Features for a motorized stage (focus stacking)

[chris_ma]

our communication tells about both of us.
jac

Indeed it does.

this is one of the most helpful forums I've ever encountered, if you have the feeling people don't want to help you or are being rude then I suspect you're doing something wrong.

[Macro_Cosmos]

Judging from the use of "absolute on-axis accuracy", it's really clear that the author listed parameters from Thorlabs without actually understanding them and how they are applicable to different systems.

[jac B]

this is one of the most helpful forums I've ever encountered, if you have the feeling people don't want to help you or are being rude then I suspect you're doing something wrong.

chris,
Are you neglecting lothman’s behaviour in this topic by referring to a forums course of events?
That this is a helpful forum and that forum members want to help is not in question, if you arguing that my (one’s) feelings are wrong, then I suspect you’re doing something wrong.
jac

[jac B]

... there's no reason to buy Thorlabs' motorised rails. They require coding, they require an expensive K-cube controller ($800 I think) and the power supply is also $300, you need a controller/interface that goes beyond "move rail to POS A", you code your own. Want the controller to also take pictures? Code it yourself using a relay circuit. You're looking at a good $2000 to get something basic running when the Stackshot (and wemacro etc) has everything already done for you. PI is several steps above Thorlabs, so I'd times that $2000 by 5. ...

Hi,
I raised this topic (as newbie) because a motorized stage, like StackShot with good references, gave the impression not to be fully specified (parameters) by the manufacturer, in an way that other motorized stages, like Thorlabs, Physike Instrumente (PI), seemed to be specified (parameters).

The comment raised for me the question: are there other (fully) specified (parameters) (plug-and-play, P&P) motorized stages in between the (P&P) StackShot and (Do-It-Yourself) Thorlabs, PI?
jac

[Macro_Cosmos]

Hi,
I raised this topic (as newbie) because a motorized stage, like StackShot with good references, gave the impression not to be fully specified (parameters) by the manufacturer, in an way that other motorized stages, like Thorlabs, Physike Instrumente (PI), seemed to be specified (parameters).

The answer to your confusion is very simple.

Thorlabs and PI stages are used for scientific and high end industrial purposes. Our lab has several. We care about SOME of these parameters because of repeatability of results and control.
Stackshot is an prosumer photography oriented product that's designed for photography purposes. Close to no one care about the parameters you've listed besides perhaps resolution and backlash. Out of everyone that use macro rails, a tiny tiny percent requires a step size of anything smaller than 1um. Several of us do have Mit's 50x, but I dare to suggest that most don't use it often. At least the gallery's new posts give me such an impression. The well-off amateur has a 5x and 10x Mitutoyo, the dedicated one has a 20x.

This is also why RRS doesn't give these numbers for their pricey macro slider, same goes with Neewer for the matter. I hope you understand now, the target audience matters. To get these numbers, Stackshot must either have a bunch of higher end metrology instruments or send a batch off for testing (especially flatness!). It's a $500-$800 rail for focus stacking, why should they do that when basically nobody cares about those parameters outside of resolution?

Some of best companies and labs use Thorlabs, Newport and PI (etc) stuff for R&D.
Notice "Stackshot" isn't in the list. They can test their rails and spew out a datasheet, but I'd rather pay $600 than $2000.

The comment raised for me the question: are there other (fully) specified (parameters) (plug-and-play, P&P) motorized stages in between the (P&P) StackShot and (Do-It-Yourself) Thorlabs, PI?

Nothing from Thorlabs or PI is plug and play. It's plug, buy all my expensive hardware, code your own stuff, hit a bunch of bugs, repeat indefinitely and in agony, and "play". (I suck at coding, I'll admit that)

Or, you can adapt different motorised stages to the Stackshot controller. This makes it "plug and play" legitimately. Any 2-phase bipolar motor can be used with the stackshot. The Thorlabs MTS25-Z8 ones we have should work, I am not 100% sure. I do have a unit with me, but I've found no reason to use it for photography.

That said, you should use google advanced search and look up "THK" on the forum. THK rails can be outfitted with an appropriate NEMA-17 stepper motor. THK's website has a load more specs than Stackshot.
https://cognisys-inc.com/focus-stacking ... motor.html

For THK rails, the KR26 is popular among us: https://www.ebay.com/sch/i.html?_from=R ... on=4&rt=nc
A full spec sheet can be found via a search engine.

[jac B]

Hi Macro_Cosmos,
Thank you.
Regards, jac

[mawyatt]

Some of best companies and labs use Thorlabs, Newport and PI (etc) stuff for R&D.
Notice "Stackshot" isn't in the list. They can test their rails and spew out a datasheet, but I'd rather pay $600 than $2000.

The comment raised for me the question: are there other (fully) specified (parameters) (plug-and-play, P&P) motorized stages in between the (P&P) StackShot and (Do-It-Yourself) Thorlabs, PI?

Nothing from Thorlabs or PI is plug and play. It's plug, buy all my expensive hardware, code your own stuff, hit a bunch of bugs, repeat indefinitely and in agony, and "play". (I suck at coding, I'll admit that)

If you watch eBay sometimes you can find the PI stages like the P601K or P603K, these are superb devices and have built-in ultra-precison strain gauges for use in closed loop systems. We've developed custom controllers for these stages, from the original open loop to the latest closed loop types, and they don't cost more that a Stackshot controller to build. The control code has been done in Python on a Raspberry Pi and does not require one to be a software guru (I'm certainly not one!!!), and is easy to adapt for custom specific use. If you search here using PI Stages you can find lots of information.

That said, you should use google advanced search and look up "THK" on the forum. THK rails can be outfitted with an appropriate NEMA-17 stepper motor. THK's website has a load more specs than Stackshot.

Yes the THK linear rails are really good!! The KR20 is also popular and has a 1mm thread pitch, coupled with a 400 step motor this is really a great setup for a precision stepper based focus rail system. If you couple this with the Trinamic type controller/drivers based upon the Arduino or Raspberry Pi then this becomes as good as I've seen for a stepper based system regardless of cost. Search on here for Trinamic for more details and information.

So there are a few options for the DIYer interested in Piezo Stages or Precision stepper motor based systems that can be accomplished by someone with modest software and hardware skills (PI stage closed loop controller/driver is much more involved tho, but it's already been done (building a couple controllers now for a university research project), so not that intimidating).

BTW the basic control for the Trinamic based controller/driver is very easy,. This is open loop and simply tell the controller where you want to go and the controller manages all the details including the velocity/acceleration/position profiles for very quick but ultra smooth operation, no overshoot, nor undershoot, just smack on the mark every time with the THK rails. Here's a snip that someone just sent that is using the 3 axis XYZ Trinamic for rotational work, with 1 axis as the rotational axis.
"I'm not sure if you remember me or not, but I purchased an XYZ controller from you a few months back and had the intention to modify for a rotational axis as well for stacked rotation videos. I just wanted to say thanks, it has been working great and I've had no problems. Coupled with the kr20 and a nema14 on a rotation stage the motion is buttery smooth fresh out of the camera, it's really been amazing! I've probably put a good 200k frames on the controller usually 10-20k at a time since December with no issues"

The PI stage controller is closed loop so just tell it where to go (position is nm, um or 16 bit DAC count) and the closed loop system manages everything and drives the stage to the exact location very quickly.

Best,