John Cohen wrote, regarding Flavio Minelli's comments:
>Re:Flavio Minelli's observation:
>>Ehmm,
>>if we're talking about linear magnification that would be about 24X to a
>>full frame image...
>>It's 24/1 mm -> 24X.
>>It would take you a microscope to get 600X.
>>Flavio
>Flavio,
>I think he actually made a microscope. To fill a microscope field with a 1
x
>1 mm square, I use a 40x objective and a 12.5x ocular. I would guess the
>area of my retina is about the area of a 35mm frame, so it should be
roughly
>comparable.
>And--scusi--I think it's more relevant to think of the area magnification,
>especially since if you're paying for the medium, that's what you pay for.
>:-)
>Ciao,
>JJ
John,
Flavio's actually correct on this one. Optics suppliers will specify
magnifications for visual and video microscopy systems in terms of linear
dimensions, rather than area. Nonetheless, I'd certainly agree that Bill
Robb's optics setup qualifies as a microscope, even though I'd rate its
magnification at 24X, rather than 575X.
Sounds like you've got quite a microscope in your lab, given the field of
view you describe. Field of view can be calculated by dividing the ocular
field stop diameter by the objective power. However, the standard 23 mm
oculars typically have field stops of around 10 mm diameter. Thus, you'd
expect a field of view on the order of only about 0.25 mm for a 40X
objective. If you can see a field of view 1mm square, you've got one hell
of a nice piece of equipment!! I'm jealous.... Last time I looked through
a 500X microscope, I think I could only see a field of view more on the
order of a tenth of a millimeter. (Maybe it's my aging eyeballs, not the
scope?)
This thread reminds me of a interesting picture someone with the right
resources might wish to try for a future extreme macro shot. I always
thought a shot of an intact, in situ living human retina would be
technically challenging, not to mention extremely cool. Someone with access
to injectable fluorescein dye and proper lighting (like an opthalmologist)
could probably get quite a nice shot. Don't know if it's possible with the
kind of equipment a typical photo enthusiast might own. Hmmm....
Have a good weekend,
Bill Peifer
Rochester, NY
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