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Depth of field
Feb 28, 2005, 11:53
Post: #1
Depth of field
Hi all,

I am in need of some advice……..I have been trying to blur the background in
Portraits etc, with my camera set to f2.8 which is as wide as it will go I don’t
think I am getting the results.
Here is a sample. Matt wishing he was else where! (1 of 4 sons)

[Image: 7_IMG_0083 copy.jpg]

Is this the limits of my camera or is there more I should be doing?
I.e.: manual focus?? I know I can use PS but this is not what I was
trying to achieve.

Thanks Russ
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Feb 28, 2005, 12:14
Post: #2
Depth of field
Simply put, take the photo at the tele end of your zoom (at 2.8ish), move in to the desired area, and you will see a nice shallow depth of field.

See below

[Image: 39081750.jpg]
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Feb 28, 2005, 12:51
Post: #3
Depth of field
DOF has three variables.

1) Focal length
2) Aperture
3) Distance between subject and camera

For a shallow DOF such as you desire

1) Long focal length
2) Big aperture (small f #)
3) Short distance between subject and camera

Hope this helps.

Teddy
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Feb 28, 2005, 15:04
Post: #4
Depth of field
Thanks for the tips! Big Grin

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Feb 28, 2005, 15:32 (This post was last modified: Feb 28, 2005 15:37 by Chomp.)
Post: #5
Depth of field
hi

well if you have a 20 mm f2.8 and you shoot a portrait at f2.8 there is not much you can do with dop. it will not blur that much!

if you wanted to be totally blur you neeed a 80mm at f2.8 or photoshop.

in cs there is a tool blur tool and you do not much experience to use it. just select and use it. and right click you get the smuge and sharpen tool too!!


[Image: 45_russt.jpg]

regards

Christian
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Feb 28, 2005, 23:44 (This post was last modified: Feb 28, 2005 23:45 by Gujustud.)
Post: #6
Depth of field
Thanks for all the tips, I think I have this right please tell me if I don't.

To create the shallow depth of field I am after.........
1..zoom in
2..open the aperture (small F)
3..get close to the subject

Here is my problem when I zoom in the largest aperture I can get is F4.9 even in manual. So I think Christian hit it on the head its PS for me.

DSLR just moved up the list Sad or break out my 35mm SLR. (I couldn't afford the film I would have wasted) Big Grin

Thanks again
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Mar 1, 2005, 00:53
Post: #7
Depth of field
My camera was the same as yours. I took this picture few weeks ago, and I think I got what I wanted with the background.

Here is the information of the picture, it might be useful...

Exposure program: Apeture priority.
Exposure bias: (-0.30)
May aperture: f/2.8
focal length: 13.1mm
I was also very close to the subject.

The picture doesn't have any post-processing work.

[Image: juergendof.jpg]

Trying to get my DOF right in Portraits I chose a tree from the garden with good background to work with. I took a lot of pictures with different settings and from different distances. I think that has helped me a lot, because I have got somehow the feeling how close I have to be from the subject. The DOF of this picture might not be perfect but taking into acount the limitations of my camera then, and my lack of knowledge about photography... believe it has been a great step ..... Smile

Irma.
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Mar 1, 2005, 02:06
Post: #8
Depth of field
Thanks Irma,

Every bit helps. I am getting a better understanding all the time. I still however have a long way to go. Digital helps fast track this as you can take heaps of meaning less shots. (gotta love that) Nice shot BTW.

Cheers
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Mar 1, 2005, 02:33
Post: #9
Depth of field
Actually, the smaller sensors on digital cameras make it harder to get a shallow DOF... one of the drawbacks of going digital I suppose. Either that, or get a DSLR with full frame sensor! Big Grin

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Mar 2, 2005, 03:58
Post: #10
Depth of field
Shuttertalk got one of the big issues with DoF in digital.....

The smaller sensors, particularly in the compacts (non -SLR) make getting shallow DoF nearly impossible........even at long focal lengths......

I had a Canon G3 before my 10D and shallow DoF was nearly non-existant with the G3....Only macro photos were the only time I had shallow DoF (but I did not want it then arrggghhh)..

