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Old Jan 18, 2007, 12:19 PM   #1
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Hi guys,

I have been attempting to take shots which have the close subject in focus, with the background out of focus and blurred... I believe this requires a shallow depth-of-field than F2.8... I have yet to see a small camera able to do that...

Is that true or have I missed out on a particular one?

Is it really only possible to get depth-of-fields shallow with a Digital SLR?

I'd love to hear thoughts on this... thanks!


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Old Jan 18, 2007, 12:30 PM   #2
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Well... Yes and no.

Part of the problem is that the sensor is so small on a P&S camera. This effects the DOF, making it very large. You have a few other choices.

- Other things do effect DOF, like distance to the subject and the focal length. I'm not sure if the very small sensor size will overpower the other things you can do... you'll have to test it. But if you get very close to your subject or if you use a large focal length it should reduce the DOF .
- Blur the background in post-processing. This is what people usually do. Heck, I some times do it even with the DSLR.


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Old Jan 18, 2007, 1:04 PM   #3
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Dial in (if possible) f/2.8. Some of the best lenses have f/2.8 as their widest aperture. You are correct about sensor size, but there are tricks and techniques you can use to affect a shjallow DOF.

One trick is to insure there is no background, or as little background as possible.Anything in a background which can be focused on will be with P&Ss.

So:get as close to your subject as possible, remembering that no background gives you not just "shallow depth of field", but no DOF.
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Old Jan 18, 2007, 2:00 PM   #4
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that f/2.8 on your point and shoot is the equivilent of about f/11 on a 35mm camera, so you end up with a pretty large DOF. Asstated you will need to get as close as possible to your subject while keeping as much distance as possible between your subject and the background.
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Old Jan 18, 2007, 3:42 PM   #5
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Zoom as far as your camera can go. If you can get a telephoto attachment lens, than can help as well. Technically this doesn't decrease your depth of field, it just enlarges everything so that a slight blur appears to be a much greater amount of blur. The subject will of course need to be well separated from the background.

Something you might want to try if you can is to focus on the subject, and then manually focus the camera on the space between you and the subject. Basically, try to get the subject right on the edge of the in focus area (circle of confusion?) to enhance the blur of the background. I never actually tried this, but I assume it would take a lot of practice.


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Old Jan 18, 2007, 4:10 PM   #6
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I wasn't sure why everyone was saying you should get close to the subject while my experience was to zoom in from a distance, so I tried a little experiment to see if I was mistaken. I took a 12" high figure of Talos from Jason and the Argonauts and placed him on the edge of my kitchen sink. With my Panasonic FZ30, I shot him from close-up at 35mm, then I tried to compose a similar shot from a distance at 450mm. Here is what I got:










Now while I think the close-up is a better looking photo (for whatever that's worth in this case), it seems to me that the one shot zoomed in has a clearly blurrier background, though the image is quite flat looking.

The zoomed in shot isn't as sharp as the close-up one, but with limited light it was hard to get a completely stable shot hand held at 450mm, 1/10 sec. In fact I think the stabilizer worked extremely well here.

On a side note, I find comparing these two photos mildly disturbing in a way I can't quite explain.
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Old Jan 18, 2007, 5:39 PM   #7
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Hey i have'nt seen that film for years..70's i think...
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Old Jan 18, 2007, 6:52 PM   #8
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Corpsy wrote:
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On a side note, I find comparing these two photos mildly disturbing in a way I can't quite explain.
maybe that you actually have a 12" high figure of Talos and know who he is? Just kidding :lol:
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Old Jan 18, 2007, 7:31 PM   #9
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Actually, I think it might have something to do with the way his head shrinks.
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Old Jan 19, 2007, 1:05 PM   #10
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Corpsy,
Unfortunately you have said something that is wrong.
If you go to any depth of field calculator on the web, you'll see that "Distance to subject" is part of the information you provide. Just run some numbers through it, changing only subject distance or only focal length and you'll see.

The closer you are to your subject, the smaller the depth of field. The longer the focal length, the less depth of field (not perceived DOF, actual measurable depth of field.)

It's due to the laws of physics and you can't get around it.

Try this DOF calculator:
http://www.dofmaster.com/dofjs.html

You can also learn more about it from this glossary:
http://www.dpreview.com/learn/?/Glos...f_Field_01.htm

For example:
Using a Canon 30D, 100mm lens, f2.8 from 3-feet away, the total DOF = 0.019 inches
Using a Canon 30D, 50mm lens, f2.8 from 3-feet away, the total DOF = 0.11 inches
Using a Canon 30D, 50mm lens, f2.8 from 30-feet away, the total DOF = 12.2 inches

The further you are away, the larger the DOF.
The more focal length you use, the smaller the DOF.

If you really want to do real-world tests, take pictures of something like a yard stick put at an angle partially away/partially towards you. Put your camera on a tripod so it doesn't move and take the same picture at different focal lengths. You don't see the absolute size of the depth of field that way, but you should see it grow or shrink based on how much of the yard stick is in focus. Note that when you change focal lengths you'll probably have to re-focus. Most lenses require this (but not all.)

I was a big fan of the old Jason and the Argonauts when I was a kid. Ray Harryhausen was the best.

Eric
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