Oscillating Tripod Theory...

Started Oct 23, 2012 | Discussions thread
Flat view
SRT201 Senior Member • Posts: 2,515
Oscillating Tripod Theory...

I had the strangest thing happen the other day while testing a Tamron 55BB 500mm mirror on my K-5. I had it mounted to a small carbon fiber tripod (Rocketfish... yeah yeah go ahead and laugh). It's fairly rigid but apparently not enough.  I didn't have anything hanging on the weight hook.

At one point I realized my whole tripod was buzzing, as was the LiveView image on the K5 because the imager plate in the K-5 was oscillating!

SR was OFF as I was using Mirror Lockup, so there's the answer to your first question.

I got it to happen again but only under specific circumstances.

I started it again once when the focused on a distant target, using LiveView and using the 8X LV setting.  The LV image slowly began swinging back and forth and obviously going open-loop.  It did NOT happen when using the 2,4 or 6X live view modes. I notice that LV switches to a slower frame rate for 8X and 10X and that seems to have something to do with it.

Once I started it by accidentally banging into the tripod.

I assume this has something to do with the constant activity of keeping the imager plate hovering in it's home position when using LV and again only at the slower update rate of the 8X or 10X views.

It hasn't troubled me since and I have never seen it using other lenses or handheld with SR.

Anybody else ever seen this?

Side note... if you don't have a Tamron 55BB 500mm mirror, just find one.  It's the most accessible, sharp handheld 500 I can imagine.  Paired with Pentax SR and CIF, it's a fun lens.  Truly a grab-and-go long tele.  Sharpness is not far behind a good 500mm refractor lens and such a lens requires a lot more planning to use than the light weight Tamron.

-- hide signature --

Any government that has the power to correct any injustice and level any inequality also has the power to do ANYTHING it wants.

Pentax K-5
If you believe there are incorrect tags, please send us this post using our feedback form.
Flat view
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow