Remedy for vibrations

Have questions about the equipment used for macro- or micro- photography? Post those questions in this forum.

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Big Pete
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Location: Ulricehamn Sweden

Remedy for vibrations

Post by Big Pete »

Hello, I have a hard time to get my smallest objekts to sit put and that brings a unsharp image. I am talking about super tiny orchids that is about 2-3mm wide at the end of a tiny tiny twig. I use a 2" thick slab of birch play wood and underneath there is Sorbothane feet and those sits on my desk top in solid oak and metal legs. Under the desk legs on the floor there is rubber feet for vibrations. What can I do to improve my rig?

Chris S.
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Re: Remedy for vibrations

Post by Chris S. »

Pete,

You have asked a difficult question. Vibration is a huge enemy in macro/micro work, and most of us have had ugly experiences with it. While you have done a nice job describing your setup, most of us would probably have to see it, or perhaps work with it, to diagnose where the problem lies.

First thought: As you likely know, using flash, instead of continuous light, can be very much like a magic want for eliminating vibration. So if you have flash units available, you might try them to compare the difference against continuous light. (In this case, do consider the settings you choose for your particular flash units, and what these settings deliver in terms of flash duration. For typical small flashes, reduced flash output usually translates to shorter output duration, so greater power in freezing your subject and reducing the impact of vibration. For large studio flashes, this may or may not be the case, depending on flash design.)

Second thought: Sorbothane works well only if the particular Sorbothane product is well-matched to things like the mass of the object on top of the Sorbothane. Oversimplifying, properly implemented Sorbothane needs to be squeezed into moderate--but not too much--deformation; if it is not deformed at all, or if it is deformed too much, it doesn't dampen vibration very well. Too many people treat Sorbothane like a magic wand that works with anything; in reality, it should be treated more like a wrench that needs to be chosen properly to match the bolt it is intended to turn.

Third thought: It might be helpful if you share some pictures of your rig and its environment.

Fourth thought: I once had a thorny problem with vibration, and in dealing with it, learned things about how devilishly difficult vibration can be to isolate. I had intermittent vibration issues from some unknown source. I was working in a basement with a concrete floor; I was far from any road traffic; my rig was on a heavy, slate pool table; my rig was made of steel, and was very heavy. What could vibrate all this?

The culprit turned out to be one of our gas furnaces--not its blower fan, but its burners. These burners produced a low-frequency "mrrr" that caused my rig to resonate. I didn't notice this sound for a while: I thought this furnace was "on" or "off" based on its fan noise. It was later that I realized that the burner and fan turned on together, then the burner stopped, while the fan continued until the internal temperature came down. Once my ears were trained to notice the distinction between the fan and the burner, this was obvious.

I share this story to demonstrate that vibration-hunting can be really, really difficult.

Good luck!

--Chris S.

Big Pete
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Location: Ulricehamn Sweden

Re: Remedy for vibrations

Post by Big Pete »

Here are some pictures of my macro rig taken by my I-phone!

https://www.flickr.com/photos/125705582 ... 0296179195

Guppy
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Re: Remedy for vibrations

Post by Guppy »

Hi Pete

When the motorized carriage moves, the camera and likewise the monitor vibrate.
It takes a long time for the high structure of the camera and the monitor, which is far out, to settle down,
so also when the environment is vibrating.

It is better to move the light object with the sled.
The camera and the object should be mounted as stably as possible on the base board.
Mount as few sleds and joints as possible between the camera and the base board, so also with the object.
Mount the monitor next to the base board.

Flash is the best!

all the best

Kurt

Big Pete
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Re: Remedy for vibrations

Post by Big Pete »

Ok Kurt, I use a studio flash with a well diffused beauty dish and a shutter speed of 200. I need to make a integrated stand for my objekts to get them as steady and solid as possible!

