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Old Jul 17, 2004, 11:14 AM   #11
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I've spent too much time looking through rifle scopes, to disagree with some of your points.

However, I've also spent too much time taking macro photos, not to believe that the percentage of the frame occupied by the subject, is a big factor where motion blur is concerned.

So, I've got a feeling that we're both partially right, and both partially wrong.

I've sent this question to someone that has a much better understanding of the physics behind these observations (the guy'sa guru on optics, and often posts replies to questions, with complex formulas and calculations, that are far beyondmy limited understanding).

Just for"good measure", I posted the samequestionson a couple of photography forums, as follows:

Subject: Optics Gurus? Motion Blur as related to magnification...

As we all know, the accepted "rule of thumb" for calculating shutter speeds needed to prevent motion blur from camera shake is the inverse of the focal length (1/focal length).

However, isn't this based on the human eyes ability to see detail, for a typical subject, at a typical print or viewing size? In other words, is the the relative size of the subject within the frame, the determing factor?

For example: if I take a photo of an object at a 50mm focal length, at a distance of 10 feet, that occupies 1/2 of the image frame; would motion blur from camera movement be identical (from a human eyes perception of the blur) to taking a photo of the same subject using a 100mm focal length, with a subject distance of 5 feet?

In both cases, the subject would occupy the same percentage of the frame, right (since I'm cutting the subject distance in half, and doubling the magnification)?

Looking at motion blur calculators (which are designed to predict blur based on subject movement versus camera movement), my assumptions seem to hold true. For example, this one:

http://www.dudak.baka.com/spcalc.html

However, would the same thing hold true for camera shake?

In other words, does it make any difference whether you use a longer focal length lens with a longer distance to subject; or a shorter focal length lens with a closer distance to subject; when calculating motion blur from camera shake -- provided your subject still occupies the same percentage of the frame?

If not, how would you calculate the differences between the two techniques, as far as motion blur from camera shake -- as in taking macros at close range (since you're typically using a shorter focal length lens setting at a closer range)?


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Old Jul 17, 2004, 6:24 PM   #12
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The more I look into this, the more likely I believe I am wrong about the relative subject size in the frame, having to do with motion blur from camera shake. This seems to apply only to motion blur from subject movement.

Here is the response I got concerning why movement is magnified with macros. The indication was that "special rules" apply (but I have yet to find any formulas explaining this). See the last paragraph below:

How blurred an object looks in an image is determined primarily by how much the image moved while the shutter was open, coupled with the viewing distance and the size of the object viewed. For example, an automobile moving across the image frame at 100 km/hr (about 28 m/sec or 62 mi/hr) will move about 28 mm if the shutter is open for 1/1000 second, assuming that the camera is still. Whether this results in noticeable blur or not depends on, among other things, how big the image is in the picture. If the car is merely one of several in a group and the image frame is several car lengths long, the blur would hardly be noticeable. However, if the shot were a close-up of the front fender, that much of blur would be noticeable. Of course, in a picture of a moving car, the viewer would expect some blur so it wouldn't necessarily be objectionable.

And then there is camera movement, of which there are several kinds. The camera can physically undergo displacement in any of three directions without rotation, but this motion is usually negligible unless the photographer is shooting from a moving platform or taking macro shots. Not even inexperienced photographers are likely to take shots while moving the camera wildly about.

The more damaging components of camera movement are likely to occur because of camera rotations. The terminology often used for these rotations - pitch, roll, and yaw - is borrowed from nautical language to describe the rotational motion of ships or planes. Pitch is rotation that would cause the nose of a plane, ship, or camera to move up or down. Yaw would cause the nose to move from side to side, and roll would be rotational movement about the long axis of the vessel - or the optical axis of the camera. Of these, camera shots are most often spoilt by excessive pitch, caused by punching the camera release instead of squeezing it. The mirror movement in SLR cameras, digital or film, also causes these cameras to pitch (or yaw if they are being held for a vertical shot). Indeed, it is probably because of the mirror movement that the 1/focal length rule became so popular, because a photographer can, with care, reasonably expect to shoot clear shots with a shutter speed half that fast with a non-SLR camera. With special care, shooting at a speed one quarter the rule of thumb is possible.

