Outgrowing Micro Four Thirds?

Started 1 month ago | Discussions thread
JakeJY Senior Member • Posts: 2,434
Re: Olympus says 6.5 stops, not 9

Tommi K1 wrote:

Messier Object wrote:


The IS Stops advantage has nothing to do with 1/FL sec.

The advantage is the difference between the best you can do without IS and the best you can do with IS ON for a given amount of image blur, or if you like a given % keeper rate.

Did you read all?

If person A can get with 12mm without any stabilization a 2 seconds exposure at 50% keeper rate, then with it a 5 seconds, that makes it effective IBIS only a 1.5 stops.

If other person with exact same gear needs a 1/50 to get 50% keeper rate and with it they an get 1".

Then which one you would use?

if you have a very steady hand then without IS you can shoot at a lower shutter speed than a more unsteady person. But both people will see the same number of Stops advantage with IS

Not exactly so. The IBIS effectiveness is different. It is how they are designed to work. Example, E-M1 with a 60mm macro, I can't take anything below 1/30 at macro level because the IBIS will blur the camera. If I instead by purpose shake the camera, I can go in 1:1 ratio to 1/2" seconds.

That is because the stabilization system goes crazy by itself when it doesn't detect the motion it is searching for. Applying some shake, it detects it and it can correct it properly and offer more effective results than more stable platform.

So if you want to measure IS Stops advantage your starting point is how well you can shoot with IS switched OFF. Take those shots and see how low a shutter speed you can go before the blur or keeper rate is unacceptable. Now switch IS ON and do the same. Your IS Stops advantage is the difference between those 2 shutter speeds

So if B would take at 12mm a 2" seconds with 50% keeper rate, and then with IBIS on a 4 seconds, then the effectiveness of the IBIS is just 1 stop, not 6.5 stops like CIPA measures?

Again, you are talking about personal performance, just like I talked about. I can get 9 stops from the rule of thumb, as that is how things are measured. That is why the rule of thumb was originally even made, to get a 50% change for average people to get a quality for a normal use, a news paper quality and 8x10" prints.

It is just that, a rule of thumb for increasing the change that a novice 135 film camera user got at least one sharp frame with few frames. Not that you have 100% sharp photos with it or that no one can go under.

It was just good fit for that, that was easy to teach to beginners and novices journalists who got responsible to use cameras for their interviews and stories and didn't really want to learn anything deep from the SLR they were given. It was easy to send people to do reportage with few lenses, 28mm or 35mm, 50mm and 100mm. And then just tell them to dial no less than the same shutter speed value as the lens focal length value was.

It was huge thing when stabilization came available for lenses, as now amount of sharp photos in common situations improved. 100mm became very useful in normal indoors with ASA 400 film that got pushed to ASA 800 or 1600 anyways.

I would like to point out the CIPA standard is there to avoid arguments like this. In general, the standard compares the performance between handshake without image stabilization (or simulated for cameras that can't turn IS off) and performance with image stabilization. While the data gathering starts at 1/focal length (35mm equivalent) and goes up in increments of 1 stop (p22, 4-4-1), that is not the comparison reference point.

First, for the vibration, CIPA chose two waveforms that they determined to most faithfully simulate camera shake when handholding (p7, 3-1-1). They measure the motion blur amount in micrometers (35mm eq) at various shutter speeds with and without IS. They use linear interpolation to figure values in between (testing is done minimum of 1 stop in between).

The stops of image stabilization is determined at 63μm of motion blur (they arrived at this figure with a A5 test image where 10% of panelists can tell the difference arriving at 70μm, and then scaled down to post card size to get 63μm). See page 41, 6-8.

This diagram on page 32 basically shows how they determine the performance:



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