Thanks a lot for looking into this, it'll be helpful as I build more focus stacking set-ups! :)
- Joel On Tue, Jan 18, 2022 at 5:29 PM huban...@gmail.com <huban...@gmail.com> wrote: > Literature on the Stackshot ( > https://cognisys-inc.com/stackshot-macro-rail-package.html ) says its > smallest step size is 2 micrometers. > > The smallest step a 9600 DPI scanner (Canon 9000F) needs to do is 2.64 > micrometers. > > The smallest step a 4800 DPI scanner (Canon 8800F) needs to do is 5.29 > micrometers. > > Of the three, the Stackshot has the smallest steps, at least on paper. > > Plus the Stackshot has a sturdy rail and mounting system that is sized to > take the weight of a mirrorless camera + lens. In comparison a scanners > rail system is weaker, plus it is not sized to support the extra weight of > a camera and lens, plus mounting is more problematic. > > Therefore, on paper, your arrangement of using these scanners to move your > camera does not offer benefits compared to the Stackshot. > > What I would recommend you instead is to find an USB-attached stepper > motor controller that you can easily direct with text commands from Linux. > That you can then trivially make it do steps from a command line. Trinamic > is a german company who does very nice work on providing very smooth > movement control for stepper motors (and also BLDC motors). They - or > someone using their parts - might have something that allows you to control > it from a serial port that you can then attach to Linux (I am assuming > Linux is a requirement for you?). > > As for mechanism, you might find someone has made a mechanism for this > exact purpose (focus stacking is an easy-to-implement but high-value niche > hobby or research project). Or if you don't, then it is not terribly > difficult to find mechanical parts normally used by hobbyists for building > home CNC machines, and whip up a linear actuator mechanism (rail + > carriage, pushed by a threaded rod turned by a stepper motor). With a > little engineering work, using precision parts and fine microstepping > enabled by Trinamic drivers and stepper motors, you might perhaps be able > to achieve even smaller step sizes than your factory-made Stackshot. > > 2022.01.14. 17:35 keltezéssel, Joel Penner írta: > > Hi everyone, > > Thanks for the feedback everyone! Thanks for the info Povilas about the > genesys backend. I do have some scanners that use it. Would you have some > pointers for how to issue those commands to a scanner via the backend? > > You're right Ralph, it might be easier to control them directly. I had > thought of the buffer approach as well, maybe I'll experiment with that. > > Thanks, > > Joel > > On Tue, Jan 4, 2022 at 12:47 PM Ralph Little <skelb...@gmail.com> wrote: > >> Hi, >> >> On 2022-01-04 9:05 a.m., Joel Penner wrote: >> > Hello, >> > >> > I am doing microscopic focus stacking with mirrorless cameras. I have >> > a Cognisys Stackshot rail that I am doing this with, but I also have a >> > bunch of Canon 9000F & 8800F scanners, so I am wondering whether I >> > could use the precision these devices have to move a camera forward by >> > small increments. >> > >> > I have already been experimenting with attaching a stepper motor to a >> > microscope, controlled by a Big Easy Driver and a Raspberry Pi. This >> > person used a scanner for focus stacking by connecting a scanner motor >> > to an external driver: >> > >> > >> https://petapixel.com/2013/01/24/focus-stacking-macro-photographs-with-a-hacked-flatbed-scanner/ >> > < >> https://petapixel.com/2013/01/24/focus-stacking-macro-photographs-with-a-hacked-flatbed-scanner/ >> > >> > >> > This would work for me, but would it be possible to manually move the >> > scanner imaging head with SANE and the scanner's firmware and >> > circuitry? Basically, I would need SANE to move the scanner imaging >> > head forward by a tiny increment, pause for a few seconds for the >> > camera to take a photo, move forward again and so on. I just need >> > total control of where the scanner imaging head is moved to and how >> > small the increments are. My goal is to use this rig to do timelapse >> > microscopic focus stacked images of plant growth. >> > >> > Ideally, the scanner imaging head light would be turned off too but I >> > could also use tape or disconnect the LED array. I have other scanner >> > models as well if the firmware or drivers of these Canon scanners >> > isn't suitable. >> > >> > Any ideas would be appreciated, thanks! >> > >> > Joel >> >> This *might* be possible if the usual movements that the scan head would >> make are sufficient for your need. >> >> What you can definitely do is to arrange for the scan head to move from >> home quickly to a start position and have the head move more slowly to >> an end position (speed depending on the requested resolution) after >> which the head would usually return to the home position. By controlling >> the rate at which the scan data is received from the machine, you might >> also be able to get the scan head to pause when the scan data buffer is >> full. Within the SANE API, those are really your options. >> >> Some scanners have a more high-level control, such is the case with the >> protocols that are handled by the pixma backend. I see that Povilas has >> answered regarding the genesys backend and the scanners that are >> supported there. The genesys controllers provide much more control over >> the hardware. Even then, using the SANE API is going to be quite >> limiting, but you could use the genesys code to directly control a >> genesys scanner. >> >> Honestly, you might be better off harvesting the components from the >> scanner and using an arduino or something. ;D >> >> Cheers, >> Ralph >> > >