The longer the lens, the less the angular field of view will be and the greater the proportion of the image frame a given angular displacement (rotation) will represent. Thus, the same amount of angular displacement will cause a larger amount of blur in a telephoto shot than in a wide angle one and a faster shutter speed (or a steadier camera) will be necessary to limit the amount of angular displacement while the shutter is open.

When shooting macros, special rules apply. Rotational effects will have a similar effect as for more distant shots, but the tight field of view means that translational, i.e., non-rotational, displacements will no longer be negligible.

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Old Jul 18, 2004, 8:13 PM   #13
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Christo wrote:
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Would someone please go through the steps on how to take a close up shot of an object on my E20. Everytime I attempt this, I just get a blurred image.

Please don't laugh:shock:but I am not an expert on this. I just want to take some close ups of objects, like a watch dial for instance, without any blurred images.
Once you get the hang of taking macros and before you spend on the MCON lens that Mikefellh mentioned (which is a really nice lens, by the way), you can play happily by placinga decent magnifying glass in front of the lens. I say "decent" because the quality of theglass really counts.

--Barbara
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Old Jul 19, 2004, 3:02 AM   #14
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Good research Jim - some interesting stuff. I still think Steve's wrong. BTW I was looking in the user guide to my A2 and it recommends that anti-shake is turned off for macro shots to save battery power.

The bit about camera shake caused by the mirror inan SLR is particularly interesting. I've long believed that the mirror's movement was a problem. SLR die-hards alwayssay it's not significant bu if it weren't they wouldn't ptovide themirror lock-up facility.

I think it's now time for the digital SLR to ditch the mirror. It's bulky, expensive and potentially degrades the picture.You can bet your life that if photography has started digitally, rather than with film, the refles mirror would never have been invented. The EVF has now got to the point (in the A2) where it's good enough, I believe. You can even manual focus with it. I know it'll probably never give the dynamic range that the eye can detect butI'll willingly trade that for the ability to see thatwhat you're taking is OK from an exposure point of view. So let's have a smaller 4/3 system detachable lens camera with an EVF (at a lower price). Olympus would need a new name for it - say the EV-1. I think they'd establish a new market.


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Old Jul 19, 2004, 9:14 AM   #15
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I still think Steve's wrong.
My own experience is that he's right on the money about the best way to take a macro. In the end, it's the result that counts.

At the technical end of things, I think we're still in digital's infancy. All that you can wish for will show up right along with things none of us even thought to wish for. I doubt I've ever been so excited about any other innovation, not even television, which first showed up in middle-class homes when I was a kid.

(Speaking of middle-class, I wish I could afford the E-1, but until then, I'll continue loving my classy little E-20.)

--Barbara
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Old Jul 19, 2004, 12:37 PM   #16
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Yes, Steve's advise is "right on".

Even taking any debate over whether or not the very close distance to subject, is similiar to the increased magnification used at longer focal lengths "out of the equation",you'd still want to do it exactly as Steve suggested.

After all, stopping down the aperture (which you'll want for greater depth of field), and using a lower ISO speed (for less noise),will require much slower shutter speeds, especially in the lightingconditions you'll have indoors.




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Old Aug 16, 2004, 10:48 AM   #17
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JimC wrote:
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Technophile wrote:
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I always hand hold macro shots and I don't see any camera shake.
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I hand held this shot with my Drebel with the 90 to 300 lens on. I get better results with the smaller lens. I guess you could say there is some blur but considering the size of the lens this is not too bad. I would go with a tripod unless you have a steady hand.


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Old Aug 16, 2004, 11:46 AM   #18
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IMO It's not motion blur: with flash (because of the recommended small aperture) the duration is so short (especially at close distance) that it is several magnitude faster than any shutter speed to cause any motion blur!

The blur is more caused by the extremely shallow DOF of the macro range: ie an out-of-focus because of distance changes of the camera relative to the subject when handheld prior to the release of the shutter and after the camera has locked on the object (which can be offset by the closing down on the aperture also)

I also handheld:




... but then I'm not millimeters away where the DOF can be considerably less and where any displacement (ie back and forth distance variation) between the camera and the object can be super critical.
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