Canon Digital Photography Forums  

Go Back   Canon Digital Photography Forums > 'Sharing Knowhow' section > Talk About Photography > General Photography Talk
Register Rules FAQ Members List Search Today's Posts Mark Forums Read



Reply
 
Thread Tools Display Modes
Old 22nd of June 2007 (Fri)   #1
CanonAmerican
Member
 
Join Date: Jun 2007
Posts: 31
Default How do you focus one object, and leave everything else blurry?

http://www.usa.canon.com/app/images/...le_image_2.JPG

I mean, does it have to do with aperture? Because even if I use aperture(and open the lens) using low aperture, I still get everything in a very high resolution. It's not like I photograph something and everthing else is blurry.
How did they manage to marvelously capture that purple flower, and at the same time leave its background blurry?
CanonAmerican is offline   Reply With Quote
This ad block will go away when you log in as member
Old 22nd of June 2007 (Fri)   #2
Box Brownie
Cream of the Crop
 
Box Brownie's Avatar
 
Join Date: Apr 2005
Location: Surrey
Posts: 9,894
Default Re: How do you focus one object, and leave everything else blurry?

Hi

Yes, it is effectively the choice of aperture that will dictate the DoF (depth of field).

But you do not say what camera you are using, so the aperture to get such an effect will need to be wide open i.e. f2.8 not f16(or wider end if for example when using a tele zoom and being fairly close to the subject ~ the choice of lens and subject distance have a bearing that I am finding hard to describe). Now what I am describing is the typical scenario when using a dSLR but if you are using a P&S you have the other 'issue' with DoF, that is the relationship of the sensor size. With a P&S the sensor size is tiny comapred to a dSLR and because of the limitations (I think you need to look up 'circles of confusion' for scientific argument about this one) even with a wide open aperture you get little DoF effect that you are trying to achieve. However, if it has a Macro setting and you can get in really close tothe subject then you see an improved effect but do not expect the P&S to give the sort of result you see from a dSLR

HTH
__________________
That was a great meal ~ you must have a good set of pans
credit line is vanity, payment is sanity ~ one day I will make that first sale.....one day change pending
Box Brownie is online now   Reply With Quote
Old 22nd of June 2007 (Fri)   #3
PaulDB
Member
 
Join Date: Oct 2004
Location: Coventry , UK
Posts: 390
Default Re: How do you focus one object, and leave everything else blurry?

It is indeed to do with the aperture. The lower the F stop number the shallower the depth of field and the more blurry the background gets.

Try setting your camera to AV mode then set the F stop as low as it will go. Set the camera to center focus point and run some test shots. Also note, the further the item in focus is away from the background the better 'blur' you will get.

EDIT - Damn you beat me to it!
__________________
Canon EOS 30D
100mm F2.8 Macro | 17-40 F4L | 100-400 F4-5.6L IS| 18-55 Kit | 580ex

Work in Progress: http://www.photos.bickerd.com
PaulDB is offline   Reply With Quote
This ad block will go away when you log in as member
Old 22nd of June 2007 (Fri)   #4
CanonAmerican
Member
 
Join Date: Jun 2007
Posts: 31
Default Re: How do you focus one object, and leave everything else blurry?

I'm using A540 PS.
Thank you so much for your tips, I'm going to try it and upload the results.
How does the camera know which is the object that I want to photograph, and which exactly is the background? I did notice that I have a green square when I use aperture, but how do I change its location?
Moreover, why does the F increase itself everytime I zoom in? If I want to take a 2.5F + Macro picture? I just can't ! Everytime I zoom in the F increases itself, and when I zoom out it decreases to a low number. How will I be able to take pictures like the one they took in the aformentioned 1st post if I can't use macro and zoom in without the F going up everytime I do it.

Last edited by CanonAmerican : 22nd of June 2007 (Fri) at 03:30.
CanonAmerican is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #5
Box Brownie
Cream of the Crop
 
Box Brownie's Avatar
 
Join Date: Apr 2005
Location: Surrey
Posts: 9,894
Default Re: How do you focus one object, and leave everything else blurry?

Quote:
Originally Posted by CanonAmerican View Post
I'm using A540 PS.
Thank you so much for your tips, I'm going to try it and upload the results.
How does the camera know which is the object that I want to photograph, and which exactly is the background? I did notice that I have a green square when I use aperture, but how do I change its location?
Moreover, why does the F increase itself everytime I zoom in? If I want to take a 2.5F + Macro picture? I just can't ! Everytime I zoom in the F increases itself, and when I zoom out it decreases to a low number. How will I be able to take pictures like the one they took in the aformentioned 1st post if I can't use macro and zoom in without the F going up everytime I do it.
I have looked at the spec for the A540 I hope the following gives you some more help.

1) The Max aperture is f2.6 at the wide end of the zoom and f5.5 at the tele end hence the changes you are reporting.

