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I have an image stabilizer in my 18-55mm kit lens that came with the Canon EOS 2000D DSLR. I recently tested it with the largest possible focal length of this lens. I saw that the viewfinder image vibrated far less with the stabilizer, so apparently it's doing something.

My 10 test shots with 1/5 second shutter and IS were occasionally shaken, even though I attempted to hold the camera steadily.

However, the 10 test shots with 1/10 second shutter speed were okay if I attempted to hold the camera steadily.

Then I tested with image stabilizer off, attempting to hold the camera steadily.

The 10 test shots with 1/20 second shutter and no IS were occasionally shaken.

The 10 test shots with 1/40 second shutter and no IS were basically okay.

Also, I have tested fast-moving subjects like cars to capture motion blur. As it's wet outside, I took the images through my small window so I have to be quick whenever I see a car driving past. My experience is that with 50mm fixed lens without IS, 1/80 second shutter will be fine even if I have to take the image really quickly and have no time to ensure my hands are steady. Also, my experience with 18-55mm kit lens with IS is that 1/20 second shutter is required with IS on, if I have to capture the image really quickly.

So, my experience is that trying to keep my hands steady, the IS helps only for 2 stops. Similarly, when taking the picture quickly, the IS also helps only for 2 stops.

However, the manufacturer claims the IS is a 4-stop IS. As the stops are exponential, the manufacturer is claiming 16-fold improvement whereas I'm observing only 4-fold improvement.

Can I trust the manufacturer's claims for IS improvement? Or is it just false marketing data?

Is the IS as effective with any focal length, or might it be the case that for this particular lens, the 4 stops advertised only works for a certain optimal focal length, and at the longest focal length, it's not 4 stops?

Note my results with steady hands somewhat contradict the 1/(focal length * crop factor) rule. 1/40 seconds was fine with steady hands even though the rule gives 1/88 seconds, with crop factor 1.6 and focal length 55 mm. However, the 1/(focal length * crop factor) rule seems to be valid for me if I have to capture the image really quickly. But perhaps that's the subject of another question...

marked as duplicate by xiota, Rafael, scottbb, Hueco, mattdm Feb 17 at 15:59

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • Related: photo.stackexchange.com/questions/14812/… – juhist Feb 10 at 18:10
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    "Can I trust... advertised... ?" -- No. – xiota Feb 10 at 20:06
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    I rather treat IS as a probability-improving device. Out of multiple attempts, more shots will be OK at low shutter speeds. But it's entirely possible, by chance, to get an acceptable shot at 1/10 without IS. Maybe 1 in 10 or so, depending on your hands. And vice versa, some IS shots will be blurry. (There are conditions where IS starts to get things worse). The practical side is that, IS or not, always take multiple shots whenever possible in such conditions. – Zeus Feb 10 at 23:35
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    @scottbb The other question is about some flawed math. If you take a hard look at the answers to this question, this question is about 18-55mm kit zooms and practical experiences with them, not some theoretical math. Neither of the answers of this question applies to the other question. So, I see the other question only as related (that's why I have the "related" comment), and not the same. – juhist Feb 14 at 17:18
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IS is good for dealing with short "back-and-forth" vibrations. It's not as good dealing with longer movements in the same direction because one can very quickly reach the limits of the lens' adjustment range.

Once you get down around 1/10 second or longer, the total angular displacement of your movements are probably exceeding the limits of the IS system.

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I have another data point.

Today, I got my 55-250mm zoom (88-400mm 35mm equivalent). At the telephoto end (250 mm / 400 mm equivalent), the optimal shutter should according to 1/focal length rule be 1/400 seconds. Canon claims 4-stop image stabilization for this lens.

I took some pictures with 1/30 second shutter speed. They are just fine. Based on this, the number of stops is at least log_2(400/30) = log_2(13.3333) = log(13.333)/log(2) = 3.74, if we can believe the 1/focal length rule.

So, I believe the 4 stop image stabilization only applies in extremely low light for the kit zoom. However, for a telephoto zoom, the useful shutter speeds are faster, and therefore, image stabilization helps more.

Based on this, I will claim: you don't necessarily benefit much from image stabilization in kit zooms. A lens without image stabilization and wider aperture would be much better in many circumstances. However, you will benefit much from image stabilization in telephoto zooms.

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