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Bratcam goes electric--StackShot controller incorporated
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Chris S.
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Joined: 05 Apr 2009
Posts: 2815
Location: Ohio, USA

PostPosted: Sun Dec 12, 2010 5:20 pm    Post subject: Bratcam goes electric--StackShot controller incorporated Reply with quote

I recently added a motorized stepping stage to the Bratcam, along with a StackShot controller to run it. This is working very well—the instrument now automatically handles even my persnickety 60x lens with ease (I have it set for .75 micron steps with this lens, but it could easily go finer). The impact of this is enormous: Images that previously took hours of tedious knob turning now take just a minute or two; set them and go do something else while the machine performs the stack. I’m far from the first to automate my rig, but for those interested, I'll document it here. Warning—it’s a long post. First, the hardware; then a discussion of integrating a StackShot controller.

For those not familiar with the Bratcam in its earlier, manually-driven form, here is the link to the detailed description posted about a year ago: Manual Bratcam.

Below is an image of the overall setup. I shoot tethered, which lets me see each capture on a large screen. For this illustration, I pulled up an image of a not-too interesting leaf mold, the subject of which I still had available to stick in front of the lens. The image was actually shot with a 60x objective, not the 10x objective shown below (oops). The subject lighting has been omitted for simplicity.




Here is a shot of the prior, manual, incarnation of the Bratcam. The orange line indicates the range of coarse adjustment available for placement of the camera stage, via travel along an Arca-Swiss compatible plate from Chris Hejnar. This is important because I use the rig with a variety of lenses with quite different working distances, with subjects ranging from the size of my hand down to the microscopic. (Often, I want to start with a “portrait” shot of something like a moss, then move in and take detail shots of specific features.) Since the entire camera stage—and not just the portion adjusted by the microscope dial—moves during initial positioning, I needed to mount a stepper motor so as to move with it. (In the current photos, you may notice that the old Hejnar plate has been replaced with a longer and slightly thicker one, also made by Chris Hejnar; I wanted longer travel without having to loosen screws to move the plate.)




I was going to build something to do this myself, but Lothman posted an image of a surplus unit he’d purchased on eBay. It seemed like precisely what I was planning to build, so I wrote the vendor to see if he had another. He did, and put it on eBay for me; I purchased it immediately. It is based on a focusing block that I think came off a Nikon Macrophot-2 or similar Nikon microscope, and was perhaps an aftermarket modification.

Here is the stepped microscope stage as it arrived from the vendor.




The image below shows the unit after some modifications (including replacement of the stepping motor) which I’ll discuss later. Note here that it has the stepping motor nicely mounted at a fixed (though slightly adjustable) distance from the microscope focus assembly. Also, the connection between motor and focusing assembly is made via timing belt. Benefits of a timing belt rather than a direct couple include reduced need for critical alignment of motor and focusing assembly, avoidance of transmitted vibration, and the ability to change gearing by replacing the timing pulleys and belt (not that I’ve found this necessary).




Below is a detail important for anyone wishing to build something similar—note the small screw for adjusting belt tension.




Don Wilson, my fabricator, helped me modify the unit for my needs. It is shown below, post modifications. (I’ve turned the unit around from the prior pictures, because individual elements are easier to see from this angle—so if anyone notices that the unit is facing backwards, it is.)

A: Four-inch quick release clamp from Kirk Enterprises

B: Top mounting plate made by Don Wilson

C: The fine and coarse focus knobs of the microscope stage on which the unit is based. Both are useable, though the fine one also turns the motor. That hasn’t actually hurt anything, but I avoid it. (I’m aware that this can send some current into the controller, though Cognisys has tested for this and not found it to damage anything.) The coarse knob does not turn the motor, so I use that one freely. Fine focus is easily done by pushing buttons on the StackShot controller. However, with an automated approach, I do a lot less fine focusing, since I like to prefer to shoot a few extra frames before and after the useful portion of the stack just in case; so now I just rough it in and hit “go.”

D: A portion of the purchased surplus unit—probably didn’t need to label this.

E: Bottom mounting plate made by Don Wilson

F: Another Four-inch quick release clamp from Kirk Enterprises. This one is mounted upside down to clamp onto rail "G," described below.

G: A 17.5-inch long, 3/8" thick Arca-Swiss style dovetail plate made by Chris Hejnar. He custom-made this one for me, but once he has the CAD file for something, it generally enters his “available on request” inventory. I use the Arca-Swiss standard in certain portions of the rig because it allows me to quickly pull the camera stage off the Bratcam for use on a tripod, and to interchangeably mount a camera, lens, or bellows on the rig. I wanted the rig to be modular.




