Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-27-2011, 05:51 PM   #1
Inactive Account




Join Date: Jul 2011
Location: nj
Posts: 11
Blurr the background

I tried to use AV mode and set the f value at the lowest when trying to zoom. I set the iso settings auto. I am not able to blurr the background. Any tips will be very useful. I use sigma 18-200mm and K-R Boday

07-27-2011, 06:01 PM   #2
Veteran Member




Join Date: Apr 2011
Location: San Diego
Photos: Gallery
Posts: 883
zoom in, get closer
07-27-2011, 06:11 PM   #3
Forum Member
suncrimson's Avatar

Join Date: Sep 2009
Location: Beijing
Photos: Albums
Posts: 52
Zoom in and step back

OR

Get closer and zoom out

(since you may need to keep the composition) : )

Long focal length will reduce the DOV effectively.

You can try to move your object far from background a little be if you can. That helps too.

If changing lens is possible, get a prime lens with large aperture, a lens like 50/1.7 will solve your problem well.
07-27-2011, 06:37 PM   #4
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,873
QuoteOriginally posted by rr4562 Quote
I tried to use AV mode and set the f value at the lowest when trying to zoom. I set the iso settings auto. I am not able to blurr the background. Any tips will be very useful. I use sigma 18-200mm and K-R Boday

When you say "set the f value at the lowest" do you mean smallest or biggest aperture? What focal length did you use for the shot? The OOF (out-of-focus) effect depends on the DOF which also depends on focal length, aperture and distance to the focus subject.

07-27-2011, 07:09 PM - 1 Like   #5
Site Supporter
psychdoc's Avatar

Join Date: Jul 2010
Location: Bham
Photos: Gallery | Albums
Posts: 942
Sigma 18-200 is not the best for getting out of focus background. And the out of focus areas are kinda harsh. Get a lens like the DA 70mm f2.4 or 50mm f1.4 etc and this is much easier to do:

However get close to the object, zoom in close and make sure whatever is in the background behind the object is far away.

This was taken with the sigma lens that you have at 63mm at f5.6 with a k2000 body. The body does not matter that much.

07-27-2011, 08:05 PM   #6
Pentaxian
aleonx3's Avatar

Join Date: Jul 2007
Location: Brampton, Ontario
Photos: Gallery | Albums
Posts: 3,873
As other posters suggested, get closer and open up the aperture (e.g. F2.5 in the picture below). This may not be the best bokeh, but you get the idea from a wide-angle lens 24mm about 10 inches from the bug.
Attached Images
 
07-27-2011, 09:16 PM   #7
Veteran Member
RioRico's Avatar

Join Date: Jun 2008
Location: Limbo, California
Posts: 11,264
You get blurred backgrounds by exploiting subject-to-camera distance, and DOF (depth of field). Separating the subject from the background is called subject isolation. The closer your are to the subject and the further away the background is, the more the background blurs.

You control DOF by selecting focal length and aperture. Your goal is thin DOF, so your subject is sharp and everything else isn't. Longer focal lengths (like 100mm) have thinner DOF than do shorter focal lengths (like 28mm). Wider apertures (like f/4) have thinner DOF than do tighter apertures (like f/11). So a 100mm lens at f/4 has better subject isolation than a 28mm lens at f/11.

As a photographer, your trick is to find the right mix of distances and focal lengths and apertures that produce the blurring you want. How to get there? Study, and practice practice practice. Have fun!
07-27-2011, 11:05 PM   #8
Veteran Member




Join Date: Nov 2010
Location: Fife, Scotland
Posts: 834
There is a very useful website that covers depth of field:

Hyperfocal Distance and Depth of Field Calculator - DOFMaster

07-28-2011, 01:07 PM   #9
Inactive Account




Join Date: Jul 2011
Location: nj
Posts: 11
Original Poster
Thanks for all the suggestions. I will give it a shot. i used the f value at 3.5 using my 18-200mm sigma lense and choose automatic iso and AV mode.
07-28-2011, 01:49 PM   #10
Ira
Inactive Account




Join Date: Mar 2009
Location: Coral Springs, FL
Photos: Gallery | Albums
Posts: 5,218
QuoteOriginally posted by rr4562 Quote
Thanks for all the suggestions. I will give it a shot. i used the f value at 3.5 using my 18-200mm sigma lense and choose automatic iso and AV mode.
As long as you're in Av mode, it's okay to use auto ISO, although I don't recommend it. With this configuration, the camera will choose shutter speed and ISO--not affecting your aperture/DOF at all.

