StackShot problem

[JKT]

I'm using StackShot in a vertical setup and moving the camera with it. StackShot is controlled with Zerene.

It has worked fine until last two sessions. A couple of days ago I noticed I occasionally had to manually add a few steps to the stack, but I thought it was just my mistake somewhere.

Today I was testing Mitutoyo 10x and things went to ####. I can run the rail manually and mark the start and stop positions, but when I try to run to start position, it goes way too low. Furthermore, running the stack seems to move the camera down instead of up.

Any ideas? Is something failing or am I just exceeding the capacity? My first thought was loose coupling, but then it shouldn't go down either. The capacity limit would be a surprise as I've run it with DSLR and MP-E and now there is just RP, manual lens and Mitutoyo.

[Phil973]

I shoot daily 15/20k pictures in the same conditions and face the same "trouble" i guess the first step is larger than others to compensate any mechanical wear (clearance...sorry, english is not my native language)
workaround is start early and finish late (mostly start early), it's anyway easy to discard files before stacking.......

[JKT]

Unfortunately that doesn't help when the camera travels in the wrong direction with the required small steps.

The display shows the stack progressing towards end, but in reality it gets even further away from the correct starting position.

Driving it then manually to correct start position, the numerical location has changed (on Zerene's StackShot control panel).

[Phil973]

That's mostly to avoid this kind of trouble that i don't control anymore the Stackshot through the computer
on my setup, camera control the stackshot steps, just need to adjust start & end points (via external monitor and "in camera" peaking, exposure, aperture and......go
Simplicity it's divinity....
No saying this is the way to do...but yes this is the way i do and it works absolutely fine

[rjlittlefield]

JKT, I have not heard before your particular set of symptoms.

But a couple of ideas come to mind.

First, reset the StackShot controller to factory settings, using the sequence described in the StackShot user's manual (https://www.cognisys-inc.com/downloads/ ... al_1_4.pdf , page 45)

With StackShot powered off,
hold down the DOWN button,
and apply power. Once the
splash screen shows up,
release the DOWN button.

Then, in the StackShot controller panel of Zerene Stacker, check both the Common Controls tab and the Configuration tab to be sure all the settings are correct. I cannot tell exactly what your workflow is, but in some situations inverting the sign of the step size might produce the symptoms you describe.

If in doubt, you can apply any plaintext editor to your zerenstk.cfg file (Zerene Stacker configuration) to remove all lines that begin with "AcquisitionSequencer." That will reset the ZS StackShot controller panel to default settings, without altering any of your other Zerene Stacker settings.

Finally, check the cable connections, especially between the StackShot controller and the rail motor. Usually if there's anything wrong there the motor won't turn at all, but it's always good to check.

Phil973, your strategy of start early and end late is always a good idea. However, the usual issue with first step larger than others is just a matter of the "backlash" setting. Another workaround for that is to always have the rail moving in the same direction when setting endpoints and when actually shooting. That is: move way back, move forward, set start, move forward, set end, move way back, then start shooting. In the Zerene Stacker interface, the "prerun distance" is used to automate this. See https://zerenesystems.com/cms/stacker/d ... t/backlash for more discussion about backlash.

--Rik

[Chris S.]

JKT,

Finally, check the cable connections, especially between the StackShot controller and the rail motor.

This is important advice. I had a stacking session where the motor started doing weird, unpredictable stuff. I contacted Cognisys (makers of the StackShot), and they told me to make sure this cable was tightly connected. I gave the connections a gentle push on each end, and presto, the problem went away. Turns out that while a non-connection will stop the motor, a poor connection can make the motor behave strangely. I think Cognisys has changed the connector type, since my unit was made, in order to reduce the occurrence of this.

Also, don't hesitate to contact Cognisys. Their customer service is excellent.

--Chris S.

[JKT]

Phil973,

That is what I used to do. However, controlling everything from the computer with the preview on same screen is SO much easier. Not to mention the pre-run distance rjlittlefield mentioned - that alone is reason enough to use Zerene for control.


rjlittlefield & Chris S,

I'll try those today. I hope they help. Thanks!

[Phil973]

JKT, I have not heard before your particular set of symptoms.

But a couple of ideas come to mind.

First, reset the StackShot controller to factory settings, using the sequence described in the StackShot user's manual (https://www.cognisys-inc.com/downloads/ ... al_1_4.pdf , page 45)

With StackShot powered off,
hold down the DOWN button,
and apply power. Once the
splash screen shows up,
release the DOWN button.

Then, in the StackShot controller panel of Zerene Stacker, check both the Common Controls tab and the Configuration tab to be sure all the settings are correct. I cannot tell exactly what your workflow is, but in some situations inverting the sign of the step size might produce the symptoms you describe.

