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 1 
 on: May 18, 2013, 05:19:26 PM 
Started by Frank Kolwicz - Last post by Bob Atkins
There's no published data from any of the major lens manufacturers that I'm aware of. Canon certainly don't publish data on stabilization other than their "up to 2/3/4 stops" statements.

I presume they are tuned for a bandwidth in the cycle/sec to the 10s of cycles/sec range. I think the IS system on the FTM lenses might be tuned for some lower frequencies because they are said to help stabilize video when walking with the camera (presumably the source of low frequency movement)

They don't need to be tuned to high frequencies because people's hands don't shake at high frequencies! The plot here (http://www.bobatkins.com/photography/tutorials/mlu.html) shows camera mirror induced vibrations, which do have a higher frequency than what you'd expect from hand held movement. The major vibrations while the shutter is open seem to be at around 30Hz. However IS systems aren't really designed to minimize mirror induced vibrations (though they may work to do that in some cases).

IS systems certainly don't work at very low frequencies because the system drifts. At zero frequency (i.e. with the lens on a tripod), IS with exposures of maybe longer than 0.5s (that's just a guess) causes blur though drift of the IS system. At don't know at what point the drift becomes larger than the stabilization. Very low frequency stabilization could also be a problem when panning the lens, for lenses that don't have the option to switch off stabilization along the panning axis.

My guess would be that the bandwidth is maybe 1Hz to 50Hz at the outside. Probably more like 0.5Hz to 25Hz. I've read that hand tremor peaks in the 8-12 Hz range so I'd assume that's where IS systems are tuned for best performance.

I've seen some data on Canon's stabilization system for professional video shooting. There the stabilization seems to be tuned for maximum effect in the 2Hz to 10Hz range. Those systems use VAP-IS (variable-angle prism image-stabilization) which is a little different then the method used in EOS lenses, but the principles are the same, though they may tune the IS to include motion due to walking with the camera as well as hand/shoulder holding it.

If you want some technical reading on the subject, try this:

http://www.image-engineering.de/library/conference_papers/image_stabilizing.pdf

I suppose you could measure the characteristics of the lens you are interested in, but I don't know what the point would be. There's nothing you could do about it and the way to minimize image blur is to put the lens on the biggest heaviest tripod you can find and use a remote release with mirror lockup. It's not like you can control the frequency at which your hands shake when handholding the lens, or easily tune a tripod for resonance in a particular frequency range. Even if you could, I doubt it would be of any practical help and tuning for resonance would only increase the vibrational amplitude, something you certainly don't want.

 2 
 on: May 18, 2013, 03:44:00 PM 
Started by Frank Kolwicz - Last post by Frank Kolwicz
I've read some about Image Stabilizers and almost all reviewers ever talk about is extra stops of shutter speed, but, it seems like there must also be some range of effectiveness for the amplitude and frequency of camera movements for which it works best, well, fairly or poorly.

I'm specifically interested in the EF600/4IS (not IS II).

Any info?

 3 
 on: May 14, 2013, 11:14:32 PM 
Started by olyduck - Last post by olyduck
Thanks everyone for your thoughts on this issue.  I appreciated the links provided as well.


-Dave

 4 
 on: May 14, 2013, 01:59:02 PM 
Started by olyduck - Last post by KeithB
Well olyduck said:
"I grew up shooting Kodachrome 25 so I'm not completely in "contrast shock" and can selectively bias my exposure, but a liitle wider range without going the HDR route would be nice."

So it looks like they know how to "expose to the left" 
8^)

 5 
 on: May 14, 2013, 01:28:00 PM 
Started by olyduck - Last post by Bob Atkins
Again though you have to look where the extra dynamic range is. If it's mostly at the shadow end of the range, it's not going tp help with blown out highliight, and as far as I know most of the added dynamic range of the Sony/Nikon sensors does come at the shadow end.

Comparing the 6D with the 40D I don't think you'll see significantly more headroom in the RAW files.

 6 
 on: May 14, 2013, 11:26:26 AM 
Started by olyduck - Last post by KeithB
Well, the DxoMark shows the 6D at about a stop higher in dynamic range than the 40D, so you will get some more headroom, but not the 3EV you would get going to the Nikon. I would think it also depends on your investment in EF lenses.

 7 
 on: May 14, 2013, 10:44:44 AM 
Started by olyduck - Last post by Bob Atkins
The DxOMark scores for Landscape DR are based on low ISO settings. Nobody shoots landscapes at ISO 1600 and up, so their "single number" ratings don't tell the whole story. However they do show about a 2EV advantage to Nikon in the low ISO range, similar to what I saw comparing the 5D MkIII with the D800.

I've been shooting with an EOS 6D for the last few weeks. I like it. So far I haven't found any real issues with either the image noise, image quality or even the relatively simple AF system.  In fact the AF system (center zone) works in extremely low light. Seems like an excellent buy if you want a FF body for under $2000. The GPS and WiFi are fun to play with too

Best deal on the 6D right now looks like $1999 from ADORAMA with a 2% credit ($40) and around $90 of "free" goodies thown in.

EOS 6D at ADORAMA - $1999

 8 
 on: May 14, 2013, 09:32:22 AM 
Started by olyduck - Last post by KeithB
Here is a recent online review of the 6D I saw referenced on TOP:
http://shutterfinger.typepad.com/shutterfinger/2013/05/why-i-like-the-canon-eos-6d.html

 9 
 on: May 14, 2013, 09:31:06 AM 
Started by olyduck - Last post by KeithB
Bob might comment on the methodology, but DxoMark has a direct rating for dynamic range in EV's. The 6D is about 12:
http://www.dxomark.com/index.php/Cameras/Camera-Sensor-Ratings/(type)/usecase_landscape


 10 
 on: May 13, 2013, 07:20:29 PM 
Started by olyduck - Last post by Bob Atkins
The Nikon sensors (made by Sony) do have more dynamic range than the Canon sensors, but it's at low ISO settings and it's on the underexposure side. You can dig information out of the shadows better. I don't think they are particularly better on the overexposure side and at high ISO settings there is less advantage. The difference mainly seems to come from the lower shadow noise of the Nikon (Sony) sensor.

I looked at the D800 and 5D MkIII and you can see the results here:

http://www.bobatkins.com/photography/digital/Canon_EOS_5D_MkIII_vs_Nikon_D800_dynamic_range.html

From all the data I've seen, the 6D and 5D MkIII should be pretty similar, even though they don't have exactly the same sensor.

Other than careful exposure, turning on HTP (High light tone priority) is probably the best way to avoid highlight clipping on EOS DSLRs, though you can lose a little shadow detail.

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