[Histonet] quick and dirty scale bar

[Ashwin Nair]

Hi,

You could try clicking the gridlines on a hemacytometer at 10X
magnification. You could then use Jruler (which I believe you can download
online) and determine the number of pixels that make up a certain length at
10X mag. Draw a line measuring the same number of pixels using photoshop on
to the images that you received from the collaborator. I hope this helps.

Regards
Ashwin



On 6/19/07, Philip Oshel <oshel1pe <@t> cmich.edu> wrote:
>
> 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
>
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-- 
Thank you.
Ashwin Nair