Calibration problems Moticam

[NeilB1]

I have a moticam 1 1280x720 Pix camera and a swift 380T microscope. I have calibrated the camera with the 4x 10x and 40x objectives successfully using the supplied motic calibration slide with dots of 1.5 mm, 0.6mm and 0.15 mm diameter. When I came to my final objective 100x I found that appropriate dot on the slide 0.07mm was just too big and the edges were cut off on the screen so I was not able to successfully calibrate. Am I doing something wrong? I’m using a MacBook Pro and everything seems to be working well except this.

[MichaelG.]

If I recall correctly: The Motic slide also has a linear scale with 10micron divisions
... Just use that across a diameter of the field.

MichaelG.

[jkexplorer]

Does your calibration slide have dots only? The only calibration slide I have has a 1mm length of small vertical bars. Using 4x, 10x, and 40x was no problem, but I have not calibrated the 100x yet, since I would have to set this up with oil immersion. Each time I switch to a higher magnification, I would have to select smaller distances. At 4x, I could see the entire 1mm length (1000um), but at 10x, I could only easily see half that (500um). At 40x, I could only see 100um, so depending on how many divisions you have, and what kind of image is on the slide, it might be tricky to calibrate the 100x.

[NeilB1]

Many thanks for your replies. I will try the central cross with the tiny divisions. I’ll look into how to do that with the software. But I’ve thought of a work around. I can set the calibration for the 10x magnification but use the 100x objective and then measure the item. The answer given by the software is then 10x too big but I can simply divide. Not sure if this introduces additional errors though.

[mrsonchus]

I'd just image something with the 40x - add measurement line or scale-bar, then use the line (which like the scale-bar will be of a known length) or scale-bar to calibrate the 100x.
This will certainly give you high accuracy - more than enough for your context I'm certain.

[MichaelG.]

This tutorial video, by Motic Europe, may help [although it demonstrates the MS Windows version]

https://youtu.be/Hoev1BO_ZSg

It would appear that your Swift has a smaller field of view than Motic expects
... making the 70 micron dot unusable; but you should have no problem with the linear scale.

MichaelG.

[NeilB1]

There are two pieces of software that come with the camera which are interlinked. The camera operating software is calibrated by the dots. The other software is for manipulating an image that has been taken by the camera. This also has a calibration wizard which allows the use of the central calibration cross on the slide. I used this to calibrate the 100x objective. The data was then automatically sent to the camera operating software. So all good.