steps in StackShot

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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soldevilla
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Joined: Thu Dec 16, 2010 2:49 pm
Location: Barcelona, more or less

steps in StackShot

Post by soldevilla »

Hi.

I'm still learning to photograph minerals. Working with a 40x is not easy, for me.

With this lens of x40 my Stackshot has reached its limit. The scale of movement must be in steps and I can not find how to regulate the steps, because the regulation goes from 6 steps (which is a bit too big) to 1 step. I would like to be able to work 3 or 4 steps, but I do not find how. Is there any possibility of doing that?

Thanks

A x40 picture of clorargirite in lavendulana, taken some days ago.
Image

Chris S.
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Post by Chris S. »

Looks like a very nice start in minerals! :D

Is the firmware in your StackShot current? On my StackShot controller, I can adjust in single step increments. My memory is fuzzy, but I believe I recall a time, years ago, when the minimum adjustment was five increments. I contacted Cognisys for advice, and they told me to update my firmware. This was very easy to do.

--Chris S.

Lou Jost
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Post by Lou Jost »

That's very nicely lit!

mawyatt
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Location: Clearwater, Florida

Post by mawyatt »

Chris S. wrote:Looks like a very nice start in minerals! :D

Is the firmware in your StackShot current? On my StackShot controller, I can adjust in single step increments. My memory is fuzzy, but I believe I recall a time, years ago, when the minimum adjustment was five increments. I contacted Cognisys for advice, and they told me to update my firmware. This was very easy to do.

--Chris S.
Chris,

Could you update the firmware without having to send the controller back to Cognisys? I have a very old Stackshot system and thought I have to send the controller back for the update.

Best,

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

Chris S.
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Post by Chris S. »

mawyatt wrote:Could you update the firmware without having to send the controller back to Cognisys? I have a very old Stackshot system and thought I have to send the controller back for the update.
Mike,

It depends on the vintage of your StackShot controller. Mine has a USB port (on the same side of the box as the other cords, to the left of the power jack), so consumer-updateable firmware is both easy and supported. Some controllers earlier than mine did not have USB ports. As I recall, these did need to go back to Cognisys for firmware updates.

This said, if your unit lacks USB, you might ask Cognisys how they address these early units. Given your knowledge of electronics, it might be something you could do yourself. My controller originally had an issue that Cognisys avoided in later units with additional internal grounding. They offered to add it to my controller for me, and also told me how to do it myself if I preferred. (I did it myself--trivial job.) I appreciate a company that will support a customer taking the cover off the box.

--Chris S.

rjlittlefield
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Post by rjlittlefield »

For updating old StackShot controllers that do not have a USB interface of their own, Cognisys has a "reflash cable" that apparently plugs into the computer's USB port and the StackShot's shutter port.

See https://www.cognisys-inc.com/store/reflash-cable.html .

--Rik

soldevilla
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Joined: Thu Dec 16, 2010 2:49 pm
Location: Barcelona, more or less

Post by soldevilla »

Thanks for the answers.

I have written to Cognisys because I can not find the firmware upgrade on its website. I find the cable very expensive (adding transport to Spain) to use it only a few minutes, but the improvement seems important...

rjlittlefield
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Post by rjlittlefield »

soldevilla wrote:I find the cable very expensive (adding transport to Spain) to use it only a few minutes, but the improvement seems important...
Agreed on both counts.

There is what appears to be a zero-cost solution to your problem. It is documented at http://www.photomacrography.net/forum/v ... 8570#68570 , a trick from 2010.

The trick involves "creative misrepresentation" of the mechanical setup, to work around the completely artificial limitation of 5 microsteps in the user interface.
What I have done here is to lie to the controller about the scale of my physical setup. Instead of the actual 200 micrometers per revolution, I have claimed that there are 200 millimeters per revolution. Then I have set my focus step to be 0.5 "millimeters". The controller happily does the division, figures out that I want 1/400 of a rotation, and turns that into the requisite 8 microsteps to drive the motor.
Those particular numbers related to having the StackShot motor drive a microscope focus block, but the same type of trick would work just as well with the basic rail.

All that said, with the old firmware there is no "high precision" mode, so the controller simply has no way to reliably make small movements. For that, see the discussion at http://www.photomacrography.net/forum/v ... hp?t=16323 .

For fine work, you should get your controller updated.

--Rik

soldevilla
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Joined: Thu Dec 16, 2010 2:49 pm
Location: Barcelona, more or less

Post by soldevilla »

Thank you.

The good people of Conigsys have already sent me the link to the upgrade. I will try to install it. Anyway, I do not rule out changing the motor for another with a planetary gear that "multiplies" by 50 the precision. I already know that the limit of precision is determined by the mechanical precision of the components, but since I always work in a vertical position, I hope that gravity will help me to minimize those errors. Everything depends on the result of the upgrade

rjlittlefield
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Post by rjlittlefield »

soldevilla wrote:since I always work in a vertical position, I hope that gravity will help me to minimize those errors.
Gravity definitely helps, especially if you step by moving upward so that all forces act to keep the same face of the screw engaged.

--Rik

Chris S.
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Post by Chris S. »

rjlittlefield wrote:For updating old StackShot controllers that do not have a USB interface of their own, Cognisys has a "reflash cable" that apparently plugs into the computer's USB port and the StackShot's shutter port.

See https://www.cognisys-inc.com/store/reflash-cable.html .
soldevilla wrote:I find the cable very expensive (adding transport to Spain) to use it only a few minutes, but the improvement seems important...
I agree on both counts--that this cable is useful for people with older StackShot Controllers, and that this cable is expensive, especially after international shipping and import taxes. Not that I fault Cognisys--it probably costs a lot to manufacture a high-quality cable in the small quantities they likely need. And they have no control over international shipping or taxes.

This said, I think this cable would be a very easy, inexpensive do-it-yourself project. We know, from Cognisys' picture and described use of this cord, what connectors are needed at each end. These connectors are easy to obtain and cheap. All we need to know is how the two ends are connected. The folks at Cognisys are friendly and supportive, so might well supply this information if asked. But if anyone on our forum who has this cable will check the electrical continuity between the ends, we can generated this information ourselves.

Here is a picture of the ends of this cable, snipped from the Cognisys Website. The top end looks like a standard RCA cable, which has two electrical contacts--the inner pin and the outer barrel. The bottom end is a standard USB type A cable, which I'll describe below.

Image


Here is information about the USB connector. As is clear, only two contacts on the USB connector carry data. (Power to the StackShot Controller is supplied by the entirely separate power connector.) These USB data contacts are the center two among the four contacts on the USB connector. Since one of these data contacts must connect to the center pin of the RCA contact, and the other data contact must connect to the outer barrel of the RCA cable, anyone who has this cable could easily tell us which one connects where by simply testing the continuity of each with a multimeter.

(Below excerpted from Leadsdirect).
Image
Image


Any takers? If so, you'll likely leave us with a recipe for making these cables ourselves.:D

--Chris S.

PS--Am tired and likely making mistakes; corrections welcome. :D

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