Using focusing rail manually with X4 objectives?

[Adalbert]

Hello Lothar,

Yes, I know this problem

I have already tested the step-size of 0,33 μm of my rail for small magnifications based on THK KR2001A:
viewtopic.php?f=25&t=39895&hilit=5130&start=45

But I could imagine that the focus block of Oly CH should be better.

Best, ADi

[rjlittlefield]

Oly is a clear winner.

The reason I specifically mentioned Olympus CH to the OP is that they are cheap, available, and would work well for his needs.

It happens that I also use a CHT in my own setup. I have spent some time to characterize its behavior. You can see that analysis at viewtopic.php?t=27549 .

For your needs there are other models of focus blocks that would be even better. I am thinking specifically of the Nikon Labophot which has roller bearings (versus the Oly's ball bearings) and is geared more finely at 100 microns per turn. But see the discussion at viewtopic.php?t=27917 to avoid damage in working with that model.

should I put a gearbox 10:1 or a belt pulley in between
or solve this issue with the micro-steps of the stepper motor?

My setup uses a belt drive, which I like because it preserves zero backlash clear out to the stepper motor.

The gearboxes that I know would all have backlash when driving the light load of a microscope focus block.

Microsteps are useful, but depending on the motor design and the drive circults, there is likely to be some nonlinearity. My experience is with StackShot controllers and motors provided by them. The significant nonlinearity due to microstepping is discussed at the link provided above (and in several other of my threads).

--Rik

[Adalbert]

Hello Rik,
Thanks a lot for your tips!
So, I will start with Oly CH because it is relatively cheap.
As far as I can get one, I will try to mount the pulley with as big gear ratio as possible.
The next problem is mounting the DCR-150 to the Oly CH.
Best, ADi

[shrek]

Hello
Where canI found all" NA 0.1, the nominal DOF is 0.055 mm."and other ?
Thank
JeanPierre

[ray_parkhurst]

Hello
Where canI found all" NA 0.1, the nominal DOF is 0.055 mm."and other ?
Thank
JeanPierre

There is a great summary page of this info on the Zerene site, here:

https://zerenesystems.com/cms/stacker/d ... romicrodof

Look at table 2-C for DOF versus NA. Other tables give DOF vs other parameters.

[Lou Jost]

If you use a focus block, the WeMacro MicroMate can automate the stacking very easily with a relatively small investiment. You might think about that. I would have lost my mind if I had to do my stacks manually. It's bad enough that I have to guide my astrophotography by hand.

[shrek]

Hello
Where canI found all" NA 0.1, the nominal DOF is 0.055 mm."and other ?
Thank
JeanPierre

There is a great summary page of this info on the Zerene site, here:

https://zerenesystems.com/cms/stacker/d ... romicrodof

Look at table 2-C for DOF versus NA. Other tables give DOF vs other parameters.

Thank very much Ray
jean-pierre

[Barrelcactusaddict]

Hi, I am very late to this, and I did not want to start a new topic (didn't know if that would be appropriate, anyway). I'm unsure about the usefulness of a manual focus rail in a vertical setup, and I was hoping someone could help me with that.

I have a makeshift copy stand made from a wood board, floor flange mount, and a 1/2" NPT steel pipe (26" long, I think). For some time I've been planning to use a 035 Super Clamp, 208 Hex Mounting Plate, low profile ball head, and a SWEBO LS-001 focus rail. I have the super clamp and mounting plate, but I haven't yet gotten the ball head or the SWEBO (I've been conflicted on whether or not to invest in a Cognisys Stackshot; more on that below). My questions are:

Can this rail be used vertically up to 4x or possibly higher magnification?

and

Does anyone here have experience with this particular rail, or could recommend a better manual focus rail for vertical use?

It has a precision of .01mm, as the rotating knob is divided into 100 segments, and the rail travels 1mm per full rotation; it appears more well-built than almost any other manual rail I've looked at. I'm really tempted to get it, but I would like to know if it would work all right at 4x to maybe 10x magnification.