So as said above, narrow DOF with the way you set the camera has to do with your camera-to-subject distance. SO....

Start shooting manual in these situations. You DO want to select the optimum ISO and shutter speed depending on what you're shooting, and getting the right shot is a balancing act amongst the 3 elements (F stop, ISO, shutter speed).

In any given situation, you want to use the lowest ISO possible. If you use auto ISO and it gives you ISO 400, and a shutter speed of 1/500, you're much better off selecting ISO 100 at 1/125th, if that's enough to freeze the subject movement.

I am NOT a fan of auto ISO.
07-28-2011, 01:57 PM   #11
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,678
As you venture further into photography and develop interests in thin depth of field, you may find yourself reaching the limits of your existing gear (specifically the lens). It's then when you realise you need a more capable lens for the job, such as a wider maximum aperture lens, and will need to invest in the appropriate one for your needs.

Nevertheless, the advice given so far will maximise your ability with your current gear to blur out the background - subject close, aperture wide.
07-28-2011, 07:11 PM   #12
Forum Member




Join Date: Jul 2011
Posts: 71
Switch to manual focus and set the focus as close as possible, move closer till focus is achieved. Explore the extreme, get over it and find a balance you can apply to what you want to shoot.
As a bit of a curiosity question, what sort of results are you getting and how much blurrier would you like it to get?
08-03-2011, 04:50 PM   #13
Veteran Member
GerryL's Avatar

Join Date: Jan 2009
Location: CA
Posts: 2,731
It's easy with the Sigma 28-200mm.
As Rio Rico said, just zoom-in and open the aperture wide.
Here's one taken with the Sigma..although I forgot at what focal length I was in and at what opening.
Attached Images
 
08-03-2011, 07:45 PM   #14
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485


Blur the background of what?

...and how much blur do you want?





For maximum 'blur' get as close as you can to your subject and still be in focus. Open the lens to the maximum aperture. Nothing wrong with auto ISO in Av mode, Focus, Shoot. Done. That's the most 'blur' you're going to get with your lens(es). Want more Blur? Get a faster lens, a macro lens, close up filters, extension tubes, bellows, etc.

08-03-2011, 11:02 PM   #15
Veteran Member




Join Date: Nov 2010
Location: Fife, Scotland
Posts: 834
QuoteOriginally posted by GerryL Quote
It's easy with the Sigma 28-200mm.
As Rio Rico said, just zoom-in and open the aperture wide.
...
It often needs a bit more thought than simply making Dof as shallow as possible. Will also the subject be in focus? Where should the sharpest point be? What will be out of focus (especially in the foreground) that will be distracting? Is the background far enough away to get a nice smooth bokeh rather than blurry clutter?

See Hyperfocal Distance and Depth of Field Calculator - DOFMaster
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
background, blurr, camera, pentax help, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Machinery '66 Mustang - Brenizer Attempt #2 - No blurr this time :) adr1an Photo Critique 2 07-08-2011 10:44 PM
Too bright background RonakG Troubleshooting and Beginner Help 11 02-21-2011 09:41 AM
Musty muslin background e035830 Photographic Technique 6 12-04-2010 07:42 PM
Blurring background with Photoshop Elements 5 WalterGA Digital Processing, Software, and Printing 3 08-08-2009 08:46 PM
Do you accept your picture is slightly blurr? raider Photographic Technique 19 01-18-2008 03:42 PM



All times are GMT -7. The time now is 09:21 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top