2) It has a multi point AF and a 'fixed' centre/single point - I presume this is selectable in the settings.

3) Minimum focusing distance is 5cm (2 inches) but it does not say it has a specific Macro mode.

I suggest you set it for the single centre AF point, use AV mode and choose the maximum aperture BUT try both wide angle and tele and get really close to the main subject and fill the frame with that main subject and if the other surrounding background 'subjects' are far enough away you should get a nice result.

I hope that makes sense and have fun trying the various settings etc. Oh and do post some images soon for any added feedback you wish to ask about.



PS I hope you have the manual because when starting out it is your friend because "we" cannot know about the setup of a camera unless "we" have it, so only you can check and change the settings according to the manual.
__________________
That was a great meal ~ you must have a good set of pans
credit line is vanity, payment is sanity ~ one day I will make that first sale.....one day change pending

Last edited by Box Brownie : 22nd of June 2007 (Fri) at 03:43.
Box Brownie is online now   Reply With Quote
Old 22nd of June 2007 (Fri)   #6
CanonAmerican
Member
 
Join Date: Jun 2007
Posts: 31
Default Re: How do you focus one object, and leave everything else blurry?

What's a wide angel and tele ?How do I choose it?
CanonAmerican is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #7
Box Brownie
Cream of the Crop
 
Box Brownie's Avatar
 
Join Date: Apr 2005
Location: Surrey
Posts: 9,894
Default Re: How do you focus one object, and leave everything else blurry?

Quote:
Originally Posted by CanonAmerican View Post
What's a wide angel and tele ?How do I choose it?
You have already used the zoom and that is what I am refering to. When you use the zoom you will see that at one 'end' the view has more in it so to speak - this is wide angle, at the other end of the zoom where you have isolated a specific part of the scene by zooming in - that is the tele end of the zoom.

HTH

PS Have you got the manual for the camera?
__________________
That was a great meal ~ you must have a good set of pans
credit line is vanity, payment is sanity ~ one day I will make that first sale.....one day change pending
Box Brownie is online now   Reply With Quote
Old 22nd of June 2007 (Fri)   #8
Vitruvius
"oh god it burns!"
 
Join Date: May 2007
Location: Washington, DC
Posts: 311
Default Re: How do you focus one object, and leave everything else blurry?

very often you zoom buttons will be labeled W and T which is what they refer to.

Some thing you can also do to isolate the flower and blur the background is when you compose your shot. The further away the background is from your subject the better that background blur will be.

The way the camera "knows" what you subject is and what your background is, is by distance focusing, thats why you usually have that green box in the center or several points around the screen, it will use those to find the range and auto focus on them.
Vitruvius is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #9
CanonAmerican
Member
 
Join Date: Jun 2007
Posts: 31
Default Re: How do you focus one object, and leave everything else blurry?

I don't understand a few things, it seems like you guys are contradicting yourself.
1) 'Use maximum aperture' - if I boost my aperture to maximum value, wouldn't it give me the contradicted result I want? I thought that the lower the aperture is, the blurrier the background will get.
2) 'Zoom in and isolate the center(the object you want to take): If I indeed zoom in, wouldn't it be hard for me to get any background at all? Wouldn't the object fill the lens, hence I won't have a chance to even capture any blurry background?


I'm sorry for my questions, but you guys are professionals, and I look up to you, but it's all so new to me. BTW - I do have the manual
CanonAmerican is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #10
In2Photos
Archive Keeper
 
In2Photos's Avatar
 
Join Date: Dec 2005
Location: Near Charlotte, NC.
Posts: 19,808
Default Re: How do you focus one object, and leave everything else blurry?

Quote:
Originally Posted by CanonAmerican View Post
I don't understand a few things, it seems like you guys are contradicting yourself.
1) 'Use maximum aperture' - if I boost my aperture to maximum value, wouldn't it give me the contradicted result I want? I thought that the lower the aperture is, the blurrier the background will get.
2) 'Zoom in and isolate the center(the object you want to take): If I indeed zoom in, wouldn't it be hard for me to get any background at all? Wouldn't the object fill the lens, hence I won't have a chance to even capture any blurry background?


I'm sorry for my questions, but you guys are professionals, and I look up to you, but it's all so new to me. BTW - I do have the manual
1. Aperture is a ratio. So when it was mentioned earlier that your max aperture was f2.6 it should have been written f/2.6. So a smaller f number is actually larger (f/2.6 is larger than f/5.5).

2. DOF is more than just aperture. Focal length, distance to subject and distance from subject to background also affect DOF.

One thing not mentioned here is that P&S cameras use a small sensor and a smaller lens. The result is smaller lens opening which will also yield a greater DOF. IT may be very difficult to blur the background wiht your camera.
__________________
Mike, The Keeper of the Archive


Last edited by In2Photos : 22nd of June 2007 (Fri) at 13:31.
In2Photos is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #11
miralee
Member
 
miralee's Avatar
 
Join Date: Jun 2007
Location: SoCal
Posts: 62
Default Re: How do you focus one object, and leave everything else blurry?