Now, about the StackShot controller—what a gem! If you are considering automating your own rig, I highly recommend using one of these. Paul DeZeeuw, at Cognisys (the company that makes and sells the StackShot), is exemplary. He deserves a much stronger word of praise, if I could think of one—vendors simply don’t get any better than this. He helped me find a stepper motor of the size I needed for my rig; then he ordered it, terminated it appropriately for connection to the StackShot controller, and tested it.

My original unit came with a five-phase stepper motor, which is hard to drive. We replaced it with a two-phase motor compatible with the StackShot. This motor has .9 degree full steps, which gives me 400 full steps per revolution (most stepper motors give 200 full steps per revolution). The StackShot controller permits microstep resolution of 1/16th full step. My rig moves .015625 microns per microstep. One might have expected the StackShot controller to be cumbersome to calibrate, since the distance the camera moves per motor revolution is unique to my rig, and for that matter, so is the motor. But setting this was trivially easy, requiring just a couple of minutes.

The StackShot controller is very well thought out, and I’m finding it a pleasure to use. I have the step increment pre-entered for each of my lenses (very easy to do), so that taking a stack involves just a few quick steps:

1. Scroll down the menu to the “program” I saved for the lens I’m using.

2. Position the camera at the starting point for the stack (in my workflow, this is the point closest to the subject—I always work from near to far) and press a button to let the controller know that this is the start point.

3. Move the camera to the end point for the stack, and push a button to tell the controller that this is the end.

4. Hit the start button and walk away.

A couple of the nice touches are worth mentioning. If the stack has started, and I think of something I’d like to change, a single button aborts the process. Even better, another button push lets me redo an aborted or completed stack from the beginning. So if I want to change the lighting, I can do so and re-run the stack very easily.

Forward and backward buttons on the StackShot move the camera very smoothly and efficiently. In my rig, I can also use the coarse focus knob freely so I use it for rough positioning. I use the StackShot for fine positioning as well as stacking. The speed and ramp-up time are adjustable.

I already had an older and rather robust controller called a “SmartStep,” but when I started to program it, I realized that I’d much rather be taking pictures than learning motion control programming. Given how well thought-out the StackShot controller is, it is a zero-regret purchase. There will soon be options to operate the StackShot controller via computer (using software from StackShot or using Zerene Stacker). When that happens, I’ll likely be even happier.




Sometimes I use a camera and macro lens on the rig, without a bellows. Here is an image of the Bratcam in one such configuration. The camera is mounted on an adapter block made for me, not surprisingly, by Don Wilson. The main purpose of the block was to compensate for the removal of the bellows, and get extra height for tall subjects, but I figured that I might as well get some additional working distance while I was at it. The block consists of two Hejnar plates mounted on solid aluminum. The plates are adjustable with screws, so that if I ever need a few more inches of working distance, I can get them. Despite the fact that I have, for this demonstration, cantilevered the camera pretty far out, it is quite stable.



There are still some things on the “to do” list.

1. Dress the motor cord to prevent strain.

2. Perhaps add safety stops (so far, not necessary, but probably prudent).

3. Ask Don Wilson to raise the 17.5-inch Hejnar plate a bit—taller specimens require that I fully lower the subject stage, and sooner or later, I’ll have a subject that’s just a bit too tall. Alternatively, I could use a couple more adapter blocks in various thicknesses.

4. Ask Don to convert the vertical pipe that holds the subject stage from a one-piece unit into a two-piece unit. Sometimes I want all the vertical travel I have; other times I’d like to have a shorter pipe to make it easier to place a background and permit me to swing the subject stage 180 degrees for more working distance (I could do it now, but the pipe would block the camera’s view). Don is confident that he can cut this pipe and add a threaded rod that will let me rejoin the two pieces as needed, without sacrificing stability. I’ve been waiting until other height issues were worked out (this motorized stage, for example, is not as tall as my old manual one) before deciding where to make the cut.

To anyone who has made it this far, sorry for such a long post. When I’m studying other people’s rigs, I appreciate details—so maybe someone else would, too.

--Chris Slaybaugh
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The Bratcam: http://www.photomacrography.net/forum/viewtopic.php?t=8247


Last edited by Chris S. on Sun Dec 12, 2010 11:07 pm; edited 3 times in total
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Will Milne



Joined: 23 Sep 2008
Posts: 82
Location: Manitoba Canada

PostPosted: Sun Dec 12, 2010 5:59 pm    Post subject: Reply with quote

Hi

Looks like you're having fun building up your rig. I notice you are using Nikon cameras. I'm assuming your using Mirror Up for each image in the stack sequence - what are you using for a delay time between each being taken?

I've been thinking of adding a Stackshot to control my Olympus BH- BHA scope for deep stacks and am using a Nikon D200 as the image cpature device. Objectives are CF Plan Nikon 4x/10x/20x/40x direct projected.

