Re: Photomicography with 2.5x objective - uniform illumination?

On Jul 16, 12:18 pm, selwyn.stle...@xxxxxxxxx wrote:
I manage reasonable photos using medium and high power objectives but
have been having difficulty with a Zeiss plan 2.5 x objective.
Visually, the image is stunning and evenly illuminated. However,
photography is another matter: there is severe vignetting and obvious
non-uniform illumination from a central bright spot outwards.

I am using a Zeiss standard 16 with inko condenser. I have removed the
top condenser (1.4 NA) lens which I am led to believe leaves a circa
0.32 NA condenser lens. I set up for Kohler as best the system will
allow. The sub-condenser switchable lens is left in place.

Do I need a condenser of lower aperture?

Do I need a diffusing filter?

Or what?

I should be grateful for suggestions.

Selwyn


Hi Selwyn,

Replacing the prism in the base with a mirror and removing the
condenser gives you a lot more freedom with lighting at low
magnification. I do just OK with 2.5x PlanPol on my WL with an Abby
condenser. Thing go to pot with a Nikon 1.2x Plan or .5x Unitron I use
on now and then. They both need a different set up all together as
things above the objective get in the way too.

Using light from a north window in a mirror will give the most even
light you can find. A larger light source and camera lenses for a
seconds can get get even lighting as can an electronic flash bounced
off a white card then into the mirror.

When I change the prism out with a mirror I have to re align the light
when I put it back or use the prism that just drops in and it is
always and a problem with alignment of lighting. If I was doing much
photography with the 2.5x with out a condenser once I found a mirror I
would buy one of the striped GFL stands from wreckers on eBay that go
begging for $5.00 or $10.00 bucks to put a mirror on and go from
there.

If you were using other objectives and lens as I am for macro
photography. It might be interesting to get one with a condenser
carrier and put a stage down on the condenser carrier as well so you
can get more range between the front of the lens and the subject.

Best Reguards
Gordon

Gordon Couger
www.science-info.net (Microscope Documentation)
www.couger.com/microscope/links/gclinks.html (Links)

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