Purposely creating good DoF??

sid_wolf

sid_wolf

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Name
Sinead
Edit My Images
Yes
Right, just a quick, probably dumb question about DoF...

How do you purposely get the background blurry but the subject in focus? Many of my shots have this, but I'm not purposely setting it up, its just luck

I got asked today how to do it, and I couldnt tell them :lol:
 
You need a large aperture i.e. f/1.8 will create a really shallow DoF so what you focus on will be sharp and everything either closer or beyond the point of focus will start to get progressively blurred where as an aperture of say f/18 will have pretty much anything in front of the lens in focus

Hope this helps

I'm sure there will be more experienced people along soon

Matt
MWHCVT
 
Low f/number, and subject as big as possible in frame - ie, move close and/or use longer focal length.

If you also want to blur the background, then put as much distance as possible behind the subject.

Input the numbers here, and it calculates exactly how much, or little, you're getting www.dofmaster.com
 
Even f/5.6 will do a fair job....

20110308_145357_4816_LR.jpg


although f/2 does it better. :)

20110307_122347_4676_LR.jpg


Try some macro photography if you really want narrow DOF.
 
OptimusBri said:
Aperture is something which takes a while to get your head round for some people, though everyone has explained it pretty well for you here :) If you want a book to help you with some basics I really recommend buying Understanding Exposure by Bryan Peterson!
Click to expand...

Was just going to suggest this. This book explains all of this perfectly.
 
sid_wolf said:
thanks guys :) at least now i know how to actually set it up, rather than it just happening :lol:
Click to expand...

You'll have a harder time achieving these shallow DOF effects with your HS10 compared to the examples from DSLRs shown above. There are four factors that influence DOF....

1. Distance to subject - the closer you are the shallower the DOF;
2. Focal length - the more you zoom in (longer focal length) the shallower the DOF;
3. Aperture - the wider/brighter you make the aperture (smaller f/ number) the shallower your DOF;
4. Sensor format - the smaller your sensor the shallower your DOF (for any given combination of the first three factors).

Because your camera has a much smaller sensor than a DSLR it means you are actually shooting with a much shorter focal length in order to achieve the same subject framing. As a result the DOF from your camera will be greater than that from a DSLR shot at the same distance, framing and aperture value.

Follow the link that Hoppy provided in post #3 and play around with some numbers. Be sure to select the right sensor format for your camera (the HS10 is listed) and make sure you use your actual focal length values (4.2mm to 126mm) rather than the 35mm equivalents (24mm to 720mm).

As an example, let's say you want to shoot a subject 20' away at 50mm (actual focal length) and f/5.6. The DOF calculator says you will have a total DOF of 2.75'.

To shoot with a full frame DSLR such as a Canon 5D you would need a focal length of 285mm for the same framing, due to the larger sensor. With the subject still at 20' away and an aperture of f/5.6 your DOF from this camera will be 0.5'.

That's quite a dramatic difference. One reason, amongst several, that people invest in DSLRs is to allow greater creative control over DOF. It's also one reason why people might choose a full frame DSLR over a crop body DSLR. The larger your sensor the shallower DOF you can potentially create. Sometimes that is a good thing. At other times it is a problem.

Further to the above, with DSLR's you can buy lenses which offer even faster/brighter apertures than the lenses on compact and bridge cameras. This gives further scope to achieve wafer thin DOF in some cases, if you so desire.
 
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