[Histonet] quick and dirty scale bar

[Philip Oshel]

Caroline,

No, you can't use the 40X scale bar, and yes, it's not that simple. 
Even if the image with the 40X scale bar were taken on the same 
microscope with the same camera and the same settings, it wouldn't be 
in an exact 1:4 relation with the 10X objective.
Further, you don't know what if any zoom your collaborator used. If 
the image was taken with a standard digital camera (e.g., a Nikon 
Coolpix) through an eyepiece adapter, there is often vignetting 
around the edges. This prompts people to use the zoom function to 
eliminate this. Which of course means the image isn't "10X".
Which it may not have been anyway, depending on the lens in the 
eyepiece adapter.
The only way to get images with known scale bars is to take a 
micrograph of a stage micrometer **without changing the camera**, 
especially the zoom, for each objective used, *at the time the 
micrographs are taken*. Otherwise it is nearly impossible to 
replicate the zoom used. Calculations/measurements based on field of 
view aren't trustworthy for the same reasons -- you don't know the 
true field of view.
If no zoom was used, then it may be possible to take a photo of a 
stage micrometer with the same objective, etc., and be OK. But I 
wouldn't trust it.

Given what you have, there are really only 2 courses: first, is there 
a structure in the micrograph you have that has a well know  size? 
RBCs don't count, they change size by a micrometer or more depending 
on how they're treated (and yes, still look like nice, biconcave 
discs). If there is, you can calculate magnification and therefore a 
scale bar from it.
But likely not. The other recourse is to have you collaborator take 
the image again, and this time also take an image of a stage 
micrometer.
Anything else is just guessing.

Phil

>Hey Guys,
>
>I'm trying to finish up some figures for a paper.  One collaborator 
>has given me 10X images that appear to have been taken from a 
>standard digital camera.  Can anyone suggest a quick and easy way to 
>add a scale bar?  Unfortunately the journal requires it and I just 
>don't have it.  I have a scale bar for a 40X picture from a 
>different microscope/experiment, any chance that I can use this? 
>I'm guessing it is not as simple as my 40X scale bar being 1/4 of 
>the 10X?
>
>Sorry, but I am clueless about this...  any suggestions would be appreciated.
>
>Thanks,
>
>Caroline
>
>
>
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-- 
Philip Oshel
Microscopy Facility Supervisor
Biology Department
024C Brooks Hall
Central Michigan University
Mt. Pleasant, MI 48859