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Old Apr 17, 2004, 8:43 AM   #1
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Default DOF revisited

On one of the forums over at Imaging Resource, I tripped across a question posted by someone having trouble getting a shallow depth of field. In reading through the resonses, it would seem a good deal of the problem is most definitely depends on your camera, and this doesn't mean whether you're using digital vs. film. Quoting one person: "Manipulating depth of field as with a 35mm film camera is difficult, approaching impossible, with most digicams. They are equipped with very short focal length lenses (as in real focal lengths, not 35mm equivalents). So while there is some ability to control depth of field, as in opening the lens to it's widest settings (f2.8 isn't that wide), [if you're] working at longer focal lengths, and working with focus point, separation of subject and background, etc., you won't be able to have as marked results as are possible with the longer focal lengths used on larger sensor cameras or with film."

Reducing this down to its minimum: autofocus will drive you nuts...and you need to zoom in with your lens. Nevertheless, if you've a camera that hasn't much in the way of manual controls, you're likely to run into trouble.
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Old Apr 17, 2004, 11:46 AM   #2
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Default Re: DOF revisited

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Originally Posted by bcoultry
Nevertheless, if you've a camera that hasn't much in the way of manual controls, you're likely to run into trouble.
*Even if* you have full manual control, it's difficult to get an adequately small depth of field with a common-or-garden small f/2 digicam, as opposed to an up-market one with a bigger sensor that's closer to a 35mm SLR.

Intuitively, you would imagine depth of field would scale with focal length just like image size etc., but if you go through the maths this isn't the case. A tiny lens with a short focal length will give you an identical finished image to a bigger lens with a proportionately longer focal length, but the printed image from the little lens will show good sharpness over more of the depth of field than the bigger one. Seems crazy, but it's true.

There are references to all this here in 'Steve's Digicam's' if you search for them. It goes part of the way to explaining the periodic enthusiasm for tiny format negatives (127, 126, 110, APS, etc), but mostly it was inventing something new to sell to a gullible public.
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Old Apr 17, 2004, 12:08 PM   #3
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Quote:
*Even if* you have full manual control, it's difficult to get an adequately small depth of field with a common-or-garden small f/2 digicam, as opposed to an up-market one with a bigger sensor that's closer to a 35mm SLR.
What it boils down to, then, is that a number of people here in this forum had trouble with the DOF challenge through absolutely no fault of their own. If I'd understood how equipment-dependent the challenge was, I'd never have posted it because it sure wasn't fair.

My apologies to everyone.
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Old Apr 17, 2004, 12:37 PM   #4
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HEY!! this is good news!!! it wasn't me that was getting the bg too "in focus" it was my camera

i really like the look of when rocks underwater look when they are a certain amount out of focus....like little circles of light
very cool looking
i'll have to get an slr to do that though :-\
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Old Apr 17, 2004, 5:52 PM   #5
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I had read similiar articles and knew it would be difficult at best to have a limited depth of field with the tiny sensors in my cameras and the very short focal lengths. I used the Epson 3000z which has a little larger sensor than my Minolta Z1 and also has an F2 lens instead of F 2.8. Even so I didn't get that great results. I did use macro mode and wonder if that helped or hurt the situation? Many of the folks did very well though. Maybe the best of them were using dSLR's with the bigger sensors.

The fact that I got some sort of results made it worth the effort and I don't think the unchallenge was unfair. It just made it more challenging.
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Old Apr 17, 2004, 6:16 PM   #6
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Quote:
It just made it more challenging.
It certainly did just that for a number of people. Nevertheless, it was still rather equipment oriented, something I'm trying to keep out of the challenges. Of course, I then followed the DOF challenge with the current one that pretty much requires software capable of doing layers. Maybe the next challenge will be to photograph the Abominable Snowman. Just to level the playing field.
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Old Apr 17, 2004, 8:34 PM   #7
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Barbara, now everyone here knows what DOF is, and probably have a better idea about how to achieve it. If they need to purchase a more expensive camera to get what they want, at least they understand the options more.

Nothing for you to apologize for. Don't apologize for stirring up the leaves of motivation, causing the dry and empty to become filled with moisture and fulness...inspiration!

If someone reads the forum, figures out what DOF is, and realizes that they need to go out and buy a better camera, that's a good thing to me. I think you have given them a gift of understanding and that you shouldn't rebuke yourself. Just my opinion.

If you lower the heights of the challenges then you will also lower the potential growth of each and every one of us who visits and contributes, from expert to amateur. If you continue to do what you are doing then we will all learn together, and have fun doing it.

In other words, don't stop doing exactly what you are doing!!

Barbara, we all respect your challenges, that's why it's so successful, so keep on keepin on, and I'm sure that everyone here agrees with me on that!
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Old Apr 17, 2004, 11:17 PM   #8
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Barbara said:
"Of course, I then followed the DOF challenge with the current one that pretty much requires software capable of doing layers. Maybe the next challenge will be to photograph the Abominable Snowman. Just to level the playing field."

The challenge was seeing double and there are more ways of doing that than doing layers. Of course the best of the shots were done that way but for me who can't do such exotic things it got me thinking. How can I get a double exposure in camera when my camera really won't do that? You gave a hint when you mentioned slow sync flash! Light bulb went on - I can do that. My picture was no prize winner but I think it met the criteria of the challenge and I learned something. What more can you ask?

Forget the Abominable Snowman. Pick the Yeti a.k.a. "Big Foot". I want to enjoy springtime and don't want to go trudging up mountains in the snow. With some of the things these folks can do with their cameras and software I'll bet you get at least one picture! Shoot, with the creativity I've seen here you'd probably get a lot more.
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Old Apr 17, 2004, 11:56 PM   #9
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Quote:
Originally Posted by bcoultry
My apologies to everyone.
I don't think apologies are required at all, as lots of us learnt a lot about DoF and our own equipment. I myself spent ages lying down none too successfully among the daffodils during last week's visit to Edinburgh. This provided plenty of entertainment for passers-by as an added benefit.

1/1100, f/2.3, 7mm lens (34mm equivalent)


Quote:
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I'd never have posted it because it sure wasn't fair.
I see no need whatever for fairness, level playing fields etc., so long as it's a good challenge
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Old Apr 18, 2004, 7:44 AM   #10
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Yes, Barb, I agree with everyone here. Without this forum and yours (and everyone's help and constructive criticism), I would be just another mid-lifer (YOUNG, tho!) with another expensive toy and no outlet or growth.
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