Guppy
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Re: Remedy for vibrations

Post by Guppy »

Hi

First do a resolution test with a resolution test target (USAF chart) with the current setup.
Then remove the monitor and its mount.
Then do a resolution test again, the resolution should be higher.
Then you can remove the high setup of the camera and mount the object on the sled, not at the same place as the camera!
And measure the resolution again.

The firing time of studio flashes is often too long.
I use 4 YONGNUO YN560III with throttled power, if possible with 1/128 power, firing time 1/35000 seconds.
The 4 flash units must be of the same type (same triggering delay) and triggered in the same way.

Kurt

lothman
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Location: Stuttgart/Germany

Re: Remedy for vibrations

Post by lothman »

take the stackshot and clamp it with a screw clamp direkt to your plywood board and do a stack. If this gets sharp, than your stack of "wobble-opportunities" between the stackshot and the plywoodboard is the source. Why so man joints and why a slider on top of another slider?

As Kurt mentioned check the flash duration in order to be short enough to freeze motion blur. I don't know the stackshot controller, but may be you can increase the time between end of stacking motion and taking the shot, the the vibration might have faded out. Use silent shutter to avoid the camera to disturb your setup.

Big Pete
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Re: Remedy for vibrations

Post by Big Pete »

"Why so man joints and why a slider on top of another slider?" The idea is to make the rig very flexible as I shoot flowers in different sizes. Everything from a couple of mm to one inch or so!

I am not in the market for smaller flashes because my wallet is thin but I do have two small Fuji flash that could be a start.

Smokedaddy
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Re: Remedy for vibrations

Post by Smokedaddy »

Just curious, is there a way to measure if the vibration is present with a Raspberry Pi or Arduino? Some sort of seismic accelerometer? I know they do it in semiconductor facilities for their scopes.

Big Pete
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Re: Remedy for vibrations

Post by Big Pete »

lothman, the flash will not fire if I change to silent shutter on my Sony A7R ii so that is not possible. But I will start to take away some parts from my rig to improve rigidity!

Pau
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Re: Remedy for vibrations

Post by Pau »

Smokedaddy wrote:
Mon Jan 24, 2022 12:49 pm
Just curious, is there a way to measure if the vibration is present with a Raspberry Pi or Arduino? Some sort of seismic accelerometer? I know they do it in semiconductor facilities for their scopes.
I have an app for Android called Sensor Kinetcs that do so
Pau

Guppy
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Re: Remedy for vibrations

Post by Guppy »

Hi
And then when you know with Sensor Kinetcs how much it trembles,
you still do not know how much it can be seen in the picture!
The camera is a very good measurement tool for photography!
Resolution measurements create relevant results for photography.

Kurt

Macro_Cosmos
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Re: Remedy for vibrations

Post by Macro_Cosmos »

Using a flash will help, in electronic shutter mode. This is not possible as a plug and play solution with most mirrorless models. The Stackshot 3x offers two shutter outputs, it should be completely possible to use one of them with a delay circuit to fire a flash. I am not sure why they (Cognisys) have not done that yet, considering MJKZZ's rails offer flash triggering. Yours is the normal single output model, which can definitely be rigged for this purpose as well. I bridged a digital output from my Wemacro controller, it was 3.3V, so I used a small boost converter to step it up to 5V which can be used to trigger my camera. I will try and implement flash triggering when I have the time.

Remove the second rail, you can adjust the distance by sliding the Stackshot rail along the tilt head'sclamp.
Mount the monitor onto the board rather than from the same plate, it looks wobbly.
Ideally, just mount the Stackshot straight to the board and use a ball head to adjust the angles of the specimen.
Additionally, weigh the entire thing down with weights or marble/granite slabs. I picked up some during big rubbish collection days, they are free!

Chris S.
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Re: Remedy for vibrations

Post by Chris S. »

Big Pete, thanks for sharing pictures of your setup. They are a big help.

I agree with the comment that your monitor should come be removed from your macro rig's base. Having that much mass on a long arm is asking for vibration that might take a long time to dissipate.