Will
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Chris S.
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Joined: 05 Apr 2009
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Location: Ohio, USA

PostPosted: Sun Dec 12, 2010 6:23 pm    Post subject: Reply with quote

Hi, Will,

Yes, there is a Nikon D200 dedicated for use on my rig. I have it on AC power, by the way, because tethering it really drains the battery. I do indeed use mirror-up, and also shoot in a darkened room with the flash firing at the end of the exposure (rear-curtain flash) to avoid any vibration associated with the shutter curtain. As has been pointed out, this is almost certainly overkill, but I prefer a robust protocol so that I can just forget about it. A second or so of mirror-up and another of open shutter would likely be plenty.

Right now, I use a three-second mirror-up period and a two-second shutter speed, with the flash making the actual exposure at the end. I'm sure this is huge overkill, but I haven't tested to see what the minimum delays would be. I also use a five second settling period before the mirror goes up, but this is mostly to give me a total of ten seconds for my flashes to recharge. They don't need this at first, but in a deep stack, the batteries can run pretty low. I'll likely change this when I move to using flash running on AC power. The "Bratlight" is the next project.

Your Olympus scope and Nikon objectives, projecting on a D200, surely work great. And if you automate with a StackShot controller, your deep stacks will be much easier. Lucky you--you can get by with a much simpler coupling than I used, since your focus knobs are merely rotating, not changing linear position.

Cheers,

--Chris
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ChrisLilley



Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)

PostPosted: Sun Dec 12, 2010 7:56 pm    Post subject: Reply with quote

Chris,

Thanks for the clear and detailed explanations and photographs. They are very helpful and much appreciated.

(I hadn't realized before that the lower Kirk clamp is upside down. I had wondered why you use an arca rail; now it makes sense).


Last edited by ChrisLilley on Mon Dec 13, 2010 6:42 am; edited 1 time in total
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Chris S.
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Joined: 05 Apr 2009
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PostPosted: Sun Dec 12, 2010 8:06 pm    Post subject: Reply with quote

Chris, you're right--the orientation of that Kirk clamp wasn't clear in this post or the prior one. I've just now edited them both as a result of your observation. Thanks!

Glad you found it interesting--thanks for reading it.

Cheers,

--Chris
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OzRay



Joined: 13 Aug 2009
Posts: 198
Location: Melbourne, Australia

PostPosted: Sun Dec 12, 2010 8:49 pm    Post subject: Reply with quote

You're absolutely right about Paul and Chris. I've been ordering motors and plates from both and the level of support (for someone located in Australia) is outstanding. I'm motorising my Olympus Electric Macroscope and I'm also in the process of building a vertical setup (hopefully both completed by late Jan 11). Without the support of Paul and Chris, the entire job would have been so much more difficult, if not impossible.

Cheers

Ray
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ChrisLilley



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Location: Nice, France (I'm British)

PostPosted: Mon Dec 13, 2010 6:45 am    Post subject: Reply with quote

It occurs to me that, if the subject stage mounting post was shorter (at the level of the rotary stage, say) then for occasions where you need longer working distance the entire subject stage could be rotated on the post 180 degrees, placing it further from the camera rail.
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Chris S.
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PostPosted: Mon Dec 13, 2010 4:19 pm    Post subject: Reply with quote

Chris, you perhaps missed item number four on my "to do" list (how could you, in such a short post? Smile ) It's something I was waiting to do until I knew the final height of the stepped stage.

Ray, I have visions of Chris H. machining brass plates for you, and Paul Z. looking forward to seeing a steampunk version of his controller.

--Chris
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ChrisLilley



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PostPosted: Mon Dec 13, 2010 5:10 pm    Post subject: Reply with quote

Guilty as charged.
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Craig Gerard



Joined: 01 May 2010
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PostPosted: Mon Dec 13, 2010 6:06 pm    Post subject: Reply with quote

Chris,

Another excellent post. The details are appreciated.

I get the feeling, sooner or later, you will find some of the offerings from Velmex to be applicable to your configerations. It may be worth perusing their catalogue for some ideas.

PM sent.

Craig
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OzRay



Joined: 13 Aug 2009
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Location: Melbourne, Australia

PostPosted: Mon Dec 13, 2010 6:14 pm    Post subject: Reply with quote

Chris S. wrote:
Ray, I have visions of Chris H. machining brass plates for you, and Paul Z. looking forward to seeing a steampunk version of his controller.

--Chris


When I sent Paul a photo of the OEM, I had to explain how it all worked. I think they all loved the concept once they got their head around it and are waiting to seen the final results. I just wish I had access to machine shops and parts suppliers like you do in the US, as things would be so much easier.

