Image Stabilization

[kdoc856]

The question has been raised as to the necessity of turning off the IS when a tripod is used. My personal opinion has been that it makes no difference, and represents an unnecessary extra step. Over the last couple days, I made several images- 2 inside with stable tripod and subject with a long shutter speed, and 2 outside on a windy day (about 40 kph), not a long shutter speed but longer than the focal length would dictate. The top image of each pair is with the IS ON, the bottom with it OFF. See what you think
.

These two:

ISO 125 1/125 F19 200mm




These two:

ISO 50 10 sec exp F27 160mm

[Colin Southern]

The question has been raised as to the necessity of turning off the IS when a tripod is used.

The type of IS unit is going to make a difference though. Newer Canon ones have tripod detection built in, wheras the older 1st and 2nd generation didn't. I've seen the results of a shoot with the original EF70-200mm F2.8L IS USM left with IS on (tripod mounted) and there was a small issue (we got around it with more agressive capture sharpening).

I discussed the issue with Canon's tech guru Chuck Westfall, and he came back with this ...

"Hi, Colin:

Time flies, doesn't it? <g>

The EF70-200mm f/4L IS USM has the ability to detect when it is mounted on a tripod. If you keep the shutter button half-pressed, or better yet, use a remote switch to simulate a half-press, the stabilizer mechanism will drift the image downwards for the first second or so, then the mechanism will stop moving. (It's for this reason as well as battery power conservation issues that the instruction booklet recommends shutting off the IS system while the lens is mounted on a tripod.) You can see this effect if you look through the viewfinder while half-pressing the shutter button.

Hope this helps!

Best Regards,

Chuck Westfall
Technical Advisor/Professional Products Marketing Division
Consumer Imaging Group/Canon U.S.A., Inc. "

and then this ...

"Hi, Colin:

For reasons known only to themselves, the folks who approve the instruction books in Japan usually seem to prefer leaving that section of the IS lens booklets somewhat ambiguous. I tried to get them to change the books for the IS super-telephotos (300/2.8L IS, 400/2.8L IS, 500/4L IS, 600/4L IS and eventually 400/4 DO IS) 7 or 8 years ago, shortly after I stumbled upon the added capabilities of those lenses while testing them, but no dice. It looks like they are finally admitting that the "Tripod IS" mode that I described online several years ago actually exists, at least with the EF200mm f/2L IS USM lens that has just been released, but I doubt that the instructions for the older lenses will ever be rewritten.

The IS mechanism in the EF70-200mm f/4L IS USM is effectively disabled when the lens detects that it is mounted on a tripod, as I previously described to you, but it is not as sophisticated as the ones in the IS super-telephotos because it does not correct for mirror slap or other subtle movement when the lens is mounted on a tripod. However, it is important to understand that this form of disabling is different than shutting off the IS function with the mode switch on the lens. In the latter case, the IS mechanism is centered and locked into place, whereas in the former case, the IS mechanism shifts the image downward slightly for a second or so, then stops moving. It's not moving, but it's not centered or locked, either. It's effectively on standby, so that it can resume its corrective capabilities instantly if movement is detected. Again, you can see this for yourself by looking through the viewfinder while pressing the shutter button halfway for at least several seconds, assuming the lens is mounted on a tripod and the IS switch is on.

To my way of thinking, this is not the optimum way to use the equipment. In my opinion, if you use the EF70-200mm f/4L IS USM on a tripod, it would be best to turn off the IS mechanism via the switch on the lens, rather than depending on the tripod detection capabilities of the IS mechanism.

Best Regards,

Chuck Westfall
Technical Advisor/Professional Products Marketing Division
Consumer Imaging Group/Canon U.S.A., Inc."

(We were talking about the EF70-200 F4.0L IS USM, but I think the info is still relevant).

[kdoc856]

Thanks, Colin. Very interesting. I took all these images with a 2 sec delay and a Sony a77, so neither the IS "drift" or the mirror slap would come into play, I guess. Mr. Westfall's explanation is compelling , though, so I guess I'll turn the darned thing off when on the tripod. The Sony alpha series has the IS built in-camera, and with the a77 they removed the external button and it must be reached now via menu. A small nuisance I was trying to avoid.

Thanks so much for your help.

Kevin

[dje]

Hi Kevin

It must be very much equipment dependant but on the images displayed, I can't pick any significant difference. I dont mind turning it off when required, just concerned that I'll forget to turn it on for hand held work.

Cheers Dave

[kdoc856]

I agree , Dave. I have never been able to discern a difference, and the RAW files I took of the images below are absolutely without an difference that I can perceive on my own monitor ( they do look v. slightly different below). It is enough of a nuisance to enter the menus with my camera, that I may just leave the IS on- I dont care about the little bit of battery usage difference that it might have. As you suggest, I think we are much better ieaving it on than forgetting to turn it back on.

[Colin Southern]

just concerned that I'll forget to turn it on for hand held work.

Been there, done that!

[calexe]

If I may:
Actually there is another problem when not disabling IS when working on tripod. Try to shoot close-ups or macro on tripod with IS on. The drift C.W. described will cause some trouble in framing exactly what you want.

[kdoc856]

Thanks Cristian. I've not done much of that to date, but good to know

[elfbob]

I have limited lens resources, 1) EFS 18-55 f/3.5-5.6 usm; 2)70-200mm F4L USM; 3) EF 70-300mm f/4-5.6 IS USM. The lens instruction guide for # 3 states: the stabilizer should be turned off when the camera is mounted on a tripod to save battery power; i had also read in a forum that this lens will introduce slight errors from the stabilizer action when the camera is tripod mounted, either reason seems appropriate to me. If i'm using a tripod & ultimate sharpness is the goal, i will be using manual focus, a remote shutter release & utilizing the camera's mirror lock up function.IS is extremely helpful when hand holding #3 with 2 exten tubes for macro captures with the camera set on M when use of a flash to stop lens end quiver would chase the critter away, fortuneately small flowers don't move as much unless there's ambient air moving around them; IS is also a great help for shooting at lower shutter speeds when aperture & iso are the main considerations. I tend to use M technique for 70% of my captures so IS is a great help when using lens #2 exceeds my abiltiy to compensate for lens end "quiver", even though #2 is sharper than #3. There are many "positional" techniques to limit lens end "quiver", but the older i get these seem to become less effective.

[Dave Humphries]

Hi Kevin,

Can I ask whether those are 1500 x 1000 crops from the center of the shots and hence displayed at 1:1?

Or are they downsized, full frame images (uncropped)?

Thanks,

[kdoc856]

Hi, Dave

sorry for delayed response, been traveling. Not exzctly sure how to answer your question correctly- I did not cropping myself. I just did the image resize to 1500x1000, and PS did the compression. I hope that answers.

Kevin

[Dave Humphries]

Hi, Dave

sorry for delayed response, been traveling. Not exzctly sure how to answer your question correctly- I did not cropping myself. I just did the image resize to 1500x1000, and PS did the compression. I hope that answers.

Kevin

It does.

Unfortunately, to critically look at what we ought to be looking at, we must see it 1:1, the downsizing will have hidden the differences.

If you open each original, full size, image and crop leaving just the rectangle from the middle of about 1,500 x 1,000 px, then upload them (they won't need downsizing), we can form a better opinion.

Cheers,