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Should the image stabilization be on or off when shooting astrophotography on a tracking mount?

On one hand i think that it might stabilize any vibration caused by the camera, shutter or whatsoever, on the other hand i am worried it might be compensating also for the tracking Mount movement.

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I have experimented with this and found that I got blobs instead of sharp Stars with IS on.

I had a Canon 7D with an EF 35mm f/2 IS Lens, mounted on top of an Equatorial Mount on top of the actual Telescope. Both the “Right Ascension” and the “Declination” Axis’ were each driven with their own Motorised Clock drives in sync with the motion of the sky. The exposures ranged from 2 minutes to 1 hour.

The Images with the IS off, were sharper then they were with the IS on, which often resulted in blobs.

Therefore, I would suggest to keep all stabilisation off when on a tripod; Tracking or not. Your thought process may be the same as mine where you may be thinking that as the stars are moving very slowly, image stabilisation will help to keep them sharp for a longer period of time.

But that is not what happened with my experiment.

if you keep the IS on, you risk creating a "Feedback loop" or sometimes known as, “Shake Return", where the camera’s Gyros detect the continued IS Vibrations and starts to move around to correct this and as a result, you end up with a blurry image.

The best results I have found, have come from very Wide Angle lenses, such as the Canon 10-22mm Non IS EF-S Lens.

  • thsnk you very much! unfortunately I only have the 70-200 lens.. – sharkyenergy Jul 12 '15 at 14:55
  • I can see your concerns now. with a 70-200mm Lens, the chances of blur are increased. perhaps starting off with just 30 Sec Exposures that doesn't require tracking is a good idea and then experiment from thereon. Good luck anyway – Abdul Quraishi Jul 12 '15 at 15:22
  • 30 seconds is far too long for a 70-200 lens unless you want star trails. The general rule of thumb is that you need to use a shutter speed that is 600 divided by the effective focal length. So a 70mm lens on a FF camera would be limited to about 8.5 seconds before star trails would be visible in an 8x10 print viewed at about 10 inches. A 200mm lens on an APS-C body can only handle just under a 2 second exposure before star trails are visible under the same viewing conditions. See photo.stackexchange.com/q/30263/15871 – Michael C Jul 12 '15 at 18:43
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    @MichaelClark You don't expect star trails when you have the camera on a tracking mount. Rule of 600 applies to a fixed camera position. – MikeW Jul 12 '15 at 22:57
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    @MikeW My comment was in the context of the previous comment which said "perhaps starting off with just 30 Sec Exposures that doesn't require tracking is a good idea and then experiment from thereon." – Michael C Jul 13 '15 at 7:02
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When to use and not use Image Stabilization/Vibration Compensation/Vibration Reduction/etc. is lens or camera specific, depending on whether the system ins lens based or camera body based. Not all implementations are the same, even within a single manufacturers ecosystem.

When shooting on a tracking mount Image Stabilization should probably be turned off, at least with every IS lens I have seen. This is because image stabilization is designed to counter movement of the camera/lens and in the case of a tracking mount the motion along the celestial equator is desired.

Some early implementations of Image Stabilization created "feedback loops" causes by the vibrations of the IS mechanism. Most newer lenses, though, can sense when a camera/lens is tripod mounted and adjust accordingly. So the oft circulated advice to always turn off IS when using a tripod is only partially correct.

There are some lenses that have panning modes that allow motion on one axis while attempting to counter it on the other axes. It might be theoretically possible to position the camera in such a way that the motion of the tracking mount is aligned with the horizontal axis of the camera and thus that desired motion would not be countered, but it is likely that in any mode that allows for panning there would also be the undesirable side effects associated with vibration created by the IS mechanism when panning as slowly as an equatorial mount moves.

There are a few very long telephoto lenses that have an IS mode designed specifically for tripod use, but those modes are limited to to eliminating vibrations created by mirror movement and would probably not allow for panning along one axis.

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Your camera manufacturer manual will tell you that using IS on a tri-pod will create image blur, you must switch IS off when using a tri-pod

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    I'm not sure that really answers the question, as such advice surely refers to a fixed tripod, not one mechanically connected to a tracking motor that could induce vibration. (I also find such advice to be an oversimplification in general. I've been in situations where high winds made stabilization helpful even on a fixed tripod.) – coneslayer Jul 13 '15 at 0:14
  • Some manuals will and some won't, because some higher end lenses actually have modes specifically designed for tripod use. – Michael C Jul 13 '15 at 7:20

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