Cheers

Ray
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AndrewC



Joined: 14 Feb 2008
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Location: Belgium

PostPosted: Tue Dec 14, 2010 2:33 am    Post subject: Reply with quote

Hi Chris,

Looking good Smile Couple of suggestions / comments:

1) For your riser block: why bolt some AS plates on to a block of aluminium ? You have the luxury of a "fabricator" - just ask him to mill some appropriate grooves (a 90deg blunt nose bit works fine) along the top and bottom of the side faces ? That's what I do for making riser blocks - I didn't use to need them but when I moved away from using a bellows to fixed length tubes and/or helicoids I "lost" several cm's of camera height.

2) Long focus distances: I often wondered why you had such a long riser post (assumed you were just covering all eventualities). I sometimes do the exact same thing as you're considering to get an extra 20cm of space - just rotate my subject stage around the vertical post and point it "backwards"
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Joaquim F.



Joined: 28 Apr 2010
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Location: Tarragona, Spain

PostPosted: Tue Dec 14, 2010 3:55 pm    Post subject: Reply with quote

Impressive Rig, that is at very high engineering level!Shocked
Thanks for sharing!

Greetings

Joaquim
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Chris S.
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PostPosted: Tue Dec 14, 2010 11:04 pm    Post subject: Reply with quote

Craig, thank you, both for your comments and your advice to look at Velmex. (PMs exchanged.) You’re right—Velmex turns out to be very interesting. I was aware of a couple of their products from discussions on this forum, but had no idea of the extent of their line. The “examples” portions of their site are well-worth looking at—they are like “idea fertilizer.” Now, I do indeed have ideas for improving the Bratcam with their products. Also, I have a couple other projects in the back of my head that could easily involve Velmex components.

Andrew, as to your first comment about simply machining the aluminum instead of screwing on Arca-Swiss plates, I have to admit that I simply hadn’t thought of it—though it seems kind of obvious once you point it out. In my defense, I already had the Hejnar plates, and was just looking to connect them with some space in between. At first, Don Wilson and I expected to use square steel tubing. The unavailability of this material in the proper dimensions induced us to go with solid aluminum. And having the A-S plates attached with machine screws does allow me to extend the length of the riser block by several inches if needed, by moving the A-S plates out. But if I had to do it over again, I might well do it as you’ve suggested. Live and learn.

As for the post that holds the subject stage, yes, I’ve long been meaning to trim it down, but have been waiting until I had some other issues handled that I knew would affect its optimal length. If I add a Velmex slider below the Hejnar plate (in which case I’d use a much shorter Hejnar plate), the camera position will rise. Similarly, I really don’t much like the Newport translation stage that I have as part of the subject stage—its stiction and backlash make it far inferior to my microscope focus blocks. If I change that out, the optimal post height will again change. And lastly, I keep thinking of building a vertical version of the Bratcam, but again making it modular so as to simply move the core of the current rig between horizontal and vertical stands as the subject requires. To continue using my subject stage in that scenario, I should add one more axis of translational movement to my subject stage, which would increase its size in the vertical dimension. So I’ll hold off asking Don Wilson to cut my post until I have these issues settled. Meanwhile, the long vertical post isn’t hurting me much, and does provide a convenient place to tape a background (though the Noga stages I'm now using hold backgrounds very well).

Joaquim, thank you! As you likely know, it takes a long time to put a post like this together, and whenever someone says “thanks you,” it means a lot to me. As for the “high” engineering level, maybe so. I’m certainly not an engineer, and am working things out from common sense (often after a lot of puzzling and head scratching). I would emphasize that nothing on the Bratcam is done just for the sake of being fancy; everything is done to make macro photography easier or produce better quality images. I can point to a keenly-felt problem that any given feature of the Bratcam is in response to. Thanks again for your praise.

Cheers,

--Chris
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NA_Joey



Joined: 21 Dec 2012
Posts: 1

PostPosted: Mon Aug 05, 2013 11:49 am    Post subject: Re: Bratcam goes electric--StackShot controller incorporated Reply with quote

Chris who is the eBay manufacturer? I like to see if he would sell me the same setup. any chance you can give me info on your setup and a good way forward?

I am doing photography work with a lab on a bio-art project and a 3d plant cell printing.
i have repro Bogen Repro Stand http://www.adorama.com/BG1723.html?discontinued=t

I am also shooting with Fuji IS Pro i am shooting in the near UV range.
and IR

i need fine tuning micro stage. the lab i working with is a DYI hacker / real scientist and engineers. we do have a 3D printer and mechincal engineer helping me. and adrino programmer i just need to know the best way forward where to begin. since you done what i want to do. but i do want to photograph at a cellular level to.

Sincerely Joey

Admin edit (Rik): to eliminate superfluous quote
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