Oil Objectives

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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75RR
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Oil Objectives

#1 Post by 75RR » Sat Nov 22, 2014 11:03 am

Never used oil objectives. Looking for some tips. As in do's and don'ts.
Hoping to avoid a little frustration. ;)
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Oliver
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Re: Oil Objectives

#2 Post by Oliver » Sat Nov 22, 2014 11:14 am

Hi,

Do's:
remove oil after use to reduce dust accumulation, but do not overclean to avoid scratches (clean lightly only, using lens paper)
use oil as mounting medium (no cover glass), no water.
use synthetic oil, natural oil can become hard
make sure specimen is flat (eg bacteria sticking on slide)

Dont's
use lower magnification objectives after using oil immersion on the same specimen to prevent contamination of lower magnification objectives.
use oil on permanet slides (can not be cleaned).
do not expect too much. area of application is specific.
not use cover glass if specimen (bacteria) adhere to slide.

Oliver.
Image Oliver Kim - http://www.microbehunter.com - Microscopes: Olympus CH40 - Olympus CH-A - Breukhoven BMS student microscope - Euromex stereo - uSCOPE MXII

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75RR
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Re: Oil Objectives

#3 Post by 75RR » Sat Nov 22, 2014 12:15 pm

use oil as mounting medium (no cover glass), no water

That would seem to void the use of oil objectives on pond life.
How were these taken?

http://www.photomacrography.net/forum/v ... hp?t=25458

Surely the euglenas were not drowned in oil?
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Oliver
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Re: Oil Objectives

#4 Post by Oliver » Sat Nov 22, 2014 1:49 pm

if you want to use pond life, then you use water, of course, and then coverglass with oil. But this is difficult, because the pond life swims in and out of focus, and the depth of field of the 100x oil objective is quite low. You must make sure that the water film is sufficiently thin. I always used Oil is for static objects, such as heat fixed bacteria or other cells, which are dry, on a flat surface (slide) and which can be observed directly with a drop of oil on it. If you want to observe chromosomes in a cell, then oil is great. If you make a regular wet mount, then the full resolution of the oil objective can not be used, because of the different refractive indexes of oil, water and cover glass. But is is certainly worth a try.
There are also water immersion objectives available (objective inserted directly into a micro-aquarium), but I heard that these are quite expensive.
Oliver.
Image Oliver Kim - http://www.microbehunter.com - Microscopes: Olympus CH40 - Olympus CH-A - Breukhoven BMS student microscope - Euromex stereo - uSCOPE MXII

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75RR
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Re: Oil Objectives

#5 Post by 75RR » Sat Nov 22, 2014 2:07 pm

If you make a regular wet mount, then the full resolution of the oil objective can not be used, because of the different refractive indexes of oil, water and cover glass.
Interesting. Thanks.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Re: Oil Objectives

#6 Post by gekko » Mon Nov 24, 2014 12:15 am

If I may add to what Oliver has said: with microorganisms swimming in water, I use a piece of filter paper (I use pieces of drip coffee filters) placed at one edge of the cover glass to wick out the excess water and I press slightly on the cover glass in order to try to reduce the thickness of the water layer between the microorganisms and the cover glass as Oliver indicated above. Having said that, most of the time I get poor results from the 100x objective (perhaps because I don't have enough practice as well as for the reasons mentioned by Oliver).
Another point (and this may be subject to objections): I clean the glass surfaces that contact immersion oil using lens paper or clean microfiber cloth moistened with lighter fluid ("Zippo", Naphtha). And that includes cover glass (if it is to be reused), objective (I know I shouldn't, but I don't like it coated with oil :oops: ), and condenser (when I use it with oil).

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