Best tip is the have the subject close to the camera and use largest aperture (f/2.8 or better).......
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Mar 3, 2005, 04:01
Post: #11
Depth of field
I'd just like to point out that I get great DoF on my non-SLR digital camera - it helps that I can stay at f/2.8 through the entire zoom range.

Question, though, while we're discussing focal length. My cam has a 35mm-equiv max. focal length of 420mm but an actual max. f-length of 72mm. (multiple lens elements are used) Which focal determines the amount of DoF I am able to achieve? From my DoF results, I would say that it's the 400mm, but something inside my logic centre says otherwise.
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Mar 3, 2005, 05:25
Post: #12
Depth of field
The 72mm length.

Can you post an example of what you consider "great DOF"? I assume you really mean "shallow" DOF. Great DOF would imply the entire image appears sharp, foreground to background.

Anyway, a 72mm lens at f/2.8 can indeed give you very nice shallow DOF. Most P&S digicams have a maximum focal length much shorter than that. DOF from the same lens at say 20mm should look quite different.
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Mar 3, 2005, 08:25
Post: #13
Depth of field
ST wouldn't the 1.5 multiplier on DSLR help with DOF? I understand it is very difficult with point and shoot cameras though. Megapixle has a good explanation of DOF. They give a good explanation on what you need to do to get a blurred background.
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Mar 3, 2005, 08:27
Post: #14
Depth of field
Go to megapixile's articles section and look for DOF. The link didn't work as I would like. :/

Teddy
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Mar 3, 2005, 09:50 (This post was last modified: Mar 3, 2005 10:08 by gd.)
Post: #15
Depth of field
teddyfingers Wrote:wouldn't the 1.5 multiplier on DSLR help with DOF?

Yes! And no! And it depends! Lol

Example 1:

Using the same field of view without changing the camera-to-subject distance (e.g., using a 50mm lens on a 10D with 1.6x "multiplier" and an 80mm lens on a 35mm film camera), the 10D image will have approximately 1.6x more DOF because of the shorter focal length.

The DOF of a 10D with a 50mm lens at f/8, subject distance 10 feet, is 3.7 feet. On a 35mm film camera with an 80mm lens (same field of view as the 10D with 50mm), the DOF will be 2.3 feet. You can plug in numbers and play around with a DOF calculator.


Example 2:

If you use the same lens on each camera and shoot from the same spot, then the 10D image will have 1.6x less DOF. Of course, the images will look completely different because the field of view will be different.


Example 3:

However, if you then crop the 35mm image from example 2 so that it has the same FoV as the 10D image, then the resulting DOF will be the same.


Example 4:

On the other hand, if you use the same lens on each camera and adjust your shooting distance so that the field of view is the same, then the 10D image will have 1.6x more DOF than the 35mm image.


Many consumers seem to think the digicam multiplier factor gives them a longer focal length. It would be more accurate to say that it gives them the effective field of view of a longer lens on a 35mm camera, but not the same DOF.
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Mar 3, 2005, 14:55 (This post was last modified: Mar 3, 2005 14:57 by StudioJ.)
Post: #16
Depth of field
slejhamer Wrote:I assume you really mean "shallow" DOF. Great DOF would imply the entire image appears sharp, foreground to background.
Sorry, yes, I meant 'shallow' -- well, actually I think I meant that I have great DoF flexibility.

both taken at f/2.8@12.1mm (actual) ~70mm (35mm-equiv) -- the key to these two is the distance to the focused subject, not the focal length.
[Image: P1000297_rz800.jpg]

[Image: P1000224_rz800.jpg]
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Mar 3, 2005, 15:44
Post: #17
Depth of field
Nice DOF (or lack of) Cailean...

I think Slejhamer hit the nail on the head - Cailean, you're blessed with a F2.8 min aperture all the way through whereas most compact digicams are around F5.6 or more at the tele end.

Hm.. interesting point about the FOV crop / multiplication factor. I guess we need to look at the real focal length of the lens, not the equivalent. My S5000 with a 10x zoom only goes up to 55mm.

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