MicrobeHunter.com Microscopy Forum

Hello to you all,

I was able to repair my Olympus BH2-RFC and try it for the first time last night !!

And this morning I tried the x100 oil but i noticed that it indeed behaves in a stranger manner : The person who gave me the microscope warned me : " it doesnt work ; its blurred" .

The next i was given the microscope I tried the x100 on my bresser trino and it worked just fine and incredibly.

ANd this morning it didnt.....until I added more oil and within a while it worked just fine.... AND i tried on another slide (after i wiped the oil off) and there again it was blurred and after a while it worked again !!

ALso i noticed this little hole on the lens :
and after to search on ebay for the same objective I could see its NOT A DEFECT : these x100 SP olympus have indeed a tiny hole in the middle.
Can anyone explain it to me??

Is it the reason it takes some seconds to fill up with oil to work properly ?? whats the optic concept ??

thanks

Chris

Your arrow is pointing to the front lens of the objective, which depending on the objective, for a 100X oil immersion will be about 1 mm across + or -. Where is this hole, that you see : in the glass of the front lens or is the front lens possibly missing?

Is this a NCG or definitely an oil immersion objective?-I only ask cos I’ve got an Olympus 100x epi short barrel that has that hole-it’s N/A .90 and is a dry epi objective-is it like a smooth scooped out hole? Like an inverted dome? Cos mine has that and may be a design element to get acceptable sharpness at low N/A. Dry epi 100x aren’t that odd as sometimes the specimen can’t have oil on it for various reasons.
My two cents.
Regards ross

I don't have an Olympus so cannot speak from experience but I wonder about a change in performance using Type B oil.
Greg

Whether it is a light or a heavy viscosity oil would be irrelevant except based on chrisimbee's experience, a heavier oil might fill in the depressional area in the objective a little easier. As Rossf pointed out, some objective front lenses are depressional with a distinct concave profile, a necessary design feature to confer wide field yet planar characteristics to their image. This feature is present on most modern dry high magnification objectives. Immersion objectives have a flat front surface.

I still wonder whether the front optic is missing entirely. Under certain conditions, oil could act as a replacement for the front lens and allow for an image formation. That could easily disappear with movement and might account for the variable nature of the image formation.
On the other hand, if it was a dry objective, a not very good image would form with oil immersion and would become better somewhat with a loss of oil contact. Oil clinging to the objective whether having an homogeneous contact or not would still foul the image a lot.

My twopenneth although I can add very little is that the type (e.g. A or B) of immersion oil, makes no difference on my BX50 with it's 100x oil objective. Personally I find that the thinner version (I have both) which is type-A, allows a lot of movement around a single slide during observation - basically the right amount of oil (here type A) allows me to navigate the entire section without problem. Perhaps surprisingly the biggest factor I've found when using oil is the nature of the applicator-bottle used...

I now use small plastic 'needle nozzle' bottles which allow me to control the placement and volume of oil application very closely. I'm struggling to imagine the front lens has a tiny hole by design, but who knows - maybe it does..... I suspect apo' is correct though in that it may be missing entirely, and the observed behaviour supprts this idea I think. What may help is a good image of the objective taken with a stereo 'scope, which would probably give enough info to firm-up an explanation. A good, stereo-'scope close-up would help a lot here.....

ALso i noticed this little hole on the lens :

There does seem to be something there. We need a better (close up) photograph - do you have a macro lens?

It looks to be a reflection from either the concave surface of the front lens, or the lens behind the missing front lens, if it is missing.

I'm not sure I totally understand the problem, but I think the issue is the complete oil contact between the objective and the specimen.

lorez

the photo is already a macro photo with my macro 60mm on D3200 NIkon.

anyway ; the "hole" isnt a reflection of light and is in fact a very tiny concave lens . I was able to find other objectives like this.

And it turned out that these objective can be quite tricky to use if an air bubble is caught.

The easiest way I found was to put the oil on the lens firts with a 000 water color paint brush and then oil on the slide.

But I received a more recent Zeiss neofluar x100 objective and it doesnt have this kind of frontal lens and the result is much better that this Olympus SP x100. (even though this zeiss is a phase objective)

this diagram from olympus show the small "hole" on the concave hemi spherical lens..