Camera vibrations

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

--
JS

On Mon, 7 Dec 2015 15:56:14 +1000, James
wrote:

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

From your description and some photography that I've done I suspect
that the camera is moving, however little. My experience, with film
cameras, is that they sometimes can be isolated from the vehicle to
eliminate high frequency vibration but not actual movement, or perhaps
I should use the term "gross movement" as vibration is, effectively,
movement.

I would wonder what would happen if you mounted the camera on your
helmet (or hat :-)?
--
cheers,

John B.

the Mobius ? odd name for a camera..

z
My Cx sports a Pollack 4i...great vib control...no probs....AAA closeups...

bark..gravel...

its the heat

mount helmet

Write...I BOUGHT A MOBIUS TO MOUNT ON MY HELMET

see ISO in the instructions ? increase the ISO

decrease tire pressures, run BIG A's

weird no ?

most buy cameras to 'take' photos ..I know like they 'take' wallaby

its the heat

mount helmet

Write...I BOUGHT A MOBIUS TO MOUNT ON MY HELMET

see ISO in the instructions ? increase the ISO

decrease tire pressures, run BIG A's

weird no ?

most buy cameras to 'take' photos ..I know like they 'take' wallaby

its the heat

mount helmet

Write...I BOUGHT A MOBIUS TO MOUNT ON MY HELMET

see ISO in the instructions ? increase the ISO

decrease tire pressures, run BIG A's

weird no ?

most buy cameras to 'take' photos ..I know like they 'take' wallaby

https://www.google.com/search?site=i...44.PQDAiiOeX_A

why are you mounting a camera ?

On 12/7/2015 12:56 AM, James wrote:
I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

Interesting. I hadn't heard of the Jello Effect. I guess this is a
good example: https://vimeo.com/69906288

The beat frequency idea seems possible to me.

If the effect is dependent on changes in pitch, I wonder if it could be
prevented by a parallelogram linkage like this:
http://www.atticpaper.com/prodimages...banner1897.jpg
Its intent is to provide vibration isolation without pitch change.

--
- Frank Krygowski

On 07/12/15 21:01, John B. wrote:
On Mon, 7 Dec 2015 15:56:14 +1000, James
wrote:

I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

From your description and some photography that I've done I suspect
that the camera is moving, however little.

That part is obvious. The question is whether it is simple up and down
movement, or changing pitch, which is worse and how to reduce.

My experience, with film
cameras, is that they sometimes can be isolated from the vehicle to
eliminate high frequency vibration but not actual movement, or perhaps
I should use the term "gross movement" as vibration is, effectively,
movement.

I would wonder what would happen if you mounted the camera on your
helmet (or hat :-)?

Helmet, shoulder or chest mount apparently works, however the first is
possibly illegal in Australia as it may affect the helmet crash
worthiness - low as it is - and I don't care to wear a camera at all.
It has to be bike mounted AFAIAC.

--
JS

On 08/12/15 02:29, Frank Krygowski wrote:
On 12/7/2015 12:56 AM, James wrote:
I bought a Mobius miniature camera to fit to my handlebars.

https://www.mobius-actioncam.com/

Image quality is great. It's small and light. Didn't cost a bundle.

I've read about vibration damping and so on, as I see when I go over
bumpy road I get the jello effect through the video.

I came across another bicycle vibration analysis study today
http://mecano.gme.usherb.ca/~jmdrouet/velus/assets/0707cham.pdf and
one part caught my eye.

Frequency 27.8Hz Front-to-back motion of fork.


This got me to thinking. The jello effect is a rippling through the
picture at a few Hz. Could this be a beat frequency between the shutter
speed (30Hz), and the front wheel moving back and forth as it rides over
bumps?

Further to this, if the camera simply moved up and down a small amount,
but continued to aim approximately in the same direction, I don't think
there would be such a big effect on the video. I think to cause the
jello effect the camera is being aimed slightly higher and lower than
the average position, at near 30Hz. That is the camera has changing
pitch, not just raised and lowered.

So I wonder how much bending is transferred through the fork steerer, on
to the head stem and through to the bars?

My next test will be to (temporarily) mount the camera in the middle of
the head tube. There may be some pitch change as the front wheel rides
over a bump and a little later the back wheel follows, but I wouldn't
have thought the bike would pitch at 30Hz.

Thoughts?

Interesting. I hadn't heard of the Jello Effect. I guess this is a
good example: https://vimeo.com/69906288

The beat frequency idea seems possible to me.

If the effect is dependent on changes in pitch, I wonder if it could be
prevented by a parallelogram linkage like this:
http://www.atticpaper.com/prodimages...banner1897.jpg
Its intent is to provide vibration isolation without pitch change.



Hmm.. I can understand how the parallelogram may act as a vertical
motion suspension arm, but I do not see how it aims the lamp straight
while the handlebars pitch (rotate to aim higher and lower).

--
JS