a balancing act to get a result you're happy with.
 
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Thanks for the quick replys I also have a 75-300mm lens would i be better switching to this and using it at around 200 as suggested above?
 
Possibly/probably, maybe even better at 300 but it depends on what apertures you can select at the various zoom lengths.

Depth of field dependes on camera to subject distance and aperture. The effect of focal length (zoom length) on depth of field is a subject that causes endless arguments :D but it's safe to say that longer zoom lengths can make the background look larger and this can make it look more out of focus.

The best thing to do is to go out and shoot some different scenes at different zoom lengths and aperture settings and look at the effect the various settings have on your pc.
 
yes certainly would, if you stand further away from subject use 300 end of that lens @F3.5 will kick background out of focus much much better.

Daz
 
urdygurdy said:
yes certainly would, if you stand further away from subject use 300 end of that lens @F3.5 will kick background out of focus much much better.

Daz
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If it'll go to f3.5 at 300mm, personally I dount it can, it'll probably be f6 at 300mm?

Gotta remember also that increasing the camera to subject distance increases the DoF, but at 300mm and f6 it's probably still going to be a winner :)
 
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Ok thanks if the weather is half decent I will give it a go tomorrow.
 
woof woof said:
Nupe. Standing closer to the subject will throw the background more out of focus, but as you'd want to use the longer end of the lens it's got to be a balancing act to get a result you're happy with.
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Ah, but the framing was done at 25mm.

Standing back an using 55mm to get the same framing would throw the background more out of focus...
 
I think it's important to realise that increasing the camera to subject distance increases depth of field and with non constant aperture lenses increasing the focal length will involve using a smaller aperture somewhere along the scale.

According to DoF master...
25mm, @f4, (assuming that's what you'll get at 25mm?)
@20ft camera to subject distance = DoF in the region of 12ft-76ft
55mm, @5.6, (assuming that's what you'll get at 55mm?)
@40ft camera to subject distance = DoF in the region of 27-70ft.

Using the longer end of the zoom lens may very probably still be a winner in many / most even situations but I think it's important to understand the balancing act :)
 
A wealth of knowledge on here. Thanks. Will post up some results when i get out with camera again :)
 
i *personally* think for general portraits, longer lenses render the background in a more pleasing way, it's all subjective of course but to my eye, wide angle lenses can make backgrounds look quite fussy. the perhaps ultimate background blurring machines are lenses like the canon 200/f2 canon 300 2.8 or even 400 2.8 but these lenses are stupidly expensive.

for significantly less though, the canon 70-200 2.8 (at the 200mm end), the 200 2.8 prime, the 135 f/2, 100 f/2, 85 1.2/1.4/1.8 primes and even the canon 50mm 1.8 prime will completely melt your background away.

the kit lens is a good starting point for photography but if you want to have fine depth of field control and you want to blur your backgrounds it's not the best tool for the job.

to give you a taste and help you build your technique, and depending on your budget, i'd give serious consideration to getting a canon 50mm f1.8 or maybe a canon 85 1.8.

the 85mm lens has much better autofocus than the 50 1.8, which although the 50m isn't a bad performer, the af is frustrating... and indecisive at times... but you can pick the lens up for £60 used.

85mm on a crop body won't be terribly useful indoors, but outside in woodland, leafy parks and so on, you'll get some wonderful background seperation and blur.

have a look on flickr. do a search for the canon 50mm 1.8 and canon 85 1.8 groups and see what results others are getting. for two relatively cheap lenses, amazing photographs are possible.
 
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