I've also been looking at the Cognisys Stackshot system, and I would love to invest in it more than the SWEBO, but I'm incredibly intimidated by it: mainly, I'm concerned about the "step level" measurement I'd have to set for each image shot interval, and it'd be based on the depth of field of the subject, as I understand it. If the Stackshot panel's software could somehow automatically set this level after I set the "before" and "after" positions on the control panel, and/or after I've selected the number of shots I want taken in a full set, I would have no issue; however, I cannot figure out if this is a feature that is present in the system. I read the DoF article Rik had expertly presented on his Zerene Stacker website (link to it from the Cognisys website), but solely due to the worthless capabilities of my mind, I cannot comprehend it, and I wish I could understand it so this hang-up of mine wouldn't be an issue; I wish I were more self-reliant. Just looking at that article as one example, I simply cannot imagine how intelligent Rik and so many others here are; I shouldn't compare myself, but I find it difficult to not dwell on my own inadequacy. I think I could learn how to use the Stackshot system eventually, but I wish I knew if the "step level" could be automatically determined.

Thank you.

-Kaegen

[JKT]

StackShot control unit has many modes. In one you choose start and stop positions and the distance between steps. In another you choose the start and stop positions and the number of steps. Zerene control for StackShot has only the first mode, but that should not be much of a problem as the formulas between them are very simple.

Let's say start position is 'A' and end position is 'B' and your dof is 'DoF'. In addition to those three you need to decide a reduction factor for the dof value when choosing the step size. Theoretically 100% might work. I use something like 66%. Some here have mentioned using 33%. You can start with relatively large number, and reduce it if you find any sharpness banding. Let's call that factor k. The step size you enter in StackShot is 'C' = 'k' x 'DoF'. The number of steps is then 'N' = ('B' - 'A') / 'C' ... or 'N' = ('B' - 'A') / 'C' + 1 depending on how 'N' is defined in StackShot, but usually that distinction is not so important. Let's assume the latter to be sure. If you know 'A', 'B' and 'N' you can likewise calculate 'C' = ('B' - 'A') / ('N' - 1) or 'C' = ('B' - 'A') / 'N' with the latter being the safe formula in this case.

The problem with the last two formulas is that they require knowing the number of steps. If you don't know your dof and/or haven't decided on the ratio between step size and dof, where does the number of steps come from?

[rjlittlefield]

SWEBO LS-001 focus rail
...
It has a precision of .01mm, as the rotating knob is divided into 100 segments, and the rail travels 1mm per full rotation; it appears more well-built than almost any other manual rail I've looked at. I'm really tempted to get it, but I would like to know if it would work all right at 4x to maybe 10x magnification.

I do not have any hands-on experience with that rail. From working with similar rails, I expect this rail will work fine at 4X and will be usable though somewhat fiddly at 10X.

The issue at 10X is that when using a 10X microscope objective, nominal DOF is a little less than 0.01 mm. As a result, you will need to turn the dial in steps that are a smaller than one full tick mark. For me this would be doable, but it would be a two-handed operation that would require some care and practice. A lot depends on how smoothly the rail moves, which I do not know.

DoF article ... I cannot comprehend it ... I wish I knew if the "step level" could be automatically determined.

In Zerene Stacker there is a DOF calculator that avoids the need to do any math yourself.

If you know the magnification, say because you're using a Laowa lens and magnifications are marked on the barrel, then you can just plug in the magnification and f-stop, and the step size will be automatically calculated for you.

For example:

If you do not know the magnification, say because you're using a reversed enlarger lens on bellows, then you can use a ruler to measure the size of the subject field, plug in that number plus your sensor size and f-stop, and again the step size will be automatically calculated:

--Rik

[Barrelcactusaddict]

Thank you so much Rik and JKT.

