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The common rule of thumb is that for handheld photography, shutter speed needs to be the inverse of focal length or shorter to avoid blur caused by camera shake; image stabilization gives you a factor of 2 to 4 longer shutter times.

But this rule breaks down for macro photography - is there a replacement (probablyinvolving subject distance or maginfication)? And does image stabilization still have the same effect?

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2 Answers 2

Im less about rules of thumbs than theoretic approaches.

You achieve higher Magnification by going closer. Using a macro lens or extension tube allows you to get closer and still be in focus. It is the increased magnification that makes any blur more visible and that is the source of your statement " this rule breaks down".

Another way to achieve this higher magnification is by using longer focal length. This longer focal length could be estimated and used in the "rule of thumb" formula.

Lets take an example 50mm lens. Typically they have maximum magnification 0.15x. This is at minimum focus distance, which is not the general distance to use it. Rules of thumb are based on normal average usage. the 50mm is typically used for body-shoulder portraits. let's say 3 meters distance. you can now calculate the magnification on a fullframe camera (the rule of thumb was made for 35mm film!):

http://www.mystd.de/album/calculator/

M= 0.02 (or 1:58 to be accurate)

For macro you have M=1 (true macro) some macro lenses have only 0.5x and still call it macro. that's fake!

To get to 1:1 you need to multiply by 58. Thats focal length you need to multiply by 58 to get the same magnification. in your timing 1/f*58 . so your 1/50s on fullframe becomes 1/(50*58) = 1/2900s. On crop you need to 1/(2900*1.6). That doesnt sound so bad, if your camera goes to 1/8000.

But notice that for the extreme narrow DOF you need to use a small aperture, too. this needs a hilarious amount of light.

So in conclusion, I strongly suggest you do not handhold the camera for macro with narrow aperture without strobe.

If you have IS you divide by the power of 2 of hte number of stops it is supposed to give you. So a 2 stop IS becomes 4/2900 = 1/725s. a 4 stop IS is 1/181s. Now it starts being easy to use again.

And note that this is to get the equal safety in shooting nonblurry as the rule of thumb gives you . it is certainly possible to get nice shots going below the rule of thumb, depending on your steady hand and chaos in the situation.

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Hm, given that I took this shot: dropbox.com/s/8ol9sa0g4c91koa/DSC03500.JPG handheld using a 35mm lens with a 16mm extension tube on an APS-C camera, f/4 and 1/1250s, your theoretic approach is not entirely convincing... –  Michael Borgwardt Apr 25 at 19:41
    
did you have IS? with a 2 stop IS you can divide the f with 4. and remember to redo the formula with 35mm cropped, and the magnification you ended up at - might not be 1:1. maybe the number ends up around 1/1250s. I've also taken nice (non macro) images with 85mm at 1/35s, no stabilizer. the starting point here is a rule of thumb, not a ground truth. but how many fails did you get when you took that image? –  Michael Nielsen Apr 25 at 22:16
    
Yes, I had IS and the shots were all good except for focus/DOF issues - but hey, rule of tumb and "IS still works the same" is just was I what asking for. Would be great to simplify the calculation to the point where you can do it on the fly in your head, but I suspect that it won't be possible to include extension tubes then. –  Michael Borgwardt Apr 26 at 18:17
    
for this calculation the extension tubes are not important. you can use the formula to compute your resulting magnification though, if you know the distance. but for the shutter speed you need the relative difference on magnification of the subject matter with that lens for which the 1/f rule was invented. 50x is probably not a bad starting point for easy calculations in the head. –  Michael Nielsen Apr 26 at 18:50

The really well-executed macro shots are not stabilized with a fast shutter speed or a steady camera, but with strobe duration, which simultaneously addresses three major problems of high magnification photography:

  1. Insufficient depth of field due to short subject distance.
  2. Insufficient light due to high magnification.
  3. Subject motion, however slight, is also magnified.

If you use a tripod, this may solve the problem with camera shake, but it does nothing for subject motion. A tripod is therefore desirable only for subjects that are completely still. Anything that moves or has the potential to move, whether under its own influence or from some external force, is difficult to shoot at high magnification if your camera is locked to a tripod.

Even the pros who focus stack live insects will frequently shoot handheld--the nature of the subject does not permit them to fiddle with a macro rail between shots. It is the flash duration that freezes both camera shake and subject motion, and permits stopping down to f/8 or smaller to get more depth of field.

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I think it is a given that he is not talking about a strobe situation. you cant talk about flashes and the 1/f rule of thumb in the same sentence. in macro you need special strobe gear, because standard flashes (builtin/top mounted) have the wrong position. and thus we are in another ballgame altogether. –  Michael Nielsen Apr 25 at 16:55

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