No expert for sure, but it's my understanding that maximum aperture = smaller f#. The smaller the f# is, the more "open" the lens is.

Even if you zoom in, you should still have some background left - just zoom in enough to where the object is nicely framed. I think this is where it's more effective if there is some distance between the object you're trying to focus on and the background, too.

If you play around with it you'll get some shots to show you how it works. I got these just playing with my camera, not knowing what was doing - both are zoomed quite a bit. (the xt, no the p&s, I haven't tried it with my p&s - I should sometime)
http://www.flickr.com/photos/9209004@N04/591279719/
http://www.flickr.com/photos/9209004...n/photostream/

ln2Photos beat me to it, and knows more than I do anyway
__________________
40D - Rebel XT
Canon EF 28-105mm f/3.5-4.5 II USM - Canon EF 50mm f/1.8 II - Sigma 10-20mm f/4-5.6 EX DC HSM - Sigma 17-70mm f/2.8-4.5 DC Macro - 430EX
Canon SD750 - Pentax Optio 555
Pictures

Last edited by miralee : 22nd of June 2007 (Fri) at 13:29.
miralee is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #12
CanonAmerican
Member
 
Join Date: Jun 2007
Posts: 31
Default Re: How do you focus one object, and leave everything else blurry?

Awesome explanation dude, and thanks for your images SoCal, they look great.
I'll upload the images tomorrow, I already have a vision...
CanonAmerican is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #13
Box Brownie
Cream of the Crop
 
Box Brownie's Avatar
 
Join Date: Apr 2005
Location: Surrey
Posts: 9,894
Default Re: How do you focus one object, and leave everything else blurry?

Just for the record the image you linked to in your OP was taken with the G7 at f4.0

Now when you look at the image it seems to have been framed such that the camera was quite close to the main flower ~ possibly no more than a couple of feet away but the flowers furher back were likely anoth couple of feet at leats and the building 100's of yards away. IMO we have all covered the various aspects to be aware of and as Mike says and I mentioned a P&S because of its small sensor size will challenge you to get just the look you trying to acheive but as shown in the link you found it is possible wit careful choice of subject matter.

Best of luck and I look forward to seeing the results of your vision
__________________
That was a great meal ~ you must have a good set of pans
credit line is vanity, payment is sanity ~ one day I will make that first sale.....one day change pending
Box Brownie is online now   Reply With Quote
Old 22nd of June 2007 (Fri)   #14
klynam
Senior Member
 
klynam's Avatar
 
Join Date: Oct 2004
Location: Photopolis
Posts: 1,237
Default Re: How do you focus one object, and leave everything else blurry?

This doesn't exactly answer the question...but I've always referred to this as "selective focus" and I believe the term generally used to describe the aesthitic quality of the end result as "bokeh". (Can someone back me up or set me straight on this )
__________________
Canon Cameras & Lenses | Masterworks Photography | God is Light
"Until you can do better, copy." Tony Gresham
klynam is offline   Reply With Quote
Old 22nd of June 2007 (Fri)   #15
In2Photos
Archive Keeper
 
In2Photos's Avatar
 
Join Date: Dec 2005
Location: Near Charlotte, NC.
Posts: 19,808
Default Re: How do you focus one object, and leave everything else blurry?

Quote:
Originally Posted by klynam View Post
This doesn't exactly answer the question...but I've always referred to this as "selective focus" and I believe the term generally used to describe the aesthitic quality of the end result as "bokeh". (Can someone back me up or set me straight on this )
Selective focus is correct. And Bokeh refers to the quality of the Out-of-Focus highlights in the image.
__________________
Mike, The Keeper of the Archive

In2Photos is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
NEW Blurry Out of Focus G6 Pix richardbruce Canon G-series Digital Cameras 39 15th of December 2005 (Thu) 09:47
UPDATE Blurry Out of Focus G6 Pix richardbruce Canon G-series Digital Cameras 2 29th of November 2005 (Tue) 07:32
Blurry Out of Focus G6 Pix richardbruce Canon G-series Digital Cameras 17 21st of November 2005 (Mon) 01:27
My 50 1/8 won't focus on distant object Keiffer Canon EF and EF-S Lenses 9 4th of August 2005 (Thu) 18:55
Blurry, out-of-focus pics with my G5 geech01 Canon G-series Digital Cameras 11 23rd of January 2005 (Sun) 03:50


All times are GMT -5. The time now is 15:55.


Powered by vBulletin® Version 3.6.12
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
This forum is not affiliated with Canon in any way and is run as a free user helpsite by Pekka Saarinen, Helsinki Finland. You will need to register in order to be able to post messages. Cookies are required for registering and posting. HTML in messages is not allowed, plain website addresses are automatically made active by the board.