Sadly I cannot at all understand the equations that were given, but I do greatly appreciate the effort to provide them. That is good news that there is a DoF calculator available; even more so that I'd just need to know the width of the subject (would that be the width of say, just the insect inclusion in amber I'm trying to focus on, or the whole field of view?), as I truly do not understand how to calculate DoF manually.

The basic Stackshot system looks very difficult to use and understand (at least for me), and even after watching the tutorials and reading the only PDF manual I could find (for the X3 rail), I still am very unsure; maybe I'll try to use the SWEBO first, and if it doesn't perform well, hopefully I can return it and get the Stackshot. I wish there were some way to get in-person support for using the Stackshot.

I wish there was an over-engineered manual focus rail with high precision like the SWEBO; I've seen some like the Oben that have two rails, but I've not been able to find anyone who has successfully used this rail vertically. I wish manual focus rails were more widely used vertically, or that there was one specifically designed to work vertically. Hopefully the SWEBO has backlash control.

[soldevilla]

Does anyone here have experience with this particular rail, or could recommend a better manual focus rail for vertical use?

Years ago I published here a DIY stacking rail made of wood and drawer guides, with a knob divided into 100 parts, so the theoretical resolution was 0.01mm. The idea was to help friends start taking their first photos free of charge.

A year ago I needed to double my equipment and before buying a new StackShot I asked a friend to build me a stepper motor controller, and I fitted a stepping motor to the M6x1 rod.

Surprisingly for me, that simple mechanic allows me to photograph regularly at x20, and once when I have needed to reach x40 it has done so with dignity. A simple mechanic works very well if it is moved with a motor, without the need to touch it with your fingers.

[Barrelcactusaddict]

Does anyone here have experience with this particular rail, or could recommend a better manual focus rail for vertical use?

Years ago I published here a DIY stacking rail made of wood and drawer guides, with a knob divided into 100 parts, so the theoretical resolution was 0.01mm. The idea was to help friends start taking their first photos free of charge.

A year ago I needed to double my equipment and before buying a new StackShot I asked a friend to build me a stepper motor controller, and I fitted a stepping motor to the M6x1 rod.

Surprisingly for me, that simple mechanic allows me to photograph regularly at x20, and once when I have needed to reach x40 it has done so with dignity. A simple mechanic works very well if it is moved with a motor, without the need to touch it with your fingers.

That sounds interesting! I wish I could do that, but I live in a tiny apartment in the city and have no access to power tools; I wish I were mechanically-inclined and knew how to build such a manual rail. Sadly, in addition to nearly everything it seems, I have no idea how stepper motors or electrical circuits work; back in High School (Chemistry, I think), I was never even able to create a simple circuit with a transistor.

Do you know of any manual focus rails readily-available on the market that are over-engineered, or know anyone who could make one? I was thinking at one point of getting a microscope stage of some kind, but the one I was looking at only has a .56mm accuracy per turn of the fine focus knob; not to mention it costs over $700 with only a 1-year warranty.
https://bolioptics.com/microscope-table ... gL1mvD_BwE

[rjlittlefield]

(would that be the width of say, just the insect inclusion in amber I'm trying to focus on, or the whole field of view?)

The whole field of view.

--Rik

[lothman]

Do you know of any manual focus rails readily-available on the market that are over-engineered, or know anyone who could make one? I was thinking at one point of getting a microscope stage of some kind, but the one I was looking at only has a .56mm accuracy per turn of the fine focus knob; not to mention it costs over $700 with only a 1-year warranty.
https://bolioptics.com/microscope-table ... gL1mvD_BwE

those with fine and coarse drive look OK but I don't know if whether they ARE OK
https://www.aliexpress.com/item/1005001 ... 75f3GOVo7B

https://www.aliexpress.com/item/4000804 ... de_order:9

Edit, just found this:
https://www.aliexpress.com/item/1005001 ... 2546%22%7D