StackShot Positioning

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Lindaavitt
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Location: Austin, Texas

StackShot Positioning

Post by Lindaavitt »

I have the basic 100-mm StackShot and will be using either a 100 mm macro lens or the ME-65 lens on a 5d mark iii. I'd be surprised if any of my subjects are ever over 2 cm deep.

With that setup, to minimize any sort of wobble or torque on the rails, is there an optimum area I should use? By that I mean, should I set up the stack in the middle of the rails? Towards either end? Does it matter?

Thanks!
Linda 8)

Lou Jost
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Post by Lou Jost »

Good question, I haven't seen anything about that.

ChrisR
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Post by ChrisR »

On mine there's a bit of wobble coming from the motor end. So at the other end, the rails are held, and the source of the wobble is further away.

With the 100mm you could be using it for something like a flower, more than 2" deep, but yes, the field of view would change by about a third as well as perspective altering, so it's not ideal at all.
Chris R

JOSE MIGUEL SOLA
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Post by JOSE MIGUEL SOLA »

And because you do not adapt the object to the rail and fix the machine that weighs more, the oscillations will be less noticeable?


¿Y porque no adaptas el objeto al carril y fijas la máquina que pesa mas, las oscilaciones se notaran menos?
José Miguel Sola
Granada- Spain

mawyatt
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Post by mawyatt »

Like Chris I found that operating near the Stackshot rail end produced less wobble. Also, using Off Axis Loading helps reduce rail wobble and backlash.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

ChrisR
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Post by ChrisR »

JOSE MIGUEL SOLA wrote:And because you do not adapt the object to the rail and fix the machine that weighs more, the oscillations will be less noticeable?


¿Y porque no adaptas el objeto al carril y fijas la máquina que pesa mas, las oscilaciones se notaran menos?
It's not really that, The wobble seems to come from the eccentricity in the screw thread.
No exactamente. La oscilacion parece ser debido a una excentricidad, en la rosca de tornillo. Quizas mi tornillo este doblado!
Chris R

mawyatt
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Post by mawyatt »

ChrisR wrote:
JOSE MIGUEL SOLA wrote:And because you do not adapt the object to the rail and fix the machine that weighs more, the oscillations will be less noticeable?


¿Y porque no adaptas el objeto al carril y fijas la máquina que pesa mas, las oscilaciones se notaran menos?
It's not really that, The wobble seems to come from the eccentricity in the screw thread.
No exactamente. La oscilacion parece ser debido a una excentricidad, en la rosca de tornillo. Quizas mi tornillo este doblado!
And the very slight play in the rail bearings.

Moving to the near end of the focus rail reduces the screw thread wobble effects but not the bearing play wobble effect, the Off Axis Loading helps more with this.

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

Lindaavitt
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Location: Austin, Texas

Post by Lindaavitt »

So I’m sure what you’re all saying. . . What exactly is off-axis loading (as it applies to the StackShot)?

Thanks for putting up with my newbie ignorance! You all are/have been so helpful!

Linda 8)

mawyatt
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Post by mawyatt »

Linda,

It's a technique to help with the focus rail wobble utilizing rubber bands pulling on the focus rail at an angle that off the optical axis. See:

https://www.photomacrography.net/forum/ ... is+loading

Best,
Research is like a treasure hunt, you don't know where to look or what you'll find!
~Mike

Lindaavitt
Posts: 23
Joined: Mon Dec 18, 2017 7:49 am
Location: Austin, Texas

Post by Lindaavitt »

Oh, sure. I’ll try it.

Linda 8)

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