Where to mount the camera to the rail used vertically

Adalbert · Post by **Adalbert** » Sat Dec 15, 2018 3:53 am

Hello everybody,
I’m assembling a new setup which can be used vertically.
Where is the best place for the mounting of the camera?

The construction should be stable, solid, most loadable and resistant to vibrations.
BR, ADi

ChrisR · Post by **ChrisR** » Sat Dec 15, 2018 4:17 am

I'd aim to support as near the centre of mass as possible.

Adalbert · Post by **Adalbert** » Sat Dec 15, 2018 4:51 am

Hello Chris,

as near the centre of mass

I have ever tried to do that in this way during the usage of my horizontal setup
but I’m not sure if the camera shouldn’t hang vertically (the right option on the picture).

BTW, the option on the left could guarantee minimal vibrations of the microscope objective,
because it would be mounted close to the nut of the rail.

BR, ADi

Lou Jost · Post by **Lou Jost** » Sat Dec 15, 2018 5:35 am

Personally I now use the leftmost approach for the reason you mentioned.

ChrisR · Post by **ChrisR** » Sat Dec 15, 2018 5:53 am

Is there any movement at all in the camera?

iconoclastica · Post by **iconoclastica** » Sat Dec 15, 2018 6:39 am

The amplitude that vibrations have in a rod depends on the free length of the rod. So keep the free end short as possible and attach it near the middle point, or rather, just above the centre of gravity (to discourage it turning unvoluntarily upside down).

Though I must admit that Lou's suggestion makes sense too if one assumes that it's more important that the fron of the lens doesn't shake.

Lou Jost · Post by **Lou Jost** » Sat Dec 15, 2018 6:44 am

The amplitude that vibrations have in a rod depends on the free length of the rod. So keep the free end short as possible and attach it near the middle point, or rather, just above the centre of gravity (to discourage it turning unvoluntarily upside down).

But this reasoning assumes that the goal is only to reduce the amplitude of the vibrations. One might also want to minimize the absolute motion of the lens end of the rod, because we are not concerned about the amplitude per se. but rather the effect of the amplitude on the image.

iconoclastica · Post by **iconoclastica** » Sat Dec 15, 2018 6:47 am

Acknowledged. You were too fast for me. Crossposted when I was still editing just that in

ChrisR · Post by **ChrisR** » Sat Dec 15, 2018 6:59 am

I'd have thought angular variation rather than amplitude of one part, is what matters.

What initiates the wobble?

If it's shutter movement, hold it still by mounting adjacent to it,
if it's stand-induced then you don't want unrestraind mass away from the mount because it'll take longer to settle.
In other words minimize stored energy in the unsupported parts.

Lou Jost · Post by **Lou Jost** » Sat Dec 15, 2018 7:02 am

Environmental vibrations are my main concern. I use only mirrorless electronic shutter cameras. If the camera itself is the source of vibrations, that raises different design issues.

ray_parkhurst · Post by **ray_parkhurst** » Sat Dec 15, 2018 7:49 am

The left diagram minimizes the effect of vibrations on the image (good), but maximizes the moment on the rail (bad for the rail) while consequently minimizing system resonance (longer settling time). The right diagram will somewhat reduce the moment on the rail and thereby increase system resonance, but not a lot, at the expense of greatly increasing the effect of vibrations on the image. Not a good tradeoff. The middle diagram is somewhere between the two.

Adding a second attach point would allow all the parameters to be improved.

Troels · Post by **Troels** » Sat Dec 15, 2018 8:28 am

In addition to the already mentioned factors we have one more.

The frequence of the disturbing vibration is important.
Every system with moving parts has its own vibration frequence. If the distubing vibration (and its strongest hormonics) is far from this, the system will not easyly be set in motion.

But if the disturbing vibration (or its strongest harmonics) is close to the systems own frequence, only a very little disturbing amplitude will create a distinct vibration, also called ressonance.

This is very difficult to calculate. So you might discover, that a minor change in the length or mass of the "arms" in your system results in a remarkable change in your observable vibrations.

The solution to shutter vibration may not be the same as the protection from heavy street traffic.

Still, all things equal: shorter arms will always make weaker vibrations.

mawyatt · Post by **mawyatt** » Sat Dec 15, 2018 8:30 am

Generally there a 3 sources of vibrations to deal with. Environmental, rail induced and camera (shutter) induced. Each has its own "optimal" setup/position and certain users may have preferences (like Lou's environmental, or someone using totally electronic shutter/curtain (no camera induced vibrations).

The observation point is important, what is it that you are trying to minimize? Generally this is the camera sensor to subject movement, since this is where vibration induced image "blur" originates. The "common mode" approach can really help with low frequencies, since both the camera sensor and subject move together is unison, and thus no differential movement. As frequency increases the phase and amplitude between the camera sensor and subject begin to deviate from the rest steady state condition and other techniques need to be employed. These setups can usually be modeled as coupled 2nd order systems and analyzed as such. Here's some discussions.

http://www.photomacrography.net/forum/v ... t&start=15

Here's some elementary MIT lecture notes on 2nd order systems.

http://web.mit.edu/2.151/www/Handouts/F ... dOrder.pdf

https://ocw.mit.edu/courses/mechanical- ... lment2.pdf

Since this overall "system" is linear (well almost), superposition can be employed for each vibration source independently and the individual results summed for the final conclusions. Use an "impulse" as the excitation source for each analysis.

If the subject is tightly linked to the camera support (common mode) the right section should have the better results for camera induced vibration since this is a "stiffer" condition near the vibration (camera) source (see MIT notes).

Anyway, a few things to think about when assembling or reconfiguring a new setup.

Best

RobertOToole · Post by **RobertOToole** » Sat Dec 15, 2018 9:23 am

Adalbert wrote:Hello everybody,
I’m assembling a new setup which can be used vertically.
Where is the best place for the mounting of the camera?

Hi ADi,

For the very best possible image quality?

Vibration is something that is never an issue in my experience when using good technique.

A big issue with a set-up like this?

Getting the subject and sensor as parallel as possible to reduce the work/steps needed in a stack up to maybe 50x.

In my experience its best to clamp or mount the set-up close to the center.
Otherwise its going to be a lot harder to get things parallel at least in my experience.

Not sure what the actual cause of the issue is but from experience center mounting gives me the best results.

Hope this helps.

Robert

Lou Jost · Post by **Lou Jost** » Sat Dec 15, 2018 10:35 am

Vibration is something that is never an issue in my experience when using good technique.

Robert, I think that depends a bit on where one lives. Vibration is always an issue if you live on a busy road with heavy trucks and buses. It is very difficult to control completely.

Where to mount the camera to the rail used vertically

Where to mount the camera to the rail used vertically

Re: Where to mount the camera to the rail used vertically