From the partial image of your studio flash, it appears that the brand is Visico. I don't know which model, but just now looked at data for one model, the Visico Studio Flash VCHH. The company lists flash duration as "1/800th~1/1200th" (of a second, presumably). By flash standards, this is pretty slow--small flashes can easily attain durations of 1/50,000 second or faster. I'm skeptical that enough vibration elimination can be expected from your type of flash.

Also, flash manufacturers should disclose their metric for measuring flash duration. I don't see this stated for Visico. One common standard is t.5, meaning that stated flash duration is declared at a point where 50 percent of the flash's light has been emitted. This still leaves lots of light coming out after flash duration has officially ended, and some flash's outputs have long "tails." Here is a link for a fuller discussion of this.

So it is possible that your studio flashes may not be capable of freezing out vibration for macro photography.

An approach you might try is to turn on live view on your camera, and zoom in as far as you can. Do you see any movement on the monitor? Take a step or two with your feet. Is movement transferred from the floor to your rig, as evidenced by movement on the monitor? Slew your StackShot forward or backward--do you see any unwanted movement? Try tapping on the baseplate of your rig and noting the magnitude and direction of any movement. Try tapping other parts of the rig, including the lens.

In each case, what sort of movement do you induce, and how long does this movement take to dissipate?

Such a process is unlikely to give you a quick answer, but it will help you understand your rig's vibrational characteristics. Once understood, these characteristics are easier to deal with.

The idea of adding weight to your rig is often a good one. But I'd urge you to characterize your rig's vibration before and after doing so. An aspect of increasing your rig's mass is that you'll be changing its resonant frequency (probably lowering it). While this is generally a good thing, it can be a bad thing if you happen to be tuning the resonant frequency to match some energy input your rig is facing. (As an example, I once put my rig on top of some small, barely-inflated inner tubes. This isolated it very well from the vibration of my furnace. Then I noticed that the rig was moving rhythmically in exact match to my heartbeat. I was standing on a concrete basement floor, with my wrist resting lightly on the heavy slate pool table that held my rig 80-pound rig. I was surprised that such a tiny input of energy could move so much mass, but it did. I had apparently tuned things to pick up on the vibrational frequency of about 70 beats/minute.

--Chris S.

ray_parkhurst
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Re: Remedy for vibrations

Post by ray_parkhurst »

When I build a new rig, I assess its sensitivity to vibrations by looking at the Live View screen at 200% and seeing how long it takes for the LV image to settle down to the point of no movement being visible. I tap and push and bump every part of the system, the desk, the lights, etc to see what external inputs are most sensitive, and if possible work on those for improvement.

I also run the stacker without shooting, just watching the 200% LV screen as each step is made to see if the system settles down enough between shots. Sometimes a longer settling time will fix the problem, but in some cases I've seen movements that continue for a very long time, multiple seconds, and those must be fixed with system changes.

One factor that is often overlooked is air movement in the room. I find that air movement is the worst offender for movements in the system. It's not really "vibration", but it does cause system resonances to be excited. I'm always surprised at how much effect a fan or AC or whatever has on system performance.

I use continuous lighting, so my systems must be extremely rigid, with fast settling times, to get sharp images. Because of this, I keep moments as small as possible, ie I minimize the amount of mass and its distance from any pivot point. Others have already commented that your system has large moments, and it is these that you will probably need to reduce in order to improve. The fact that you are using flash, and still having problems, shows that the system moments and resonances are poorly-controlled.

Finally, coupling the camera/lens as tightly as possible to the subject holder is very important. In reality even large moments are acceptable, even irrelevant, as long as the subject moves with the camera and lens. It's not clear to me in your pictures how the subject is held in place, so I can't comment on ways to improve the "common-mode" coupling. Can you show the system configured for an actual shoot? Or perhaps I am missing something in the photos?

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