If in doubt, you can apply any plaintext editor to your zerenstk.cfg file (Zerene Stacker configuration) to remove all lines that begin with "AcquisitionSequencer." That will reset the ZS StackShot controller panel to default settings, without altering any of your other Zerene Stacker settings.

Finally, check the cable connections, especially between the StackShot controller and the rail motor. Usually if there's anything wrong there the motor won't turn at all, but it's always good to check.

Phil973, your strategy of start early and end late is always a good idea. However, the usual issue with first step larger than others is just a matter of the "backlash" setting. Another workaround for that is to always have the rail moving in the same direction when setting endpoints and when actually shooting. That is: move way back, move forward, set start, move forward, set end, move way back, then start shooting. In the Zerene Stacker interface, the "prerun distance" is used to automate this. See https://zerenesystems.com/cms/stacker/d ... t/backlash for more discussion about backlash.

--Rik

Good advise, i'll revert my start & ending points in order to check if the first larger step then disappear. About controlling through Zerene (or Helicon), due to the very large amount of specimens i have to shoot daily i rather keep my workflow as light as possible, on computer i really just want stack and edit (i do that during the stacks shooting sequences....LOL)
Thanks Rik for your thought

[Phil973]

JKT, I have not heard before your particular set of symptoms.

But a couple of ideas come to mind.

First, reset the StackShot controller to factory settings, using the sequence described in the StackShot user's manual (https://www.cognisys-inc.com/downloads/ ... al_1_4.pdf , page 45)

With StackShot powered off,
hold down the DOWN button,
and apply power. Once the
splash screen shows up,
release the DOWN button.

Then, in the StackShot controller panel of Zerene Stacker, check both the Common Controls tab and the Configuration tab to be sure all the settings are correct. I cannot tell exactly what your workflow is, but in some situations inverting the sign of the step size might produce the symptoms you describe.

If in doubt, you can apply any plaintext editor to your zerenstk.cfg file (Zerene Stacker configuration) to remove all lines that begin with "AcquisitionSequencer." That will reset the ZS StackShot controller panel to default settings, without altering any of your other Zerene Stacker settings.

Finally, check the cable connections, especially between the StackShot controller and the rail motor. Usually if there's anything wrong there the motor won't turn at all, but it's always good to check.

Phil973, your strategy of start early and end late is always a good idea. However, the usual issue with first step larger than others is just a matter of the "backlash" setting. Another workaround for that is to always have the rail moving in the same direction when setting endpoints and when actually shooting. That is: move way back, move forward, set start, move forward, set end, move way back, then start shooting. In the Zerene Stacker interface, the "prerun distance" is used to automate this. See https://zerenesystems.com/cms/stacker/d ... t/backlash for more discussion about backlash.

--Rik

Good advise, i'll revert my start & ending points in order to check if the first larger step then disappear. About controlling through Zerene (or Helicon), due to the very large amount of specimens i have to shoot daily i rather keep my workflow as light as possible, on computer i really just want stack and edit (i do that during the stacks shooting sequences....LOL)
Thanks Rik for your thought

I reverse the start & ending points and it works like a breeze, the only dowside is that in the situation, it reverse my shooting workflow (Obviously....) i'll fix that by mounting the rail up side down....

[rjlittlefield]

Another workaround for that is to always have the rail moving in the same direction when setting endpoints and when actually shooting. That is: move way back, move forward, set start, move forward, set end, move way back, then start shooting.

I reverse the start & ending points and it works like a breeze, the only dowside is that in the situation, it reverse my shooting workflow

No need to reverse the start and end points. To avoid backlash, just to be sure that you start shooting while moving in the same direction as when you set endpoints. If you want to shoot while moving backward, the sequence is: move way forward, move back, set start, move back, set end, move way forward (beyond start), then start shooting.

This works well even when using only the StackShot controller. No need to involve the computer. Using the computer just makes it simpler to be sure that you have moved beyond start before you begin shooting. Watching Live View while moving the StackShot can work around that issue.

--Rik

[JKT]

Feeling silly again.

The symptoms were correctly described, but the root cause was ever so slightly off...

It so happens that the lens I was testing (Tamron Adaptall2 135 mm) extends a bit when focusing closer. It is also in such a nice condition that the focusing moves quite smoothly and easily. So the weight of the Mitutoyo and the little vibration during shooting and moving were enough to adjust focus. And this naturally also changed the required camera position for certain point to be in focus.

[rjlittlefield]

Thanks for the update.

Was this in vertical orientation, where the weight of the lens promotes focus creep?

--Rik

[JKT]

Indeed it was.

[rjlittlefield]

For me this is a common problem with some lenses. I solve it with a piece of blue painter's tape across the joint between ring and barrel. Perhaps other people have more elegant approaches.

--Rik

[JKT]

My tape wasn't blue...

This was my first infinite objective, so I had not run into that problem before.