Natural Science Forum / Physics / Optics / June 2008

Hello Julian

As a fellow hobbyist I haven't come across the model mentioned, but a
web search seems to show it as a student compound microscope with
built in lamp, three or so objectives and variety of eyepiece options.

Bresser are a well known name of badged budget optics. Part of their
range did include the well regarded (for hobbyists) Russian Biolam
stands which I've used for thirty years. The Biolux doesn't look like
one of those but hopefully they have sourced some competent optics.

It's hard to tell at a distance where the problem may lay. Here's a
few suggestions.

If you have access to some prepared slides, like thin plant sections
or part insect mounts, try those first rather than pond life. From
lowest objective mag upwards, do the images look crisp and in focus
across most of field without any marked rainbow effects at edges of
subject. Decide especially which eyepiece is best. I suspect you'll
find a fixed mag eyepiece if supplied at 7-10x will be better than any
zoom optics supplied. You may get so-called empty magnification with
the zooms, ie magnifying the modest objectives beyond their
capabilities.

You could also try a piece of magazine paper with a colour photo on
under lowest powers in good light from above, this should show if
crisp image and fairly flat.

If the two lowest objectives perhaps a 5x and 10x, give crisp images
with a say a 10x optical eyepiece then you have 50x to 100x total mag
which will reveal a lot of pond life and detail in other microcope
subjects.

Depending on where Bresser sourced the microscope, the objectives on
the nosepiece above 10x may or may not be good enough for higher power
work or they may be limiting.

Ponds contain a wide variety of micro critters from water fleas over a
1mm to tiny bacteria and protozoa. It's best not to be too ambitious
with a budget student microscope. Start by examining the larger
organisms like waterfleas, cyclops, fly larvae and detail within. Look
for well vegetated ponds that may support a variety of life and
collect with a fine net. Or grab some weed put in a flat dish in water
and isolate critters you see by eye or hand lens. Muddy pools etc may
only support a limited amount of tinier life like bacteria and smaller
protozoa that needs more demanding optics and sample prep.

Preparation of the temporary mount needs care as well. Clean
microscope slides, cover slips and a few droppers and needles are
required. The water film should be as thin as possible ie a fraction
of a mm with cover slip on. A little vaseline at corners of slip can
create some thickness for avoiding crushing specimens. Avoid putting
thicker bit of plant under scope. If any fine algae present tease some
filaments under a slip in water, they should give flat subjects and
crisp outlines with some cell detail. You should see some larger
protozoa browsing the algae if a good pond and other critters.

If the microscope has a substage condenser with iris or stops that
needs to be setup properly for good images. The manual should describe
how to do this. A good book like Nachtigall's 'Exploring with the
microscope' is worthwhile. Check www.abe.com or www.alibris.com for
any lower priced used copies as out of print.

Note that this is a more professional orientated forum where scope
requirements are much more demanding. As long as the optics are
reasonably competent you can get a lot of fun out of these sort of
stands. I have for thirty years and only recently moved up to bigger
name kit.

You may wish to try a Yahoo forum like http://tech.groups.yahoo.com/group/Microscope/
where many hobbyists with kit in all sorts of price ranges can advise.

Websites like www.micscape.org also have articles on getting the most
out of hobbyist type microscopes.

Hope this helps and have fun.
regards
David

Did you just place a drop of water on the slide, and then view it?
You need a coverglass on top of the drop, to"flatten" the viewing
field, thereby keeping moving critters in the depth of focus--just a
possibility?